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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #327755
Title: Cover crops for enriching soil carbon and nitrogen under bioenergy sorghum

Author
item Sainju, Upendra
item SINGH, HARI - Fort Valley State University
item SINGH, BHARAT - Fort Valley State University

Submitted to: Springer Verlag
Publication Type: Book / Chapter
Publication Acceptance Date: 11/12/2016
Publication Date: 1/1/2017
Citation: Sainju, U.M., Singh, H.P., Singh, B.P. 2017. Cover crops for enriching soil carbon and nitrogen under bioenergy sorghum. In: Field, D.J., Morgan, C.L.S., McBratney, A.B., editors. Global Soil Security, Progress in Soil Science. Switzerland: Springer Verlag. p. 181-191. doi:10.1007/978-3-319-43394-3.

Interpretive Summary: Sorghum crops, such as forage and sweet sorghum, can be used for bioenergy production because of their relatively higher biomass yields compared with other bioenergy crops. Continuous removal of aboveground biomass for bioenergy can reduce soil organic matter which is a key factor for maintaining long-term soil fertility. Soil carbon and nitrogen can be enriched with cover crops under agronomic crops, but little is known about their enrichment under bioenergy crops. We evaluated the effects of legume (hairy vetch), nonlegume (rye), a mixture of legume and nonlegume (hairy vetch and rye) and a control with no cover crop on soil organic carbon, total nitrogen, and nitrate-nitrogen contents under bioenergy sorghum from 2010 to 2013 in the southeastern United States. Cover crop biomass and carbon and nitrogen contents were greater with vetch/rye mixture than rye and the control. Soil organic carbon at 5-15 and 15-30 cm was greater with vetch/rye than other treatments under forage sorghum and at 0-5 cm and 5-15 cm was greater with vetch/rye and vetch than rye or the control under sweet sorghum. Soil total nitrogen at 5-15 cm was greater with vetch/rye and the control than rye under forage sorghum and at 0-5 and 5-15 cm were greater with vetch/rye and rye than the control under sweet sorghum. Both soil organic carbon and soil total nitrogen at all depths increased linearly from 2010 to 2013, regardless of cover crops and sorghum species. Nitrate-nitrogen content at all depths varied with cover crops from 2011 to 2013. Bicultural cover crops, such as hairy vetch/rye mixture, has greater potential to sequester carbon and nitrogen than monocultures, such as hairy vetch and rye, or no cover crop due to greater crop residue returned to the soil under bioenergy sorghum where aboveground biomass is harvested for bioenergy or feedstock.

Technical Abstract: Soil carbon (C) and nitrogen (N) can be enriched with cover crops under agronomic crops, but little is known about their enrichment under bioenergy crops. Legume (hairy vetch [Vicia villosa Roth]), nonlegume (rye [Secaele cereale L.]), a mixture of legume and nonlegume (hairy vetch and rye) and a control with no cover crop were grown in the winter to evaluate their effects on soil organic C (SOC), total N (STN), and nitrate-N (NO3-N) contents under bioenergy sorghum from 2010 to 2013. Cover crop biomass and C and N contents were greater with vetch/rye mixture than rye and the control. The SOC at 5-15 and 15-30 cm was greater with vetch/rye than other treatments under forage sorghum and at 0-5 cm and 5-15 cm was greater with vetch/rye and vetch than rye or the control under sweet sorghum. The STN at 5-15 cm was greater with vetch/rye and the control than rye under forage sorghum and at 0-5 and 5-15 cm were greater with vetch/rye and rye than the control under sweet sorghum. Both SOC and STN at all depths increased linearly from 2010 to 2013, regardless of cover crops and sorghum species. The NO3-N content at all depths varied with cover crops from 2011 to 2013. Bicultural cover crops, such as hairy vetch/rye mixture, has greater potential to sequester C and N than monocultures, such as hairy vetch and rye, or no cover crop due to greater crop residue returned to the soil under bioenergy sorghum where aboveground biomass is harvested for bioenergy or feedstock.