ARS | Publication request: IRRIGATION INCREASES CARBON IN AGRICULTURAL SOILS

Submitted to: International Soil Tillage Research Organization Proceedings
Publication Type: Proceedings/Symposium
Publication Acceptance Date: July 20, 2003
Publication Date: July 20, 2003
Citation: Entry, J.A., Sojka, R.E., Shewmaker, G.E. 2003. Irrigation increases carbon in agricultural soils. Proceedings of the 16th Triennial Conference of International Soil Tillage Research Organization: Soil Management for Sustainability. p. 391-395.

Interpretive Summary: We measured organic and inorganic 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 the amount of possible organic, 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 ICT 2.24 % 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 1.174 % 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 meaningful reductions in atmospheric carbon dioxide.

Technical Abstract: We measured organic and inorganic 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 the amount of possible organic, 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, a possible total (organic +inorganic) C 2.72 % 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, a possible 2.24 % 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 a possible gain of 1.174 % 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 meaningful reductions in atmospheric carbon dioxide.