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Long-Term Tillage And Cropping Sequence Effects On Dryland Residue And Soil Carbon Fractions, Upendra M. Sainju, Thecan Caesar-Tonthat, Andrew W. Lenssen, Robert G. Evans, Robert Kolberg Nov 2007

Long-Term Tillage And Cropping Sequence Effects On Dryland Residue And Soil Carbon Fractions, Upendra M. Sainju, Thecan Caesar-Tonthat, Andrew W. Lenssen, Robert G. Evans, Robert Kolberg

Andrew W. Lenssen

Long-term management practices are needed to increase dryland C storage and improve soil quality. We evaluated the 21-yr effects of combinations of tillage and cropping sequences on dryland crop biomass (stems + leaves) returned to the soil, residue C, and soil C fractions at the 0- to 20-cm depth in a Dooley sandy loam (fine-loamy, mixed, frigid, Typic Argiborolls) in eastern Montana. Treatments were no-till continuous spring wheat (Triticum aestivum L.) (NTCW), spring-tilled continuous spring wheat (STCW), fall- and spring-tilled continuous spring wheat (FSTCW), fall- and spring-tilled spring wheat–barley (Hordeum vulgare L.) (1984–1999) followed by spring wheat–pea (Pisum sativum L.) …


Diversified Cropping Systems In Semiarid Montana: Nitrogen Use During Drought, Andrew W. Lenssen, J. T. Waddell, G. D. Johnson, G. R. Carlson Jun 2007

Diversified Cropping Systems In Semiarid Montana: Nitrogen Use During Drought, Andrew W. Lenssen, J. T. Waddell, G. D. Johnson, G. R. Carlson

Andrew W. Lenssen

Improved nitrogen use efficiency would be beneficial to agroecosystem sustainability in the northern Great Plains of the USA. The most common rotation in the northern Great Plains is fallow–spring wheat. Tillage during fallow periods controls weeds, which otherwise would use substantial amounts of water and available nitrogen, decreasing the efficiency of fallow. Chemical fallow and zero tillage systems improve soil water conservation, and may improve nitrogen availability to subsequent crops. We conducted a field trial from 1998 through 2003 comparing nitrogen uptake and nitrogen use efficiency of crops in nine rotations under two tillage systems, conventional and no-till. All rotations …


Dryland Plant Biomass And Soil Carbon And Nitrogen Fractions On Transient Land As Influenced By Tillage And Crop Rotation, Andrew W. Lenssen, Upendra M. Sainju, Thecan Caesar-Thonthat, Jed Waddell Apr 2007

Dryland Plant Biomass And Soil Carbon And Nitrogen Fractions On Transient Land As Influenced By Tillage And Crop Rotation, Andrew W. Lenssen, Upendra M. Sainju, Thecan Caesar-Thonthat, Jed Waddell

Andrew W. Lenssen

Soil and crop management practices may alter the quantity, quality, and placement of plant residues that influence soil C and N fractions. We examined the effects of two tillage practices [conventional till (CT) and no-till (NT)] and five crop rotations [continuous spring wheat (Triticum aestivum L.) (CW), spring wheat–fallow (W–F), spring wheat–lentil (Lens culinaris Medic.) (W–L), spring wheat–spring wheat–fallow (W–W–F), and spring wheat–pea (Pisum sativum L.)–fallow (W–P–F)] on transient land previously under 10 years of Conservation Reserve Program (CRP) planting on the amount of plant biomass (stems + leaves) returned to the soil from 1998 to 2003 and soil C …