Abstract. Erosion is a major environmental and sustainable cropping issue for the Palouse region of Idaho. Barley and wheat crop residue is needed to maintain adequate residue groundcover through a following grain legume crop and into winter wheat seeding. On-farm trials were conducted with plow chisel, paratill and direct seed treatments following a spring barley and wheat crop and before planting dry pea. Cereal residue levels were followed after tillage, pea planting, after pea harvest and planting of the following winter wheat crop. Barley and wheat residue persisted through the following pea crop and winter wheat seeding and establishment. Pea establishment was good when a direct seeding drill was used and pea yields were 200 lb/a more in the direct-seeding and paratill treatments than in the plow treatments in one trial. After pea harvest, there was over 750 lb/a of carryover cereal residue in the direct seed treatment. Other direct seeding trials in the area also have shown the practicality of maintaining barley residue. Pea residue alone was not adequate for erosion protection and the carryover residue available after a spring barley or wheat crop and direct seeding of pea is a valuable product of the spring cereal crop.
Materials and Methods. Two spring cereal trials were conducted using farm scale equipment at the UI Kambitsch Research farm near Genesee, Idaho to evaluate spring barley and wheat residue production and carryover through pea seeding and into winter wheat establishment. One trial was started in 1996 and finished in 1998 and the other a year later. Barley and wheat strips were 16 ft. wide and 300 to 550 ft long. After harvest of the spring cereal crops, four tillage treatments, plow, chisel, paratill, and direct seed were applied in the fall. After pea harvest, fertilizer was applied by 'ripper-shooter' and winter wheat seeded. Residue groundcover was followed from after spring cereal harve st through winter wheat establishment.
Results and Discussion. In the 1996-1998 trial, the spring cereal crops did not yield as much as desired due to poor seeding conditions followed by dry weather (Table 1). The residue groundcover was lower than desired, but the barley was higher than the wheat. The pea crop did not establish as well as desired in the direct seed treatment due to limitations on soil penetration by the drill. The winter wheat crop did establish well and was productive. A greater amount of cereal residue was carried over through the pea crop in the direct seed than in all other tillage systems and averaged about 600 lb/a higher. Carryover cereal residue levels did not change for barley or wheat when evaluated for the year following their production. 1998 wheat yields were not different for tillage or 1996 crop and averaged 107 bu/a.
Table 1. Yields and performance in a cereal residue carryover through a pea crop trial at the UI Kambitsch Farm, Genesee, ID, 1996-1998.
| 1996 Spring Crop | Cereal Seed Yield | Post-Harvest Crop Residue | Tillage Fall 1996 | 1997 Pea Popl'n | 1997 Pea Yield | Post-Harvest Residue | |||
|---|---|---|---|---|---|---|---|---|---|
| Pea | Cereal | Total | 1998 Winter Wheat yield | ||||||
| bu/ac | % | plants / ft2 | lb/ac | bu/ac | |||||
| Wheat | 20 b | 66 b | Plow | 8.72 | 1890 | 2564 | 66 | 2630 | 108 |
| Barley | 38 a | 78 a | Plow | 9.48 | 1850 | 2555 | 44 | 2599 | 105 |
| Wheat | Chisel | 9.46 | 1810 | 2300 | 189 | 2489 | 102 | ||
| Barley | Chisel | 9.62 | 1830 | 2228 | 176 | 2403 | 105 | ||
| Wheat | Paratill | 10.49 | 1750 | 2991 | 142 | 3136 | 112 | ||
| Barley | Paratill | 8.86 | 1760 | 2431 | 141 | 2572 | 104 | ||
| Wheat | No Till | 7.55 | 930 | 2012 | 767 | 2779 | 107 | ||
| Barley | No Till | 7.02 | 890 | 2513 | 791 | 3304 | 101 | ||
| LSD (5%) | between | tillages | 0.78 | 316 | NS | 264 | NS | NS | |
| LSD (5%) | 14 | 5 | NS | NS | NS | NS | NS | NS | |
| C.V. | 21.0 | 3.4 | 12.5 | 9.1 | 21.2 | 52 | 22.0 | 5.6 | |
In the 1997-1999 trial, spring barley and wheat were productive and gave high amounts of residue (Table 2). Barley grain yield was near the county average and spring wheat was low due to a high infestation of Hessian Fly. However, the Hessian Fly infestation did not reduce the residue from the spring wheat. The pea crop was established well with no differences in pea population among tillages or previous crop. Pea yields were highest in paratill and direct seed treatments and lowest in the plow treatment. Within the paratill treatment, pea following wheat yielded 339 lb/a more than following barley. Winter wheat was established following the pea crop.
