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This article in AJ

  1. Vol. 77 No. 4, p. 539-542
     
    Received: Jan 3, 1984


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doi:10.2134/agronj1985.00021962007700040008x

The Residual Effect of P and Lime on the Performance of Four Tropical Grasses in a High P-fixing Oxisol1

  1. Walter Couto,
  2. Gilberto G. Leite and
  3. Euclides Kornelius2

Abstract

Abstract

Pastures sown after several years cropping may take advantage of the residual lime and P fertilizers applied earlier. A field experiment was conducted to (i) compare the potential of different grasses to use previously applied P fertilizer at two levels of applied lime and (ii) evaluate the capacity of two soil tests to predict P availability to grasses. Four grasses [Andropogon gayanus var. bisquamulatus (Hochst) Hack] cv. Planaltina; Panicum maximum CV. Makueni; P. maximum var. trichoglume cv. Green panic and Seturia anceps cv. Kazungula were sown on an old experimental site where P fertilizers and lime have been applied over a period of 6 years for total rates of 0, 44, 87, 131, and 175 kg ha−1 of P and 4 Mg ha−1 of lime. Despite the well-known P-fixing capacity of the soil (clayey, kaolinitic, isohyperthermic, Typic Haplustox), grasses responded markedly to residual P and lime. Andropogon and to some extent Setaria performed better than the other grasses in both, limed and unlimed plots, at low levels of applied P. Makueni performed well only on limed plots at high levels of applied P (175 kg ha−1). Available soil P and dry matter yield correlated well but the range of P availability was too small for prediction purposes. It was concluded that despite high P-fixing capacity a large portion of residual P remained available to grasses. Soil test procedures should be improved to better reflect the P availability to grasses.

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