2000 Table of Contents

2000 STEEP III Progress Report

RESEARCH PROJECT TITLE: Long-Term Alternative Crop Rotations Using No-Till in Low-Rainfall Dryland Areas: Years 4 through 6.

INVESTIGATORS:

William Schillinger (PI), WSU Research Agronomist, Lind
Ron Jirava, Grower, Adams County
Brad Wetli, Grower, Douglas County
R. James Cook, WSU Plant Pathologist, Pullman
Neil Christensen, OSU Extension Soil Scientist, Corvallis
Ann Kennedy, USDA-ARS Soil Microbiologist, Pullman
Harry Schafer, WSU Agricultural Research Technician, Lind
Doug Young, WSU Agricultural Economist, Pullman
Bruce Sauer, WSU Farm Manager, Lind
Ghana Giri, WSU Graduate Student, Pullman
Keith Saxton, USDA-ARS Hydrologist, Pullman

DURATION: Fourth of six years. This study is a continuation of a STEEP-funded project with the same title (years 1 through 3).

OBJECTIVES:

The objective of the study is to determine the long-term feasibility of diverse, cereal-based, no-till cropping systems for low-rainfall dryland areas of the inland Pacific Northwest. Specific objectives are:

1. Evaluate and compare three long-term no-till annual spring cropping systems: (i) a 4-year safflower/yellow mustard/wheat/wheat rotation; (ii) a 2-year wheat/barley rotation, and (iii); continuous wheat.
   
2. Measure the effects of the three annual spring-sown rotations on root disease, soil moisture dynamics, and grain yield of wheat.
   
3. Record weed species shifts and weed ecology as related to no-till sowing and alternative annual spring cropping systems.
   
4. Document the long-term cumulative effects of minimum disturbance no-till sowing practices on physical and biological properties of the surface soil.
   
5. Evaluate the agronomic and economic of potential of diverse annual spring cropping compared with winter wheat/summer fallow.
   
6. Through field days, research reports, and winter meetings, demonstrate and promote no-till and alternative farming practices to growers and agricultural support personnel.
   

KEY WORDS: No-till, low-rainfall, alternative rotations, dryland

STATEMENT OF PROBLEM:

Farming in the dryland areas of the Pacific Northwest (less than 12 inch annual) has been mostly an intensive tillage-based wheat-fallow system since the land was broken out of native grassland and sage in the 1880s. Tillage is well known to accelerate the loss of soil organic matter by increasing biological oxidation and often by increasing soil erosion. The loss is exacerbated with fallow because oxidation of carbon exceeds carbon input from crop residues during the 2-year cycle. Because of the decline in organic matter and associated soil quality, most tillage-based farming systems in dryland environments are not sustainable in the long-term. Options for maintaining and improving soil quality in the drylands are to simultaneously increase the cropping intensity and reduce or eliminate tillage.

ZONE OF INTEREST: The low-rainfall (6-to 12-inch annual) dryland area of east-central Washington and north-central Oregon. This zone encompasses 3.5 million cropland acres.

ABSTRACT OF RESEARCH FINDINGS:

We have completed four years of a planned six-year study to compare three no-till annual spring cropping systems: (i) a 4-year safflower/yellow mustard/wheat/wheat rotation; (ii) a 2-year wheat/barley rotation, and (iii); continuous wheat. Experiment sites are located in Adams and Douglas counties.

Rhizoctonia root rot bare patches in wheat and barley covered 5.4 and 8.4% of total plot area in Adams county in 1999 and 2000, respectively. Rhizoctonia infection was just as severe in safflower and yellow mustard as in cereals. Data from a nutrient study conducted at the Adams county site in 2000 overwhelmingly support the conclusion that micronutrient deficiencies are not a factor contributing to the appearance of Rhizoctonia root rot. Russian thistle is the dominant weed at both sites. Because no labeled in-crop herbicides are available for safflower and yellow mustard, Russian thistle presents a formidable obstacle to successful production of these crops in low-rainfall dryland regions. Safflower and yellow mustard extract up to two inches more water from the soil profile than spring wheat. The water deficit after growing deep-rooted broadleaf crops may continue for several years after the rotation reverts back to spring wheat. In addition, soil water storage efficiency during the winter after safflower and yellow mustard is generally reduced compared with after wheat or barley. The 4-year grain yield average for annual no-till soft white spring wheat and barley at the Adams county site is 43 bu/a and 1.37 t/a, respectively, thus there is wide-spread grower interest in this study.

