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This article in SSSAJ

  1. Vol. 49 No. 1, p. 152-155
    Received: May 17, 1984
    Accepted: Sept 11, 1984

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Soybean Shoot and Root Growth and Phosphorus Concentration as Affected by Phosphorus Placement1

  1. C. M. Borkert and
  2. S. A. Barber2



Effect of P placement on shoot and root growth and their relation to recovery of applied P is important for economic crop production. Few studies have investigated the effect of varying the P-fertilized soil volume on soybean (Glycine max L. Merr.) root growth, P uptake and soybean yield. The objective of this research was to investigate the effect of localizing P in decreasing volumes of soil on soybean seedling root morphology and distribution, and P uptake in order to determine the placement giving maximum plant growth. An experiment with soybeans grown in Raub silt loam (Aquic Argiudoll) was conducted in 3-L pots in a controlled climate chamber. Adding the same amount of P per pot (60 mg/kg soil) in decreasing volumes of soil stimulated root length in the fertilized portion while the root radius became smaller in this zone. The relation between soil volume fraction fertilized with P and fraction of total root length in the fertilized soil could be described by y = x0.70 (r2 = 0.96), where x is the proportion of the soil volume treated with P and y is the predicted proportion of the total root length in the P-treated soil. Shoot P concentration increased as the volume of fertilized soil was reduced to 0.125 but did not increase further as fertilized soil volume was reduced to 0.0625. Also, maximum shoot dry weight was obtained when 0.125 of the soil was P fertilized and did not increase further as P-treated soil volume was reduced to 0.0625.

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