Measuring Water Use Patterns and Efficiency in Living Mulch and Cover Crop Systems.

A living mulch (LM) system that uses white clover to produce corn is being developed in Georgia. Establishment methods for the clover and the corn have been determined, but questions remain regarding LM water needs. The objectives of this study were to determine the intra- inter-row water use of the LM system compared to cereal rye (CR) and crimson clover (CC) cover crops as well as the water use efficiency of each system.  Soils in a field site were physically and pedologically characterized for uniformity.  Soil moisture was measured within and between corn rows growing in LM, CC, and CR field plots No differences were observed in the water use efficiencies of the three systems. The volumetric water content in the 15-30 centimeter depth of the living mulch was lower than that in the cereal rye treatment at all but one sampling date, suggesting the white clover may be limiting water supply to the corn.  All treatments used more water from within than between rows.  CR had the greatest soil water content in 0-15 and 15-30 cm depths for both within and between rows, LM and CC had similar water content within rows, but LM had the least water content between rows.  LM and CC had similar total water use but CR had the least total water use.  Corn yields were 14.5, 12.9, and 13.4 for the CC, LM, and CR treatments, and water use efficiency was 33.3, 28.1, and 37.7 kg ha^-1 mm^-1 water used, respectively.