|Return Tillage Handbook|
Chapter 2 - Conservation Tillage Systems and Equipment No.16b (pdf format, 3mb)
Returning CRP Land to Crop Production
Summary of 1994-1996 Research Trials in Washington State
Northwest Columbia Plateau Wind Erosion - Air Quality Project
AUTHORS: Roger Veseth, WSU/UI Conservation Tillage Specialist, Moscow, ID; Baird Miller, WSU Dryland Cropping Systems Agronomist, Pullman; Tim Fiez, WSU Soil Fertility Specialist, Pullman; Tim Walters, WSU Graduate Student, Pullman; Harry Schafer, WSU Research Technician, Ritzville.
Table of Contents
Section 15. Weed Management Prior to CRP Contract Expiration
Section 16. Choice of Spring Planting Versus Fall Planning
Project Leaders: Roger Veseth, WSU/UI Conservation Tillage Specialist, Moscow, Baird Miller, WSU Agronomist, Pullman, and Tim Fiez, WSU Soil Fertility Specialist, Pullman; with support from Tim Walters, WSU Crop Science Graduate Student, Pullman, and Harry Schafer, WSU Research Technician, Ritzville.
Growers - This large-scale on-farm test project has relied heavily on the active participation of growers who helped plan the field trials, provided the land and equipment, and conducted the field operations. Growers involved in CRP take-out trials in 1994 and 1995 included: George Young and David Carlton in Columbia County, George O'Neal and Remie DeRuwe in Franklin County, Lenard Roth in Adams County, Clay Barr in Garfield County, and Jim Richardson and Darrell Roberts in Lincoln County. Growers involved in CRP take-out trials in 1996 included Dale and Gary Galbreath, and Ron Jirava in Adams County, Andy and John Rustemeyer in Lincoln County, and Tony Viebrock and Mike Grande in Douglas County.
Local Trial Establishment and Data Collection - Roland Schirman, WSU Extension Agent, Dayton; Bill Schillinger, WSU Agronomist, WSU Dryland Research Unit, Lind; Dean Brown, Monsanto Sales Representative, Spokane; Mike Sporcic, NRCS Area Agronomist, Othello; Mark Bareither, NRCS District Conservationist, Waterville; Jeff Harlow, NRCS District Conservationist, and Jim Schawley, NRCS Soil Conservation Technician, Pomeroy; David Bragg, WSU Extension Agent, Pomeroy; David Lundgren, Lincoln County Conservation District Manager, Davenport
Herbicide Kill of CRP Grass - Sheldon Blank, Monsanto Research Agronomist, Pasco; Steve Reinertsen, The McGregor Co. Research Agronomist, Colfax
Soil Quality Changes - Ann Kennedy, USDA-ARS Soil Microbiologist, Pullman; Virginia Gewin, WSU Graduate Research Assistant
Root Disease Sample Analysis and Interpretation - R. James Cook, USDA-ARS Plant Pathologist; Monica Mezzalama, Visiting Plant Pathologist working with Dr. Cook
Soil Surface Characterization for Erosion Potential - Bill Pan, WSU Soil Scientist, Pullman; Rhonda Bafus, WSU Soils Research Technician, Pullman
- Kathleen Painter, WSU Agricultural Economist, Pullman
The Pacific Northwest has over 2.5 million acres of cropland in the Conservation Reserve Program (CRP). In Washington State there is over 1.045 million acres of CRP land. This represents nearly 14% of the 7.6 million acres in a 20 county area of eastern Washington. About 80% of the Northwest CRP contracts are scheduled to expire in 1997, representing over 800,00 acres in Washington State alone.
A majority of the CRP land in Washington and the Northwest is in the low rainfall, winter wheatsummer fallow regions. These areas typically receive from 7 to 14 inches annual precipitation and are susceptible to wind erosion, as well as water erosion. Serious soil erosion problems could result if intensive tillage and residue removal practices are used to return CRP land to crop production.
A Washington State research project was initiated in 1994 to evaluate management strategies for returning CRP land to crop production. It was designed as an umbrella project for a comprehensive, "grass roots" effort to evaluate prospective, locallyidentified management options for specific agronomic zones of the state. The research focus was on the low-rainfall, crop-fallow region where much of the CRP land was located. Crested wheatgrass is the predominant CRP grass in this area.
Washington State University Cooperative Extension was responsible for coordinating the statewide CRP take-out research project, as authorized by the Washington Farm Service Agency (FSA). As indicated earlier in the CRP take-research team description, the project relied on active involvement of growers, extension specialists and agents, researchers, and personnel from agricultural support agencies and industry.
The project goal was to identify management strategies that optimize agronomic performance and profitability of the first crops following CRP take-out, while providing effective soil erosion control and preserving soil improvements gained during CRP. There were two primary research thrusts in this statewide project: 1) evaluate management strategies for returning CRP land to winter wheat production following summer fallow; and 2) evaluate management strategies for returning CRP land to spring crop production.
Criteria evaluated to determine the relative success of different CRP take-out systems included: soil water storage efficiency; crop establishment and development; soil erosion potential; pest incidence; crop yield and quality; and economics.
project was funded in part by two grant programs from the USDA Cooperative
States Research, Extension and Education Service (CSREES) through WSU:
STEEP II (Solutions To Environmental and Economic Problems) and the Columbia
Plateau Wind Erosion/Air Quality Project.
Before field experiments were initiated, a series of local planning meetings were conducted in six counties with high CRP acreage. Each meeting included four to six growers, county extension agents, researchers and personnel from USDANRCS, conservation districts and the agricultural service industry. This group identified prospective tillage and residue management systems to be studied in the CRP take-out field research trials. The tillage systems in most 1994 and 1995 trials relied primarily on commonly available tillage equipment within the different cropping regions. Direct seeding was also evaluated in one 1995 field trial in Columbia County and in three 1996 field trials in Adams and Douglas Counties.
This field research project used the large-scale, replicated, on-farm testing approach with farmscale equipment operated by the growers. This approach increases grower confidence in the research results and facilitates rapid grower adaptation of research results. Treatment area for each plot were generally 30 to 50 feet wide, depending on the implements used, and 800 to 1,000 feet long. Each treatment was replicated four times. Most trials included 4 to 6 management systems (treatments) and were 12 to 30 acres.
The project leaders and cooperators worked with growers to design and lay out the field experiments, and collecting the data. The growers performed all of the crop production operations. Yield measurements are made using the growers combine and portable truck scales or weigh wagons.
Data collection included initial grass biomass, soil water content in the spring and at fall planting, soil fertility analysis for fertilizer application, surface residue cover and surface roughness for evaluating soil erosion potential, pest incidence, plant stands, and crop yield. Comparative crop enterprise budgets were generated to evaluate the profitability of the different systems. Some of the trials were followed through the next crop rotation to evaluate the longer term effects of take-out treatments on soil erosion potential, pest incidence and soil quality.
with other university and industry researchers, experiments were also
conducted to evaluate alternative spring crop choices, fertility management
in CRP take-out, nonselective herbicide rates and timings for killing
CRP grass before direct seeding, root disease interactions, and changes
in soil quality under different take-out systems.
Explanation of Surface Residue Cover and Roughness Data
To give the reader a better understanding of surface residue cover and surface roughness data presented in this report, the following is a brief explanation of their relative effectiveness for reducing wind erosion potential in low-rainfall, crop-fallow regions. Measurements of surface residue cover and surface roughness were made on CRP take-out field trials to evaluate the comparative effect of different take-out systems on wind erosion potential. In addition to reducing wind erosion, surface residue cover and roughness are also very important in reducing water erosion potential.
Surface residue cover was measured as percent surface cover using the line-point method, the standard residue measurement method of the USDA-NRCS. Surface roughness was estimated using reference roughness photos developed by the USDA-ARS in the Northwest for use by NRCS staff in the region. The surface roughness, called "random roughness" refers to surface soil cloddiness and is measured in inches as the average variance (standard deviation) from the mean height of soil clods above the soil surface. For comparison, a random roughness of less than 0.25 inches is a smooth field surface that could be highly susceptible to wind erosion, while a random roughness of 1.0 inch is about the roughest field surface possible after seeding without significantly reducing agronomic performance. Random roughness does not include the furrow and ridge patterns created by implements in field operations. That is a separate roughness measurement called "oriented roughness" which was not collected in these field trials, but generally enhances the erosion protection of random roughness.
Surface residue cover and surface roughness are important components in predictions of wind erosion potential. Figures 1 and 2 illustrate the effectiveness of different combinations of surface residue cover and surface roughness for controlling wind erosion. They were developed from actual soil erosion measurements using a large portable wind tunnel in extensive field evaluations across the crop-fallow regions of eastern Washington from 1993-1996. The research was conducted by ARS agricultural engineer Keith Saxton, with ARS research associates Lance Horning and Larry Stettler, as part of the Columbia Plateau Wind Erosion/Air Quality Project.
Figures 1and 2 shows wind erosion potential as a "Soil Loss Ratio". The soil loss ratio is calculated from the field-measured soil erosion during the wind tunnel tests under specific surface residue and roughness levels, divided by the soil loss measured from an adjacent "standard" field condition site with no surface residue and a smooth surface with soil clods removed. For example, the soil loss ratio of 1.0 would be the highest wind erosion potential on a site with no effective protection from surface residue or roughness. In contrast, a soil loss ratio of zero would mean no wind erosion potential because of effective protection by surface residue and/or surface roughness.
One way to help visualize the wind erosion potential from the two figures is to view the soil loss ratio under different levels of surface residue and roughness as a percentage of the erosion potential without residue or roughness protection. The following are two examples to help illustrate the effectiveness of surface residue cover and surface roughness for wind erosion control.
Example from Figure 1 on Surface Residue Cover Effectiveness -- Example 1 illustrates how a moderate level of surface cover of 25%, under a low random roughness of 0.3 inches, would have a soil loss ratio of about 0.25, or a 75% reduction in erosion potential compared to that under a field with no surface residue or roughness. Erosion potential could be reduced further to about 85% (soil loss ratio of 0.15) with a moderate roughness of 0.6 inches at the same 25% surface residue cover.
from Figure 2 on Surface Roughness Effectiveness -- Example
2 illustrates how a moderate surface random roughness of 0.6 inches, under
a low surface residue conditions of 5% cover, could reduce erosion potential
by about 65% (soil loss ratio of 0.35) compared to a smooth soil surface.
If surface residue cover was increased to 30% with the same 0.6 inch random
roughness, the soil erosion potential could be reduced further to about
87% (soil loss ratio of about 0.13). As surface residue cover increases,
random roughness becomes less important for erosion control. Surface roughness
is less effective than surface residue in reducing wind erosion in the
low-rainfall, crop-fallow regions, but can still be an important component
of a wind erosion management strategy.
