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This article in SSSAJ

  1. Vol. 74 No. 4, p. 1248-1258
    Received: June 19, 2009

    * Corresponding author(s): famontei@esalq.usp.br
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Nitrogen and Sulfur Fertilization and Dynamics in a Brazilian Entisol under Pasture

  1. Fabiano Daniel De Bona and
  2. Francisco Antonio Monteiro *
  1. Soil Science Dep., “Luiz de Queiroz” College of Agriculture, Univ. of São Paulo, 13418-900 Piracicaba, SP, Brazil


Nutrient dynamics in tropical soils sustaining forage grasses are still poorly understood. We conducted a study to evaluate the effect of combined N and S fertilizer rates on the growth of ‘Marandu’ palisade grass [Brachiaria brizantha (Hochst. ex A. Rich.) Stapf], uptake of these elements from the soil by plants, soil organic matter concentration, soil pH, and the mineral and organic fractions of N and S in an Entisol. Combinations of five N rates (0, 100, 200, 300, and 400 g N m−3) with five S rates (0, 10, 20, 30, and 40 g S m−3) were evaluated in a partial 5 × 5 factorial in a pot experiment, with and without plants. Nitrogen and S were supplied as NH4NO3 and CaSO4·2H2O, respectively. The N addition in excess did not enhance the palisade grass production due to low plant-available S in the soil. The supply of low rates of S with N greatly improved the overall N uptake efficiency by the forage plant. The contents of total N, NO3 –N, and NH4 +–N in the soil varied with N rate and with N uptake by the plants. The association of palisade grass with S fertilization increased the ester-bonded S fraction in the soil. The results suggest that soil residual S could be a potential source of S for plants. Proper N and S fertilizer rates promoted increased grass production due to increased uptake of these nutrients and the dynamics of the organic N and S fractions and mineral fractions in this tropical soil.

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