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Agronomy Journal Abstract -

Evaluation of Short-Term Efficiency of Diammonium Phosphate versus Urea plus Single Superphosphate on a Calcareous Soil1

 

This article in AJ

  1. Vol. 79 No. 5, p. 896-900
     
    Received: Nov 10, 1986


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doi:10.2134/agronj1987.00021962007900050028x
  1. D. Q. Lu,
  2. S. H. Chien,
  3. J. Henao and
  4. D. Sompongse2

Abstract

Abstract

Although research has been done on the fertilizer efficiency of diammonium phosphate (DAP) as a source of N or P, little information has been reported on its effectiveness as a dual source of N and P to plants. The objective of this study was to compare DAP with urea plus single superphosphate (SSP) as sources of fertilizer N and P on a calcareous clay soil (Typic Ustochrept). The influence of methods of fertilizer placement (surface broadcast, incorporation, and deep placement) on crop growth and nutrient uptake were investigated in a short-term (6-week) greenhouse evaluation using maize (Zea mays L.) as a test crop. Ammonia volatilization losses from both sources, when surface-applied to the soil followed by daily water additions, were small, less than 6% of the applied N. Olsen P in the soil treated with urea + SSP was higher than the soil treated with DAP regardless of the method of fertilizer placement. Surface broadcasting apparently reduced the accessibility of P to the plant roots and resulted in a lower P uptake and plant yield than incorporation. Nitrogen uptake was as high with DAP as with urea + SSP when the fertilizers were either incorporated or deep-placed. Surface application, however, resulted in lower N uptake from DAP than from urea + SSP. Both DAP and urea + SSP showed the same relationship in terms of P uptake as a function of Olsen P in the soil for a given method of fertilizer placement. The plant yields obtained with urea + SSP were higher than those obtained with DAP, regardless of the method of fertilizer placement.

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