Perennial groundcover crop effects on soil moisture and water use efficiency in cotton cropping systems

Abstract Cotton ( Gossypium hirsutum L.) production in the southeastern US Coastal Plain is frequently affected by periods of limited water availability. Perennial groundcover crops (PGCC) may conserve soil moisture and reduce additional input costs for cotton. This study evaluated the effects of PGCC species red clover ( Trifolium pratense L.) and white clover ( Trifolium repens L.) on soil moisture retention and electrical conductivity (EC), and on cotton drought stress and water use efficiency compared to paradigms of weedy fallow and a terminated annual cover crop. Plots were strip‐tilled and planted with cotton in May of each year with clovers remaining alive between rows year‐round. Results showed that soils with PGCC had greater volumetric water content and EC than soil grown with annual cover crops at 15‐cm (0.10–0.18 m 3 m −3 and 15–40 µS cm −1 ) and 45‐cm (0.21–0.33 m 3 m −3 and 73–190 µS cm −1 ) depths, but less at 30‐cm (0.16–0.21 m 3 m −3 and 28–82 µS cm −1 ). Additionally, cotton leaf water potential (−1200 to −2300 kPa) and seedcotton (1.6–2.77 kg mm −1 ) and lint (0.74–1.22 kg mm −1 ) water use efficiencies did not differ among treatments. However, cover crop biomass moisture concentrations were negatively correlated (−0.71) to seedcotton and lint water use efficiencies during a wet growing season. These findings indicated that perennial clovers could be grown alongside cotton to provide ecosystem service benefits without reducing the cotton crop's access to limited water resources.