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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #340016
Title: Root and soil total carbon and nitrogen under bioenergy perennial grasses with various nitrogen rates

Author
item Sainju, Upendra
item Allen, Brett
item LENSSEN, ANDREW - Iowa State University
item Mikha, Maysoon

Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2017
Publication Date: 12/1/2017
Publication URL: https://handle.nal.usda.gov/10113/5848743
Citation: Sainju, U.M., Allen, B.L., Lenssen, A.W., Mikha, M.M. 2017. Root and soil total carbon and nitrogen under bioenergy perennial grasses with various nitrogen rates. Biomass and Bioenergy. 107(12):326-334. https://doi.org/10.1016/j.biombioe.2017.10.021.
DOI: https://doi.org/10.1016/j.biombioe.2017.10.021

Interpretive Summary: Perennial grasses used for the bioenergy production can enhance soil carbon and nitrogen sequestration due to their extensive root systems compared with annual cropping systems, but extensive removal of aboveground biomass can affect soil and environmental quality. Little information is available about soil carbon and nitrogen stocks under bioenergy perennial grasses. Improved management practices are needed to improve soil carbon and nitrogen stocks while sustaining aboveground biomass yield in bioenergy perennial grasses. We evaluated the effect of perennial grasses and nitrogen fertilization rates on root biomass carbon and nitrogen and soil total carbon and nitrogen stocks at the 0-120 cm depth from 2011 to 2013 in the northern Great Plains, USA. Perennial grasses were intermediate wheatgrass, smooth bromegrass, and switchgrass, and nitrogen fertilization rates were 0, 28, 56, and 84 kg of nitrogen per hectare. Root biomass carbon and nitrogen at 0-15 and 0-120 cm were greater with intermediate wheatgrass and switchgrass than smooth bromegrass in 2011, but the trend reversed for root biomass carbon at 0-15 cm in 2012. Soil total carbon at 0-15, 30-60, and 0-120 cm varied among grass species and years. At 30-60 cm, soil total carbon increased with increased nitrogen rates under intermediate wheatgrass and switchgrass, but decreased under smooth bromegrass. At 60-90 cm, the trend for soil total carbon reversed. Soil total nitrogen at 15-30 cm was greater under intermediate wheatgrass than smooth bromegrass and switchgrass. Root biomass carbon and nitrogen at 0-120 cm were 12 to 16 times greater and soil total carbon and nitrogen 8-9% greater under perennial grasses than annual spring wheat. Although intermediate wheatgrass returned more root carbon and nitrogen to the soil than other grasses, both soil total carbon and nitrogen stocks varied among grass species and nitrogen rates. Increased root carbon and nitrogen inputs, however, increased soil total carbon and nitrogen stocks under perennial grasses compared with annual spring wheat.

Technical Abstract: Information is scanty about root and soil C and N under bioenergy perennial grasses with various N fertilization rates in semiarid regions. We evaluated the effect of perennial grasses and N rates on root biomass C and N and soil total C (STC) and total N (STN) stocks at the 0-120 cm depth from 2011 to 2013 in the northern Great Plains, USA. Perennial grasses were intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth and Dewey), smooth bromegrass (Bromus inermis L.), and switchgrass (Panicum virgatum L.), and N fertilization rates were 0, 28, 56, and 84 kg N ha-1. Root biomass C and N at 0-15 and 0-120 cm were greater with intermediate wheatgrass and switchgrass than smooth bromegrass in 2011, but the trend reversed for root biomass C at 0-15 cm in 2012. The STC at 0-15, 30-60, and 0-120 cm varied among grass species and years. At 30-60 cm, STC increased with increased N rates under intermediate wheatgrass and switchgrass, but decreased under smooth bromegrass. At 60-90 cm, the trend for STC reversed. The STN at 15-30 cm was greater under intermediate wheatgrass than smooth bromegrass and switchgrass. Root biomass C and N at 0-120 cm were 12 to 16 times greater and STC and STN 8-9% greater under perennial grasses than annual spring wheat. Differences in root C and N inputs had variable effects on STC and STN among grasses, but these were greater under perennial grasses than annual spring wheat. Nitrogen fertilization had little effect on these parameters.