Plant and Soil

, Volume 236, Issue 2, pp 175–184

Source of the soybean N credit in maize production

  • L.E. Gentry
  • F.E. Below
  • M.B. David
  • J.A. Bergerou
Article

DOI: 10.1023/A:1012707617126

Cite this article as:
Gentry, L., Below, F., David, M. et al. Plant and Soil (2001) 236: 175. doi:10.1023/A:1012707617126

Abstract

Nitrogen response trials throughout the United States Corn Belt show that economic optimum rates of N fertilization are usually less for maize (Zea mays L.) following soybean (Glycine max L.) than for maize following maize; however, the cause of this rotation effect is not fully understood. The objective of this study was to investigate the source of the apparent N contribution from soybean to maize (soybean N credit) by comparing soil N mineralization rates in field plots of unfertilized maize that had either nodulated soybean, non-nodulated soybean, or maize as the previous crop. Crop yields, plant N accumulation, soil inorganic N, and net soil mineralization were measured. Both grain yield (6.3 vs. 2.8 Mg ha−1) and above-ground N accumulation (97 vs. 71 kg ha−1) were greatly increased when maize followed nodulated soybean compared with maize following maize. A partial benefit to yield and N accumulation was also observed for maize following non-nodulated soybean. Cumulative net soil N mineralization following nodulated soybean, non-nodulated soybean, and maize was 112, 92 and 79 kg N ha−1, respectively. Net mineralization of soil N appeared to be influenced by both quality (C:N ratio) and quantity of residue from the previous crop. In addition to an increase in plant available N from mineralization, the amount of soil inorganic N (especially in soil 5 cm from the row) was greater following nodulated soybean than non-nodulated soybean or maize. Based on these data, the soybean N credit appears to result from a combination of a decrease in net soil mineralization in continuous maize production and an increase in residual soil N from symbiotic fixation.

corn crop rotation maize mineralization residual nitrogen soybean nitrogen credit 

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • L.E. Gentry
    • 1
  • F.E. Below
    • 2
  • M.B. David
    • 1
  • J.A. Bergerou
    • 2
  1. 1.Department of Natural Resources and Environmental SciencesUniversity of IllinoisUrbanaU.S.A
  2. 2.Department of Crop SciencesUniversity of IllinoisUrbanaU.S.A.

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