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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #309152
Title: Soil carbon and nitrogen in response to perennial bioenergy perennial grasses, cover crop, and nitrogen fertilization

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

Submitted to: Pedosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2016
Publication Date: 3/3/2017
Publication URL: http://handle.nal.usda.gov/10113/5652357
Citation: Sainju, U.M., Singh, H.P., Singh, B.P. 2017. Soil carbon and nitrogen in response to perennial bioenergy perennial grasses, cover crop, and nitrogen fertilization. Pedosphere. 27(2):223-238. https://doi.org/10.1016/S1002-0160(17)60312-6.
DOI: https://doi.org/10.1016/S1002-0160(17)60312-6

Interpretive Summary: Interest is growing to use ligno-cellulosic feedstock materials, such as perennial grasses, for bioenergy production. Biomass from such crops can be used either to produce ethanol or generate electricity, which can substantially reduce the use of fossil fuel and the amount of petroleum imported from foreign countries. Removal of aboveground biomass for bioenergy, however, can have adverse effect on soil and environmental quality. Novel management practices, such as cover crop, N fertilization, and improved species of grasses, are needed to enhance soil and environmental quality by increasing soil organic matter and reducing the potential for N leaching while sustaining aboveground biomass yield. We evaluated the effects of cover crops and nitrogen (N) fertilization rates on soil organic carbon (C), total N, ammonium- (NH4-N), and nitrate-nitrogen (NO3-N) contents at the 0-30 cm depth under bioenergy perennial crops from 2010 to 2013 in the southeastern USA. Treatments included an incomplete combination of two perennial grasses (energy cane and elephant grass), two cover crops (crimson clover vs. none), and three N fertilization rates (0, 100, and 200 kg N ha-1). Soil organic C and total N at 0-5 cm were greater in elephant grass with cover crop and 100-200 kg N ha-1 than energy cane without cover crop and nitrogen fertilization. Similarly, NO3-N content at 0-5 and 5-15 cm was greater in energy cane with cover crop and 200 kg N ha-1 than energy cane and elephant grass without cover crop and N fertilization or energy cane with cover crop. Cover crop increased soil organic C at 5-15 cm compared with no cover crop, and N fertilization increased soil organic C, total N, and NO3-N at 0-5 cm compared with no N fertilization, but energy cane reduced soil organic C and total N at 5-15 cm compared with elephant grass. Regardless of treatments, soil organic C increased at 0.45-0.82 Mg C ha-1 yr-1 and total N increased at 0.06 to 0.10 Mg N ha-1 yr-1, but NH4-N and NO3-N varied from 2010 to 2013. Elephant grass with crimson clover cover crop and 100 kg N ha-1 has the potential to increase soil C and N storage compared with the other treatments. Long-term studies, however, are needed to confirm the result. Because of similar soil organic C, total N, and NO3-N contents between 100 and 200 kg N ha-1, N fertilization rate >100 kg N ha-1 should be avoided to perennial grasses to sustain soil C and N storage and reduce the cost of N fertilization and the potential for N leaching.

Technical Abstract: In bioenergy perennial grasses, removal of aboveground biomass for feedstock to produce cellulosic ethanol may reduce soil C and N contents and therefore on soil quality. Cover crop and N fertilization may reduce such negative impacts. The objective of this study was to evaluate the effects of cover crops and N fertilization rates on soil organic C (SOC), total N (STN), NH4-N, and NO3-N contents at the 0-30 cm depth under bioenergy perennial crops from 2010 to 2013 in the southeastern USA. Our hypothesis was that elephant grass (Pennisetum purpureum L.) with cover crop and N fertilization can increase soil C and N storage and reduce the potential for N leaching compared with energy cane [Sacharum spontaneum L.] with or without cover crop and N fertilization. Treatments included an incomplete combination of two perennial grasses (energy cane and elephant grass), two cover crops (crimson clover [Trifolium incarnatum L.] vs. none), and three N fertilization rates (0, 100, and 200 kg N ha-1) arranged in a randomized block design with three replications. The SOC and STN at 0-5 cm were greater in elephant grass with cover crop and 100-200 kg N ha-1 than energy cane without cover crop and N fertilization. Similarly, NO3-N content at 0-5 and 5-15 cm was greater in energy cane with cover crop and 200 kg N ha-1 than energy cane and elephant grass without cover crop and N fertilization or energy cane with cover crop. Cover crop increased SOC at 5-15 cm compared with no cover crop, and N fertilization increased SOC, STN, and NO3-N at 0-5 cm compared with no N fertilization, but energy cane reduced SOC and STN at 5-15 cm compared with elephant grass. Regardless of treatments, SOC increased at 0.45-0.82 Mg C ha-1 yr-1 and STN increased at 0.06 to 0.10 Mg N ha-1 yr-1, but NH4-N and NO3-N varied from 2010 to 2013. Elephant grass with crimson clover cover crop and 100 kg N ha-1 has the potential to increase soil C and N storage compared with the other treatments. Long-term studies, however, are needed to confirm the result. Because of similar SOC, STN, and NO3-N contents between 100 and 200 kg N ha-1, N fertilization rate >100 kg N ha-1 should be avoided to perennial grasses to sustain soil C and N storage and reduce the cost of N fertilization and the potential for N leaching.