Overview of Field Trials
Ten large-scale on-farm trials were conducted, primarily in crested wheatgrass CRP fields. Three trials in Adams, Franklin, and Lincoln Counties evaluated different tillage and residue management systems for CRP takeout with summer fallow and were planted to winter wheat in 1995. Spring take-out trials for spring wheat were completed in Columbia County in 1994 and 1995, along with a small plot satellite study on spring crop choice under high and low residue systems in 1995. A direct seeding trial with spring barley was also conducted in Columbia County in 1995. Four small plot research trials on non-selective herbicide use for killing CRP grass were conducted in Franklin and Adams Counties in 1994-95 by Monsanto. Another study on nonselective herbicide use in CRP take-out was conducted by the McGregor Company in 1995, adjacent to a large scale trial in Columbia County.
Three trials on
spring take-out with hard red spring wheat were conducted in 1996. Each
trial compared 3-5 direct seeding systems with a tillage comparison. Two
were located near Ritzville and one near Waterville. A fourth spring 1996
take-out trial evaluated several tillage and residue management systems
for spring barley in tall wheatgrass CRP near Sprague.
trials were initiated in fall 1994 in Adams, Franklin, and Lincoln Counties
to evaluate fall versus spring CRP take-out and management practices for
summer fallow and winter wheat planting.
The trial site was north of Lind on the Lenard Roth farm in a 10-inch annual rainfall zone. The field had been in crested wheatgrass for 8 years. Ritzville and Willis silt loams were the dominant soil series. Grass residue averaged about 4,700 lb/A. Primary tillage and residue management treatments are listed in Table 1.
Table 1. Primary tillage and residue treatments in a fall versus spring CRP take-out trial with summer fallow - winter wheat in Adams County - Lenard Roth, grower cooperator.
Fall tillage and residue management treatments were established in early October and spring treatments on March 28. After the initial tillage operations, all treatments were managed as one field. Subsequent field operations included the following implements: skewtreader, rotary hoe, shank fertilizer injector, rodweeding three times and seeding to Eltan soft white winter wheat August 24 at 35 lb/A with a John Deere HZ deep furrow drill.
Soil test results in April of the fallow season showed a total of 94 lb N/A -- 10 lb/A ammonium-N in the top foot and 61 lb/A nitrate nitrogen to 6 feet, plus an estimated N mineralization of 23 lb/A from the 1.1 % soil organic matter. Based on the soil test results, a 40 bu/A yield goal and nitrogen requirement of 2.7 lb N/bu, a N fertilizer application of 40 lb N/A was made in June with a conventional shank fertilizer applicator. The fertilizer and applicator were provided by the Lind Grange Supply.
Results from the trial through winter wheat establishment in 1995 are shown in Table 2. One of the most striking difference between treatments was in plant-available soil water to a 6-foot depth in March 1995 before spring tillage operations. Fall discing reduced overwinter water storage by about 2 inches compared the undisturbed grass cover in spring take-out treatments. The fall harrow-fall chiseling treatment caused a smaller but still significant water loss, whereas fall flailing did not.
The loss of soil water in the two fall tillage treatments was still evident at winter wheat seeding time in September, although the differences were not as great as in the spring, ranging from 1.8 to 3.3 inches available water to 6 feet. All of the treatments showed substantial water loss during the summer fallow period. A total of 11.2 inches of precipitation occurred from the late August planting through the following June. However, most precipitation amounts were less than 0.5 inches so effective precipitation was much lower. Based on an estimation of 4 inches of water needed for crop development to the reproductive stage and 5 bu/A yield of winter wheat per inch of additional water, yield potential was about 47 to 54 bu/A.
Although differences in surface residue levels between treatments after seeding were not always significant, fall discing and fall harrowing/chiseling resulted in the lowest residue levels, about 12 percent cover. The fall combine flail-spring sweep resulted in the highest residue level of 15 percent. However, the surface residue level on all the treatments is relatively low, indicating that each of the primary tillage and residue management combinations and/or the following secondary tillage operations should have been less intensive.
Surface random roughness after seeding was similar in all the treatments. The secondary tillage operations with the skewtreader and rotary hoe significantly reduced soil cloddiness, consequently eliminated earlier differences in soil roughness between treatments.
The lower soil
water storage in the fall disc treatment may have caused the slightly
lower plant stand, about 5.4 plants/square foot compared to 6.0 to 6.6
plants/square foot in the other treatments.
Table 2. Data through wheat establishment on the 1994-96 fall versus spring CRP take-out with summer fallow - soft white winter wheat in Adams County - Lenard Roth, grower cooperator.
Table 3. Harvest data on the 1994-96 fall versus spring CRP take-out with summer fallow - soft white winter wheat in Adams County - Lenard Roth, grower cooperator.
Harvest data and
economics are shown in Table 3. The fall disc treatment yield was significantly
lower than the other treatments. The yield reduction was probably due
the lower water storage over winter and reduced plant population in fall
1995. Yield with the 2X fall harrow - fall chisel was also lower than
spring tillage treatments. The highest yielding treatment was the fall
combine - spring sweep, which was the lowest tillage intensity system
resulting in the highest surface residue level and a high surface roughness
after seeding. There were only small differences in test weight and protein
between treatments. Profitability ranking of the take-out systems was
similar to the yield results, with spring tillage take-out systems being
more profitable. Although fall flailing increased initial tillage and
total costs of the flail - sweep systems over spring take-out systems,
there was no difference in profitability.
A fall versus spring CRP take-out trial with summer fallow - winter wheat was established on the George O=Neal and Remie DeRuwe farm north of Connell on the edge of Franklin County. It was in a 9-inch rainfall zone and the field had been in crested wheatgrass for 8 years. Shano and Burke fine sandy loams were the dominant soils. These soils have weak soil structure and are susceptible to wind erosion. Grass residue averaged 4,700 lb/A.
Table 4 describes
the primary treatments included in the trial. Fall tillage and residue
management treatments were established in 1994 (disc - Oct. 10; flail
and harrow - Nov. 2). Roundup RT was applied at a 1-pint per acre rate
to all the plots before spring field operations. After the initial spring
tillage operations were established (March 24), the trial was managed
as one field. Subsequent field operations included a conventional shank
fertilizer applicator, rodweeding three times during the summer and seeding
Hatton hard red winter wheat on August 29 with an International Harvester
deep furrow drill.
Table 4. Treatments in the fall versus spring CRP take-out trial with summer fallow - winter wheat in Franklin County - George O'Neal and Remie DeRuwe, grower cooperators.
Soil test results in April 1995 of the fallow season showed a total of 87 lb N/A -- 10 lb/A ammonium-N in the top foot and 63 lb/A nitrate nitrogen to 6 feet, plus an estimated N mineralization of 14 lb/A from the 0.7 percent soil organic matter. Based on the soil test results, a 35 bu/A yield goal and a N requirement of about 3 lb N/bu, a fertilizer application of 40 lb N/A, 10 lb P2O5/A and 5 lb S/A was made in June with a conventional fertilizer applicator.
Table 5 summarizes the trial results through winter wheat establishment. Soil samples were taken to a 6-foot depth before spring tillage operations. All tillage and residue management treatments in the fall resulted in significantly lower overwinter water storage because of greater water loss by evaporation. Where the grass residue was left undisturbed over winter for the spring burn and spring disc treatments, there was just over 4 inches of plant-available soil water to a 6-foot depth before the spring treatments were established. Both of the fall residue treatments of harrowing and flailing resulted in slightly lower soil water contents of 3.6 inches. The fall disc treatment resulted in the greatest loss of water over winter, with only 2.2 inches of available water, which was 2 inches lower that under undisturbed grass cover over winter. This was similar to the soil water loss with fall discing in the Adams County trial.
Six-foot soil samples were again taken just after winter wheat seeding. All of the treatments lost about half of the water content present in the spring, ranging from 0.9 to 2.2 inches/6 feet. As in the spring sampling, the fall discing still had the lowest water content (0.9 inch), which was just over 1 inch less than the spring take-out treatments. There was 11.4 inches of precipitation from winter wheat seeding through the following June. However, most precipitation amounts were less than 0.5 inches so effective precipitation was much less. Based on an estimation of 4 inches of water needed for crop development to the reproductive stage and 5 bu/A yield of winter wheat per inch of additional water, yield potential was roughly 42-48 bu/A.
Surface residue cover was measured through the fallow season and after seeding. Although surface residue levels in all the treatments were low, the fall flail - spring sweep treatment resulted in the highest surface residue level of about 9 percent. This was one of the least intensive tillage systems. The lowest residue treatment was the spring burn - sweep with about 2 percent cover. The other three treatments with one or two disc operations had surface residue levels of 5 to 6 percent.
The two treatments with the highest surface roughness in July 1995 of the fallow season were the two lowest intensity tillage treatments...the fall flail - spring sweep and the spring burn - spring sweep. All the other treatments included one or more disc operations. This illustrates the well know fact that the disc can reduce soil structure and aggregation, particularly in these light textured soils. There were no real differences in surface roughness after seeding.
There were no
significant differences in plant stands between the treatments, except
for the fall disc treatment, which contained about half the population
of the other treatments. The lower soil water content at seeding probably
reduced germination and establishment.
Table 5. Data through wheat establishment on the 1994-96 fall versus spring CRP take-out with summer fallow - hard red winter wheat in Franklin County - George O'Neal and Remie DeRuwe, grower cooperators.
Table 6 shows downy brome populations and harvest data. It is not surprising that downy brome populations in crop in March 1995 were lower in the fall disc and spring burn treatments,but there was no yield effect due to different populations. Grain yield was significantly lower (about 6 bu/A) and protein was significantly higher (about 1%) in the fall disc treatment compared to the other treatments. This is believed to be largely the result of lower available soil water (about 1 inch) which directly reduced yield potential (Table 5). Winter wheat yields generally increase about 5 bu/A for each inch of additional water available within the normal yield potential for the area. In addition, the lower water content at winter wheat seeding also reduced plant stands, which added to the lower yield potential. Test weight was relatively uniform across treatments.
Table 6a shows
the costs and returns for the take-out systems. The fall disc - spring
disc treatment resulted in the lowest average annual returns because of
the lowest yield and relatively high cost. The two spring take-out systems
and fall 2X harrow - spring disc systems resulted in the highest returns.
Flailing resulted in lower returns because of the highest initial treatment
Table 6. Downy brome population and harvest data in the 1994-96 fall versus spring CRP take-out with summer fallow - hard red winter wheat in Franklin County - George O'Neal and Remie DeRuwe, grower cooperators.
Table 6a. Economics of the 1994-96 fall versus spring CRP take-out trial with summer fallow - hard red winter wheat in Franklin County - George O'Neal and Remie DeRuwe, grower cooperators.
This trial was located north of Ritzville near the town of Lamona. Grower cooperators were Jim Richardson and Darrell Roberts. The site was in a 10-inch annual rainfall zone on Renslow silt loam soil and had been in crested wheatgrass for 8 years. Initial grass residue averaged about 5,600 lb/A.
