Effect of Rye Residue on Soil Properties and Nitrogen Fertilization of Cotton

Abstract

Conservation tillage systems that use rye (Secale cereale L.) as a cover crop have many benefits on soils properties and crop productivity. However, rye biomass could be harvested for alternative uses, which could jeopardize the long-term sustainability of cropping systems. The objective of this study was to determine: (i) the effect of rye residue management on selected soil properties, and (ii) the impact of rye residue management and cotton (Gossypium hirsutum L.) nitrogen (N) fertilization rates on cotton growth parameters and yield, in a Marvyn loamy sand (fine-loamy, kaolinitic, thermic Typic Kanhapludult) of central Alabama, United States. Three rye residue managements (no winter cover crop, rye residue removed and rye residue retained) and four N fertilization rates for cotton (0, 50, 100 and 140 kg ha-1) were evaluated. Treatment arrangement was a split-plot in a randomized complete block design with four replications. After two growing seasons, total soil organic carbon (C), particulate organic matter C, mineral-associated + water-soluble C and total soil N were significantly higher in rye residue retained than in other treatments, to a depth of 5-cm. The soil water retention across matric potentials was reduced by 7 % and bulk density was increased by 5 % for rye residue removed compared to rye residue retained. Rye residue removal decreased the soil water content early in the cotton season compared to rye residue retained. There were no significant differences between rye residue retained and removed for the other measured soil properties. The highest values of soil penetration resistance were observed with no winter cover crop. In one of the two years, cotton population, leaf and plant nitrogen concentration, cotton biomass and N uptake at first square, and cotton biomass production between first square and cutout were higher in rye residue retained followed by rye residue removed and no winter cover crop. Nonetheless, leaf N concentration at early bloom and cotton biomass N concentration between first square and cutout were higher for no winter cover crop, followed by rye residue removed and retained. The highest seed cotton yield was recorded in rye residue retained with either 125 kg N ha-1 or 140 kg N ha-1. Short-term rye residue removal appears to have negative effects on some surface soil properties of these Coastal Plain soils. This could negatively affect cotton growth, seed cotton yield and the cotton response to N fertilization.