RESULTS AND INTERPRETATION:

This study was initiated in 1997 at two locations. The Adams county site is on the Ron Jirava farm near Ritzville. Precipitation at the Jirava site averages 11.5 inches, elevation is 1850 ft asl, and the soil is a deep Ritzville silt loam. The second research site is located northwest of Mansfield in Douglas county on the Brad Wetli farm. Annual precipitation at the Wetli site is 10.5 inches, elevation is 2700 ft asl, and depth of the Touhey loam soil averages only 2.5 feet.

The plot design at both sites is a randomized complete block with four replications. We are testing three spring-sown cropping systems: 1) a 4-year safflower/yellow mustard/wheat/wheat rotation; 2) a 2-year wheat/barley rotation and; 3) continuous wheat. All phases of all rotations are sown each year (i.e., 28 plots at each site). The experiment covers 20 acres in Adams county and 8 acres in Douglas county. All crops are sown with an 8-foot-wide Cross-slot drill which causes minimal soil disturbance and delivers seed and all fertilizer in one pass. Fertilizer rate (nitrogen, phosphorous, and sulfur) is held constant in all plots at each site and is based on soil test and soil moisture availability.

Sowing and Soil Water: As with previous years, glyphosate was applied at 16 oz./acre at both locations at least three weeks before sowing in 2000. All crops at both sites were sown with the Cross-slot drill. Seeding rates were 70, 70, 40 and 10 lb/acre for wheat (Alpowa), barley (Baronesse), safflower, and yellow mustard, respectively. Solution 32 (NH4NO3 + urea) provided the base for liquid fertilizer applied with the drill to supply 35 lb N, 10 lb P, and 15 lb S per acre in Adams county (sown on April 10-11, wheat yield goal 40 lb/a) and 30 lb N, 10 lb P, and 10 lb S per acre in Douglas county (sown on May 2, wheat yield goal 25 bu/a).

Total water content in the 6-ft soil profile in Adams county in April 2000 ranged from 8.73 inches (after safflower or yellow mustard) to 11.1 inches (continuous wheat). Soil water data from the Adams county site and from a related study at the WSU Dryland Research Station show safflower and yellow mustard extract up to two inches more water from the soil profile than spring wheat. This water deficit after growing deep-rooted broadleaf crops may continue for at least three years after the rotation reverts back to spring wheat (data not shown). In addition, soil water recharge during the winter after safflower and yellow mustard is generally reduced compared with after wheat or barley, presumably because the broadleaf crops leave less standing residue.

Table 1. Plant stand establishment of four crops sown no-till in long-term cropping systems studies in Adams and Douglas counties in 1997, 1998, 1999 and 2000.

* All crops were sown into spring wheat stubble in 1997, which was the first year of the study. A Flexi-coil 6000 drill was used in 1997, 1998, and 1999 at the Adams county site. A Cross-slot drill was used in Douglas county during all years and in Adams county beginning in 2000.

Plant Stand Establishment: In previous years (1997-1999), plant stand establishment of safflower and yellow mustard were hampered at the Adams county site when plots were sown with the Flexi-Coil 6000 drill. In 2000, we sowed all crops in Adams county with the Cross-slot drill, and stand establishment for the broadleaf crops was markedly improved compared with previous years (Table 1). In Douglas county, stand establishment with the Cross-slot drill has been adequate during all years, except 2000, when yellow mustard stands were poor (Table 1) due to a dry seed zone in the top one inch of soil.

Weeds: Russian thistle was again a problem weed in safflower and yellow mustard at both sites. In mid-August 2000, there were an average 17 and 16 Russian thistles per ft2 at Adams county and 24 and 12 Russian thistle per ft2 at Douglas county in yellow mustard and safflower, respectively. Russian thistle was only a minor problem in spring cereals in Douglas county (in-crop herbicide was 12 oz./a LV-6). In Adams county, the in-crop cereal herbicide was 8 oz. LV-6 + 0.3 oz./a Harmony Extra. A 0.2 inch rain in May (after herbicide application) caused a flush or Russian thistles in Adams county, and by mid-August an average of 4 Russian thistles per ft2 infested spring cereals. Surefire herbicide was applied to all plots at both sites after harvest to prevent seed production by Russian thistle. Comprehensive data sets on weed populations in all crops at both sites have been collected since the beginning of this project in 1997 (data not shown).