CRP take-out treatments compared at the Lincoln County trial are listed in Table 7. Fall tillage and residue management treatments were established in 1994 (harrow - Oct. 5, disc - Nov. 2). Spring flailing was done on March 6. Roundup RT was applied March 28 at 1-pint per acre to all the plots before spring field operations on April 19. Both the disc and sweep had a 3-bar tine harrow attached. After the initial tillage operations, the plots were managed as one field. Subsequent field operations included conventional fertilizer shank applicator, three rodweeder operations during fallow, and seeding Eltan soft white winter wheat on August 24 at 55 lb/A with a John Deere HZ deep furrow drill.
Soil test results
in April of the fallow year showed a total of 77 lb N/A -- 10 lb/A ammonium-N
in the top foot and 39 lb/A nitrate nitrogen to 6 feet, plus an estimated
N mineralization of 28 lb/A from the 1.4 percent soil organic matter.
Based on the soil test results, a 40 bu/A yield goal and a N requirement
of 2.7 lb/A, a fertilizer application of 50 lb N/A, and 8 lb S/A was made
in June with a conventional fertilizer applicator.
Table 7. Treatments in the 1994-96 fall versus spring CRP take-out trial with summer fallow - winter wheat in Lincoln County - Jim Richardson and Darrell Roberts, grower cooperators.
* attached 3-bar tine harrow
Table 8 summarizes the trial results through wheat establishment. There were no significant differences in overwinter soil water storage between fall and spring take-out treatments in the early spring, in contrast to results at the Adams and Franklin County trials. There were also no differences in soil water content at seeding time, but early fall rains before sampling probably overshadowed treatment differences. Beginning with the 4.9 to 5.3 inches of available water to 6 feet at seeding, there was an additional 11.8 inches of precipitation through June. However, most precipitation amounts were less than 0.5 inches so effective precipitation was lower. Based on an estimation of 4 inches of water needed for crop development to the reproductive stage and 5 bu/A yield of winter wheat per inch of additional water, yield potential was less than about 64 bu/A.
Surface residue measurements in July 1995 of the fallow season showed the spring burn had the lowest percent cover -- about 14 percent. Fall or spring discing resulted in about 49 to 51 percent surface cover. Harrowing or flailing ahead of spring discing further reduced the surface cover to about 40 to 44 percent. In a spring planting system, this surface residue level and soil roughness would have been more than adequate for effective erosion control prior to crop canopy cover with the spring crop.
Surface cover at planting was still lowest in the burn-sweep with 4 percent. The other four disc treatments ranges from 13 to 16 percent cover, with harrowing and flailing treatments still being slightly lower. Surface random roughness after seeding was significantly higher with the spring burn - sweep treatment. The other four treatments with the disc as primary tillage had similar levels of surface roughness. There were no differences in winter wheat plant stands between the treatments. Early fall rains provided uniform seed zone water and crop establishment appeared to be good under all the treatments.
Table 9 shows
March 1996 downy brome populations in crop and the trial harvest data.
Down brome population in spring 1996 were substantially lower in the spring
burn than the other treatments, but a fall metribuzin application and
competitive wheat crop minimized weed survival and competitive effects
on the crop. Yields, test weight and protein content were nearly identical
between treatments. Profitability of the systems was also similar (Table
9a). The main difference was a higher initial tillage system cost with
flailing, resulting in a lower average net return.
Table 8. Fallow data and plant stands on the 1994-96 fall versus spring CRP take-out trial for winter wheat on summer fallow in Lincoln County - Jim Richardson and Darrell Roberts, grower cooperators.
Table 9. Downy brome populations and harvest results from the 1994-96 fall/spring CRP take-out with summer fallow for soft white winter wheat in Lincoln County - Jim Richardson and Darrell Roberts, grower cooperators
Table 9a. Economics of the 1994-96 fall/spring CRP take-out trial with summer fallow for soft white winter wheat in Lincoln County - Jim Richardson and Darrell Roberts, grower cooperators
Spring take-out trials with soft white spring wheat were conducted in 1994 and 1995 in Columbia County. The 1994 spring crop trial site was summer fallowed in 1995 and seeded to soft white winter wheat. The 1995 site was recropped to soft white spring in 1996. A smaller satellite trial near the large trial in 1995 also compared soft white spring wheat, hard red spring wheat, spring barley and spring oats under plow and 2X disc treatments. A no-till spring barley study was conducted with two rates of preplant Roundup at a separate but similar location in Columbia County.
Three trials on
spring take-out with hard red spring wheat were conducted in 1996. Each
compared several direct seeding systems with a reduced or conventional
tillage system. Two were located near Ritzville and one near Waterville.
A fourth 1996 spring take-out trial in tall wheatgrass evaluated several
tillage and residue management systems with spring barley.
Two years of a trial on spring CRP take-out for soft white spring wheat using four different tillage and residue management systems were conducted in Columbia County in both 1994 and 1995. The trials were south of Starbuck in a 14-inch annual rainfall area on the George Young farm and conducted in cooperation with Roland Schirman, WSU Columbia County Extension Agent. The dominant soil is the Walla Walla silt loam.
The CRP field had been in crested wheatgrass for 8 years at the 1994 trial establishment. Initial residue level in 1994 ranged from about 2,220 to 10,200 lb/A and averaged 6,550 lb/A. Initial residue in 1995 ranged from about 2,700 to 9,200 lb/A and averaged 6,500 lb/A. Roundup RT was applied at 1 pint/A as an aid to tillage about 3 weeks prior to tillage and residue management treatments each year. After the initial management treatments (Table 10) were established, the trial was treated as one field with fertilizer injection using with a shank applicator, followed by skewtreading and seeding Penawawa soft white spring wheat at 80 lb/A with a conventional John Deere double disc drill on 7-inch row spacings. Seeding dates were March 20 in 1994 and March 30 in 1995.
Soil tests in 1994 showed a total of 42 lb N/A -- 9 lb/A ammonium-N in the top foot and 33 lb/A nitrate nitrogen to 4 feet, plus an estimated N mineralization of 30 lb/A. Fertilizer application in 1994 was 70 lb N/A, 15 lb P2O5/A and 15 lb S/A based on a yield goal of 35 bu/A for the 14-inch annual rainfall zone. Soil tests in 1995 showed a total of 31 lb N/A -- 9 lb/A ammonium-N in the top foot and 22 lb/A nitrate-N to 4 feet, plus an estimated N mineralization of 37 lb/A. Fertilizer application in 1995 was 40 lb N/A, 15 lb P2O5/A and 10 lb S/A.
and Yield Potential -- Water was very limiting in 1994
with only 3.7 inches of plant available soil water to 4 feet depth at
planting and a total 3 inches of precipitation occurred by harvest, although
precipitation effectiveness was limited since most rain events were less
than about .25 inches. Based on an estimation of 4 inches of water needed
for crop development to the reproductive stage and 5-7 bu/A yield of spring
wheat per inch of additional water, yield potential was roughly 13 to
19 bu/A. Yields much lower than this range are likely the result of weed
competition, plant diseases or a variety of other environmental stresses
and agronomic limitation. The 1995 trial had wetter conditions with 8.2
inches of available water to 4 feet at planting and 4.5 inches of precipitation
in the growing season, although precipitation events were light. Based
on the estimation of 4 inches of water needed for crop development to
the reproductive stage and 5-7 bu/A yield of spring wheat per inch of
additional water, yield potential was about 43 to 61 bu/A.
Table 10. Primary Treatments in the 1994 and 1995 Spring CRP Take-out Trials with Soft White Spring Wheat in Columbia County - George Young, grower cooperator.
Table 11 summarizes part of the trial data for 1994. Plow and burn-sweep treatments averaged 10 and 15% surface residue, respectively, while 2X disc and disc-sweep treatments were significantly higher, averaging 55 and 58%, respectively.
Plow and burn-sweep treatments had higher plant stands than the 2X disc and sweep-disc. Very dry conditions after seeding and poorer seed-soil contact probably reduced stand establishment in the high residue treatments.
Plow and burn-sweep treatments had a higher incidence of dryland foot rot largely because the thicker, more advanced stand of wheat resulted in increased drought stress under the dry spring conditions, which is a major contributor to the disease. The crop was also fertilized for a 35 bushel/acre yield (not possible under the drought conditions), adding to the drought stress conditions favored by the disease.
Yields of all
treatments were low due to the very dry spring conditions, but were very
close to the 13-19 bu/A yield potential with the available water and were
similar to recrop spring wheat yields in the area that year. Although
yield difference between high and low residue treatments were statistically
significant, the largest differences were only about 3.5 bu/A. Treatment
differences in profitability (Table 11a) largely reflect differences in
Table 11. Results of the 1994 spring CRP take-out trial with soft white spring wheat in Columbia County - George Young, grower cooperator.
Table 11a. Economics of the 1994 spring CRP take-out trial with soft white spring wheat in Columbia County - George Young, grower cooperator.
Continued data collection on the 1994 trial site on spring CRP take-out for spring wheat provided an opportunity to evaluate the effects of the different tillage and residue management systems in a spring wheat - fallow - winter wheat rotation on downy brome populations in winter wheat and economics of the 3-year rotation. The trial site was chiseled in the fall 1994, summer fallowed in 1995 and seeded to winter wheat. Summer fallow operations included an April application of Roundup RT at 1 pint/A, initial spring tillage in late-May with a Caulkins Chisel-Chopper, followed by two rodweedings. It was seeded to a Madsen/Rod blend of soft white winter wheat with a John Deere HZ deep furrow drill in September.
Before the initial
spring tillage operations for fallow, downy brome seedling populations
were determined on each 1994 treatment plot (Table 11). The plow and burn
treatments had relatively low downy brome populations compared to the
sweep - disc and 2X disc treatments, confirming the effectiveness of these
practices in destroying the downy brome seed, reducing germination or
reducing emergence. However, the 3-year crop rotation of spring wheat
- fallow - winter wheat was also very effective in reducing downy brome
seed carryover in the soil. Downy brome populations in the winter wheat
crop in January 1996 were very uniform and averaged less than 0.5 plant/square
foot, with no significant differences between treatments.
Table 12. Downy brome population in April 1995 of the fallow year following the 1994 spring CRP take-out trial for spring wheat, and in the winter wheat crop in January 1996.
Winter wheat harvest
results (Table 13) show relatively small yield differences due to 1994
take-out systems. on the winter wheat crop. The sweep-disc, one of the
highest surface residue treatments, had the highest yield although it
was not significantly higher than the plow-disc. Grain protein content
in the burn-sweep was significantly lower than all the other treatments,
possibly indicating lower nitrogen availability because of lost grass
residue available for nitrogen mineralization during residue decomposition.
Differences in average annual returns over the spring wheat - fallow -
winter wheat rotation after CRP (Table 13a) generally follow differences
in winter wheat yields. Averaged over the 3-year rotation, one of the
high-residue take-out systems in 1994 resulted in economic returns equal
to the low-residue systems .
