Soil and Sweet Corn Quality Responses to Tillage, Residue, and Nitrogen Management in Southern Iran

Abstract

Conservation tillage can drastically influence the environment by conserving soil due to enhancing soil structure and quality, thereby maintaining stable crop productivity and quality. To evaluate the effects of tillage practices, wheat residue management, and rate of nitrogen fertilization on soil and sweet corn quality, a 2-year (2014–2015) field study was conducted at the School of Agriculture farm, Shiraz University, Shiraz, Iran. Treatments consisted of three tillage systems including conventional (CT), reduced (RT), and no tillage (NT) as main plots, four N rates (0, 69, 138, and 207 kg N ha−1) as sub plots, and wheat residue management, removed versus retained, as sub–sub plots. Increasing N rates slightly increased ECe but not to the detrimental levels for crop or soil health. Soil pH was buffered due to the calcareous nature of the experimental soil. Soil organic carbon and total nitrogen were higher under RT and NT than CT, although the changes were considerably low. Soil bulk density was higher under NT treatment, which resulted in lower marketable yield after 2 years probably due to the limitations in nutrient uptake and N immobilization and applying high rates of N could reduce or eliminate N immobilization and limitations in nutrient uptake, resulted in comparable yield to CT. The higher N rates increased kernel protein content but reduced soluble solids of kernels (brix). Reduced tillage was slightly superior to the other two tillage practices in case of soil and kernel quality and marketable yield, while applying high N rate (207 kg N ha−1) to NT practice could compensate yield reduction during the transition from CT to NT practice.