Grower Direct Seed Pea Trials
in Eastern Washington and Northern Idaho

Roger Veseth, WSU/UI Conservation Tillage Specialist, Moscow; Duncan Cox, UI/WSU Project Support Scientist, Moscow;
Stephen Guy, UI Crop Management Specialist, Moscow; Donn Thill, UI Weed Scientist, Moscow;
John Hammel, UI Soil Scientist, Moscow; Tim Fiez, WSU Soil Fertility Specialist, Pullman;
and Joe Yenish, WSU Weed Scientist, Pullman.

 

Some revolutionary changes in tillage practices for spring dry pea, lentil and other spring grain legumes are underway in the Inland Northwest. They offer exciting potential benefits in soil erosion control, soil quality, yield potential and profitability. Innovative growers and university scientists have combined efforts to develop integrated management systems for the use of minimum tillage in legume-winter wheat crop sequences. The following is a brief description of why a change is needed and the new management systems that are being developed.

The Need for Change

In the Palouse region, soil erosion can be a serious problem in crop rotations with grain legumes followed by winter wheat. Intensive tillage has traditionally been used to bury the previous cereal crop residue, incorporate herbicides and prepare a finely-tilled, low-residue seedbed for spring grain legumes. Spring field operations when soils are wet can result in significant soil compaction from tractor traffic and tillage implements. The combination of little or no cereal crop residue retained on the soil surface after legume planting and soil compaction from the spring tillage operations can leave legume fields vulnerable to soil erosion during intense rainstorms in the spring and early summer. Soil compaction also can directly reduce crop yield potential.

Grain legumes produce relatively little crop residue, which is fragile and shatters easily during dry harvest conditions, and decomposes rapidly under moist conditions. Even though Palouse growers have made a significant shift towards minimum tillage or direct seeding of winter wheat, surface residue cover from the legume crop alone is often inadequate for erosion control. Without carryover cereal residue preceding the legume crop and prevention of soil compaction often associated with the legume production, a winter wheat crop after grain legumes can be highly vulnerable to erosion during the critical November to April period, when about 70% percent of the yearly precipitation occurs. Winter wheat is usually seeded in October to reduce the risk of a number of weed, insect and disease problems, and/or because of dry soil conditions earlier in the fall. Consequently, the wheat crop usually over-winters as small plants and provides little erosion protection.

Surface runoff and soil erosion can both cause yield losses in grain legume and winter wheat crops. Water running off the fields is water not stored for grain production. The greatest impact would occur on upper slopes and ridgetops where yields are most limited by available water. Erosion can reduce current crop yields by loss of plant stands and reduced plant vigor. Soil loss will also reduce the yields of future crops due to loss of soil fertility, water holding capacity, rooting depth and other soil quality and productivity factors.

A Promising Solution

Some innovative growers in the Palouse have been experimenting with direct spring seeding grain legumes with or without minimum tillage the previous fall. Beginning in 1996, a 3-year research project by scientists from University of Idaho and Washington State University was initiated in to assist growers in developing integrated management systems for direct seeding of grain legumes. The project is partially supported by UI and WSU grants from the STEEP III (Solutions To Environmental and Economic Problems) conservation farming research program in Idaho, Oregon and Washington. The research is a combination of researcher-managed experiments on university research farms and grower fields, and grower-managed, field experiments with field-scale equipment. The grower-managed trials are the focus of this Conference paper. Results from the researcher-managed trials are available in the 1997 and 1998 STEEP III Research Progress Reports.

The goal for growers and scientists is to develop integrated management systems for direct spring seeding of grain legumes. This would retain more of the previous cereal crop residue on the surface and minimize spring soil compaction, thus reducing the potential for runoff and soil erosion, and improving water infiltration. The crop and pest management systems for grain legumes must optimize yield, quality and residue production. In addition, winter wheat planting systems must then continue to retain surface residue from the legume and previous cereal crops, and maintain soil physical conditions for effective water infiltration. The overall goal is to improve erosion control, yield potential and profitability in the legume-winter wheat rotational cycle.

