Composition and Decomposition of Peanut Residues in Georgia

Abstract

Abstract Legumes typically mineralize rapidly and can contribute to nitrogen (N) requirements of succeeding crops, but limited information exists on the mineralizable N content of peanut (Arachis hypogaea L.) residue. The objective of this study was to determine net N mineralization from two types of peanut residue for two soil types. Aboveground peanut residue (cv. Georgia Green) was collected 1 d prior to digging (PRE) and immediately after peanut threshing (POST). Leaf and stem residues were mixed and analyzed for carbon (C), N, lignin, and cellulose. Peanut residue equivalent to 4.5 Mg/ha was applied to a Greenville fine sandy loam (fine, kaolinitic, thermic Rhodic Kandiudults) and a Tifton loamy sand (fine-loamy, kaolinitic, thermic Plinthic Kandiudult) and aerobically incubated for 98 d in the dark at 25 C to determine C and N mineralization. Each soil was incubated simultaneously, with and without residue. PRE harvest residue had lower C, lignin, and cellulose concen-trations, but higher N concentrations than POST harvest residue. Differences in residue quality corresponded to differences in cumulative C mineralized and C turnover for the Tifton soil, but did not result in differences for cumulative N mineralized or relative N mineralized within either soil type. These data indicate that peanut residue will not supply significant amounts of N to a subsequent crop for these two soil types.