Title: Constraints on Conservation Tillage under Dryland and Irrigated Agriculture in the United States Pacific Northwest
Abstract: The Pacific Northwest (PNW) supports significant areas of both irrigated
and rainfed agriculture. This bimodality is also impacted by the diversity of
crop and animal agriculture it supports. Drilled grain and pulse crops, row
crops, vegetable and horticultural crops, grass sod, and perennial alfalfa
(Medicago saliva L.) hay are among the choices that can appear in a farm's
cropping system. Developing soil management practices and tillage systems to
accommodate such diversity has been a challenge to soil conservationists. To
date most research published from the region has concentrated on small grain
production in the dryland areas. Another smaller body of literature has dealt
with conservation tillage of irrigated field crops. The potential for development
of conservation tillage in the PNW derives from the region-wide severity of
erosion in both dryland and irrigated agriculture. Residue management has
been the essential element of the tillage systems in both cases. Although
preserving crop residues at the soil surface is a key strategy, conservation
tillage in the PNW has embraced other practices as well. Furthermore, greater
recognition of the extent and severity of erosion under irrigated conditions is
warranted, and research on erosion and conservation tillage for irrigated systems
should be a high priority.