Water Balance and Nitrate Leaching under Corn in Kura Clover Living Mulch

Kura clover (Trifolium ambiguum M. Bieb.) living mulch has potential to improve the environmental impact of corn (Zea mays L.) production, especially in the context of corn silage or stover harvest. Our objective was to determine the effects of kura clover living mulch on the water balance and nitrate leaching under corn near Arlington, WI. Treatments in the 2.5-yr experiment (April 2006 November 2008) were N-fertilized no-till corn following killed kura clover as the control and no-till corn in living mulch with fertilizer rates of and 90 kg N ha(-1) yr(-1). Soil water storage was 37 to 50 mm lower under the living mulch than the control in the spring, while the control experienced 29 to 36 mm greater soil water depletion than the living mulch in the summer. Evapotranspiration was similar across treatments, except in May when it was greater under the living mulch by 11 to 41 mm. The living mulch did not appreciably reduce drainage. Nitrate-N storage in the soil profile and nitrate-N concentrations in the soil solution at 1-m depth were significantly reduced (p = 0.10) under both living mulch treatments relative to the control. Flow-weighted nitrate-N concentrations were 23 mg L-1 for the control, 17 mg L-1 for the living mulch with 90 kg N ha(-1) yr(-1), and 6 mg L-1 for the living mulch with 0 kg N ha(-1) yr(-1). Total nitrate-N leached was reduced 31 and 74% relative to the control under the living mulch with 90 and 0 kg N ha(-1) yr(-1), respectively.