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1998 STEEP III Progress ReportRESEARCH PROJECT TITLE: Rotation designs for direct seed cropping systems INVESTIGATORS: David Huggins, Research Agronomist, USDA-ARS, Pullman, WA.; Eric Gallandt, Weed Ecologist, Dept. of Crop and Soil Sci., WSU, Pullman, WA; Roger Veseth, Conservation Tillage Specialist, PSES, Univ. of Idaho, Moscow, ID and Dept. of Crop and Soil Sci. WSU, Pullman, WA; Timothy Fiez, Soil Fertility Specialist, Dept. of Crop and Soil Sci. WSU, Pullman, WA; Claudio Stockle, Crop modeler, Biological Systems Eng. Dept., WSU, Pullman, WA; Joe Yenish, Weed Scientist, Dept. of Crop and Soil Sci. WSU, Pullman, WA; PROJECT OBJECTIVES:
KEY WORDS: alternative crops, no-till, water use efficiency, crop rotations STATEMENT OF PROBLEM: Crop rotation designs for direct seed systems have not been extensively developed for the annual cropping region of the Pacific Northwest. Attempts to use conventional crop rotations in no-tillage systems have been largely unsuccessful due to agronomic problems with crop growth, weeds, diseases, and equipment (i.e. drill) performance. For example, a crop rotation of winter wheat, spring barley, and spring pea or lentil requires the establishment of spring crops into relatively large amounts of surface residues in two of three cropping seasons. The residues create a shaded, cold, wet environment that adversely affects shoot and root growth, enhances the potential for adverse weed pressure, promotes soil-borne diseases, increases soil compaction, and reduces drill performance. Furthermore, the rotation emphasis on spring crops does not take advantage of the greater yield potential of fall sown crops in the high rainfall zone. A re-examination of crop rotation design for continuous direct seed systems may offer methods to alleviate or avoid many of the constraints of presently used rotations. Large amounts of cereal residues retained on the surface can benefit the production of Austrian winter pea and winter lentil (Huggins and Pan, 1991). But what about other winter crops such as canola/ rapeseed, or spring sown crops such as corn, canola, yellow mustard, linola, millet and safflower? Little is known about positive or negative effects that these crops may have in cereal-based direct seed rotations. AGRONOMIC ZONE OF INTEREST: Field studies will focus on the high rainfall, annual cropping region and modeling efforts will be applicable to the high and intermediate rainfall areas. ABSTRACT OF RESEARCH FINDINGS: Winter wheat residue is a formidable barrier to direct seed rotations in the high precipitation zone of the Palouse. We initiated two studies in the spring of 1998: one focusing on crop modeling of 10 different spring crops following winter wheat, and the other comparing no-till with conventionally established spring crops after winter wheat. Water use efficiency was greatest for corn and spring wheat while safflower depleted the soil water to the largest extent. Small, shallow seeded spring crops had difficulty establishing in both no-till and conventional till treatments. Moisture conserving surface residues aided the establishment of yellow mustard and linola in no-till. Millet yielded well despite reseeding on June 26th. No differences in yield occurred between no-till and conventionally established canola, yellow mustard, linola, safflower, and millet while spring wheat yielded 28% greater under conventional tillage as compared to no-till. The study has just begun and trials are planned for the next two seasons. The reported results are very preliminary and no conclusions can be made at this time. RESULTS AND INTERPRETATION: Two field studies were initiated at the Palouse Conservation Field Station near Pullman, WA to evaluate spring crop performance following winter wheat under no-till conditions. The crop modeling study consisted of 10 different spring crops: canola (Sunrise), yellow mustard (Tilney), hard red spring wheat (WB 926R), peas (Columbia), corn (Pioneer 3970), proso millet, dry beans (Bill Z pinto), soybeans (Monsanto Roundup Ready), safflower (S-208) and linola (989) on 50 by 30 foot plots. A no-till double disk drill (Fabro, Inc.) with an offset, leading disk, starter and deep band fertilizer capabilities (all 7.5 inch spacing), and a cone seeder was used to no-till seed into standing Madsen winter wheat stubble (grain yield of about 85 bu/ac). Data for calibrating the Cropsys model was collected throughout the growing season. Daily air temperature, precipitation, global radiation, net radiation, wind speed, and relative humidity were collected by an on-site weather station. Daily seed zone temperature and water (2 inch depth) and root zone water (0 to 5 feet by 1 foot intervals) were monitored with thermocouples and water content reflectometers in each of the ten crops. Crop development, aboveground biomass accumulation, and leaf area index were assessed throughout the season. A plot combine was used to harvest grain yield. The second study consisted of seven spring crops: canola, yellow mustard, hard red spring wheat, proso millet, pinto beans, safflower and linola, seeded both no-till and conventionally (fall moldboard plow, spring disk), following winter wheat (Madsen). The same no-till drill, seeding dates and rates, and fertilizer applications were used in the tillage comparison and crop modeling studies (Table 1).
Crop modeling study Growing conditions were cooler than normal during mid-May. Cumulative growing degree days contrast the thermal requirements of cool season crops (wheat, mustard, canola; base temperature 3oC, optimum 30oC) versus warm season crops (corn, millet, dry beans; base temperature 10oC, optimum 30oC) that drive their vegetative development (Figure 1). The dry beans and proso millet did not emerge well during this cold period and stand establishment was poor. Millet is a short season crop and was replanted on June 26th, dry beans were not replanted and the bean plot was abandoned. Seasonal patterns of water consumption differed among the crops and reflect differences in evapotranspiration and growth (Figure 2). Evident in Figure 2 is the more rapid use of water by wheat and mustard during mid to late June as compared to corn. Water use efficiency (WUE) of each crop was evaluated using the following analyses: WUE = Gw/Ws = ET/Ws X Gw/ET, where Gw = Grain weight (lbs/ac) Ws = Water supply (inches) = soil water at planting in 0-5 foot soil profile plus rain from planting to physiological maturity. ET = evapotranspiration (inches) = soil water at planting minus soil water at physiological maturity plus rain during that period (assumes no runoff or leaching). This analysis partitions WUE (Gw/Ws) into water uptake efficiency (ET/Ws) and water utilization efficiency (Gw/ET). |
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