Submitted to: USDA Greenhouse Gas Symposium
Publication Type: Abstract Only
Publication Acceptance Date: November 20, 2006
Publication Date: February 6, 2007
Citation: Sainju, U.M. 2007. Dryland soil carbon dioxide emission and carbon storage as influenced by tillage, cropping, and nitrogen fertilization. Positioning Agriculture and Forestry to Meet the Challenges of Climate Change. In Fourth USDA Greenhouse Gas Conference. February 6-8, 2007. Baltimore, MD. p. 30. Technical Abstract: Soil and crop management practices may influence dryland soil CO2 emission and C sequestration. We evaluated the combined effects of tillage, cropping system, and N fertilization [no-till barley with 78 kg N ha-1 (NTBFN), no-till pea with 0 kg N ha-1 (NTPON), no-till fallow with 0 kg N ha-1 (NTFON), and conventional till fallow with 0 kg N ha-1 (CTFON)] on dryland soil surface CO2 flux and C storage at the 0 to 20 cm depth from 2005 to 2006 in eastern Montana. The CO2 flux increased immediately after substantial rain during the summer. In June and July, CO2 flux was greater in NTBFN and CTFON than in NTFON in 2005 but was greater in NTPON than in CTFON in 2006. Averaged across measurement dates, CO2 flux was greater in NTBFN than in other treatments in 2005 and greater in NTBFN and NTPON than in NTFON and CTFON in 2006. Cropping and N fertilization increased CO2 flux compared with fallow and no N fertilization, respectively, in both years and tillage increased the flux compared with no-tillage in 2006. The CO2 flux was linearly related with soil temperature and water content at the time of measurement. Soil C content was not influenced by treatments. Short-term management practices may not alter dryland soil C storage but can influence CO2 emission due to changes in soil temperature, water content, and nutrient levels. Increased respiration due to increased crop biomass and mineralization of soil organic C could have increased CO2 flux with than without cropping, N fertilization and tillage.