Mares tail, prickly lettuce, and tansy mustard were minor weeds at both sites in 2000. An experiment to determine seed germination characteristics, growth, and timing and extent of seed production of mares tail and prickly lettuce was initiated by WSU graduate student Ghana S. Giri in 2000.

Crop Yields: Grain yields from all crops during all years from both sites are shown in Tables 2 and 3. Crop year (Sept. 1999 -Aug. 2000) precipitation in Adams county was 12.15 inches. Soft white spring wheat grain yield across treatments averaged 41 bu/a, which was slightly greater than average for the area. Second year wheat after broadleaf crops produced significantly less yield (38.1 bu/a) than wheat after barley (44 bu/a, Table 2). We suspect that these differences are due to less water available to the subsequent crops after growing broadleaf crops (data not shown). However, there was no significant yield decline in first year wheat after broadleaf crops, indicating that a beneficial rotation affect may be occurring which might offset the greater soil water depletion with broadleaf crops. Spring barley produced 1.3 tons/a in 2000, which was good in comparison to neighboring fields. Safflower and yellow mustard yields in 2000 were below optimum in Adams county due to heavy infestation of Russian thistle. Yellow mustard has been successful in only one year in four in Adams county (Table 2).

Yellow mustard and safflower have never done well in Douglas county, possibly due to cool temperatures and shallow soils (2.5 feet). Spring cereal yields in 2000 in Douglas county were below those of previous years (Table 3), despite average precipitation at the site. We speculate that seedlings may not have had access to adequate early-season fertilizer, as the Cross-slot drill delivers fertilizer to the side of the seed, and no substantial rainfall occurred to move nitrogen further into the soil profile until several weeks after sowing. There have never been any differences in spring wheat grain yield as affected by rotation in Douglas county (Table 3).

Table 2. Crop yields in three rotations in Adams county: a 4-year safflower/yellow mustard/wheat/wheat rotation; a 2-year wheat/barley rotation and; continuous spring wheat. All crops were direct sown with a Flexi-Coil 6000 drill in 1997, 1998, and 1999, and with a Cross-slot drill in 2000.

* All crops were sown into spring wheat stubble in 1997, which was the first year of the study.
** Wheat yields among treatments were not significantly different at the 5% probability level in 1998 nor in 1999. Within column wheat yield means in 2000 followed by different letters are significantly different at the 10% probability level.

Table 3. Crop yields in three rotations in Douglas county: a 4-year safflower/yellow mustard/wheat/wheat rotation; a 2-year wheat/barley rotation and; continuous spring wheat. All crops were direct sown with a Cross-slot drill.

* All crops were sown into spring wheat stubble in 1997, which was the first year of the study.
** Wheat yields among treatments were not significantly different at the 5% probability level in 1998, 1999, or 2000.

Rhizoctonia Root Rot: Severe infection of Rhizoctonia root rot occurred in wheat and barley at the Adams county site in 1999 and again in 2000. The clearly visible Rhizoctonia patches were mapped with a global positioning unit (data not shown). Though cereal grain yields in Adams county were quite satisfactory in 2000, the percent of land area with Rhizoctonia patches increased in all cereal treatments from 1999 to 2000 (Table 4).

We have been surprised to find the high incidence of Rhizoctonia severity in the four-year rotation where wheat follows two years of broadleaf crops. A survey conducted in May 2000 by Richard Smiley, OSU plant pathologist, showed that root lesion nematodes were not present at the Adams county site and therefore these parasites are not associated with the stunted plant growth within the patches. There were no significant differences in area infected by Rhizoctonia in 2000 when all treatments were analyzed together. However, when the wheat treatments were analyzed separately, continuous wheat had significantly (P = 0.02) more Rhizoctonia than either wheat after barley or first year wheat after broadleaf crops (Table 4).

Table 4. Percent land area in each treatment with Rhizoctonia root rot patches at the Adams county site in 1999 and 2000 as measured by a global positioning system.