Table 13. Harvest results on the 1996 soft white winter wheat crop after fallow as the second crop following the 1994 spring CRP take-out trial for soft white spring wheat in Columbia County - George Young, grower cooperator.
Table 13a. Three-year average economic returns in the 1994-96 spring CRP take-out with soft white spring wheat (1994), fallow (1995) and soft white winter wheat (1996) in Columbia County - George Young, grower cooperator.
In the 1995 spring take-out trial (Table 14), surface residue differences were similar to the 1994 trial, but all residue levels were slightly lower in 1995, possibly because of higher soil moisture conditions.
Plant stands were not significantly different. Two reasons for similar plant stands among treatments in 1995 (in contrast to 1994) include better seedzone soil moisture conditions at and after seeding, and slightly lower surface residue levels than in 1994 (~34% compared to ~57%). Although original plant populations were very similar shortly after emergence, there was some evidence of loss of stand and a Apatchy stand appearance@ in both of the higher residue treatments. Rhizoctonia root rot was identified on roots of plants in the affected areas and is believed to be at least part of the reason for the loss of stand and reduced yields. The disease was also present on plant roots in the low residue treatments, but did not appear to be having as much impact on the plants.
There were significantly
higher yields in the low residue treatments (as in 1994), but again the
yield differences between low and high residue systems were still small...2-5
bu/A. Northwest research has shown that using conservation tillage drills
with deep fertilizer placement below seeding depth and near the seed row,
and with better residue handling capability in the high residue treatments
would probably have improved yield potential under these higher residue
conditions compared to fertilizing and seeding with conventional tillage
equipment. As in the 1994 spring wheat trial, low residue take-out systems
were more profitable (Table 14a) because of slightly higher yields.
Table 14. Results of the 1995 spring take-out trial with soft white spring wheat in Columbia County - George Young, grower cooperator.
The trial site
was recropped to soft white spring wheat as one field in the spring of
1996. Field operations included chiseling in fall 1995, spraying with
1 pint/A Roundup RT in spring 1996, cultivating, fertilizing with conventional
fertilizer injector and seeding with a conventional John Deere double
disc drill. There was no significant difference in yield from the take-out
treatments established in 1995 (Table 15). Economic
rankings (Table 15a) of the take-out systems averaged over the two consecutive
years of spring wheat were similar to that of the initial take-out year
Table 14a. Economics of the 1995 spring take-out trial with soft white spring wheat in Columbia County - George Young, grower cooperator.
Table 15. 1996 Harvest results on the soft white spring wheat crop as the second crop following the 1995 spring CRP take- out trial for soft white spring wheat in Columbia County - George Young grower cooperator.
Table 15a. Two year average economic returns of the spring CRP take-out trial with soft white spring wheat in 1995 and recropped to soft white spring wheat in 1996 in Columbia County - George Young, grower cooperator.
Four spring cereals
were compared under high and low residue take-out systems at a satellite
trial near the 1995 Columbia County trial mentioned above. The primary
tillage treatments were moldboard plow-disc and 2X disc, followed by skewtreading,
fertilizer injection and seeding with a small plot research drill. Except
for seeding with a small plot drill, all the management treatments and
fertilizer applications were the same as in the large plots. Percent surface
residue cover after seeding averaged 9% after the plow and 34% after the
2X disc. Spring cereal crops included soft white common wheat, hard red
wheat, oats and spring barley. Yields of all crops under the high-residue
2X disc system were equal to or greater than yields under the low-residue
plow system (Table 16). Yield ranking of crops from highest to lowest
on a pounds/acre basis was: barley > white wheat > red wheat >
Table 16. Yield of four spring cereal crops in the 1995 spring crop choice trial with spring CRP take-out in Columbia County - George Young, grower cooperator.
A CRP take-out trial with direct seeding spring barley into CRP grass sprayed with two application rates of Roundup RT was conducted in 1995 in Columbia County by David Carlton (grower) and Roland Schirman, WSU Extension Agricultural Agent. The trial site was in a 14-inch annual rainfall zone. The CRP field had been in crested wheatgrass for 9 years.
Two treatments were 16 oz/A (1 pint) and 32 oz/A of Roundup RT rates applied on February 27 1995. The trial was then direct-seeded to Baronesse spring barley on March 4 with a Yielder drill without any prior tillage or residue management.
Percent kill of
the CRP grass at planting time (4/4/95) were 58% and 78% for the 16 oz/A
and 32 oz/A rates, respectively. Yields of direct-seeded spring barley
following the two herbicide rates were not significant different -- 3345
and 3520 lb/A, respectively.
The trial is located east of Ritzville on the Dale and Gary Galbreath farm in a 10- to 12-inch annual rainfall zone. The field was in crested wheatgrass for 9 years. Initial grass residue averaged 3,500 lb/A. The predominant soils are Ferrell and Stratford very fine sandy loams about 40 inches to sand and gravel.
All treatments were sprayed with Roundup RT at 48 oz/A on March 11. Soil tests showed 58 lb/A available nitrogen -- 19 lb/A ammonium-N in the top foot, 9 lb/A nitrate-N in the top 3 feet and 30 lb/A estimated nitrogen mineralization from organic matter during the growing season. Based on soil test results, a 40 bu/A yield goal, 3 lb N/A nitrogen fertilizer requirement, and about 15 lb N/A addition for microbial tie-up in residue decomposition, the fertilizer application was 65 lb N/A, 16 lb P2O5/A and 11 lb S/A. Fertilizer and fertilizer applicator were provided by Ritzville Chemical through Howard Reimer. Butte 86 hard red spring wheat with Vitavax 200 seed treatment was seeded at 77 lb/A on March 29.
Water Availability and Yield Potential -- There was 7.4 inches of available water to a 3 foot depth at planting and 4.3 inches of rainfall occurred from planting through June, although most precipitation amounts were less than 0.5 inches so effective precipitation was lower. Based on an estimation of 4 inches of water needed for crop development to the reproductive stage and 5-7 bu/A yield of spring wheat per inch of additional water, yield potential was less than about 38 to 54 bu/A. Yields much lower than this range are likely the result of grass competition, plant diseases or other environmental stresses.
using a Yielder drill with 5" X 10" paired-rows was compared
to a reduced tillage system seeded with a conventional IH double disc
drill with 7-inch rows (Table 17). Three grass residue management options
were evaluated under direct seeding: standing undisturbed grass, flailing
and burning. The Yielder drill applied fertilizer in the deep band within
the 5-inch pair of rows, 3 inches below seed depth, and also as a starter
with the seed. In the reduced tillage system, most of the nitrogen fertilizer
was applied with a conventional fertilizer applicator on 12" spacings
and starter fertilizer with the seed. Treatments 5 and 5A (lower fertilizer
rate) allow the comparison of seeding with the Yielder drill into both
undisturbed CRP grass and CRP ground that was disced once and coil packed.
Table 17. Treatments in the 1996 spring CRP take-out trial on direct seeding systems with three residue management treatments for hard red spring wheat in Adams County - Dale and Gary Galbreath, grower cooperators.
Table 18 shows
the plant populations 18 and 39 days after seeding and field surface condition.
Plant populations at both dates were higher under the conventional drill
after disc - coil pack - fertilize operations than under direct seeding.
An intermediate population density was noted where the Yielder drill was
used after the disc and coil packer. Surface residue cover after seeding
ranged from 1% in burn - direct seed to 50-53% in direct seeding of standing
CRP grass. Flailing before direct seeding resulted in a slight reduction
in surface residue cover (46%). Tillage with the disc and coil packer
ahead of the conventional drill and Yielder drill reduced residue cover
to 10-12%. Both tillage treatments resulted in relatively low surface
Table 18. Crop establishment and seedbed conditions in the 1996 spring CRP take-out with hard red spring wheat direct seeded into three residue management systems in Adams County - Dale and Gary Galbreath, cooperators.
Table 19 shows
the effects of CRP take-out method on the percent of roots with lesions
from take-all and Rhizoctonia root rot, and the survival of the CRP grass.
The percent of roots with take-all lesions was higher in both of the tillage
treatments and in the burn-direct seed treatments than the other direct
seeding treatments. Roughly one-third of the plant roots had Rhizoctonia
root rot lesions and no significant differences were found between treatments.
CRP grass survival in June was lowest where the disc was used (0.4-1.7
plants/yd2) compared to direct seeding (4.1-5.8
Table 19. Root disease incidence and CRP grass survival in the 1996 spring CRP take-out for hard red spring wheat under direct seeding with three residue management treatments in Adams County - Dale and Gary Galbreath grower cooperators.
Table 20 summarizes
the harvest results and economics. The higher grass population and increased
competition with the crop in direct seeded treatments is believed to be
one of the primary reasons for lower yields compared to tilled treatments.
Test weight was good in all treatments, but tended to be slightly higher
with tillage compared to direct seeding. Protein was below the 14% minimum
for hard red spring wheat in all treatments and lowest in burn - direct
seed and conventional planting. The low yields and protein content resulted
in negative returns on all treatments. Flailing before direct seeding
did not significantly increase yield, but also increased production costs
and further reduced profitability. The tillage comparison (#4) resulted
in the highest plant populations, lowest grass survival and slightly higher
yields and profitability. Discing and coil packing before seeding and
fertilizing with the Yielder drill significantly increased yield and profitability
(reduced losses) compared to direct seeding (see Section B).
Table 20. Harvest results and economics for the 1996 spring CRP take-out for hard red spring wheat under direct seeding with three residue management treatments in Adams County - Dale and Gary Galbreath grower cooperators.
Treatments are grouped by fertilizer rates for analysis of harvest results. (Treatments in Section A had a higher fertilizer rate than in Section B.)
Section B: Comparison of direct seeding in undisturbed CRP grass versus discing and coil packing before seeding both treatments with the Yielder drill (lower fertilizer rate than in Section A)
This trial was conducted as part of the June 18, 1996 "Fields of Tomorrow" field day program in cooperation Monsanto and a number of Ag support groups. It was located 11 miles east of Waterville near Farmer in an 11-inch annual rainfall zone. Dominant soil type is the fine sandy loam Deercut-Aarup-Whiteye complex with caliche hardpan at 16-24 inches. The field was in its 9th year of crested wheatgrass. Grower cooperators were Tony Viebrock and Mike Grande.
Two residue management options included: 1) "cut and flail" with a combine in September 1995; and 2) leave standing grass residue undisturbed. Initial grass residue averaged 3,000 lb/A. The fine sandy loam soils (Deercut-Aarup-Whiteye soil series complex) are susceptible to wind erosion and are underlain by caliche hardpan at 16-24 inches depth. Roundup RT Ultra was applied to the CRP grass April 9 at 48 oz/A.
