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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #303967
Title: Soil carbon and nitrogen affected by perennial grass, cover crop, and nitrogen fertilization

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

Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/25/2015
Publication Date: 9/8/2015
Citation: Sainju, U.M., Singh, B.P., Singh, H.P. 2015. Soil carbon and nitrogen affected by perennial grass, cover crop, and nitrogen fertilization. In: Janick, J., Whipkey, A., and Cruz, V.M., editors. Proceedings of New crops: Bioenergy, Biomaterials, and Sustainability. AAIC 25th Annual Meeting, October 13-16, 2013, Washington D.C. p. 228-236.

Interpretive Summary: Biomass from perennial bioenergy 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. Because of higher root biomass, perennial grasses can increase soil organic C and total N even when aboveground biomass is removed for livestock feed or biofuel production compared to annual crops. Similarly, cover crop and N fertilization can increase the amount residue returned to the soil and therefore soil organic C and total N compared to no cover crop and N fertilization. We evaluated the effects of the combinations of perennial grasses (energy cane vs. elephant grass), cover crops (clover cover crop vs. none), and N fertilization rates (0, 100, and 200 kg N/ha) on soil organic C, total N, ammonium- and nitrate-N concentrations at the 0-90 cm depth from 2011 to 2012 in central Georgia. Soil samples were collected in the fall after crop harvest and analyzed for soil C and N. Soil organic C at 15-30 cm and total N at 0-5 cm were greater for elephant grass with cover crop and 100 kg N/ha than for energy cane and elephant grass with no cover crop and N fertilization. In contrast, soil nitrate-N at 0-5 cm was lower for energy cane with no cover crop and N fertilization than for energy cane with cover crop and 100 to 200 kg N/ha. Elephant grass increased soil total N at 0-5 cm compared to energy cane. Cover crop increased soil organic C at 5-30 cm, total N at 5-15 cm, and nitrate-N at 15-30 cm compared to no cover crop. Nitrogen fertilization increased soil organic C and total N at 0-5 cm and nitrate-N compared to no N fertilization, but soil organic C at 15-30 cm was lower with 200 than with 100 kg N/ha. Soil organic C, total N, and nitrate-N decreased from 2011 to 2012, regardless of treatments. Preliminary results suggest that elephant grass with clover cover crop and 100 kg N/ha can sequester more soil C and N than other treatments and increased N fertilization rate can increase the potential for N leaching. Long-term studies are needed to exactly evaluate the effects of treatments on soil C and N.

Technical Abstract: Soil C and N sequestration and the potential for N leaching can be influenced by the type of perennial grass, cover crop, and N fertilization due to differences in crop yields and the amount of residue returned to the soil. We evaluated the effects of the combinations of perennial grasses (energy cane vs. elephant grass), cover crops (clover cover crop vs. none), and N fertilization rates (0, 100, and 200 kg N/ha) on soil organic C, total N, ammonium- and nitrate-N concentrations at the 0-90 cm depth from 2011 to 2012 in central Georgia. Soil organic C at 15-30 cm and total N at 0-5 cm were greater for elephant grass with cover crop and 100 kg N/ha than for energy cane and elephant grass with no cover crop and N fertilization. In contrast, soil nitrate-N at 0-5 cm was lower for energy cane with no cover crop and N fertilization than for energy cane with cover crop and 100 to 200 kg N/ha. Elephant grass increased soil total N at 0-5 cm compared to energy cane. Cover crop increased soil organic C at 5-30 cm, total N at 5-15 cm, and nitrate-N at 15-30 cm compared to no cover crop. Nitrogen fertilization increased soil organic C and total N at 0-5 cm and nitrate-N compared to no N fertilization, but soil organic C at 15-30 cm was lower with 200 than with 100 kg N/ha. Soil organic C, total N, and nitrate-N decreased from 2011 to 2012, regardless of treatments. Preliminary results suggest that elephant grass with clover cover crop and 100 kg N/ha can sequester more soil C and N than other treatments and increased N fertilization rate can increase the potential for N leaching.