Fertilizer usage of indigenous phosphate deposits, 1: application of apatitic phosphate rock for corn and upland rice in a hydric dystrandept
1985
Briones, A.M. | Vicente, P.R. (University of the Philippines at Los Banos, College, Laguna. Coll. of Agriculture)
Relative agronomic effectiveness (RAE) of indigenous apatitic phosphate rock in three forms (finely ground, mini-granulated and partially acidulated) applied to an acidic, P-deficient Isarog soil (thixotropic, isothermic Hydric Dystrandepts) was evaluated in a pot experiment. The RAE values indicated generally comparable effectiveness of each form of apatitic rock with single superphosphate (SSP). The responses of corn (Zea mays L.) and upland rice (Oryza sativa L.) due to the application of finely ground apatitic rock and SSP at various P levels were determined under field conditions. At optimum N level, crop responses to applied P were not significantly different between apatitic rock and SSP at respective P rates except for corn treated with 40 kg P/ha where SSP was superior to apatitic rock. The optimum rates of P application were 80 kg P/ha for corn and 40 kg P/ha for upland rice each in combination with 120 kg N/ha. Low residual availability of the initially applied P severely limited grain production of the subsequent corn crop while relatively moderate limitation was observed in upland rice. Effectiveness of the phosphate rock as affected by three methods of application (broadcast, band and drill) was evaluated in separate field trials for corn and upland rice. Both crops demonstrated the following order of effectiveness: broadcast bond drill
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