2001 Table of Contents

2001 STEEP III Progress Report

TITLE:

No-till Sowing into Standing Irrigated Stubble Instead of Burning

INVESTIGATORS:

William Schillinger (PI), WSU research agronomist, Lind
Harry Schafer, WSU research technician, Lind
Bruce Sauer, WSU farm manager, Lind
Tim Paulitz, USDA-ARS plant pathologist, Pullman
Ann Kennedy, USDA-ARS soil microbiologist, Pullman
Doug Young, WSU agricultural economist, Pullman
Don Wysocki, OSU extension soil scientist, Pendleton
Kurt Schroeder, WSU graduate student, Pullman
Candis Claiborn, WSU civil engineer, Pullman

GROWER ADVISORS:

Neil Fink, Clark Kagele, Keith Schafer, Jeff Schibel, and Gary Schell are deep-well irrigators in east-central Washington. John Aeschliman and Perry Dozier are dryland growers in the high-precipitation zone of Washington. These growers actively encouraged this type of research and helped design the project. They will serve as advisors throughout the life of the project.

INTERIM REPORT:

First year

OBJECTIVES:

The objective of this long-term (6-year) project is to determine the feasibility of direct seeding into high levels of residue as a substitute for burning in irrigated cropping systems. Specific objectives are to:

1. Test a 3-year crop rotation of winter wheat - spring barley - winter canola. Crops will be sown with a Cross-slot no-till drill into (i) standing stubble, (ii) after mechanical removal of stubble, and (iii) after burning the stubble. An additional treatment of annual winter wheat sown after stubble burning + moldboard plowing (sown with a double-disc drill) will be included as a check.
   
2. Evaluate and develop effective techniques for sowing crops into heavy surface stubble using no-till methods.
   
3. Document cumulative effects of a diverse no-till crop rotation under three stubble management practices on soil physical and biological properties, water use efficiency, diseases, weed ecology, and farm economics. Compare these effects to those under the check treatment (i.e., continuous winter wheat after stubble burning + moldboard plowing).

KEY WORDS:

Heavy residue, no-till, irrigated, diverse rotations, stubble burning.

STATEMENT OF PROBLEM:

Many deep-well irrigators in east-central Washington practice a continuous winter wheat rotation (i.e., grow winter wheat on the same field every year). Irrigated wheat grain yields range from 90-to 140-bushels per acre with residue production of 10,000 pounds or more per acre. After grain harvest in August, the traditional practice is to burn the stubble and invert the surface soil with moldboard plow tillage in preparation for sowing in September. Generally, growers feel they need to burn their fields because high residue levels hamper sowing. Alternatives to field burning are needed to reduce smoke emissions and maintain air quality.

Another reason why irrigated growers burn and moldboard plow winter wheat stubble is to control downy brome, a winter annual grass weed. Previous research has shown that long-term control of downy brome is very difficult in continuous irrigated winter wheat using no-till. Therefore, new crop rotation and stubble management strategies are needed to make no-till (without burning) work.

AGRONOMIC ZONE OF INTEREST:

Irrigated. The research is also applicable to the high precipitation zone where cereal stubble after harvest may exceed 10,000 lb/acre.

ABSTRACT OF RESEARCH FINDINGS:

An irrigated cropping systems study was initated in 2000 at the WSU Dryland Research Station at Lind. The crop rotation is 3-year winter wheat - spring barley - winter canola sown i) directly into standing stubble, ii) after mechanical removal of stubble, or iii) after burning the stubble. The traditional practice of continuous annual winter wheat sown after burning and moldboard plowing is also included as a check treatment. First year (2001) grain yields averaged across residue and soil management treatments was 74 bu/a for winter wheat, 2.93 t/a for spring barley, and 2450 lb/a for canola with no significant yield differences within any crop. Winter wheat yields were lower than anticipated due to a late May frost. Over-winter water storage/retention was significantly reduced in all in plots where residue was burned in the fall. For winter wheat as well as for spring barley, Rhizoctonia and take-all root disease were low in all residue management treatments.

RESULTS AND INTERPRETATION:

This study was initated on 10 acres of prime cropland at the Washington State University Dryland Research Station at Lind. To obtain baseline residue levels to begin the experiment, the entire 10 acres was planted uniformly to Madsen winter wheat in September 1999. Grain yield (harvest August 2000) was 110 bu./a and straw production exceeded 10,000 lb/a.

