Availability of phosphorus at varying soil pH in soils grown to corn (Cotabato Province) [Philippines]
1990
Escabarte, R.S. Jr. | Navarro, A.A. (Southern Mindanao Univ., Kabacan, Cotabato (Philippines). Coll. of Agriculture)
A pot experiment was conducted to determine the influence of soil pH on availability of phosphorous (P) in five soil series of Cotabato province [Philippines] and to determine the relationship between soil pH and P uptake of corn. Effect of soil P on dry matter yield of corn was also determined. Available P (Bray 2) was found highest both before and after the experiment in Faraon soil with pH of 7.2. Lowest available P was observed at pH 4.2 of Kidapawan soil. Soil pH and available P were linearly related with r value of 0.92. Corn grown in kabacan soil, pH 5.5, had highest dry matter yield and P uptake. Those grown in Faraon, pH 7.2 and San Manuel, pH 5.8 were not significantly different with that of Kabacan soil, pH 4.2. Significant logarithmic relationship was found between available P and dry matter yield (r= 0.92) and between available P and P uptake of corn (r= 0.94). Dry matter yield and P uptake increased steeply when available P increased from 96 to 135 ppm. However, dry matter yield and P uptake decreased with further increase in available P beyond 183.8 ppm. This level (183.8 ppm available P) corresponds to maximum crop response in terms of dry matter yield and P uptake represented by corn grown in Kabacan soil.
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