Soil respiration and litter decomposition responses to nitrogen fertilization rate in no-till corn systems

• Published in: Agriculture, ecosystems & environment ecosystems & environment, 2013-10, Vol.179, p.35-40
• Main Authors: Grandy, A. Stuart, Salam, Dure Shahwar, Wickings, Kyle, McDaniel, Marshall D., Culman, Steve W., Snapp, Sieglinde S.
• Format: Article
• Language: English
• Subjects: agricultural soils; Agronomy. Soil science and plant productions; aromatic compounds; Arthropoda; Biological and medical sciences; carbohydrate metabolism; Carbon; carbon sinks; corn; cropping systems; Cropping systems. Cultivation. Soil tillage; Decomposition; Dynamical systems; Dynamics; Enzymes; Fertilization; fertilizer rates; Fertilizing; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; Litter; monophenol monooxygenase; Nitrogen; nitrogen fertilizers; Nitrogen, phosphorus, potassium fertilizations; no-tillage; organic matter; Soil (material); Soil organic matter; soil respiration; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Triticum aestivum; wheat
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2013.04.020

•N fertilization reduced potentially mineralizable C by as much as 58%.•Total, light fraction, and permanganate oxidizable C were not influenced by N.•Soil and litter enzymes showed small, temporally variable responses to N.•Results do not support N fertilization as a contributor to depletion of C stocks. Litter decomposition dynamics are influenced by soil nutrient status, yet the specific effects of soil nitrogen (N) on litter decomposition in agricultural systems are not well understood. We explored litter decomposition and related soil organic matter dynamics in no-till, corn-based Midwestern U.S. cropping systems receiving 0, 134, and 291kgNha−1y−1. We found that total soil carbon (C) and N, light fraction organic matter, and permanganate oxidizable C were similar among treatments, but N fertilization at rates of 134 and 291kgNha−1y−1 reduced potentially mineralizable C by as much as 37% and 58%, respectively, compared to the unfertilized treatment. Litter mass remaining after one year of field decomposition was greater with wheat litter (37%) than with corn litter (23%), but was not influenced by N fertilizer rate. In litter, N fertilization led to increases in the activities of two hydrolase enzymes involved in simple carbohydrate metabolism (β-d-cellobiohydrolase and β-1,4-glucosidase) and periodic increases in one related to N metabolism (β-1,4-N-acetylglucosaminidase), but had no effects on enzymes regulating the breakdown of aromatic compounds (phenol oxidase), or on enzymes measured in the soil. N fertilization also decreased arthropod densities in decomposing litter. We found contrasting effects of N fertilizer on processes regulating decomposition, but altogether our results were consistent with a limited or nil role for N fertilization in accelerating litter and soil C turnover, and thus do not support N fertilization as a contributor to depletion of C stocks in agricultural soils.