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Cover Crop and Nitrogen Fertilization Influence Soil Carbon and Nitrogen Under Bioenergy Sweet Sorghum
- Upendra M. Sainju, Hari P. Singh, Bharat P. Singh, Wayne F. Whitehead, Anuj Chiluwal, Rajesh Paudel
- Agronomy journal 2018 v.110 no.2 pp. 463-471
- Secale cereale, Sorghum bicolor, Vicia villosa, bioenergy, biomass production, cover crops, fertilizer rates, nitrate nitrogen, nitrogen, nitrogen fertilizers, rye, soil, soil organic carbon, sweet sorghum, winter, Southeastern United States
- Sustainable production of sweet sorghum (Sorghum bicolor [L.] Moench) grown for bioenergy production depends on practices that maintain soil C and N levels. The objective of this study was to evaluate the effect of winter cover crops (hairy vetch [Vicia villosa Roth], rye [Secaele cereale L.], hairy vetch/rye mixture, and the control [no cover crop]) and N fertilization rates (0 and 90 kg N ha⁻¹) on soil organic C (SOC), total N (STN), NH₄–N, and NO₃–N contents at the 0- to 30-cm depth from 2010 to 2014 in the southeastern USA. Cover crop biomass yield and C content were greater with vetch/rye than vetch and the control and N content greater with vetch and vetch/rye than the control in 2013 and 2014. The SOC and STN at 0 to 5 cm were greater with vetch/rye than the control and at 15 to 30 cm were greater with vetch than vetch/rye. At 0 to 5 cm, SOC increased at 0.55 Mg C ha⁻¹ yr⁻¹ and STN at 0.06 Mg N ha⁻¹ yr⁻¹, regardless of treatments. At most depths, NH₄–N content was greater with rye than the control and greater with 0 than 90 kg N ha⁻¹, but NO₃–N content was greater with vetch/rye than rye. Because of greater cover crop C and N inputs, soil C and N stocks can be enhanced and N availability can be optimized by growing vetch and vetch/rye mixture cover crops to replace the stocks reduced by the removal of aboveground sweet sorghum biomass.