Conservation Management Practices for Reducing Sediment Losses in Arkansas Cotton

Conservation practices are routinely implemented to improve water quality of surface runoff from agricultural systems. Adoption of conservation practices by farmers remains a challenge to many extension workers and government agencies because of varying levels of effectiveness of these practices. A field study with cotton (Gossypium hirsutum, L.) was conducted to determine the impact of conservation management system on quality of runoff water. The experiment was designed as a randomized complete block design with 2 irrigation (Irrigated vs Rainfed) and crop management systems (Conventional:[cereal rye winter cover crop/no-till/ mowed turn-row and with vegetated field buffer strip]  vs Conservation: [re-bedding in spring, furrow tillage prior to first irrigation, non-vegetated turn-row & field border]) replicated three times. Water samples were collected during field runoff due to rainfall and irrigation. Soil sediment concentrations (SSC) and total suspended solids (TSS) ranged from 23 to 2,027 mg sediments L^-1 and 4 to1,663 mg L^-1 throughout study period. Mean lint yields ranged from 792 to 1,774 kg ha^-1 and were not significantly affected by irrigation or conservation practice (P = 0.179 – 0.371). The implementation of multiple conservation practices did not significantly reduce TSS and SSC during the first year. However, SSC and TSS significantly reduced by 56-65% in conservation systems compared to conventional systems. The reductions of TSS and SSC were 2 to 5 times lower in non-growing season compared to growing season indicating that multiple conservation practices i.e. reduced furrow tillage, vegetative buffer strip and winter rye cover effectively reduced sediment losses during the non-growing period. This study suggests that long-term measurement of surface water quality runoff in conservation systems is needed to better assess the multiple benefits of this practice in irrigated cotton.