Strip Tillage and Cover Cropping for Enhanced Water Use Efficiency in Western Washington Organic Vegetable Farms.

Tillage is an important tool in organic systems for weed control, residue management, seedbed preparation, and regulation of spring soil temperature. Because excessive tillage wastes energy and degrades soil quality, organic producers are encouraged to reduce tillage. Soil water also evaporates more quickly from bare, tilled soils, potentially increasing irrigation demand. This integrated research and extension project compares water use efficiency of strip tillage  and full tillage for organic winter squash production following a rye cover crop. Organic strip tillage is a biologically intensive strategy that addresses the nexus of food, energy, and water with the potential to increase farming system resiliency to climate change by conserving agricultural water resources in Washington State.

A Rrye cover crop terminated with flail mowing was subjected to strip tillage or full tillage prior to transplanting squash. Separate drip irrigation application schedules were maintained per treatment utilizing the WSU AgWeathernet irrigation scheduler platform paired with daily in-field volumetric moisture sensor correction. For the 2016 season, full tillage demanded more irrigation than the strip tillage treatment. Total treatment irrigation will be compared with marketable yield (harvest occuring fall 2016) to determine WUE between the two tillage systems. Infiltration, bulk density, penetrometer resistance, mid season and post harvest soil nitrogen, and weeding labor will also be assessed.