Reduced Tillage, Direct Seeding and Water Management in Semi-Arid Pacific Northwest.

Dryland cropping is practiced on 3,348,000 hectares in the Inland Pacific Northwest of the United States. Wind erosion is a major agricultural concern in the low-precipitation (<300 mm annual) dryland zone where a tillage-based winter wheat-summer fallow (WW-SF) rotation is practiced.  Excessive tillage in the intermediate (300-450 mm annual) and high (450-600 mm annual) zones is a major cause of water erosion that has plagued the region since the inception of farming.  For the WW-SF zone, the key question is what management strategies can be used to maximize storage of over-winter precipitation in the soil, conserve seed-zone water during the dry summer, and simultaneously be effective for wind erosion control.  In the steeply-sloped intermediate and high precipitation zones, the major concern is how to efficiently and profitably farm the land while retaining adequate surface residue over the winter months to control water erosion.  Adoption of conservation-till and no-till farming by growers throughout the region is a slow, gradual, but ongoing process.  Long-term research has focused on (i) development of flexible and profitable cropping systems that maximize year-round surface cover and (ii) testing of implements to establish low-soil-disturbance preferential flow pathways to allow infiltration of water runoff into frozen soils.  These and other recent research findings will be presented.