Rhizoctonia-Zinc Association Study: In 2000 we superimposed experiments in the cropping systems plots in Adams county to study the possible association of zinc with Rhizoctonia disease. The objective of this study was to determine whether application of zinc (Zn) fertilizer would reduce the incidence or severity of Rhizoctonia root rot bare patch. Soil was sampled to a depth of six inches prior to planting. Two composite soil samples were collected from within each of four replications. One sample was from an area infected by Rhizoctonia root rot in 1999 while the other sample was from an area without Rhizoctonia symptoms. Soil samples were air dried for several days before submission to the Central Analytical Laboratory (CAL) at Oregon State University for analyses. Samples were analyzed for pH (1:2 H20), P (NaHCO3 extractable), K, Ca and Mg (NH4 acetate extractable), Cu, Mn and Zn (DTPA extractable), SO4-S (Ca phosphate extractable) and total N (Leco CNS-2000 Macro Analyzer).

One 8-foot drill pass through each 60-ft.-wide plot also received 1 lb Zn/acre as a Zn chelate mixed with Solution 32. Continuous spring plots were sampled to assess the nutrient status of plants. Entire aboveground wheat plants at heading were collected from within three areas in each replication. Samples included 1) healthy plants from drill strips where Zn was not applied, 2) healthy plants from drill strips receiving Zn, and 3) stunted plants from bare patches in drill strips receiving Zn. Plant samples submitted to the CAL were oven dried prior to microwave digestion and analysis for P, K, Ca, Mg, Mn, Cu, B, and Zn using a Perkin Elmer Optima 3000DV inductively-coupled plasma emission spectrometer. Samples were also analyzed for total C, N and S using the Leco CNS-2000 Macro Analyzer. Nutrient concentration data were subjected to an analysis of variance and means were compared using least significant differences when the F statistic indicated significant differences at the 0.05 probability level.

Laboratory analyses revealed only minor differences between soil samples collected in and out of Rhizoctonia root rot bare patches (data not shown). Soil pH and extractable K were lower, and Mn was higher, in areas where bare patch was observed the previous year. Despite being statistically significant, these differences are unimportant from an agronomic standpoint. Soil pH in the 6.1 to 6.2 range indicates that elemental toxicities were absent and that soil reaction was favorable for plant availability of both macro- and micronutrients. Even though K soil test concentrations ranged from 285 to 562 ppm, the lowest concentration exceeded the threshold for wheat response to applied K. Similarly, DTPA extractable micronutrients exceeded critical concentrations of Cu (0.20 ppm), Mn (1.0 ppm) and Zn (0.80 ppm) reported for corn, a Zn sensitive species.

Nutrient concentrations in plants were all within the sufficiency range reported for small grains (data not shown). Concentrations in healthy plants were not significantly affected by Zn fertilizer application at planting. In contrast, Mn, Zn and B concentrations were significantly higher in stunted plants from bare patch areas as compared to healthy plants. Stunted plants tended to have lower K and higher N concentrations than did healthy plants. Higher concentrations of Mn, Zn, B and N are probably a "concentration effect" related to stunting of plants by Rhizoctonia root rot. The tendency for lower K concentration in stunted plants may be a consequence of reduced root growth.

The soil test for DTPA extractable Zn indicated that wheat was highly unlikely to respond to Zn fertilizer application. An adequate supply of Zn for wheat was confirmed by Zn concentrations in plant tissue and by the absence of a visual response to Zn fertilizer applied in drill strips through each replicated treatment in all three crop rotations. Besides having no effect on the growth and nutrient concentration of healthy plants, Zn application had no visual impact on the incidence or severity of Rhizoctonia root rot bare patches. These data and visual observations overwhelmingly support the conclusion that micronutrient deficiencies are not a factor contributing to the appearance of Rhizoctonia root rot in the cropping systems study at the Ron Jirava farm in Adams County.

Table 5. Soil analyses for samples collected in April 2000 from areas with and without Rhizoctonia bare patch in 1999.

Table 6. Plant nutrient concentrations as influenced by Zn fertilizer application and absence or presence of Rhizoctonia bare patch in 2000.

Figure 1. Map of Rhizoctonia root rot infected areas in wheat and barely in 1999 (A) and in wheat, barley, safflower and yellow mustard in 2000 (B). Data are from the long-term alternative cropping systems study at the Ron Jirava farm near Ritzville, WA. Rhizoctonia infection is expressed as the percent of total area per plot.

Figure 2. Soil water in the six-foot soil profile after crop harvest (fall) and just before planting (spring) at the cropping systems research site on the Ron Jirava farm in Adams County, WA. Note that soil water content was consistently reduced after two years of broadleaf crops (e.g. after yellow mustard) compared with continuous spring wheat, and that the soil water deficit may continue for several crop cycles.

