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This article in SSSAJ

  1. Vol. 54 No. 6, p. 1772-1777
    Received: June 9, 1989

    * Corresponding author(s):
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Agronomic Evaluation of Two Unacidulated and Partially Acidulated Phosphate Rocks Indigenous to Niger

  1. S. H. Chien ,
  2. J. Henao,
  3. C. B. Christianson,
  4. A. Bationo and
  5. A. U. Mokwunye
  1. Agro-Economic Division, International Fertilizer Development Center (IFDC), P.O. Box 2040, Muscle Shoals, Alabama 35662
    IFDC/ICRISAT Collaborative Project, ICRISAT Center Sahelien, B.P. 12404, Niamey, Niger Republic
    IFDC-Africa, B.P. 4483, Lomé, Togo



A field study was conducted on a sandy soil in Niger to evaluate the agronomic effectiveness of various P fertilizers for millet production during 1985 to 1987. The P fertilizers tested were two finely ground phosphate rocks (PR) indigenous to Niger (Tahoua and Parc W rocks), PR partially acidulated with H2SO4 at 50% acidulation level (PAPR), single superphosphate (SSP), and triple superphosphate (TSP). In 1985, application rates were 0, 6.5, 13.0, and 19.5 kg P ha−1 for each of the P fertilizers. In 1986, half of the plots received the same rates of P as in 1985 and half of the plots received no additional P. In 1987, P additions were repeated only in half of the plots that received P during 1986. A significant (P = 0.05) millet response to P was observed in all the trials. The major findings of this study were: (i) finely ground Tahoua PR was more effective than Parc W PR because of its higher reactivity and was 82 to 91% as effective as SSP for millet production in both the initial and two subsequent seasons; (ii) partial acidulation of Parc W PR can significantly increase its agronomic effectiveness in the first year, but not in terms of residual effect; (iii) partial acidulation was not a desirable technology for increasing the effectiveness of Tahoua PR, because its high Fe2O3 plus Al2O3 content resulted in a product containing relatively low amounts of water-soluble P; and (iv) over a period of 3 yr, one initial application of a large dose of P fertilizer was found to be more effective than three small annual applications in terms of total grain production.

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