Beginning in the 2001 crop year, a 3-year crop rotation of winter wheat - winter canola - spring barley was grown under three stubble management methods. These are sowing crops: i) directly into standing stubble, ii) after mechanical removal of stubble (i.e., after swathing and bailing), and iii) after burning of stubble. A check treatment of continuous annual winter wheat sown after stubble burning + moldboard plowing is also included. The experimental design is a split-split plot with four replications. Each portion of the 3-year no-till crop rotation in each stubble management method is sown each year. Thus there are 40 plots (3 crops x 3 stubble management practices + the check continuous winter wheat x 4 replications).

2001 Crop Year.
A complete list of field operations for the 2001 crop year are shown in Table 1. Hand broadcasting winter canola and then applying irrigation water resulted in spotty and inadequate stands. For this reason, spring canola was substituted for winter canola in 2001. We also had difficulty planting winter wheat into fresh winter wheat stubble in excess of 10,000 lb/a (this is not part of the crop rotation but was necessary in the fall of 2000 to begin the rotation cycle). Planting spring barley into winter wheat stubble was not a problem because over-winter decomposition made the straw fairly friable. The Cross-slot no-till drill did not do well in the traditional check plots that had been burned and moldboard plowed. Grain yields for the 2001 crop year are shown in Table 2. There was variability in grain yield among replications, resulting in no significant differences within residue management treatments. Spring barley was pleasant surprise because it was easy to establish, there were no weeds, and grain yields were excellent. A total of 15 inches of irrigation water (6" fall, 9" spring) plus 9 inches of precipitation was used to produce these crops.

Table 1. Generalized list of field operations for the 2001 crop year.

Aug:

• Broadcast winter canola seed (8 lb/a) before winter wheat harvest in standing stubble and mechanical removal plots.
  
• Mechanically remove stubble by swathing and bailing in 3-year rotation.
  
• Burn stubble in 3-year rotation.
  
• Burn stubble in the annual winter wheat plots.

Sept.

• Broadcast winter canola (8 lb/a) in burned 3-year rotation.
  
• Broadcast dry fertilizer (120 N, 30 P, 30 S) in all winter canola plots.
  
• Irrigate 6 inches all plots (including standing stubble in 3-year rotation).
  
• Moldboard plow and pack conventional continuous winter wheat plots.
  
• Apply post-harvest herbicide (glyphosate @ 22 oz./a) to no-till plots if needed.
  

Oct.

• Sow winter wheat (100 lb/a) and apply liquid fertilize (120 N, 30 P, 30 S) to all winter wheat plots in one pass using the Cross-slot drill.
  
• Apply grass herbicide (Assure II @ 8 oz/a) to winter canola plots.

March

• Kill poor stand of winter canola with glyphosate @ 20 oz/a.

Apr.

• Sow spring barley @ 100 lb/a and fertilize 120 N, 30 P, 30 S with Cross-slot drill.
  
• Top dress winter wheat with granular nitrogen.
  
• Sow spring canola @ 10 lb/a with 20 N, 5 P, 10 S (as a substitute for failed winter canola).
  
• Apply 1.5 pints bronate in-crop broadleaf herbicide in winter wheat.

May

• Apply 1.5 pints bronate in-crop broadleaf herbicide in spring barley.
  
• Irrigate 3 inches all plots.

June

• Irrigate 6 inches all plots.

Aug:

• Harvest winter wheat, spring canola, and spring barley.
  
• Cycle begins again.

Table 2. Grain yields of winter wheat, spring barley, and spring canola in 2001 as affected by various stubble and soil management practices.

Soil Water Content.
Soil water content in all 40 plots is measured to a depth of six feet by neutron attenuation in August (just after harvest) and again in April before irrigation water is applied. In April 2001, the stubble burn residue management treatment had an average of 2.1 inches less soil water compared to the standing stubble treatment (Table 3). These data well illustrate the accelerated soil water evaporative loss that occurs over winter from a bare soil surface compared to a soil surface covered with residue.

Table 3. Soil water content in the 6-foot profile in April 2001 (before spring irrigation) and in August after grain harvest with three crops and various stubble and soil management practices. The stubble was 10,000 lb/a from winter wheat in the 2000 crop year.^x

^x Within-column averages followed by a different letter are significant at the 5% level.
^y All plots received six inches of irrigation water in September 2000.

Weeds.
Weeds within a 3 sq. yard area were identified by species, counted, and collected just before grain harvest in all plots. Samples were allowed to dry in a low-humidity greenhouse for several weeks before recording their dry weight. Weeds per unit area were lowest in the burn no-till and burn + moldboard plow winter wheat treatments but there were no differences in spring barley or spring canola (Table 4). We achieved excellent stands of spring barley and there were no weeds in any of the residue management treatments for barley (Table 4).

