WHEAT STUBBLE MANAGEMENT AFFECTS GROWTH, SURVIVAL, AND YIELD OF WINTER GRAIN LEGUMES

The adoption of no-tillage systems in the Pacific Northwest will benefit from the development of crop rotations that complement winter wheat (Triticum aestivum L.). Experiments were conducted during 1986-1987 and 1988-1989 to determine the effects of wheat residue and fertility management on the growth, winter survival, and yield of 'Glacier' Austrian winter pea (Pisum sativum subsp. arvense L.) and winter lentil (Lens colinaris Medik.). No-tillage (NT) and no-tillage with reduced stubble (NT-SR) enhanced soil moisture conservation and increased the early growth of Austrian winter pea (AWP), compared with conventional tillage (CT). Decreased shoot mass of winter lentil (WL) in NT, and elongated stems and reduced branching of AWP and WL in NT, were attributed to shading by stubble that reduced photosynthetically active radiation and red/farred ratios. Winter survival of AWP during 1986-1987 was reduced in NT (78%), compared with NT-SR (91%) and CT (96%), but no differences occurred in 1988-1989. Less aboveground tissue necrosis of surviving AWP occurred in NT than in NT-SR and CT for both years. Greater average yields in NT (3568 kg ha-1) and NT-SR (3530 kg ha-1) than in CT (2700 kg ha-1) were correlated with greater fall growth and less winter injury. Residue management did not influence the yield of WL. Applied P and K did not have consistent effects on winter survival or yield. These results indicate that winter grain legumes can be used to complement wheat production in the design of no-tillage rotations.