The research effort focuses on the following management considerations:

Need for a Longer Rotation -- An important point to keep in mind is that direct seeding / minimum tillage establishment of spring legumes will be much more successful in a crop rotation of three years or longer, such as winter wheat-spring cereal-legume, than in a 2-year winter wheat-legume rotation. The additional year of spring crop, or a winter non-cereal crop, in the rotation is very important in reducing the potential for soilborne diseases and winter annual grass weeds that can be problems under a direct seed system in a 2-year rotation. In addition, direct spring seeding of grain legumes after spring cereals is easier than after winter wheat because residue levels are usually much lower.

Grower On-Farm Trials

The following are brief descriptions and summaries of preliminary results from eight on-farm tests conducted in 1998 to compare various intensities of tillage and residue management for establishment of spring pea in a cereal - pea - winter wheat rotational sequence. The large-scale trials are established and managed by cooperating growers with their field equipment. All the trials are conducted for a 2-year period beginning in the fall after harvest of a spring or winter cereal, through a pea crop and the subsequent winter wheat crop. Nearly all the trials have compared a spring direct seed system without prior tillage with some type of fall minimum tillage and direct seeding in the spring without any spring tillage. Some of the trials included additional tillage and residue management treatments to address specific grower’s interests and equipment available. All trials have 4 replications of each treatment. Plots range from 30 to 50 feet wide and 700 to 1,500 feet long. Surface residue evaluations were conducted after fall tillage of the cereal crop, before and after pea planting, after pea harvest and after winter wheat planting. Other data collected generally included pea plant stands and yields, winter wheat yield, and monitoring for differences in specific agronomic factors or crop pests.

Wayne Jensen - Genesee, ID -- The second 2-year on-farm trial comparing two tillage practices for spring pea following a 70 bu/A hard white spring wheat was completed in 1998 on the Wayne Jensen farm northwest of Genesee, ID (Table 1). The two treatments following hard white spring wheat were 1) Fall Plow-Spring Cultivate-Seed - fall (1996) moldboard plow with trash boards - spring Pursuit herbicide application and 2X cultivation - seed; and 2) Fall Chisel/Cultivate - Spring Direct Seed - fall chisel - late fall cultivate/harrow - spring Roundup-Pursuit herbicide application - spring direct seed. Both treatments were seeded with a John Deere 455 offset double disc drill. The soft white winter wheat crop was direct seeded that fall with a Yielder double disc drill.

Table 1. Tillage comparison following spring wheat through 1997 spring pea and 1998 winter wheat crops, Wayne Jensen, Genesee, ID - 20-to 24-inch rainfall zone.

 

 

 

 

Treatment

 

 

Pre-plant residue cover

 

 

Post-plant residue cover

 

 

 

 

Spring pea emergence

 

 

 

Spring pea yield

 

 

Post-harvest residue cover

Post-winter wheat planting residue cover

 

 

 

Winter wheat yield

-----------%-----------

plants / ft^2

lb / ac

-----------%----------

bu / ac
Fall Plow-Sp. Cult-Seed

11 B

6 B

10.0

2870

32 B

30 B

109
Fall Chisel-Fall Cult.-Direct Seed

47 A

34 A

9.5

2630

50 A

47 A

108
LSD (5%)

29

8

NS

NS

14

13

NS
C.V. (%)

5.6

16.8

7.6

4.7

14.7

15.2

2.4

Values followed by different letters are significantly different at the 95% confidence level.

The results from this trial show that the minimum fall tillage - direct spring seed system resulted in greater erosion protection with higher surface residue levels after seeding peas and the subsequent winter wheat crop than with the fall plow treatment, 34 vs. 6% and 47 vs. 30%, respectively. There were no differences in plant establishment, pea yield or yield of the following winter wheat crop. The results of this trial are very similar to the results of Jensen’s first trial with these two treatments in 1995-97. In that study, surface residue levels after seeding peas and the subsequent winter wheat crop were 59% and 51%, respectively, in the fall chisel/cultivate - direct spring seed treatment versus 10% and 24% with the fall plow treatment, respectively. There were also no significant differences in spring pea and winter wheat yields between the treatments.

