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This article in AJ

  1. Vol. 85 No. 4, p. 898-905
     
    Received: Aug 24, 1992
    Published: July, 1993


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doi:10.2134/agronj1993.00021962008500040022x

Nitrogen Efficiency Component Analysis: An Evaluation of Cropping System Differences in Productivity

  1. D. R. Huggins  and
  2. W. L. Pan
  1. U niv. of Minnesota Southwest Exp. Stn., Lamberton, MN 56152-0428
    D ep. of Crop and Soil Sciences, Washington State Univ., Pullman, WA 99164-6420

Abstract

Abstract

The development of cropping systems that use N efficiently requires methods that evaluate system differences in N use. A procedure, based conceptually on soil and plant processes that affect N use, was developed to evaluate differences in N use efficiency among cropping systems. The method uses measurements of yield, grain N, aboveground plant N, applied N, and postharvest inorganic soil N to partition cropping system differences in yield and grain N into N efficiency components. The components consist of N supply, available N efficiency, available N uptake efficiency, N utilization ellficiency, grain N accumulation efficiency, and N harvest index. The N efficiency component analysis was demonstrated for a field study with hard red spring wheat (Triticum aestivum L. ‘WB 906R’) where conventional tillage had a greater yield and grain N than no-tillage. At low N rates, 78% of the difference in yield between the two was attributed to N supply and available N efficiency components. At high levels of applied N, 88% of the yield difference was attributed to the N utilization efficiency component. Differences in grain N were attributed to N supply and available N efficiency components, whereas components of grain N accumulation efficiency, available N uptake efficiency, and N harvest index were nonsignificant. Overall, this new approach transcends empirical analyses and provides insight into underlying mechanisms of cropping system differences in N use.

Contribution of the College of Agriculture and Home Economics, Washington State Univ., Departmental Paper no. 9301-04, Project 0725.

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