Effects of Long-Term Agricultural Nitrogen Fertilization on Organic Carbon Cycling

Abstract

The maintenance and improvement of soil organic carbon (SOC) pools is crucial to global food and fiber production as well as the management of carbon (C) emissions. Because SOC and nitrogen (N) cycles are linked, the effects of long-term agricultural N fertilization rates on SOC should be examined to improve soil management practices. Carbon and N were evaluated in soils of a long-term (38 yr) experiment in central Texas under two fertilization rates. A sorghum–wheat–soybean–fallow (SWS) rotation under no tillage was evaluated temporally across two seasons at the surface, and SWS was compared to monoculture wheat with depth to 1 m. No effects of N fertilization rate on SOC were found in the seasonal study, though temporal dynamics were observed. Increased SOC due to a greater rate of N fertilization was reported for the 1-m soil cores.