Nathan and Steve Riggers - Nezperce, ID -- Four tillage and residue management systems were compared following a 65 bu/A hard red spring wheat crop west of Nezperce, ID (Table 2). Treatments included: 1) Direct Spring Seed; 2) Spring Burn - Direct Spring Seed; 3) Fall Disc - Direct Spring Seed; 4) Fall Moldboard Plow-Spring Cultivate - Seed

The two treatments with overwinter stubble received a late October application of Roundup. In early April, all treatments except the plow treatment received a second Roundup application. All treatments were seeded with a Flexi-Coil 5000 no-till hoe air-seeder on May 4 with Karita peas, a semi-leafless variety. All the plots were harrowed after seeding. All treatments received separate post-emergence applications of Basagran and Assure II. Winter wheat was direct seeded in the fall with the same Flexi-Coil 5000 no-till hoe airseeder.

Residue groundcover levels and pea yield was highest in the direct seed system (Table 2). Surface residue after pea and winter wheat planting were highest in the direct seeded pea treatments at 72 and 60%, respectively. Pea emergence was not significantly different among the treatments, but lower than expected because the low seed lot germination (<85%) was not known at planting. Direct seed pea yield was significantly higher than burn and plow treatments, with yields in the trial increasing with increasing surface residue levels.

Table 2. Comparison of four tillage and residue management practices following 1997 hard red spring wheat through 1998 spring pea and 1999 winter wheat crops, Nathan and Steve Riggers, west of Nezperce, ID - 24- to 26-inch rainfall zone.

 

 

 

Treatments

 

Post-Pea Planting Residue Cover

 

 

Spring

PeaEmergence

 

 

 

 

Pea Yield

 

Post-Pea Harvest Residue Cover

Post-Winter Wheat Planting Residue Cover

%

plants / ft^2

lb / ac

----------%----------
Direct Seed

72 A

6.7

2435 A

94 A

60 A
Spring Burn-Direct Seed

10 C

6.2

2208 B

82 B

32 C
Fall Disc-Direct Seed

45 B

7.0

2313 AB

90 A

47 B
Fall Plow-Spring Cultivate-Seed

6 C

7.0

1955 C

75 C

28 C
LSD (5%)

10

NS

166

5

6
C.V. (%)

19.7

10.5

4.6

3.7

8.7

Values followed by the same letter are not significantly different at the 95% confidence level.

 

Randy and Larry Keatts - Lewiston, ID -- Five tillage and residue management practices were compared for spring pea following a 1997 soft white spring wheat crop south of Lewiston, ID in a 12- to 16-inch rainfall zone (Table 3). Previous crops were winter wheat (1996), and spring pea (1995). Treatments included: 1) Spring Direct Seed; 2) Spring Burn - Spring Direct Seed; 3) Fall Disc - Spring Direct Seed; 4) Fall Subsoil/Disc - Spring Direct Seed - fall R & R subsoiler - fall disc - direct seed; 5) Fall Chisel - Spring Direct Seed - fall chisel/harrow - direct seed.

The trial received mid-October and early March applications of Roundup. All treatments were seeded to Columbia pea (common type) on March 18 with a Tye no-till disc drill, then harrowed and rolled. Winter wheat was seeded in the fall with a 2-pass systems of direct-shank application of fertilizer and then seeding with the Tye no-till disc drill.

Pea plant stand in the direct seed treatment was lower that most of the other treatments and a difference in seeding depth between fall-tilled treatments and the direct seed treatment in undisturbed residue likely contributed to the lower plant stand. The field trial was seeded as one field and it was difficult to set seeding depth accurately for all treatments. Consequently, direct seed plots in undisturbed residue were seeded shallower than desired (½-1 inch) and tilled plots were seeded slightly deeper than desired (2-3 inch). This shows the importance of selecting and setting a direct seed drill to give good seed placement.