Low Water Availability and Yield Potential: There was 4.1 inches of available water to the two-foot rooting depth at planting and only 1.5 inches of precipitation occurred from planting through harvest. Most precipitation events were less than 0.2 inches so there was very little effective precipitation during the growing season. Consequently, crop yields on these shallow soils were very low. Based on an estimation of 4 inches of water needed for crop development to the reproductive stage and 5-7 bu/A yield per inch of additional water, expected yield potential was only about 8 to 11 bu/A.
Soil test results
(2 foot depth to caliche) showed 46 lb N/A -- comprised of 9 lb/A ammonium-N
in the first foot, 9 lb/A nitrate-N to two feet and 28 lb N/A estimated
N mineralization during the growing season. Bases on the soil test results,
a 25 bu/A yield goal, and 3 lb N/bu N requirement, all treatments received
35 lb N/A, 10 lb P2O5/A
and 5 lb S/A. The fertilizer and fertilizer injector were supplied through
Western Farm Service of Waterville by Dale Henderer. Fertilizer placement
depended on drill capability (Table 21). All fertilizer was deep banded
at planting on drills with deep banding options. For drills with only
starter fertilizer placement capability, 28 lb N/A of dry fertilizer was
banded at a 4-inch depth on 7.5-inch spacings before planting. The remainder
was applied as a starter fertilizer with the seed. Butte 86 hard red spring
wheat was seeded on April 18 with Goucho and Apron seed treatments.
Table 21. Treatments in the 1996 spring CRP take-out trial comparing direct seeding drills with hard red spring wheat east of Waterville in Douglas County - Tony Viebrock and Mike Grande, grower cooperators.
Table 22 shows
the plant populations, surface residue and surface roughness. Populations
ranged from 11.1 to 15.1 plants/yd2. As expected,
surface residue was also higher under the two disc drills than hoe drills
in direct seeding. The tillage treatments had the lowest surface residue
cover at 4 %. Also not surprising was a lower surface roughness under
the disc drill compared to hoe drills for direct seeding. The tillage
treatment not only had very low surface residue for erosion protection,
but also had very low surface roughness. Without adequate surface residue,
finely-tilled fields with a surface random roughness of .26 inches would
be particularly vulnerable to erosion. The percent of wheat roots with
Rhizoctonia root rot lesions is the highest of any of the 1996 trials
evaluated, ranging from 52 to 72%. Because water was so limiting to yield
at this site, disease impacts on yield appear to have been minimized.
Grass survival was lowest in the tillage treatment. The Concord had the
lowest grass population of the direct seeding drills, possibly because
the wide hoe opener killed more grass compared to narrower hoe or disc
Table 22. Plant populations, surface cover, surface roughness, root disease and grass survival in the 1996 direct seeding drill comparison for spring CRP take-out with hard red spring wheat in grass combine "failed" in fall 1995 in
Douglas County - Tony Viebrock and Mike Grande grower cooperators.
Yields were very
low in all treatments (Table 23) but were close to the 8-11 bu/A yield
potential with the low available water (see the "Low Water Availability
and Yield Potential" section above). The slight yield advantage of
the conventionally tilled treatment and Concord drill may correspond to
more available water with the lower grass population. These two treatments
also had higher grain protein contents. The low yields resulted in negative
net returns over total costs on all treatments. However, the Concord and
Flexi-Coil 5000 direct seeding implements that could deep band fertilizer
near the seed row at seeding (compared to a separate operation in the
other systems) had lower production costs, the highest yields of the direct
seeding systems, and highest overall profitability.
Table 23. Harvest results and economics from the 1996 direct seeding drill comparison in spring CRP take-out with hard red spring wheat in grass combine "flailed" in fall 1995 in Douglas County - Tony Viebrock and Mike Grande, grower cooperators.
similarly in standing CRP grass (Table 24) as where the CRP grass was
combine-flailed the previous fall (Tables 22 and 23). However, plant populations
were slightly lower and surface residue cover and surface roughness were
slightly higher. The same general treatment rankings and results also
were found in yield and protein (Table 25) as in the flailed trial. Data
on root disease and grass survival were not collected on the standing
grass trial. Although net returns are negative as in the flailed trial,
losses are less without the combine-flail cost. The Concord and Flexi-Coil
5000 direct seeding drills deep banded all the fertilizer near the seed
row and below seed depth at planting (compared to a separate operation
in the other systems) had the lowest production costs. The Concord resulted
in a slight economic advantage over all the other systems.
Table 24. Plant populations, surface cover and surface roughness in the 1996 direct seeding drill comparison in spring CRP take-out with hard redspring wheat in standing CRP grass in Douglas County - Tony Viebrock and Mike Grande, grower cooperators.
1996 Recrop Spring Wheat Comparison
The trial was also repeated in spring wheat stubble in an adjacent cropped area with the same soil type (previously part of the same field). It provided an opportunity to make general comparisons of the same treatments in both CRP take-out and spring recropping. This crop was the fifth year of recrop spring wheat, the last three years being direct seeded with the John Deere HZ deep furrow drill used in the trial. Initial spring wheat residue was light, averaging 1,200 lb/A. Planting systems used on April 18 were the same except the tillage system comparison consisted of a minimum tillage system of one pass with a sweep and attached 3-bar tine harrow, and no fertilizer injector was used. A 1pint/A application of Roundup RT was made about three weeks before seeding.
Soil test results for available N (2 foot depth to caliche) were higher than in the adjacent CRP take-out trial. There was a total of 72 lb N/A -- 12 lb/A ammonium-N in the first foot, 32 lb/A nitrate-N to two feet and 28 lb N/A estimated N mineralization during the growing season. Based on the soil test results, a 25 bu/A yield goal and a general nitrogen requirement 3 lb N/bu for hard red spring wheat, only a starter fertilizer with 7 lb N/A, 10 lb P2O5/A and 5 lb S/A was applied. Depending on the drill design (Table 21 above), the fertilizer was deep banded at planting or applied as a starter fertilizer with the seed.
Low Water Availability and Yield Potential -- Similar to the adjacent CRP take-out trial, there was 3.9 inches of available water to two feet depth at planting and only 1.5 inches of precipitation occurred from planting through harvest. Most precipitation events were less than 0.2 inches so there was very little effective precipitation during the growing season. Consequently, crop yields on these shallow soils were very low. Based on an estimation of 4 inches of water needed for crop development to the reproductive stage and 5-7 bu/A yield per inch of additional water, expected yield potential was only about 7 to 10 bu/A.
Table 26 shows
plant populations, surface residue, surface roughness and root disease
comparisons. The Concord and John Deere 750 had significantly higher plant
populations than the other direct seeding drills and under minimum tillage.
Surface residue cover was low in all treatments but significantly higher
with the two direct seeding disc drills (16.5%). The lowest surface cover
was 10% in the minimum tillage systems. Surface roughness was lowest after
the two disc drills, which retained the highest surface residue cover.
The percent of root with Rhizoctonia root rot lesions was lower in recrop
spring wheat than in CRP take-out (Table 22). Most treatments had 35-40%
of the roots with lesions.
Table 26. Plant populations, surface residue cover, surface roughness and root disease data for the 1996 direct seeding drill comparison with hard red spring wheat in the fifth year of spring recropping with hard red spring wheat -- last three years direct seeded with the John Deere HZ (used in the trial) inDouglas County -- Tony Viebrock and Mike Grande, grower cooperators.
There were no
significant differences in yield (Table 27) between the five direct seeding
systems and the minimum tillage system. Yields were very low, ranging
from 8.2 to 9.9 bu/A, but still yielded to the limits of the available
water for the growing season. In contrast to the CRP take-out trials,
all treatments made the minimum grain protein of 14%. The Concord and
Flexi-Coil 5000 implements (that deep banded all the fertilizer below
seeding depth near the seed row at planting), and the minimum tillage
system had the lowest production costs, resulting in a slight economic
advantage over the other systems, although differences were small.
Table 27. Harvest results and economics for the 1996 direct seeding drill comparison with hard red spring wheat in the fifth year of spring recropping with hard red spring wheat -- last three years no-till seeded with the John Deere HZ in Douglas County Tony Viebrock and Mike Grande, grower cooperators.
This trial and drill demonstration were conducted as part of the June 20, 1996 "Fields of Tomorrow" program sponsored by Monsanto and a number of area grower and Ag support agencies and industries. The trial was located 4 miles west of Ritzville in a 10- to 12-inch annual rainfall zone. The field was in its 10th year of crested wheatgrass and soils are predominantly a deep Ritzville silt loam. Ron Jirava was the grower cooperator.
Low Water Availability and Yield Potential: Soil tests showed 5 inches of available water to three feet at planting and only 3.1 inches of precipitation occurred from planting through harvest. Most precipitation events were less than 0.5 inches so there was little effective precipitation during the growing season. Consequently, crop yield potential was low. Based on an estimation of 4 inches of water needed for crop development to the reproductive stage and 5-7 bu/A yield per inch of additional water, yield potential was only about 20 to 29 bu/A.
Roundup RT was
applied at 48 oz/A on March 17. Soil tests results showed a total of 45
lb N/A -- 5 lb/A ammonium-N in the first foot, 12 lb/A nitrate-N to three
feet and 28 lb N/A estimated N mineralization during the growing season.
Based on soil tests and a 25 bu/A yield goal, 45 lb N/A nitrogen fertilizer
was applied preplant or at planting, depending on drill fertilizer placement
capability. Dry starter fertilizer was applied with the seed at a rate
of 56 lb/A of 16-20-0-14 with all drills. The fertilizer and fertilizer
injector were provided by Ritzville Chemical through Howard Reimer. Laura
hard red spring wheat was planted at 70 lb/A on April 4 with five direct
seeding drills and air seeders, and under a reduced tillage system (Table
Table 28. Treatments in the 1996 spring take-out trial comparing direct seeding drills with hard red spring wheat in Adams County west of Ritzville - Ron Jirava, grower cooperator.
The minimum tillage
system resulted in lower plant stands than the direct seeding drills at
both 16 and 34 days after seeding (Table 29). The same trend occurred
with surface residue cover, 12% with tillage versus 18-28% with direct
seeding. The minimum tillage system seedbed had a relatively low surface
random roughness of 0.43 inches. Surface roughness has little importance
under most direct seeding systems because of anchored residue and minimal
Table 29. Plant populations, surface residue cover and surface roughness data from the 1996 spring take-out direct seeding drill comparison with hard red spring wheat in Adams County - Ron Jirava grower cooperator.
Table 30 shows
root disease levels and grass survival. A low percent of the roots had
take-all lesions (2-4%) compared to Rhizoctonia root rot (42-50%). Treatment
differences are relatively small in regards to potential agronomic impact.
Compared to other spring CRP take-out trials, direct seeding treatments
in this trial had low grass populations, 0.3 to 1 plant/yd2.
The tillage comparison treatment again had the lowest grass survival at
0.1 plant/yd2, but treatment differences
Table 30. Root disease ratings and CRP grass survival in the 1996 spring take-out direct seeding drill comparison with hard red spring wheat in Adams County - Ron Jirava grower cooperator.
