Influences of the phosphate and potassium fertilizers on the growth and yield of rice grown in the Bangkok Plain [in Thailand]
1982
Suriya Sassanarakkit
Two pot experiments were conducted to study the effects of the phosphate and potassium fertilizers on rice grown on paddy soils which originated from brackish water alluvium (Sena, Rangsit and Rangsit very acid series) non acid marine sediments (Bangkok series) and fresh water alluvium (Ratchaburi series) of the Bangkok plain. Results from the first experiment indicated that soils which originated from brackish water alluvium were very deficient in phosphorus. Rice grown in the Rangsit very acid and Sena series showed responses to the application of both rock phosphate and triple superphosphate. Generally the application of both rock phosphate at the rates 20 and 100 grams per pot gave responsiveness of rice yield 28.5% and 64.2% of triple superphosphate applied at the rate of 13 grams per pot, but rock phosphate at the rates of 200 grams per pot gave 91.8% response of rice yield as compared to that of triple superphosphate. This studies indicated that rock phosphate at the appropriate rates could be used as a good source of available phosphorus for rice grown on acid sulfate soils, while at the same time, rock phosphate could supply calcium to help reduce the acidity of the soils. The second experiment indicated that rice did not response to potassium fertilizer except on the Rangsit very acid soil
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