RELATIVE AVAILABILITY TO PLANTS OF PHOSPHORUS FROM ROCK PHOSPHATE AND TRIPLE SUPERPHOSPHATEIN RELATION TO LIMING ON MALAYSIAN PEAT

W.Y. CHEW, Y.K. CHIN, L. ISMAIL and K. RAMLI

SUMMARY

Two greenhouse experiment studied the effects of liming and P fertilization on sorghum and napier grass on acid  peat . Liming increased soil soluble P. crop dry matter and P uptake, sorghurm being more sensitive to peat acidity than napier grass. Both crops responded to applied P only with liming. On limed peat napier grass was more responsive to applied P than sorghum producing optimum dry matter at 20 kg/ha, compared to 10 kg for sorghum. In both crops. Triple superphosphate gave greater growth, plant P content and P uptake than rock phosphate. Increasing rate of either P carrier increased plant dry matter, plant P content and P uptake but positive responses to increasing rates of P and to P carriers were obserred only in the first sorghum and first two napier grass harvests, and not subsequently. The % recovery of applied P decreased in sorghum, but increased in napier grass, as P was increased.

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