Yields were very
close between all the treatments (Table 31) ranging from 20.5 to 22.8
bu/A. Test weights and proteins were also similar across treatments. None
of the treatments made the 14 percent minimum protein content.
The Concord and Flexi-Coil 5000 drills, that deep banded
fertilizer near the seed row at seeding rather than having a separate
fertilizer injection operation, had slightly lower production costs than
the other direct seeding implements and minimum tillage system. Although
net returns were negative on all systems, the direct seeding systems performed
similar to or better than the minimum tillage system.
Table 31. Harvest results and economics for the 1996 spring take-out direct seeding drill comparison with hard red spring wheat in Adams County - Ron Jirava grower cooperator.
The trial site is north of Sprague on the Andy and John Rustemeyer farm in a 13-inch annual rainfall zone. The field was in its 10th year of CRP and predominantly tall wheatgrass with residue 4-6 feet tall. Initial residue ranges from 11,500 to 15,600 lbs/A and averaged 13,700 lb/A. The predominant soil series is the Bagdad very deep silt loam. Four tillage and residue management combinations were compared (Table 32).
Table 32. Treatments in the 1996 tall wheatgrass spring CRP take-out trial with tillage for spring barley north of Sprague in Lincoln County - Andy and John Rustemeyer, grower cooperators.
No herbicide was applied to help kill the CRP grass prior to establishment of the trial because of the difficulty of spray application in the heavy canopy of 4- to 6-foot tall grass, and limited spring growth. A replicated trial with 0, 16, 24 and 32 oz/A rates of Roundup RT Ultra was established across the end of the large plots 3 days before tillage operations began on May 7. Grass populations were low on all treatments at the June 13 rating. The no-herbicide check averaged 1 plant/yd2, compared to 0.3 plants/yd2 for each of the three herbicide rates. The difference was small but statistically significantly at the 95% probability level (LSD of 0.16 plants/yd2 ).
Soil test results showed about 60 lb/A available nitrogen -- 10 lb/A ammonium-N in the top foot, 12 lb/A nitrate-N to three feet and 42 lb N/A estimated N mineralization from the 2.1% soil organic matter. Nitrogen fertilizer was applied at 80 lb N/A with a conventional fertilizer applicator. This rate was based on soil test results, a 3,000 lb/A yield goal, 4 lb N/100 lb barley yield potential, plus 20 lb N/A to help offset N tie-up during residue decomposition. Baronesse spring barley was seeded at 70 lb/A on May 8, which was 3 weeks later than initially planned for the trial. A variable N fertilizer trial was established across the end of the large plots to help develop more specific N fertilizer recommendations under the different tillage and residue treatments. The results of that study will be published in a separate report (see Section 19).
Low Water Availability and Yield Potential -- There was 6.8 inches of available water to three feet at planting but only 2.6 inches of precipitation occurred from planting through July. Most precipitation events were less than 0.5 inches so there was little effective precipitation during the growing season. Consequently, crop yield potential was low. Yield potential was only about 1,400 to 1,800 lbs/A, based on an estimation of 3.8 inches of water needed for spring barley development to the reproductive stage, and 250-320 lbs/A yield potential per inch of additional water.
Table 34 shows
plant stands, surface residue and roughness and the percent of roots with
Rhizoctonia root rot lesions. Plant stands were very uniform across treatments.
However, lower plant stands would likely have resulted on the higher residue
treatments without a rain of about 0.5 inches shortly after seeding, since
seeding depth was less uniform than after the burn treatments. Surface
residue cover was lowest were the grass was burned, however a light disc
operation prior to burning nearly doubled surface residue retention from
5.6 to 9.9 % compared to no pre-burn tillage. On the non-burned treatments,
surface residue was slightly lower on with the flail - 2X sweep than the
2X disc. Surface roughness was lowest on the intensively tilled 2X disc
than with the three 2X sweep treatments, although differences were relatively
small. The percent of roots with Rhizoctonia root rot lesions was relatively
high on all treatments.
Table 33. Plant population, surface residue cover, surface roughness and root disease level data from the 1996 spring take- out of tall wheatgrass CRP with tillage for spring barley in Lincoln County - Andy and John Rustemeyer, grower cooperators.
Yields were about
600 lbs/A higher in the two burn treatments (Table 34). Part of the reason
for the lower yield in the tilled treatments compared to the burned treatments
is believed to be from increased temporary tie-up of nitrogen and other
nutrients in surface soils during microbial decomposition of incorporated
residue (initail average of 13,700 lb/A). Although root disease levels
in the June samples do not help explain yield differences, disease impacts
during earlier crop establishment and development may also have caused
at least part of the yield reduction with the higher residue treatments.
Test weight and plumpness differences were small. Economic comparisons
of the treatments (Table 34a) showed that additional residue management
operations of flailing before 2X sweep and of shallow disc before burn
- 2X sweep increased production costs but did not increase yield or profitability
compared to the other respective high and low residue treatments. Net
returns were negative on all treatments because of the low yields (that
still reached the 1,400-1,800 lb/A yield potential with available water
in the growing season), and higher fertilizer expenses invested for the
3,000 lb/A barley yield goal.
Table 34. Harvest data from the 1996 spring take-out of tall wheatgrass CRP with tillage for spring barley in Lincoln County - Andy and John Rustemeyer, grower cooperators.
Table 34a. Economics of the 1996 spring take-out of tall wheatgrass CRP for spring barley in Lincoln County - Andy and John Rustemeyer grower cooperators.
Monsanto Field Trials
Sheldon Blank, Monsanto research agronomist in Pasco, conducted four cooperative field trials on Roundup RT rates and timings for killing crested wheatgrass without tillage. Highlights of the results of these small plot experiments are described below.
Fall Versus Spring Timing, Rate and Fall Residue Removal - This study by Blank was conducted in a 9-inch annual rainfall zone in 9-year old crested wheatgrass fields near Connell and Kahlotus in Franklin County. The trials were established in August 1994 with two residue treatments: mowing and removal of the residue versus undisturbed. Roundup RT was the sprayed at 1, 2, or 3 pints/A rates on November 28, 1994 or March 7, 1995. The crested wheatgrass had 2-3 inches new growth at both the fall and spring application times.
Results - Fall herbicide application at all rates was ineffective (0-5% control) because of grass dormancy even though grass regrowth was present and spraying conditions were good. Mowing and residue removal had no significant effect on grass kill. Spring applications rates of 2 -3 pints/Ae gave 96.5 to 100% control by June and 94.5 to 99% control by October. Spring application of 1 pint/A gave significantly lower control than the 3 pint/A rate -- 85 to 90% control by June and 87.5% control by October.
Spring Herbicide Timing and Rate - Blank established this experiment adjacent to the large-scale CRP take-out trials near Connell in Franklin County and Lind in Adams County. Both sites were in 9- to 10-inch annual rainfall areas on 9-year stands of crested wheatgrass. Roundup RT was applied at 8, 16, 24, 32 and 48 oz/A in March, April and May 1995. Heights of new growth at spraying times at the Connell site were 3-5 in March, 5-7 inches in April and 9-12 in May. At the Lind site, new growth heights were 3-4 inches in March, 3-6 inches in April and 6-9 inches in May.
- There was little difference in grass control between March, April and
May applications. An early application time would conserve more soil water
for crop production following CRP take-out. The 24 - 32 oz/A rates gave
70+% control by June. The 48 oz/A rate gave 80 - 99% control by June.
McGregor Company Field Trials
A small-plot satellite
study on Roundup RT application rates for control of crested wheatgrass
without tillage was conducted near the direct seeding trial in 1995. It
was established on March 1 by Stephen Reinertsen, McGregor Co. Research
Agronomist. Application rates of 8, 16, 24, 32, and 48 oz/A gave 10, 39,
53, 59 and 80 percent grass control, respectively, in May.
Plant and root samples to a depth of about 10 inches were collected in mid-June on all four of the 1996 spring take-out field trials. The roots were washed and analyzed for root disease lesions in a cooperative effort with R. James Cook, USDA-ARS plant pathologist, and Monica Mezzalama, visiting plant pathologist from Italy. The two primary root diseases found were Rhizoctonia root rot and take-all. A percentages of roots with lesions were then calculated for each disease and the results are reported in the summary of each field trial in this report. Actual yield loss to the disease in the trials is not known because there were no "disease free" checks.
Rhizoctonia root rot was present at all sites. The percent of roots with root lesion ranged from a low "chronic" level of 20 to 35% to over 70%. Little difference was noted between tillage and residue management treatments. Take-all root disease was generally found at a very low incidence or not at all. Crested wheatgrass is know to be an alternate host for take-all. Growers need to be aware that the disease can build up rapidly when wheat is planted after wheat for several years.
rot, as well as other root diseases, have been shown to increase significantly
in direct-seeded spring cereals when there is a "green bridge"
of volunteer grain and other host plants growing between harvest and spring
planting. It is important that CRP grass be killed as early as possible
before spring seeding, at least 2-3 weeks earlier and preferrably longer.
Although killing the CRP grass the previous fall with a minimum tillage
operation, such as a sweep or undercutter, was not included in any of
the field trials, this approach may help reduce the root disease level
in spring cereals, particularly under direct spring seeding. Fall herbicide
kill of crested wheatgrass has not been successful (See Section 11).
of the large-scale CRP take-out trials in this project were conducted
by Kathleen Painter, WSU agricultural economist. Highlights of the economic
data are included at the end of each trial summary. The economic analyses
were based on standard cost estimated from enterprise budgets and not
the actual costs of the cooperating growers. Custom rates were used for
direct seeding systems.
Ann Kennedy, USDA-ARS soil microbiologist, and Virginia L. Gewin, WSU research associate in soil microbiology, have been conducting an evaluation of soil quality changes as the CRP land is returned to crop production. Soil samples were collected from most of the large-scale trials. The following is a brief summary they provided.
One aspect in the evaluation of management practices and the long term benefits is to study changes in the soil condition. Soil quality can be evaluated by monitoring physical, chemical, and biological components. The value of looking at these parameters collectively is that they may change with one another, but on differing time scales. Microorganisms are responsible for many processes that can affect certain physical and chemical parameters of the soil such as nutrient cycling and erosion potential; therefore, they can function as early indicators of the status of a soil.
By investigating the changes in soil quality parameters for CRP takeout using various tillage practices ranging from conventional tillage to notill, we can better assess the impact of management on these lands once they are put back into production. Samples from eight farms participating in CRP Takeout trials have been analyzed for changes in specific soil quality indicators with an emphasis on the microbial portion. Four original sites, identified as O'Neal (Franklin Co.), Roth (Adams Co.), Richardson (Lincoln Co.), and Young (Starbuck), were sampled in spring 1995, fall 1995, and spring 1996. Four additional sites, identified as Rustemeyer (Lincoln Co.), Jirava (Adams Co.), Viebrock (Douglas Co.), and Galbreath (Adams Co.), were also sampled but only for spring 1996. The Jirava, Viebrock and Galbreath sites were specifically added to assess soil quality changes associated with direct seeding in CRP takeout.