Groundcover residue measurements in the 1997-1999 trial were taken over-winter following the spring cereal crops (Table 3). In all cases after the spring cereal crops, there was more groundcover in direct seeding than in paratill, which had more than the chisel and the plow treatment was lowest. That relationship held through pea planting. After pea harvest, direct seeding was highest in residue and was also greater than plow after winter wheat planting. These trials show the practicality of carrying spring cereal residue of both barley and wheat through the pea crop and having adequate residue groundcover after paratill and direct seeding, but not when plowing before pea. This is true even when wheat is seeded in a low disturbance system of shank-and-seed. The pea crop alone does not provide adequate residue for erosion control on the steep slopes of the Palouse. Managing spring barley and wheat residue to persist on the soil surface through a pea crop works well when reduced tillage or direct seeding systems are used for pea and subsequent winter wheat establishment. This residue is a further advantage and benefit from having spring barley or wheat as a component of the rotation.
Table 2. Yields and performance in a cereal residue carryover through a pea crop trial at the UI Kambitsch Farm, Genesee, ID, 1997-1999
| 1997 Spring Crop | Cereal Seed Yield | Post-Harvest Crop Residue | Tillage Fall 1997 | 1998 Pea Population | 1998 Pea Yield by tillage w/in till. | |
|---|---|---|---|---|---|---|
| bu / ac | % | plants / ft2 | lb/ac | |||
| Wheat | 40 b | 97 | Plow | 11.3 | 1431 c | 1362 a |
| Barley | 83 a | 97 | Plow | 19.8 | 1500 a | |
| Wheat | Chisel | 11.4 | 1540 b | 1682 a | ||
| Barley | Chisel | 11.1 | A 1560 a | |||
| Wheat | Paratill | 10.6 | 1621 a | 1709 a | ||
| Barley | Paratill | 8.2 | 1370 b | |||
| Wheat | No Till | 9.9 | 1637 a | 1676 a | ||
| Barley | No Till | 8.4 | 1598 a | |||
| LSD (5%) | 6 | NS | NS | 78 | 217 | |
| C.V. | 4.4 | 0.6 | 48.5 | 9.1 | 9.1 | |
Table 3. Groundcover residue levels in the cereal residue carryover through pea crop trials at the UI Kambitsch Farm, Genesee, ID, 1997-1999
| 1997 Spring Crop | Tillage After 1997 Crop | Measurement Date | ||||||
|---|---|---|---|---|---|---|---|---|
| 14 Nov | 20 Jan | 19 Feb | 2 April | 11 May After pea planting | 28 Aug After pea harvest | 21 Oct After wheat planting | ||
| % groundcover | ||||||||
| Wheat | Plow | 6 | 6 | 6 | 5 | 5 | 72 | 19 |
| Barley | Plow | 7 | 9 | 7 | 5 | 5 | 72 | 21 |
| Wheat | Chisel | 28 b | 39 | 34 | 29 | 24 | 75 | 33 |
| Barley | Chisel | 34 a | 36 | 35 | 32 | 23 | 75 | 30 |
| Wheat | Paratill | 86 | 89 | 87 | 80 | 35 b | 75 | 32 |
| Barley | Paratill | 88 | 92 | 90 | 78 | 48 a | 79 | 34 |
| Wheat | No Till | 98 | 99 | 96 | 94 | 68 | 88 | 43 |
| Barley | No Till | 98 | 99 | 98 | 95 | 76 | 90 | 48 |
| LSD (5%) between tillage means | 3 | 6 | 3 | 4 | 9 | 6 | 17 | |
| LSD (5%) within tillage treatments | 4 | NS | NS | NS | 10 | NS | NS | |
| C.V. | 2 | 4 | 5 | 8 | 18 | 6 | 16 | |