The direct seed treatment maintained the highest percent surface residue for erosion control after pea and winter wheat planting, 83 and 49%, respectively. Pea yield was not significantly different among treatments.

Table 3: Comparison of tillage and residue management practices following a 1997 soft white spring wheat crop through 1998 spring pea and 1999 winter wheat crops. Randy and Larry Keatts, Lewiston, ID -12- to 16-inch rainfall zone.

 

 

 

 

 

Treatments

 

 

 

Pre-plant surface residue cover

 

 

Post-plant surface residue cover

 

 

 

 

 

Spring pea emergence

 

 

 

 

 

Spring pea yield

 

 

Post-harvest surface residue cover

Post-winter wheat planting surface residue cover

----------%----------

plants / ft^2

lb / ac

----------%----------
Direct Seed

100 A

83 A

8.0 C

1158

93 A

49 A
Spring Burn-Direct Seed

100 A

19 C

10.4 A

1269

83 B

30 B
Fall Disc-Direct Seed

52 B

40 B

9.8 AB

1048

84 B

35 B
Fall Subsoil/Disc-Dir. Seed

47 B

32 B

8.8 BC

1121

78 B

31 B
Fall Chisel-Direct Seed

47 B

36 B

9.5 AB

962

79 B

32 B
LSD (5%)

7

10

1.1

NS

8

5.4
C.V. (%)

6.5

15

7.7

20.8

6.4

9.9

Values followed by the same letter are not significantly different at the 95% confidence level.

Art Schultheis - Colton, WA -- Two tillage systems were compared for establishing a 1998 spring pea crop following a 90 bu/A 1997 winter wheat crop just northwest of Colton in a 20- to 22-inch annual rainfall zone (Table 4). Previous rotation crops were lentils in 1996 and spring barley in 1995. Treatments include: 1) Fall Disc-Subsoil - Spring Direct Seed - fall (1997) John Deere disc-ripper - spring harrow - direct seed; and 2) Spring Direct Seed. The winter wheat stubble was flailed after harvest when the residue was dry. Roundup was applied on the direct seed treatments in the fall and on both treatments in the early April. The trial was seeded in late April to Columbia pea with a Flexi-Coil single-disc air seeder. The disc-rip treatments were harrowed after seeding. Basagran and Thistrol were applied post emergence to the disc-rip treatments only (no weeds observed at that time on the direct seed treatments). Assure II was applied to both treatments for grass weed control. Winter wheat was direct seeded with a John Deere 750 single disc no-till drill in the fall.

Direct seeding provided more residue groundcover and better soil erosion protection in both the pea and winter wheat crops. The percent residue cover was significantly higher after planting pea and winter wheat, 96 vs. 19 and 84 vs. 41, respectively. Pea plant stands and yields were not significantly different.

Table 4: Comparison of tillage practices following a 1997 soft white winter wheat crop through 1998 spring pea and 1999 winter wheat crops. Art Schultheis, Colton, WA - 20- to 22-inch annual rainfall zone.

 

 

 

 

Treatment

 

 

 

Pre-plant residue cover

 

 

 

Post-plant residue cover

 

 

 

 

Spring pea emergence

 

 

 

 

Spring pea yield

 

 

Post-harvest residue cover

Post-winter wheat planting residue cover

------------%-------------

plants / ft^2

lb / ac

-----------%----------

Fall Disc-rip

-Direct Seed

37 B

19 B

13.8

2409

81 B

41 B
Direct Seed

100 A

96 A

14.2

2404

98 A

84 A
LSD (5%)

4

5

NS

NS

9

7
C.V. (%)

3.1

5.3

6.1

1.9

5.7

6.1

Values followed by different letters are significantly different at the 95% confidence level.

