ARS | Publication request: Carbon balance of sugarcane agriculture on histosols of the everglades agricultural area: review, analysis, and global energy perspectives

Submitted to: Soil and Crop Science Society of Florida Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 3, 2008
Publication Date: June 1, 2009
Citation: Allen Jr, L.H. 2009. Carbon balance of sugarcane agriculture on histosols of the everglades agricultural area: review, analysis, and global energy perspectives. Soil and Crop Science Society of Florida Proceedings. 66:7-14

Interpretive Summary: Biofuels from crops, including sugarcane, has received much attention. In Florida, sugarcane is grown on drained organic soils of the Everglades Agricultural Area (EAA). Subsidence of these organic soils has occurred since drainage began in the early 1900s. Subsidence by oxidation releases carbon dioxide to the atmosphere. An ARS scientist at Gainesville, Florida compared the balance of carbon released by soil oxidation with carbon uptake by sugarcane production. The emission of carbon from the EAA has been 22,600 lb/acre per year, equivalent to a plant biomass of 56,500 lb/acre per year. Average sugar yields are about 8,100 lb/acre per year. Thus, the losses of soil carbon have been 7 times greater than the carbon uptake in sugar yields. Reducing subsidence by high water table management, growing adapted cultivars, and utilization of all aboveground plant parts might decrease the ratio of carbon lost to carbon gain to about 1. With an average depth of 33 inches remaining, the EAA has enough organic soil, if burned as fuel, to supply global energy needs for only 11.5 days! Finally, the biomass production of at least 750 miles X 750 miles of land would be required to supply all the energy needs of the USA. [GRACEnet].

Technical Abstract: Biofuels production from crop products and cellulosic by-products, including sugarcane, has received much attention. In Florida, most sugarcane is produced on drained Histosols (organic soils) of the Everglades Agricultural Area (EAA). Subsidence has occurred via microbial oxidation since drainage in the early 1900s. Oxidation results in carbon (C) release as carbon dioxide to the atmosphere. The purpose is to compare C balance of soil oxidation and plant biomass production yields in the EAA, and to provide global energy perspectives. The emission of C from the EAA has been 25,400 kg/(ha-yr), equivalent to a plant biomass of 63,500 kg/(ha-yr). Mean sugar yields are about 9,100 kg/(ha-yr). Thus, the subsidence losses of C have been 7.0 times greater than sugar yield C. Reducing oxidative subsidence by high water table management, growing adapted cultivars, and utilization of all aboveground plant components might decrease this ratio to about 1.0. With an average Histosol depth of 0.84 m remaining, the EAA has enough organic soil, if burned as fuel, to supply global energy needs for only 11.5 days. Finally, the biomass production of about 1,200 km X 1,200 km would be required to supply all the energy needs of the USA. [GRACEnet].