Submitted to: Washington State University College of Agriculture and Home Economics
Publication Type: Other
Publication Acceptance Date: July 1, 2000
Publication Date: N/A
Interpretive Summary: Winter wheat production in the low to intermediate rainfall areas of the Pacific Northwest has relied on a winter wheat-fallow rotation to provide sufficient soil moisture to raise an economically viable wheat crop. This system involved raising a winter wheat crop one year followed by a weed- free dust mulch using mechanical tillage practices the subsequent year. Long-term, this system has been responsible for exposing the soil to environmental conditions that accelerate wind erosion and increase weed, insect, and disease problems. Sustainability of the wheat fallow rotation has been challenged by these problems. A long-term, interdisciplinary study is researching best management practices for continuous no-till spring cropping systems that will enhance sustainability of the region's agriculture while maintaining or improving profitability. Two systems, continuous no-till hard red spring wheat and no-till hard red spring wheat in rotation with barley have been agronomically feasible. More yield enhancing research and public support for these soil and air quality conserving system is needed to convince growers to make the transition from the wheat-fallow system to no-till spring cropping systems.
Technical Abstract: The winter wheat/fallow cropping system has become extensively integrated across the inland Northwest. Problems inherent with this system have included soil erosion and economic losses from weed, insect, disease concentrations, and re-seeding costs when winter wheat plantings fail. The use of alternative cropping systems designed to alleviate these conditions have not been widely accepted or researched. A long-term field study was initiated in 1995 to look at alternatives to the conventional winter wheat cropping system. A multidiscipline research team was formed to examine soil, insect, disease, economic, crop variety, and weed factors. Cropping rotation systems of 1) winter wheat/fallow, 2) spring wheat/fallow, 3) continuous spring wheat, and 4) spring wheat/spring barley were established on a dry-land wheat farm near Ralston, Washington. Individual plots were 500 by 30 feet allowing the use of standard farm-size equipment. Duration of Phase I of the study continued through year 2000. Several satellite studies were established to examine factors including crop varieties, seeding rates, and alternative crops. Above average precipitation in the first two crop years produced good yields in winter wheat and spring crops. Using no-till technology in growing spring crops has been effective in maintaining a soil cover of crop residue throughout the year that could substantially reduce soil erosion. Weed, insect, and disease factors are being analyzed, as each of the first four years have produced varied conditions. Continuation of the study through average and below average rainfall years will help determine economic viability of cropping systems being studied.