Sulfur Oxidation Influence on Rock Phosphate Solubilization in Soil PDF Download

Author: Osni Correa de Souza
Publisher:
ISBN:
Category : Soils
Languages : en
Pages : 86

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Book Description
The low solubility of many rock phosphate (RP) around the world is the main cause of their ineffectiveness when applied to soil as a source of P for crops. The low solubility decreases their value as P fertilizers and prevents their widespread use, especially for high P demanding crops. One method proposed to enhance RP solubility is to add sulfur (S) as an amendment. The oxidation of S to H2SO4 in the soil results in dissolution of the applied RP. This study tested three Brazilian RP sources (Araxa, Catalao, and Patos de Minas) mixed with S at a ratio of 5:1 (RP:S). The application of the RP-S mixtures proved to be a promising alternative method for increasing RP solubility and thus their effectiveness as P sources. The soil pH decreased proportionally to increasing rates of RP-S application. The NaHCO3 extractable soil P increased as a consequence of increased soil acidefication. The ryegrass growth, P uptake, plant P concentration and P recovered from RP sources were enhanced only when S was mixed with the RPs. On the other hand, when RP sources were applied directly without S, the available soil P as measured by NaHCO3 extraction was depleted with time regardless of source or rate of RP. The inefficiency of the directly applied RP sources to supply adequate P was evidenced by less plant growth than applied with S. Also, in addition to this inadequate supply of for plant assimilation, the directly applied RP sources failed to develop a residual reserve of available P in the soil, even at very high application ...