INTERACTION WITH OTHER SCIENTISTS CONDUCTING RELATED ACTIVITY:
In addition to the co-investigators of this project, the PI is cooperating with: Doug Young, WSU Pullman, on economic evaluation of reduced tillage systems at Lind as well as no-till spring wheat vs. winter wheat-fallow in the Horse Heaven Hills; Roger Veseth, WSU/UI Moscow, on cropping systems technology transfer; Don Wysocki, OSU Pendleton, on irrigated cropping systems research at Lind; Keith Saxton, USDA-ARS Pullman, on Cross-slot drill technology; Kim Campbell, USDA-ARS Pullman, on winter wheat seedling emergence; Frank Young, USDA-ARS, on the Ralston integrated spring cereal project; and Dan Ball, OSU Pendleton, on evaluation of narrow leaf lupines. The authors thank Richard Smiley, OSU Plant Pathologist, for his research in 2000 on root lesion nematodes at the Adams County cropping systems site.

REFERENCES :
Christensen, N.W. 2000. Impact of zinc application on Rhizoctonia root rot. pp. 3 (personal communication).

Smiley, Richard. 2000. Survey of root lesion nematodes in PNW dryland crops. pp. 10 (personal communication).

PUBLICATIONS AND PRESENTATIONS: (current year only):

Published Abstracts

Schillinger, W.F. 2000. Russian thistle infestation in dryland spring cereals. Crop Science Society of America annual meeting, 5-9 Nov., Minneapolis, MN. ASA, CSSA, and SSSA Abstracts p. 132.

Schillinger, W.F., and F.L. Young. 2000. Soil water recharge after annual no-till spring wheat vs. winter wheat-fallow. Western Society of Crop Science annual meeting, 18-21 June, Moscow, ID. ASA, CSSA, and SSSA Abstracts.

Popular Publications

Schillinger, W. 2000. Residue retention and water storage in low-rainfall systems. Wheat Life Vol. 43, 7:24-25.

Experiment Station Research and Extension Reports

Albrecht, S.L., W.F. Schillinger, and C.L. Douglas. 2000. Soil microbial activity in annual spring wheat and wheat-fallow rotations in the very low rainfall areas of the Columbia Plateau. pp. 24-28. In: 2000 Columbia Basin Agric. Research Center Annual Report. Special Report 1012, Pendleton, OR.

Schillinger, W.F. 2000. Residue retention and water storage in low-rainfall systems. pp. 58-61. In: 2000 Field Day Proceedings: Highlights of Research Progress. Department of Crop and Soil Science Technical Report, Washington State University, Pullman, WA.

Schillinger, W., R. Jirava, B. Wetli, R.J. Cook, et al. 2000. Alternative dryland crop rotation research using no-till: The first three years in Adams and Douglas counties. pp. 62-69. In: 2000 Field Day Proceedings: Highlights of Research Progress. Department of Crop and Soil Science Technical Report 00-1, Washington State University, Pullman, WA.

Cook, R.J., S. Ullrich, and W. Schillinger. 2000. Performance of advanced line and varieties of spring barley seeded directly into wheat or barley stubble. pp. 84-85. In: 2000 Field Day Proceedings: Highlights of Research Progress. Department of Crop and Soil Science Technical Report 00-1, Washington State University.

Dofing, S., W. Schillinger, H. Schafer, and P. Reisenhauer. 2000. Crop management practices for direct-sown cereals. pp. 95-97. In: 2000 Field Day Proceedings: Highlights of Research Progress. Department of Crop and Soil Science Technical Report 00-1, Washington State University.

CONFERENCE PROCEEDINGS:

Schillinger, W.F. 2000. Residue retention and water storage in low rainfall systems. pp. 11-17. In: Proceedings of the Northwest Direct Seed Cropping Systems Conference, D. Wysocki (ed.), 4-6 January, 2000, Pendleton, OR.

Schillinger, W.F., R.J. Cook, D.L. Young, A.C. Kennedy, and K.E. Saxton. 2000. Alternative no-till cropping systems research in the semiarid Pacific Northwest USA. In: Proceedings of the 11th Meeting of the International Soil Conservation Organization, 22-27 October, 2000, Buenos Aries, Argentina.

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