Submitted to: Western Society of Soil Science
Publication Type: Abstract Only
Publication Acceptance Date: June 16, 2007
Publication Date: June 16, 2007
Citation: Sainju, U.M., Caesar, T., Lenssen, A.W., Evans, R.G., Pikul Jr, J.L. 2007. Dryland crop yields and soil organic matter as influenced by long-term tillage and cropping sequence. Western Society of Soil Science. p. 87. Technical Abstract: Long-term management practices are needed to sustain dryland crop yields and maintain soil organic matter in the northern Great Plains. We evaluated the 21-yr effects of no-till continuous spring wheat (NTCW), spring till continuous spring wheat (STCW), fall and spring till continuous spring wheat (FSTCW), fall and spring till spring wheat-barley (1984-1999) followed by spring wheat-pea (2000-2004) (FSTW-B/P), and spring till spring wheat-fallow (STW-F) on crop grain and biomass (stems + leaves) yields and soil C, N, and pH levels in eastern Montana. Spring wheat grain and biomass yields varied among years due to variation in rainfall and were lower in STW-F than in other treatments. Similarly, grain and biomass yields of barley and pea in FSTW-B/P varied among years. Soil inorganic and organic C contents at the 0- to 20-cm depth in 2004 were greater in NTCW, STCW, and FSTCW than in STW-F. Similarly, soil total N content was greater in NTCW and STCW than in FSTW-B/P and STW-F and greater in FSTCW than in STW-F. Potential N mineralization was greater in STCW than in NTCW, FSTW-B/P, and STW-F. In contrast, NH4-N and NO3-N contents were greater in FSTW-B/P than in NTCW and STCW. Soil pH did not differ among treatments. Long-term reduced tillage and continuous cropping increased spring wheat and biomass yields and soil C and N storage compared with the conventional system, such as STW-F. Tillage and inclusion of legumes, such as pea, in the crop rotation increased soil mineralizable and available, thereby potentially reducing the rate of N fertilization to the succeeding crops.