Contribution of Conservation Practices to Water Quality in Arkansas Cotton: Results of 2-Year Study

Conservation management practices has been implemented in the Mid-south to mitigate nutrient and sediment losses during field overflow. A 2-year 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. Concentrations of nutrients (NH₄-N, NO₃-N, NO₂-N, P) and sediments in irrigation runoff water and lint yields were measured in the four systems. After implementation of conservation practices (cover crop, vegetated buffer strip), mean N concentrations in the runoff were mainly <0.2 mg N L^-1, with NO₃-N being relatively the highest among N forms. Concentrations of runoff dissolved P were <0.5 mg P L^-1 and were affected by volume of runoff water. Values for pH and specific electrical conductivity of water runoff were generally minimal and peaked only during heavy rain events.  Total suspended sediments and soil sediment concentrations did not differ between conventional and conservation practice with greatest losses observed during early planting season. However, higher sediment losses occurred in irrigated compared to rainfed system. Our results suggest that conservation system i.e. cover cropping and buffer strip has the potential to reduce the excess nutrients and sediments from the field before it can reach waterways. Continued research on conservation practice for higher water quality is required to better asses these systems and help maintain agricultural production while minimizing environmental degradation.