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Agronomy Journal Abstract -

Nitrogen Utilization from Fertilizer and Legume Residues in Legume-Corn Rotations1


This article in AJ

  1. Vol. 79 No. 4, p. 726-731
    Received: June 16, 1986

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  1. O. B. Hesterman,
  2. M. P. Russelle,
  3. C. C. Sheaffer and
  4. G. H. Heichel2



Legume-corn (Zea mays L.) rotations are common throughout the U.S. Corn Belt, but little information is available about the efficiency of legume residue N utilization, or about fertilizer-N use efficiency in different cropping sequences. Our objective was to determine the contribution of N from soil, fertilizer, and legume residues for six legume-corn sequences. The effect of applied fertilizer N rate was also examined. Field studies were conducted on a Udorthentic Haploboroll and a Typic Hapludoll. First-phase (Year 1) rotation components included alfalfa (Medicago sativa L.), corn, soybean [Glycine max L. (Merr.)], or fallow. Nitrogen-15-depleted (NH4)2S04 was applied to second-phase (Year 2) corn. Fertilizer-N use efficiency for second-phase corn was 51% for the whole plant and 36% for grain, with no effect of first-phase treatment. Average use efficiency of legume-N (uptake of legume-N/legume-N incorporated) was 43% for the whole corn plant and 30% for grain. Second-phase corn derived a greater proportion of its N from residue of alfalfa (36%) than soybean (12%). When the rate of N applied to corn was increased from 56 to 168 kg N ha−1, the proportion of N derived from legume residue decreased from 44 to 19% in whole corn plants and from 57 to 23% in grain. Results suggest that the N credit commonly attributed to legumes in crop rotation may be inflated by as much as 132%.

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