Effect of various sizes, rates and phosphate rock residue on rice yield at Rangsit series
1987
Laddawon Meesook | Yupin Soravisuitra | Revadee Deemark (Department of Agriculture, Bangkok (Thailand). Soil Science Div. Fertilizer Research Group)
Mesh size and rate of grounded phosphate rock is regarded as major factor in releasing available phosphoric acid form. Therefore, two long term experiments from 1982 to 1986 with objectives of determining effect of rates and mesh size on rice production were investigated. The soil of the experimental plots is classified to be the acid sulphate with pH 3-4.5. Application of phosphate rock before transplant RD 23 was practiced once in the first year. Ammonium sulfate fertilizer at the rate of 12 kg.N per rai was splitted application at transplanting and panicle initiation stage. The final year result, response of rice to pellet sine -35+65 mesh was observed and rate of application was not significantly different under the condition of soil P 3-4 ppm and pH 3-4 in soil reaction. On the contrary, no effect of mesh and rate was found under relative high 7-8 ppm of soil phosphorus.
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