Richard Druffel and Sons - Pullman, WA Two tillage practices were compared for establishing a 1998 spring pea crop after a 1997 soft white spring wheat crop south of Pullman in a 20- to 22-inch annual rainfall zone (Table 5) . Treatments included: 1) Fall Disc-Subsoil - Spring Direct Seed - fall (1997) John Deere disc-ripper - spring harrow - direct seed; and 2) Spring Direct Seed.

Roundup was applied to all treatments on March 22. There was 4 to 6 inches growth on the volunteer spring wheat at a moderately high plant density in the direct seed compared to a light population of 2- to 4-inch high volunteer in the fall disc-subsoil treatment. All treatments were seeded to Columbia peas on April 10 with a Palouse Zero Till double disc drill. Fargo and Pursuit were applied post-plant pre-emergent with a harrow-sprayer. The harrow was used to incorporate the herbicides on the disc-ripper treatments, but was lifted off the soil on the direct seed treatments. Winter wheat was direct seeded with the Palouse Zero Till drill in the fall.

Percent surface residue was significantly higher in the direct seeding than in the fall disc-subsoil treatment after pea and winter wheat planting, 81 vs. 22% and 54 vs. 36%, respectively. Pea plant emergence and yield were not significantly different between the two treatments.

Table 5: Comparison of tillage practices following a 1997 soft white spring wheat crop through 1998 spring pea and 1999 winter wheat crops. Richard Druffel and Sons, Pullman, WA - 20- to 22-inch annual rainfall zone.

 

Treatments

Post-plant residue cover

 

Spring pea emergence

 

Spring pea yield

 

Post-harvest residue cover

Post-winter wheat planting residue cover

%

plants / ft^2

lb / ac

--------------%---------------
Fall Disc-Subsoil - Direct Seed

22 B

7.9

2603

81 B

36 B
Direct Seed

81 A

9.2

2354

94 A

54 A
LSD (5%)

11

NS

NS

9

5
C.V. (%)

9.7

28.6

13.7

4.4

5.2

Values followed by different letters are significantly different at the 95% confidence level.

Larry Cochran - Colfax, WA --Two tillage practices were compared for establishing a 1998 spring pea crop after 1997 spring barley crop northeast of Colfax in a 18- to 20-inch annual rainfall zone (Table 6). Treatments included: 1) Fall Chisel/Cultivate/Harrow - Spring Direct Seed; and 2) Spring Direct Seed. Roundup was applied in late fall and in mid April. All treatments were direct seeded to Columbia peas on May 1 with a John Deere 750 single disc no-till drill then rolled. Herbicide was applied post emergence. Winter wheat was direct seeded with a John Deere 750 single disc no-till drill in the fall.

Direct seeding retained higher surface residue levels after pea and winter wheat planting, 84 vs. 43% and 55 vs. 43%, respectively, although both systems provided good erosion protection. Pea plant stands, yields and residue cover after pea were not different.

 

Table 6: Comparison of tillage practices following a 1997 spring barley crop through 1998 spring pea and 1999 winter wheat crops. Larry Cochran, Colfax, WA - 18- to 20-inch annual rainfall zone.

 

 

 

Treatment

 

 

Pre-plant residue cover

 

 

 

Post-plant residue cover

 

 

 

Spring pea emergence

 

 

 

Spring pea yield

 

Post-harvest residue cover

Post-winter wheat planting residue cover

---------------%-------------

plants / ft^2

lb / ac

-----------%------------
Fall Chisel / Cultivate -Direct Seed

76 B

43 B

11.2

1399

92

43
Direct Seed

100 A

84 A

10.4

1665

96

55
LSD (5%)

5

15

NS

NS

NS

NS
C.V. (%)

4.9

10.5

14.2

9.9

3.0

11.1

Values followed by different letters are significantly different at the 95% confidence level.

