Resumen

MARCANO C, Ángel E; RODRIGUEZ, Julio C  y  MOHSIN, Mohammad. Efecto del azufre elemental sobre el ph y la solubilidad de algunos nutrimentos en fosfocomposts. INCI [online]. 2003, vol.28, n.9, pp.504-511. ISSN 0378-1844.

The effect of addition of elementary sulphur (Sº) on the pH and solubility of some plant nutrients was studied in fosfocomposts prepared with 1kg water hyacinth (Eichhornia crassipes), 800g cow manure, 200g phosphate rock (RF) and 5g sulphate acid soil, using Thiobacillus sp bacteria as inoculum. 0, 5, 10, 15 and 20g of Sº per 2kg of composts were applied with two replicates each and a control without RF nor Sº. After a 6 month incubation, soluble P, Mg, Ca, Fe, Cu, Mn, Zn, NO₃-, NH₄⁺ and SO₄ ^2-, pH, and C/N ratio were determined, as were total content of each metal and P, N, S and C. The percentages of total P and Ca were higher in the phosphocomposts than in the control, while the concentrations of N, K, Mg, Fe, Cu, Mn and Zn were higher than in the control (p<0,001). The lowest pH value was found in the phosphocompost with highest quantity of Sº. A significant correlation exists between pH and SO42-; the relation increases with a decrease in pH affecting negatively the decomposition of organic matter and resulting in lower soluble NO3-, P and K. A positive association was found between NO₃ ^- and pH. Ca, NH₄⁺, Fe, and Mn were more soluble with increasing acidity. Soluble Zn and Mg varied significantly among the composts without relation to pH. More soluble Ca with high Sº was an indication of a higher dissolution of the added RF. However, available P diminished in the phosphocomposts with acid pH, possibly due to its immobilization with Fe and the low decomposition of the organic matter.

Palabras clave : Abono ; Eichhornia crassipes ; Fosfocompost ; Roca Fosfórica .