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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #178375
Title: IRRIGATION INCREASES CARBON IN AGRICULTURAL SOILS

Author
item Entry, James
item Sojka, Robert
item SHEWMAKER, GLENN - UNIVERSITY OF IDAHO

Submitted to: Grassland International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/14/2005
Publication Date: 7/1/2005
Citation: Entry, J.A., Sojka, R.E., Shewmaker, G.E. 2005. Irrigation increases carbon in agricultural soils. Grassland International Congress Proceedings.

Interpretive Summary: We measured inorganic and organic C stored in southern Idaho soils having long term land use histories that supported native sagebrush vegetation (NSB), irrigated moldboard plowed crops (IMP), irrigated conservation (chisel) tilled crops (ICT) and irrigated pasture systems (IP). Inorganic C and total C (inorganic + organic C) in soil decreased in the order IMP>ICT>IP>NSB. We use our findings to estimate that amount of possible inorganic and total C sequestration if irrigated agriculture were expanded by 10%. If irrigated agricultural land were expanded by 10% worldwide and NSB were converted to IMP, 2.78 % of the total C emitted in the next 30 yr could be sequestered in soil. If irrigated agricultural land were expanded by 10% worldwide and NSB were converted to ICT, 1.87 % of the total C emitted in the next 30 yr could be sequestered in soil. If irrigated agricultural land were expanded worldwide and NSB were converted to IP, 0.04 % of the total C emitted in the next 30 yr could be sequestered in soils. Altering land use to produce crops on high output irrigated agriculture, while selected less-productive rainfed agricultural land were returned to temperate forest or native grassland, there could be reductions in atmospheric carbon dioxide.

Technical Abstract: We measured inorganic and organic C stored in southern Idaho soils having long term land use histories that supported native sagebrush vegetation (NSB), irrigated moldboard plowed crops (IMP), irrigated conservation (chisel) tilled crops (ICT) and irrigated pasture systems (IP). Inorganic C and total C (inorganic + organic C) in soil decreased in the order IMP>ICT>IP>NSB. We use our findings to estimate that amount of possible inorganic and total C sequestration if irrigated agriculture were expanded by 10%. If irrigated agricultural land were expanded by 10% worldwide and NSB were converted to IMP, 2.78 % of the total C emitted in the next 30 yr could be sequestered in soil. If irrigated agricultural land were expanded by 10% worldwide and NSB were converted to ICT, 1.87 % of the total C emitted in the next 30 yr could be sequestered in soil. If irrigated agricultural land were expanded worldwide and NSB were converted to IP, 0.04 % of the total C emitted in the next 30 yr could be sequestered in soils. Altering land use to produce crops on high output irrigated agriculture, while selected less-productive rainfed agricultural land were returned to temperate forest or native grassland, there could be reductions in atmospheric carbon dioxide.