Simulation-based assessment of alternative crops in the dryland pacific nothwest

Abstract

Dyrland cropping systems in the US Pacific Northwest (PNW) have traditionally beenshort, wheat-based rotations that have provoked soil erosion and decreased soil productivity The success of improved cropping systems is dependant on longer rotations and greater cropdiversification. However, because of the long history of wheat based cropping systems in thePNW, there is little information about the performance of alternative cropsIn this study, the crop simulation model CropSyst (Stockle et al., 1994) was used to assessthe suitability of selected alternative crops for the dryland region of the US PNW. Oncecalibrated and corroborated with measured experimental data, the model was used to simulatelong-term and .region-wide production of the alternative crops using historical weather dataand regional soil information The adaptation to the dryland PNW of yellow mustard, spring canola, spring pea,linola, hard red spring wheat, saffiower, millet and corn was analyzed in terms of totalproductivity, yield stability and water use efficiency. Region-wide simulations of 30 years ofcrop production showed that yields of the tested crops were related to the probability ofivreaching maturity, total water supply and water use efficiency. The cool season crops yellowmustard, spring canola, spring pea, linola and hard red spring wheat yielded the highest in thecooler and wetter zones and the warm season crops saffiower, millet and corn in the warmerand wetter areas of the region. Thermal time restrictions reduced average yields of the warmseason crops in the cooler areas. Yield variations of the cool season crops were higher in thewarmer than in the cooler areas. For warm season crops, yield variations were higher in thecooler areas. The rank of the crops in terms of total productivity throughout the region fromthe highest to the lowest was: hard red spring wheat, millet, corn, saffiower, yellow mustard,spring pea, linola, spring canola Economical ranking varied by zone, but overall highest to lowest the ranking was hardred spring wheat, spring pea, saffiower, linola, yellow mustard, corn, spring canola and millet.