Microbial biomass (population numbers of microorganisms), readily mineralized carbon and dehydrogenase (measures of microbial activity), nitrifier populations (group of organisms that transfer ammonium to nitrate and nitrite), and microbial community structure have been analyzed in conjunction with soil physical and chemical parameters to monitor changes in these lands due to different management practices. Bulk density, organic matter content, and aggregate stability were also monitored as the land was put back into production.
Microbial community functions can provide insight into the levels of aggregation, nutrient cycling, and organic matter breakdown. Microbial community structure has been analyzed to monitor potential shifts in the microorganisms based on management practices. Fatty acid methyl ester (FAME) analysis and substrate utilization provide "fingerprints" which have shown that differences occur among treatments. By monitoring communities as well as population numbers and activity, we can determine the effect of these management practices on ecosystem function.
Dryland cropping practices were analyzed individually for differences between treatments and adjacent land still in CRP. Organic matter content over all eight sites ranged from 2.5% at the Rustemeyer site to around 1.04% at the O'Neal site. Analyses are still being conducted to see if tillage affected % organic matter at the individual sites. Bulk density measurements were lower in CRP than in all the treatments at the Roth and O'Neal sites. Aggregate stability was altered as land was put back into production. Correlation analyses are being conducted in order to establish relationships between aggregate stability, readily mineralized carbon, and % organic matter.
The O'Neal, Richardson, Young, and Roth fallow -winter wheat sites had higher pH and lower nitrifier populations in CRP when compared with all the take-out treatments. Two notill drill sites, Viebrock (Douglas Co.) and Jirava (Adams Co.), were analyzed together. Moisture was higher and nitrifer populations were lower in CRP than in all the treatments, but there were no significant differences between take-out treatments. Treatments at the O'Neal, Richardson, Roth, and Young sites were contrasted against one another. Differences between treatments did occur, but not as frequently as differences between all treatments and land still in CRP. In most instances the treatments with the least disturbance at a site were found to be different from one of the other treatments involving more disturbance. For example, differences were found at the O'Neal site between the BurnSweep and FlailSweep (least disturbed system at O'Neal). The BurnSweep treatment was lower in readily mineralized carbon, pH, and nitrifier populations than the FlailSweep. The same was true for the Young site at Starbuck. The PlowDisc was lower in dehydrogenase activity than both the 2X Disc and the SweepDisc (least disturbed system) treatments. These findings suggest that not only does the condition of the land change when it is tilled, but the degree to which changes occur depends on the level of disturbance.
The physical and chemical parameters dictate the environment in which the biological portion of the soil will function. The biological portion, however, will affect the physical and chemical environment. Activity levels, biomass numbers, and community shifts can reflect the stability of a system with respect to level of nutrient cycling, the amount of carbon utilized in a system, and the overall community structure and function in a soil system. These variables will impact certain physical and chemical parameters of interest to growers such as pH, aggregate stability, organic matter content, and nitrogen cycling.
Tillage choices will need to be made as we bring these CRP lands back into production. Monitoring changes in soil quality parameters with different management practices can provide information on their impact. Our findings suggest that those tillage practices with low disturbance will lessen the change in soil quality as CRP land is returned to crop production. Assessing microbial and soil quality changes as a result of various management practices used in CRP takeout can aid growers in maximizing profits by more effectively retaining improvements in soil quality and decreasing erosion potential.
Analyses of these
data are continuing and will be available in the Master's thesis of Virginia
L. Gewin and other publications in the future. For more information the
research results, contact Ann Kennedy at 509-335-1552 or by E-mail (email@example.com).
nonselective or selective herbicides at rates labeled for CRP at least
one or two years ahead of contract expiration to begin reducing the seed
bank and populations of winter annual grass weeds and other problem weeds
in CRP grass stands. Spot spraying of perennial weeds should also begin
as early as possible.
There are a number of factors to consider in selecting a spring or fall planting with CRP take-out. These could include specific winter annual or summer annual weed problems, water availability based on soil water storage and precipitation probabilities, time and options for managing CRP grass residue, seasonal work load, economics of crop options and take-out management systems, and so on. With new crop rotation flexible under the farm program, growers have more flexibility to select rotations based on agronomic needs, crop profitability and available soil water. The following are several scenarios where spring planting or winter wheat planting may have specific advantages:
Spring planting might be considered under the following scenarios:
Summer fallow-winter wheat might be considered under the following scenarios:
In the low precipitation
areas, early kill of CRP grass is important for both spring crops and
summer fallow - winter wheat. Fall planting after summer fallow starting
at a July CRP take-out (Acurrent@ authorized take-out time for contracts
expiring in October) is not considered an acceptable option for most of
the low-rainfall, crop-fallow region in the Inland Northwest. Extensive
soil water use by the CRP grass would probably not leave adequate seed
zone water for timely winter wheat establishment, requiring later seeding
after fall rains or seeding into dry soil. This CRP take-out approach
could result in serious weed problems in fields with a high soil seedbank
of downy brome and other winter annual grasses. This take-out timing may
work in higher precipitation areas and in years with summer rains.
The results of CRP take-out research trials in Franklin and Adams Counties for summer fallow - winter wheat demonstrate the potential disadvantage of intensive fall tillage and residue removal. Compared to leaving the grass undisturbed over winter, there was approximately 2 inches less soil water storage in the spring after fall discing, with most of the water loss taking place in the top 3 feet. The water loss was due to increased evaporation. By fall planting, available water storage was still up to about 1 inch lower. This water loss resulted in lower plant stands and a 3-5 bu/A yield reduction at both sites. This loss of soil water storage with fall discing reaffirms years of Northwest research on increased overwinter evaporative water loss from soils if much of the soil surface is exposed. Plowing, burning or other tillage practices that remove much of the residue and bare the surface soil would result in similar or greater evaporative water losses over winter than with intensive fall discing.
Fall flailing, fall harrowing, and fall harrowing and chiseling also reduced overwinter storage at the Franklin and Adams summer fallow trial sites, but the reductions were smaller and less consistent than with fall discing. Stand counts and yields were not affected by these fall residue management practices compared to other spring take-out treatment.
Undercutters with wide flat blades, and other similar tillage implements that cut the grass roots but do minimal disturbance to the surface soil and residue, could be considered in the fall for summer fallow the following year. No CRP take-out research trials were conducted to evaluate these management options. In combination with harrowing or other additional residue management practices with minimum soil disturbance, these implements could allow the establishment of minimum tillage summer fallow after CRP, effectively retaining surface residue and roughness, as well as seed zone water.
Runoff Areas - In areas with a high frequency of overwinter
runoff on frozen soil, practices such as subsoiling or wide-spaced chiseling
(e.g. 24" to 72" or more) could be considered in the fall before
CRP take-out. These tillage operations can improve water infiltration
under frozen soil conditions with minimal surface residue and soil surface
disturbance, consequently providing good water storage potential over
Burning Before Fallow - Burning should not be considered in crested wheatgrass CRP take-out with summer fallow because very low surface residue levels remain for erosion control and water conservation. Surface residue cover after winter wheat seeding on fallow following a spring burn was only about 2% at the Franklin and Lincoln County sites. The moderate to low surface residue levels with crested wheatgrass (generally 4,000-6,000 lbs/A) do not warrant the use of burning to achieve manageable residue levels at seeding time after fallow. Although burning allow the use of less intensive, subsurface tillage implements such as sweeps to help maintain surface roughness, surface residue is more effective in reducing erosion, particularly in soils with weak soil structure.
Compared to other spring treatments, burning in the Franklin and Lincoln County sites did not result in significant differences in plant stand, yield, test weight, protein or net returns. Burning did significantly reduce down brome populations in winter wheat compared to the other treatments. However, Metribuzen was applied in the fall for downy brome in the Lincoln County and provided effective downy brome control in the competitive winter wheat crop. No grass herbicide was used for downy bromein the Franklin County site because of the low population and competitive crop. Downy brome seed production was low at both sites.
Flailing - In the Franklin and Adams County trials, fall flailing of CRP grass with a flail or with a combine and then using a sweep in the spring for summer fallow establishment was an effective way to minimize problems with long grass residue and reduce tillage intensity. Compared to other take-out treatments, however, the flail-sweep treatment did not significantly increase surface residue cover or roughness after winter wheat seeding, nor did it improve plant stands or grain yield, so the additional cost of flailing was difficult to justify. Similarly, spring flailing ahead of discing at the Lincoln County trial did not affect erosion protection or agronomic performance compared to spring discing alone, and consequently reduced profitability.
Harrowing - In the Franklin County trial, a fall 2X tine harrowing - spring disc treatment was evaluated as an option to reduce tillage intensity for CRP take-out for fallow. Compared to two spring discings, there were no significant differences in plant stands, surface residue and roughness after seeding, yield or net returns. In Lincoln County, fall 2X tine harrowing - spring disc with attached 3-bar tine harrow was compared with the spring disc/3-bar tine harrow alone. Fall 2X harrowing did not significantly affect surface residue cover or roughness after seeding, yield or net returns. It did, however, result in a slight reduction in downy brome population in the winter wheat crop (13 plants/yd2 v.s. 17 plants/yd2) due to increased weed germination in the fall before summer fallow. Late summer or fall harrowing for spring fallow establishment with sweeps or undercutters was not evaluated in any of the field trials, but would probably provide an economical minimum tillage system for CRP take-out.
Maintaining Effective Erosion Protection - The results of all three CRP take-out research trials for summer fallow-winter wheat in Adams, Franklin and Lincoln Counties indicate that all tillage and residue management combinations used were overly intensive, resulting in excessive removal of surface residue. Although surface residue cover on CRP take-out trial with summer fallow was often 20-50 % in June or early July, residue cover at seeding time was only 5 to 16 % (2-4% in burn treatments), providing only limited erosion protection and water conservation.
The disc, in particular, should only be used with caution in very low rainfall, wind erosive areas that have light textured soils with weak soil structure, such as the Shano series. If the disc is used in CRP take-out, minimize the depth of operation. Subsurface tillage implements, such as sweeps or undercutters with wide flat blades provide better retention of surface residue and soil structure. The moldboard was not used in the CRP take-out trials with summer fallow, but would be even less desirable than the disc under these light soil and low residue conditions.
In order to maintain
a greater level of soil structure (aggregate stability) in CRP take-out
with summer fallow on light textured soils, consider starting primary
tillage operations when there is still good surface soil moisture (not
wet). Use a minimum tillage summer fallow system to retain adequate surface
residue, and roughness for erosion control. Direct fall seeding of winter
wheat on chemical fallow was not effectively evaluated in the research
effort. This may be an option, particularly in the intermediate precipitation
zones. However, the ability to maintain seed zone water for winter wheat
establishment with chemical fallow would be the biggest challenge in low
rainfall areas of the Northwest. A fallow combination of fall or spring
subsurface tillage, such as with an undercutter or sweep, and then partial
chemical fallow before rod weeding might provide effective grass kill
with lower herbicide rates than under chemical fallow, and still effectively
retain seedzone water, and surface residue and roughness for erosion control.
