1998 Table of Contents

1998 STEEP III Progress Report

RESEARCH PROJECT TITLE: Residue Production and Retention in Small Grain Cereal and Legume Rotational Systems With Different Tillage Practices.

INVESTIGATORS:

Stephen Guy, Extension Crop Management Specialist, Plant, Soil and Entomological Sciences (PSES), UI

Donn Thill, Weed Scientist, PSES, UI

Roger Veseth, Extension Conservation Tillage Specialist, PSES, UI and Dept. of Crop and Soil Sci., WSU

John Hammel, Soil Physics and Tillage, PSES, UI

Timothy Fiez, Extension Soil Specialist, Dept. of Crop and Soil Sci., WSU

Joe Yenish, Extension Weed Specialist, Dept. of Crop and Soil Sci., WSU

Duncan Cox, Support Scientist, PSES, UI

Cooperators:

Wayne Jensen, Art Schultheis, Nathan and Steve Riggers, Eric Hasselstrom, Randy and Larry Keatts, Richard Druffel, Larry Cochran, Bob Garrett (growers) and Roy Patten and Brad Bull (UI Plant Science Farm)

PROJECT OBJECTIVES:

1. Evaluate pea and lentil residue production and durability between and within species in rotational systems with different tillage practices to provide residue levels for effective runoff and erosion control during establishment and early growth of the following winter wheat crop.
2. Develop integrated management systems for minimum tillage and direct seeding of pea and lentil after spring cereals that retain adequate surface residue, surface roughness, and water infiltration and storage potential to effectively control surface runoff and soil erosion during pea and lentil establishment and in the following winter wheat crop.

KEY WORDS: Tillage, residue, rotation, integrated management systems

STATEMENT OF PROBLEM: Winter wheat established after legumes using conventional tillage systems can leave the soil vulnerable to erosion. About 65-75% of annual precipitation falls after wheat seeding when plants are small and can occur during freeze-thaw cycles. Erosion can be reduced with greater residue cover and soil roughness, and improved water infiltration. Residue cover is usually most effective. Growers have reduced tillage before planting winter wheat after legumes, but fragile legume residues and low residue production often leave little soil cover overwinter. Surface residue levels going into winter wheat could be increased by carrying over spring cereal residue grown before the legume crop. However, spring cultivations are often indicated for incorporation of many legume herbicides. After fall and spring tillage, little cereal crop residue remains to carry through winter wheat planting. Conventional tillage practices for legume production can also increase soil compaction in wet spring condition, reducing water infiltration and increasing erosion potential.

ZONE OF INTEREST: Higher precipitation Palouse region of ID and WA.

ABSTRACT OF RESEARCH FINDINGS: Eight on-farm trials were conducted with field scale equipment in cooperation with growers in eastern Washington and northern Idaho to compare a variety of tillage and residue management systems for establishing spring peas in a cereal - pea - winter wheat rotation sequence. Compared to more intensive tillage or residue removal systems, spring direct seeding of peas resulted in higher surface residue levels for improved erosion protection after planting spring pea and subsequent winter wheat crops, similar stand establishment and equal or higher yields. In other tillage trials, there was not adequate residue from the previous pea crop alone when plowing is done before the pea crop, but when previous cereal residue is carried through the pea crop, adequate residue is maintained through winter wheat seeding. Pea and lentil residue can survive adequately through winter wheat establishment and the greater the tillage intensity, the less surface groundcover. Herbicide experiments within some of these trials indicate that imazamox can injure peas. Fall versus spring application of imazethapyr is did not result in differences in weed control or pea yields. No benefit was seen for direct seeded peas receiving small amounts of starter fertilizer N,P, and/or S at planting. No soil moisture differences were seen to result from direct seeding at the one trial where this data was collected. These trials show that yields can be as good and sometimes better under direct seeding cropping compared to conventional systems. There are many values to reduced tillage and even more so to direct seeding systems shown in these studies, including: soil conservation, ease of operation, and reduced cost. These studies support the viability of direct seeding systems in the higher rainfall areas of the Palouse.

RESULTS AND INTERPRETATION:

Objective 1: Two trials were conducted using farm scale equipment to evaluate dry pea and lentil residue production and durability across cultivars and tillage intensity. These trials include two cultivars of pea and two of lentil grown in large blocks. The legume plot areas are prepared for winter wheat seeding by different tillage systems designed to give progressive levels of tillage intensity by: no-till, rip-shoot (RS), RS + cultivation, and RS + two cultivation. Equivalent fertilizer to the rip-shoot application was applied while planting the direct seed treatment. Groundcover residue was followed from legume harvest through winter wheat establishment. Legumes were harvested by field scale combines, but wheat yield were the average of two swaths from a small plot combine.

All crops of the 1997-1998 trial performed well (Table 1). Pro 2100 pea yielded more seed and than the lentils and Columbia pea. The pea cultivars produced more than twice the crop residue than the lentils. However, the groundcover after the four legumes was not very different after tillage was done and throughout the rest of winter wheat establishment. Increasing tillage intensity did decrease the residue cover following all four legume treatments. After planting winter wheat, the groundcover did not change much following pea, but seems to decline faster for the lentil residue overwinter. Lentil residue also seems to be buried more easily by tillage.

The legume seed yields in the 1998-1999 trial were very similar to the previous trial (Table 2). However, residue yields were lower following pea and higher after lentil, with Pro 2100 and Brewer lentil producing the most residue. Residue groundcover after harvest and tillage was lower for pea than lentil. After planting winter wheat on October 7, residue groundcover was lower than in the previous year. The same trend of less residue as tillage intensity increased occurred again.

Table 1. Crop yields and residue with different tillage intensity following legume crops at the UI Kambitsch Farm, Genesee, ID, 1997-1998

* LSD for within legume crop only.

Table 2. Crop yields and residue with different tillage intensity following legume crops at the UI Kambitsch Farm, Genesee, ID, 1998-1999

Objective 2: Two spring cereal trials were conducted at the UI Kambitsch Research farm to evaluate wheat and barley residue carryover through pea seeding into winter wheat establishment. One trial was started in 1996 and finished in 1998 and the other was a year later. After harvest of the spring cereal crops, four tillage treatments, plow, chisel, paratill, and direct seed were applied in the fall. Broadcast burn down of weeds was applied in the spring before seeding pea with direct seeding drills. Pursuit herbicide provided weed control in the pea crop. After pea harvest, fertilizer was applied by 'ripper-shooter' and winter wheat seeded. Residue groundcover was followed from after spring cereal harvest through winter wheat establishment. Herbicide evaluation across tillages were conducted for the pea crop and many soil physical measurements were taken.

Table 3. Yields and performance in a cereal residue carryover through a pea crop trial at the UI Kambitsch Farm, Genesee, ID, 1996-1998.

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 3). 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 be productive. The cereal residue levels for this trial were published in last years STEEP report. 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. 1998 wheat yields were not different for tillage or 1996 crop and averaged 107 bu/a.

In the 1997-1999 trial, the spring cereal crops did well (Table 4). The barley 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 lower 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.

Table 4. Yields and performance in a cereal residue carryover through a pea crop trial at the UI Kambitsch Farm, Genesee, ID, 1997-1999

*LSD for within tillage does not apply to comparisons across tillage treatments.

Groundcover residue measurements in the 1997-1999 trial were taken over-winter following the spring cereal crops (Table 5). 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 and was also greater than plow after winter wheat planting. These trials show the practicality of carrying spring cereal residue 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.

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.

Table 5. Groundcover residue levels in the cereal residue carryover through pea crop trials at the UI Kambitsch Farm, Genesee, ID, 1997-1999