Influences of Winter Cover Crops and Irrigation Systems On Tomato Water Use Efficiency and Yield.

The use of groundwater for crop irrigation in California increases because of the shortage of surface water, which may be exacerbated in the long-term due to climate change. Management practices that decrease water losses from cropland and increase irrigation efficiency may provide good solutions. This study evaluates the effects of three winter cover crop treatments (winter fallow, triticale, and mixture of bell bean and vetch) and two irrigation practices (subsurface drip and furrow irrigation) on tomato growth and water use efficiency. We expected that winter cover crops could increase soil profile moisture and groundwater recharge from rainfall events than winter fallow. Total water applied for furrow irrigation was in the order of mixture > triticale > fallow as water infiltrated more rapidly in cover crop treated plots. Tomatoes had greater canopy cover and stomatal conductance following mixture than following triticale or fallow under furrow irrigation. There was less difference in canopy cover or stomatal conductance among cover crop treatments under drip irrigation. However, greater canopy cover, stomatal conductance and dry biomass were usually observed under drip than furrow irrigation. It is expected that drip irrigation has higher yield and greater water use efficiency.