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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #193947
Title: MANAGEMENT OF IRRIGATED AGRICULTURE TO INCREASE ORGANIC CARBON STORAGE AND MICROBIAL DIVERSITY IN SOILS

Author
item Entry, James
item Sojka, Robert
item MILLS, DEETTA - FLORIDA INT'L UNIVERSITY
item FUHRMANN, JEFFRY - UNIVERSITY OF DELAWARE
item MATHEE, KALAI - FLORDA INT'L UNIVERSITY
item JAYACHANDRAN, KRISH - FLORIDA INT'L UNIVERSITY
item SHEWMAKER, GLENN - UNIVERSITY OF IDAHO

Submitted to: New Research on Environmental Pollution
Publication Type: Book / Chapter
Publication Acceptance Date: 4/4/2006
Publication Date: 9/1/2007
Citation: Entry, J.A., Sojka, R.E., Shewmaker, G.E. 2007. Management of irrigated agriculture to increase organic carbon storage in soils. In: Plattenberg, R.H., editor. Environmental Pollution: New Research. New York, NY: Nova Science Publishers. p. 121-139.

Interpretive Summary: Atmospheric carbon dioxide is expected to double during the next century producing a rise in air temperature of 1.5 to 5 degrees Celsius. Sequestering carbon (C) in soils may be one method to reduce the concentration of carbon dioxide in the atmosphere. We measured inorganic and organic C, bacterial biomass and structural community diversity 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 inorganic and total C potentially sequestered if the use of irrigated agriculture were increased. If irrigated agricultural land were expanded by10% worldwide and NSB were converted to IMP, 4.38 % of the total C emitted in the next 30 yr could potentially be sequestered in soil. If irrigated agricultural land were expanded by 10% worldwide and NSB were converted to ICT, 16.32 % of the total C emitted in the next 30 yr could be sequestered in soil. We measured bacterial diversity in all soils and at all depths. Diversity was the greatest in the NSB 5-15 cm soil and lowest in the IMP soil. ICT and IP increase soil C and to some extent increase diversity relative to IMP. Irrigated agricultural systems can produce twice the yield compared to non-irrigated land. Irrigation also favors economic sustainability and increasing soil C relative to native semi arid or arid sites, but decreases bacterial diversity compared to native sagebrush soils. Altering land use to produce crops on high output irrigated agriculture, while returning less-productive rainfed agricultural land to temperate forest or native grassland, could reduce atmospheric carbon dioxide.

Technical Abstract: If fossil fuel burning continues at the present rate, atmospheric carbon dioxide is expected to double during the next century producing a rise in air temperature of 1.5 to 5 degrees C. Sequestering carbon (C) in soils may be one method to reduce the concentration of carbon dioxide in the atmosphere. We measured inorganic and organic C, bacterial biomass and structural community diversity 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 inorganic and total C potentially sequestered if the use of irrigated agriculture were increased. If irrigated agricultural land were expanded by10% worldwide and NSB were converted to IMP, 4.32 % of the total C emitted in the next 30 yr could potentially be sequestered in soil. If irrigated agricultural land were expanded by 10% worldwide and NSB were converted to ICT, a possible 16.32 % of the total C emitted in the next 30 yr could be sequestered in soil. We employed amplicon length heterogeneity (ALH) DNA profiling to access the eubacterial diversity in all soils and at all depths. The Shannon-Weaver diversity index was used to measure the differences using the combined data from three hypervariable domains of the eubacterial 16S rRNA genes. Diversity was the greatest in the NSB 5-15 cm soil and lowest in the IMP soil. ICT and IP increase soil C and to some extent increase diversity relative to IMP. Irrigated agricultural systems can produce twice the yield compared to non-irrigated land. Irrigation also favors economic sustainability and increasing soil C relative to native semi arid or arid sites, but decreases eubacterial diversity compared to native sagebrush soils. Irrigation decreases soil eubacterial diversity compared to native sagebrush soils at the 0-5 cm depth, but because irrigated agriculture produces higher yields, less land needs to be put into production relative to rainfed agriculture. Altering land use to produce crops on high output irrigated agriculture, while returning less-productive rainfed agricultural land to temperate forest or native grassland, could reduce atmospheric carbon dioxide.