Table 4. Weeds per unit area in winter wheat, spring barley, and spring canola measured just before grain harvest in 2001 as affected by various stubble and soil management practices.^{x y}

^x Within-column averages followed by a different letter are significantly different at the 5% probability level.
^y Percentage composition of weed species in the total population averaged across treatments was: downy brome, 42.7% (but found only winter wheat); Russian thistle, 13.6%; prickly lettuce, 10.4%; mares tail, 9.5%; other weeds, 23.8%. Other weeds were tumble mustard, tansy mustard, wild oat, field pennycrest, western salsify, and sowthistle.

Diseases.
For winter wheat (Table 5), the least take-all was measured in the standing stubble, whereas the least Rhizoctonia was in the stubble burned treatment. The total root length and surface area were less in the burn + moldboard plow treatment compared to the standing stubble and mechanical stubble removal treatments (Table 6). These data paralleled the data for number of tillers (i.e., the standing stubble and mechanical removal had a greater number of tillers). These differences are probably a reflection of plant stand (data not shown) which was greatest in the burn no-till and burn + moldboard plow treatments. Level of take-all and Rhizoctonia were at relatively low levels.

For spring barley, the levels of take-all were extremely low compared to winter wheat (Table 7). Rhizoctonia levels were higher on barley compared to winter wheat, but there were no differences among residue management treatments in spring barley in terms of root infection, number of crown roots, or number of tillers. The same lack of difference was seen in root length measurements (Table 8) where overall levels of Rhizoctonia and take-all were low in all residue management treatments.

The only disease data available with canola is for Rhizoctonia. More Rhizoctonia was isolated from the standing stubble than from the other residue management treatments (data not shown).

Table 5. Plant measurements and root disease ratings for winter wheat grown at Lind, WA using various management practices^x.

^x Plants were sampled on 5/9/01 for agronomic measurements and Rhizoctonia root rot disease evaluation, and a second sampling was made on 6/27/01 to evaluate roots for take-all.
^y Number of seminal roots with Rhizoctonia root rot symptoms divided by the total number of roots.
^z Values with the same letter are not significantly different using Fischer's (LSD) test at P = 0.05.

Table 6. Root architecture measurements for winter wheat grown at Lind, WA using various management practices^y.

^y Plants were sampled on 5/9/01 for root measurements, which were made using WinRHIZO V5.0a.
^zValues with the same letter are not significantly different using Fischer's (LSD) test at P = 0.05.

Table 7. Plant measurements and root disease ratings for barley grown at Lind, WA using various management practices^x

^x Plants were sampled on 5/9/01 for agronomic measurements and Rhizoctonia root rot disease evaluation, and a second sampling was made on 6/27/01 to evaluate roots for take-all.
^y Number of seminal roots with Rhizoctonia root rot symptoms divided by the total number of roots.
^z Data were analyzed using Fischer's (LSD) test and none of the values were found to be significantly different at P = 0.05.

Table 8. Root architecture measurements for barley grown at Lind, WA using various management practices^y.

^yPlants were sampled on 5/9/01 for root measurements, which were made using WinRHIZO V5.0a.
^zData were analyzed using Fischer's (LSD) test and none of the values were found to be significantly different at P = 0.05.

2002 Crop Year.
Due to the failure to achieve adequate stands of winter canola following winter wheat in 2000, project researchers and growers decided to modify the crop rotation. Instead of winter wheat - winter canola - spring barley, the new rotation (which began in August 2001) is winter wheat - spring barley - winter canola. We had very good success sowing winter canola into barley stubble just after harvest and then applying six inches of irrigation water. The flush of volunteer barley that occurred after irrigating was controlled with Assure II grass herbicide. There were no differences in winter canola stand establishment in 2001 among any of the residue management treatments (data not shown). We had no difficulty sowing spring barley into winter wheat stubble (after it had a winter season to partially decompose) during the first year of the study, thus we have confidence in this method. Similarly, sowing winter wheat into canola stubble presents no problem.

PUBLICATIONS AND PRESENTATIONS (Current year only)

Schillinger, W., H. Schafer, B. Sauer, A. Kennedy, D. Young, D. Wysocki, and T. Paulitz. 2001. No-till seeding into standing irrigated stubble instead of burning. pp. 95-97. In: 2001 Field Day Proceedings: Highlights of Research Progress. Department of Crop and Soil Science Technical Report 01-4, Washington State University, Pullman, WA.

This project was shown and discussed by Schillinger and Paulitz to 160 people at the Lind Field Day on June 14, 2001. In addition, a researcher-grower advisory meeting for this project was held at Lind on November 20, 2001 (15 attended).

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