Mow-plow crop residue management influence on soil erosion in north-central Oregon

Soil loss from dryland farms on the Columbia Plateau in Oregon and Washingt on (USA) results primarily from rain falling on frozen, cultivated soil. So ils are most susceptible to erosion when moldboard plowed, summer-fallowed, repeatedly rod-weeded or cultivated, and fall planted to winter-wheat. The se tillage practices are used because they help control weed and disease in festations and consistently produce good crops. Unfortunately, they also de stroy soil structure and lead to considerable soil loss by water erosion. C onservation-tillage-practices have not been widely accepted because of asso ciated weed and disease problems. A new conservation system using crop resi due management, the mow-plow system, has shown promise for weed control. Th e moldboard plow is the primary tillage tool, but standing crop residue is cut ahead of the plow and distributed onto the adjacent plowed surface. The system requires a single pass of the equipment. We evaluated runoff and er osion responses in two levels of residue application in the mow-plow (L sim ilar to 23% and H similar to 36% cover), traditional moldboard plow, and ch isel plow winter-wheat/summer-fallow systems near Pendleton, OR, USA. Follo wing extended periods of subfreezing air and soil temperatures, we simulate d rainfall at 9, 13, and 19 mm h(-1) and collected runoff to evaluate water and soil loss as the soil thawed. Runoff was not significantly different a mong treatments. For each of the three rainfall intensities, the chisel plo w treatment provided the best protection against soil erosion at 0.11, 0.39 , and 0.95 Mg ha(-1) h(-1), followed closely by the mow-plow (H) 0.26, 0.55 , and 0.90 Mg ha(-1) h(-1). The moldboard plow treatment was the least effe ctive treatment for erosion control (0.57, 1.38, and 3.76 Mg ha(-1) h(-1)). The erosion response from the mow-plow (L) treatment was variable and not statistically different from the moldboard plow treatment (0.33, 2.49, and 1.71 Mg ha(-1) h(-1)). These results demonstrate the importance of maintain ing cover on the soil surface. The mow-plow system, where adequate straw re sidue is available, is superior to moldboard plow system for soil conservat ion. Published by Elsevier Science B.V.