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Abstract

Phosphatic fertilizer was applied to Tropical Kudzu [Pueraria phaseoloides, (Roxb) Benth] in dosis ranging from 0-300 Kg P₂O₅/Ha/year, to study its effects on dry matter yield and chemical composition. Fertilizer application significantly (P<.01) increased dry matter yields, from 5.41 MT/Ha/year in the control treatment to 10.41 MT/Ha/year in the 250 Kg P₂O₅/Ha/year treatment, being the response curve of a positive gamma function type. Yields showed significant (P<.05) differences between cuts and were highly correlated with rainfall. Phosphatic fertilizer did not markedly increase dry matter crude protein content; however crude protein seasonal fluctuation showed significant (P<.01) differences, ranging from 12.9% in the fifth cut (26/5/73) to 17.82% in the sixth cut (25/7/73). Dry matter phosporous content was significantly (P<.01) increased by P₂O₅ applications, from 0.18% in the control treatment to 0.27% in the 300 Kg P₂O₅/Ha/year treatment, being the response curve of a positive cuadratic root nature. Phosporous seasonal content in dry matter showed significant (P<.01) differences, from 0.26% in the third cut (26/1/73) to 0.21% in the sixth cut (25/7/73). Dry matter calcium content was significantly (P<.05) affected by treatments, without showing a definite tendency. Calcium seasonal content in dry matter showed significant (P<.01) differences, from 0.68% in the fourth cut (26/5/73) to 0.40% in the fifth cut (27/3/73). Dry matter magnesium content was not significantly affected by P₂O₅ applications, but magnesium seasonal content showed significant (P<.01) differences.