Efficiency of phosphate fertilizers II. Residual effects

Abstract

This study was conducted to determine residual effect of eight phosphate fertilizers on two soils of low phosphorus content, using corn (Zea mays L.) as test crop. The experiments were carried out in greenhouse. Dry matter yields and amount of N, P and K uptaken were used to evaluate fertilizer effectiveness. The results indicated that the fertilizer with best residual effect were calcium metaphosphate and potassium metaphosphate, followed by thermophosphate and Olinda rock phosphate in regosol. There were no significant difference for dry matter yield in latosol, but in general the calcium metaphosphate, Olinda rock phosphate and potassium metaphosphate gave best results. The fertilizers with lowest residual effect were those with high content on water soluble phosphorus: triple superphosphate, ordinary superphosphate, DAP and ammonium poliphosphate.