Based on the results of Monsanto=s cooperative small-plot research trials in 1994-95 on herbicide kill of CRP grass, a 48 oz/A (3 pints) rate may be needed to kill a high percentage (90%+) of the crested wheatgrass for direct seeding systems without tillage. This rate was used in three 1996 spring CRP take-out trials with direct-seeding spring wheat. Two large-plot spring CRP take-out trials in 1994 and 1995 using tillage operations that effectively cut the roots of the wheatgrass plants had effective grass kill with a 1 pint/A application of Roundup RT prior to tillage and residue management operations. As in normal summer fallow system, the advantage of the herbicide in the spring would be to help prevent the reestablishment of the grass and weeds, and weed seed production under prolonged wet spring conditions. Fall Roundup RT application did not kill crested wheatgrass even with 2-3 inches fall growth and good weather conditions.
Northwest research on direct seeding spring crops after cereals has shown that the nonselective herbicide should be applied to volunteer grain and weeds at least 14 to 21 days before direct spring seeding to effectively break the "green bridge" for Rhizoctonia root rot and other root diseases hosted on the roots of those plants. The same principle is believed to be important in crested wheatgrass CRP take-out with direct spring seeding, although that has not been specifically studied. Rhizoctonia root rot was common on all the spring CRP take-out trials with spring cereals under both direct seeding and tillage systems.
Although the comparison
of fall versus spring CRP take-out trials was not conducted for spring
cereals, it is believed that the reduction in overwinter water storage
with intensive fall tillage documented in the field trials with summer
fallow - winter wheat would have a significant impact on spring crop yield
potential in the region. Spring crops are shallower rooted than fall-seeded
crops and are generally more responsive to changes in water availability
in the top few feet of soil. Spring wheat yields generally increase from
5 to 7 bu/A with each inch of additional water storage, versus about 5
bu/A for winter wheat. Consequently, based on the 2-inch overwinter water
loss with intensive fall tillage in the CRP fields in the summer fallow
- winter wheat field trials, yield losses in spring wheat could be 10
to 14 bu/A. However, the potential for earlier seeding and a lower root
disease potential with fall tillage and grass kill may offset yield losses.
Less intensive fall tillage, such as with an undercutter, and direct spring
seeding would provide improved water conservation along with better agronomic
Some residue management
practices, such as flailing, may help improve agronomic performance in
direct seeding or other minimum tillage systems in the spring. Using a
combine to cut and chop the grass residue when it is dry in the fall worked
effectively in the Adams County trial with fallow-winter wheat near Lind,
and in preparation for the 1996 direct seeding spring wheat trial near
Waterville in Douglas County. The Waterville trial, with five direct seeding
and one conventional tillage system, was conducted in both fall combine-flailed
grass and standing undisturbed grass (3,000 lb/A). Although the adjacent
trials were not designed to compare planting systems across the two residue
treatments, spring wheat stands and yields were very similar. Consequently,
the added expense of flailing may not be recovered in increased returns
from the crop. Flailing the 3,500 lb/A grass residue ahead of direct seeding
spring wheat with a Yielder drill in a 1996 spring CRP take-out trial
east of Ritzville did not affect plant stands, root disease level or yield,
and consequently was less profitable than direct seeding without flailing.
Surface residue cover after seeding was only reduced from 53% to 46% by
flailing. Late summer or fall harrowing may provide a more economical
residue management option than flailing.
Three trials included spring burning of CRP before seeding spring wheat or spring barley in 1994-96. Spring burn - sweep was one of four spring take-out treatments for spring wheat in a 13-inch annual rainfall area of Columbia County in 1994 and 1995. The other treatment were moldboard plow - disc, sweep - disc and 2X disc. Surface residue cover averaged 10% with burn - sweep, 10-15% with the plow - disc and 34-58% with the two "high residue" treatments. Burn treatments were slightly higher yielding (2-3 bu/A) and consequently more profitable than the higher residue treatments. Yields with the plow systems were not significantly different from the burn - sweep.
The effect of burning before direct seeding of hard red spring wheat with a Yielder drill was evaluated near Ritzville in 1996. The burn - direct seed system yielded about 3 bu/A higher than direct seeding into standing grass and about 3 bu/A lower than with a tillage comparison of disc - coil pack - fertilize and seed with conventional double disc drill. Economic returns with burn - direct seed were intermediate between the two other systems. Surface residue cover in the burn - direct seed was only 1% compared to 53% with direct seed and 10% with the tillage treatment.
Burn - sweep was compared with flail - sweep and 2X disc for spring take-out of tall wheatgrass CRP for barley near Sprague in Lincoln County in 1996. Initial residue was about 14,000 lb/A and residue retention after seeding averaged 6% after the burn and 15-17% after the other non-burn treatments. Although plant stands and the level of Rhizoctonia root rot were not different between treatments, barley yield was about 600 lbs/A higher in the burn - sweep. Root disease levels were similar in June, so much of the yield difference may be attributed to increased microbial tie-up of nitrogen and other soil nutrients in the high residue treatments.
before direct spring seeding would provide good seedbed conditions, but
would also increase soil water loss by evaporation. Another consideration
with burning is the loss of the grass residue contribution to the soil
organic matter and plant nutrients.
Soil quality research on CRP take-out shows that direct seeding systems can retain more of the soil quality improvements gained under grass cover compared to tillage take-out systems. Soil water conservation can also be greater under direct seeding, allowing higher yield potential if the crop can effectively utilize the increased water availability. A direct seeding CRP take-out trial in Columbia in 1995 (13-inch annual rainfall) resulted in high spring barley yields of 3,300 - 3,500 lbs/A with about 55 to 80% grass control, respectively with two Roundup RT rates. There were no comparisons with tillage or with complete grass control in the study.
Three 1996 spring CRP take-out trials in Adams and Douglas Counties compared direct seeding to minimum or conventional tillage systems for spring wheat. The degree of CRP grass survival measured in June was believed to be one of the major factors in determining yield differences between the direct seed and tillage systems. In the direct seeding management trial east of Ritzville, the tillage comparison of disc - fertilizer injector - coil pack - conventional double disc drill yielded 3-6 bu/A higher than the three direct seeding management treatments, and averaged 0.4 grass plants/yd2 compared to 4-6 in the direct seed systems. Profitability was not significantly different between the minimum tillage systems and two of the three direct seed systems.
In the direct seeding drill comparison trial with spring wheat near Waterville, the tillage system of 3X disc - fertilizer injector - deep furrow drill averaged 1-4 bu/A higher yields than five direct seeding systems. Grass survival in June was 0.1 grass plants/yd2 under tillage versus 2-4 plants/yd2 under direct seeding, probably contributing to at least part of the small yield advantage with tillage. Rhizoctonia root rot levels were slightly lower in the conventional tillage as well. Soil erosion potential was much higher at seeding time under the conventional system with 4% surface cover and low surface roughness (.26 inches random roughness) as compared to the direct seeding systems with 21-35% surface cover. Net returns with three of the five direct seeding systems were equal to or greater than with the conventional tillage system.
In the direct seeding drill comparison trial with spring wheat west of Ritzville, yield of the minimum tillage treatment was not significantly different than three of the five direct seeding systems and only 2 bu/A higher than the other two systems. In contrast to the other two trial above, CRP grass survival was low in all systems, ranging from 0.1 grass plants/yd2 under minimum tillage to 0.3-1.0 in the five direct seeding systems. Root disease levels were not significantly different between treatments. Two direct seeding systems were more profitable than the minimum tillage system and the other three were not significantly different from the minimum tillage system.
An important part
of the success of direct seeding would depend on having a drill that could
effectively penetrate the grass residue and soil for good seed-to-soil
contact and accurate seeding depth. Northwest research on direct seeding
of spring cereals after cereals also shows that deep banding of fertilizer
below seed depth and below or near the seed row can reduce the impacts
of root diseases and increase yield potential. This management practice
in CRP take-out would likely improve yield of direct-seeded spring crops.
Tim Fiez, WSU
soil fertility specialist, cooperated in the establishment of nitrogen
fertilizer trials across the large-scale CRP take-out trials in winter
wheat after summer fallow in Franklin and Adams Counties, in spring wheat
in Columbia County and in spring barley in Lincoln County. These studies
were designed to develop adjustments in nitrogen fertilizer recommendations
for CRP take-out under different tillage and residue management systems.
The primary focus was on evaluating the temporary tie-up of soil nitrogen
during microbial decomposition of CRP grass residue and roots with different
intensities of tillage and surface residue incorporation or removal. The
results of these trials will be compiled in a separate PNW Conservation
Tillage Handbook Series publication early in 1997. To receive a copy of
this research summary publication when available, contact the WSU Crop
and Soil Science Dept. Extension office at 509-335-2915.
Choose the best
adapted and disease resistant crop varieties. Use seed treatments for
protection against wireworms, seed rots and smuts.
Additional copies of this PNW Conservation Tillage Handbook Series publication are available the Crop and Soil Sciences Dept. Cooperative Extension office, Washington State University, Pullman, WA 99164-6420, or call 509-335-2915. This Handbook Series publication on CRP take-out can also be accessed on the World Wide Web Home Page here in pdf format (3mb)(http://pnwsteep.wsu.edu) -- Pacific Northwest STEEP Conservation Farming Systems Technology Source. For more information on the CRP take-out research project, contact the project leaders:
The Pacific Northwest Conservation Tillage Handbook is a large three-ring binder handbook that is updated with new and revised Handbook Series publications. It currently contains 135 Handbook Series publications on new PNW research developments in crop management systems for conservation tillage. The Handbook can be purchased for $20 through PNW county extension offices or by calling the state Extension publications offices (Idaho - 208-885-7982; Oregon - 451-737-2513; Washington - 509-335-2999). The entire Handbook is being put on the World Wide Web Home Page (http://pnwsteep.wsu.edu) on Pacific Northwest STEEP Conservation Farming Systems Technology Source. PNW Conservation Tillage Handbook Series publications are jointly produced by University of Idaho Cooperative Extension System, Oregon State University Extension Service and Washington State University Cooperative Extension. Similar crops, climate, and topography create a natural geographic unit that crosses state lines in this region. Joint writing, editing, and production prevent duplication of effort, broaden the availability of faculty, and substantially reduce costs for the participating states.
For herbicide application recommendations, refer to product labels and the Pacific Northwest Weed Control Handbook, an annually revised extension publication available from the extension offices of the University of Idaho, Oregon State University and Washington State University. To simplify information, chemical and equipment trade names have been used. Neither endorsement of named products is intended, nor criticism implied of similar products not mentioned.
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