Impact of Cover Crop on Nutrient Losses in an Upland Soil

Abstract

ABSTRACT Nutrient losses through leaching and surface runoff are the main problems in no-till upland soils in Mississippi. A two-year study was conducted in 2016 and 2017 on an Atwood silt loam soil to evaluate the impact of winter wheat (Triticum aestivum L.) cover crop (WCC) in no-till dryland cotton (Gossypium hirsutum L.) received poultry litter (PL) on nitrogen (N) and phosphorus (P) losses in leached and surface runoff water. Experimental design comprised a split-plot with a 2 × 2 treatment arrangement replicated 3 times. Treatments included WCC and winter fallow (WF) were assigned to the main plots, while PL at the rate of 6.7 and 0 Mg ha−1 was assigned to the subplots. Wheat was planted after harvesting cotton and leachates were collected from October to April using suction cup lysimeters. Surface runoff was collected from the edge of the plots. Nitrate-N concentrations in leachate samples were 45% and 21% less with WCC (9.9 and 17.2 mg L−1) than winter fallow (WF) (18.2 and 22 mg L−1) in the first and second year, respectively. Residual soil NO3-N concentration at the top 15 cm depth before planting cotton was 41% greater with WF than with WCC. In each year, runoff volume and water-soluble P (WP) concentrations were greater with WCC than with WF. It appears that the cover crop utilizes N during its growth period and slowly releases it for the subsequent crops as evidenced by greater cotton dry matter, lint yield, and cotton N uptakes mainly in the first year.