부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.still.2006.08.012 Byline: A.W. Lenssen (a), J.T. Waddell (a), G.D. Johnson (b), G.R. Carlson (c) Keywords: Spring wheat; Field pea; Chickpea; Lentil; Yellow mustard; Safflower; Sunflower; Zero tillage; Soil nitrate; Nitrogen recovery index; Nitrogen harvest index; Crop yields Abstract: 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 included spring wheat, two rotations included field pea, while lentil, chickpea, yellow mustard, sunflower, and safflower were present in single rotations with wheat. Growing season precipitation was below average in 3 of 4 years, resulting in substantial drought stress to crops not following fallow. In general, rotation had a greater influence on spring wheat nitrogen accumulation and use efficiency than did tillage system. Spring wheat following fallow had substantially higher N accumulation in seed and biomass, N harvest index, and superior nitrogen use efficiency than wheat following pea, lentil, chickpea, yellow mustard, or wheat. Preplant nitrate-N varied widely among years and rotations, but overall, conventional tillage resulted in 9kgha.sup.-1 more nitrate-N (0-60cm) for spring wheat than did zero tillage. However, zero tillage spring wheat averaged 11kgha.sup.-1 more N in biomass than wheat in conventional tillage. Nitrogen accumulation in pea seed, 45kgha.sup.-1, was superior to that of all alternate crops and spring wheat, 17 and 23kgha.sup.-1, respectively. Chickpea, lentil, yellow mustard, safflower, and sunflower did not perform well and were not adapted to this region during periods of below average precipitation. During periods of drought, field pea and wheat following fallow had greater nitrogen use efficiency than recropped wheat or other pulse and oilseed crops. Author Affiliation: (a) USDA, ARS, ASRU, 1500 North Central Avenue, Sidney, MT 59270, USA (b) Department of Animal and Range Sciences, Linfield Hall, Montana State University, Bozeman, MT 59717, USA (c) Montana State University, Northern Agricultural Research Center, 3848 Fort Circle, Havre, MT 59501, USA Article History: Received 21 May 2006; Revised 22 August 2006; Accepted 25 August 2006