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Title: Growing Cover Crops Improve Biomass Accumulation and Carbon Sequestration: A Phytotron Study

Author
item WANG, Q - University Of Florida
item LI, Y - University Of Florida
item Alva, Ashok

Submitted to: Journal of Environmental Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2010
Publication Date: 6/1/2010
Citation: Wang, Q., Li, Y., Alva, A.K. 2010. Growing Cover Crops Improve Biomass Accumulation and Carbon Sequestration: A Phytotron Study. Journal of Environmental Protection. 1: 73-84.

Interpretive Summary: Enhanced buildup of carbon is an important criterion for improving soil quality. Cover crops contribute to enhanced carbon sequestration. In this study carbon sequestration potential of six winter and summer cover crops was investigated in two major agricultural soils (one from Washington potato production region; and one from South Florida vegetable growing region). Among the winter cover crops, bellbean demonstrated highest while clover has the lowest carbon accumulation. Likewise, sunnhemp and caster bean demonstrated the highest and lowest carbon accumulation among the summer cover corps, respectively. The mean increase in soil organic carbon across two soils from different agricultural regions was 14 to 39 percent. This study demonstrated the beneficial role of cover crops in enhancing soil carbon and, in turn, soil quality. Furthermore, investigations are in progress to indentify additional benefits of cover crops, i.e. nitrogen mineralization, reduce soil erosion, etc.

Technical Abstract: Six of each winter and summer cover crops were grown in two soils, Krome gravelly loam soil (KGL), and Quincy fine sandy soil (QFS), in phytotrons at 3 temperatures (10/20, 15/25, 25/30 oC for winter/summer cover crops) to investigate their contributions for carbon (C) sequestration. The winter cover crops were white clover, purple vetch, bell bean, triticale, mustard, and ryegrass, and the summer cover crops were sunn hemp, velvetbean, cowpea, sorghum sudangrass, okra, and castor bean. Among winter cover crops, the highest and the least amounts of C accumulated were by bellbean (597 g m 2) and white clover (149 g m-2), respectively, in the QFS soil. Among summer cover crops, sunn hemp accumulated the largest quantity of C (481 g m-2), while that by castorbean was 102 g m-2 at 30 oC in the KGL soil. The mean net biomass C remained following the 127 d decomposition were 187 g m-2 of C (73% of the total) and 91 g m-2 (52% of the total) for the winter and summer cover crops, respectively. Following a full cycle of winter and summer cover crops grown, the mean soil organic C (SOC) increased by 13.8 and 39.1% in the KGL and QFS soil, respectively, compared to the respective soils before. The results suggest that triticale, ryegrass, and bellbean are the promising winter cover crops in the QFS soil, while sunn hemp, velvetbean, and sorghum sudangrass are recommended summer cover crops under favorable temperatures.