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This article in AJ

  1. Vol. 79 No. 3, p. 452-458

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Modeling Long-Term Crop Response to Fertilizer Phosphorus. II. Comparison with Field Results1

  1. B. H. Janssen,
  2. D. J. Lathwell and
  3. J. Wolf2



Results obtained using a simple model for computing the residual effect of applied fertilizer P were compared with results of long-term field trials with maize (Zea mays L.), sorghum [Sorghum bicolor (L.) Moench], and rice (Oryza sativa L.), carried out in Brazil, Australia, and Madagascar, respectively. The calculated and experimentally found residual effects of fertilizer P were in close agreement, provided the applications rates were not too high and seasonal effects not too strong. At all locations the same values for the time constants of P transfer between the labile and stable pools could be used, irrespective of the method of application and the type of fertilizer. As a consequence, the residual effect of fertilizer P is directly related to the first-year recovery fraction. For given recovery fractions, the residual effects are calculated for different types of P fertilizers.

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