Soil organic matter, greenhouse gas emissions, and sorghum yield in semi‐arid drylands

Abstract

Abstract Sorghum [Sorghum bicolor (L.) Moench] serves as a low‐cost alternative to corn (Zea mays L.) in semi‐arid regions of the world because of its high N and water use efficiencies. However, there has been a concern regarding N loss to the atmosphere as nitrous oxide (N2O) from semi‐arid drylands. This study investigated various soil C and N components, including CO2 and N2O emissions, and crop yield with a dairy compost (13.5 Mg ha−1) and four rates of chemical N fertilizer (0, 22.4, 44.8, and 67.3 kg ha−1) in dryland sorghum. There was no significant difference in soil C and N fractions among N fertilizer rates, although compost addition numerically increased soil C storage and 67.3 kg ha−1 N rate resulted the highest yield in both years. Potential nitrogen mineralization (PNM) was negatively related to crop yield and positively related to grain N content. Soils with greater inorganic N and PNM had a lower carbon dioxide (CO2) emissions, while soils with greater potential C mineralization (PCM) had lower N2O emissions. The results of this study show no significant improvements in yield of dryland sorghum in the semi‐arid environment of southern Great Plains in the short term. However, compost and 44.8 kg N ha−1 applications appeared to be beneficial when both yield and quality were compared.