Bob Garrett - Endicott, WA -- Two tillage practices were compared for establishing a 1998 spring pea crop after 1997 soft white spring wheat (Table 7) and soft white winter wheat (Table 8) crops northwest of Endicott in a 15- to 18-inch annual rainfall zone. Treatments on both the spring wheat and winter wheat fields included: 1) Fall Chisel/harrow - Spring Direct Seed - fall (1997) chisel (with narrow fertilizer knife openers on 12-inch spacing) and attached harrow - direct seed; 2) Spring Direct Seed. Roundup was applied in mid-November and on March 22. Both treatment systems on the spring wheat and winter wheat field trials were direct seeded to Columbia peas on April 16 using a Great Plains 3000 no-till drill with straight coulters and offset double discs. All plots were harrowed after seeding. Sencor was applied post-plant pre-emergence and Assure II and Basagran were applied post emergence as a tank mix about 5 weeks after seeding. Winter wheat was established in the fall using a minimum tillage 2-pass systems with the same low-disturbance chisel as direct-shank fertilizer applicator and seeding with the Great Plains 3000 no-till drill.

Although there were slightly higher surface residue levels pre-plant and post-plant in spring peas under direct seeding compared to fall chisel/harrow - direct seed, no differences were noted later in pea plant stands, pea yield or in surface residue levels. Both tillage systems provide effective erosion protection in the pea crop and subsequent winter wheat crop. Seeding depth was generally ½ to 1 inch, slightly shallower than planned and contributing to lower plant stands than expected. Although the reasons for the low pea yields are not known, post-emergence herbicide injury is suspected as one important factor in reducing plant growth and yield potential in both trials.

 

Table 12: Comparison of two tillage practices following a 1997 soft white spring wheat crop through 1998 spring pea and 1999 winter wheat crops, Bob Garrett, Endicott, WA - 15- to 18-inch annual rainfall zone.

 

 

 

 

Treatment

 

 

 

Pre-plant residue cover

 

 

 

Post-plant residue cover

 

 

 

 

Spring pea emergence

 

 

 

 

Spring pea yield

 

 

Post-harvest residue cover

Post-winter wheat planting residue cover

---------%---------

plants / ft^2

lb / ac

---------%----------
Fall Chisel/Harrow -Direct Seed

82 B

70 B

8.0

564

88

33
Direct Seed

100 A

88 A

6.7

645

89

35
LSD (5%)

5

4

NS

NS

NS

NS
C.V. (%)

2.5

22.2

2.9

14.0

2.9

13.4

Values followed by different letters are significantly different at the 95% confidence level.

Table 8: Comparison of two tillage practices following a 1997 soft white winter wheat crop through 1998 spring pea and 1999 winter wheat crops, Bob Garrett, Endicott, WA - 15- to 18-inch annual rainfall zone.

 

 

 

 

Treatment

 

 

 

Pre-plant residue cover

 

 

 

Post-plant residue cover

 

 

 

 

Spring pea emergence

 

 

 

 

Spring pea yield

 

 

Post-harvest residue cover

Post-winter wheat planting residue cover

------------%-----------

plants / ft^2

lb / ac

----------%----------
Fall Chisel/Harrow -Direct Seed

87 B

83 B

7.4

522

82

37
Direct Seed

100 A

92 A

7.4

528

89

41
LSD (5%)

9

5

NS

NS

NS

NS
C.V. (%)

6.4

2.4

7.0

4.1

8.2

8.2

Values followed by different letters are significantly different at the 95% confidence level.

Preliminary Conclusions from On-farm Trials

Compared to more intensive tillage systems in these large scale field trials managed by Northwest growers, spring direct seeding systems for pea establishment after cereals offer the potential for increasing surface residue retention for erosion control through the cereal - grain legume - winter wheat rotation without sacrificing yield potential in peas and following winter wheat crop. Production costs may also be reduced by eliminating field operations. Spring direct seeding of peas resulted in the higher pea test weight in five of the 1998 direct seed pea trials, although differences were not always statistically significant at the 95% probability level. This could indicate a higher level of soil water may be present at grain filling than under more intensive tillage systems. Economic comparisons have not yet been completed, but production costs may also be reduced with spring direct seeding by eliminating field operations.


 

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