 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Effects of Fresh and Residual Calcined Phosphates on Flooded Rice in Acid Sulfate soils) ผู้เขียน: นายปิยะ ดวงพัตรา, ศาสตราจารย์ ,  Paiboon Prabhuddham, Chairerk Suwannara สื่อสิ่งพิมพ์:pdf AbstractPot and field experiments were conducted during the wet seasons 1985 and 1987 to evaluate the relative effectiveness of a calcined phosphate fertilizer, Phospal-34 (PP-34), on flooded rice in acid sulfate soils. The experiments comprised 1) 2 consecutive pot trials and 3 consecutive field trials to assess the effects on rice of fresh and residual P from 2 sources, PP-34 and Monoammonium phosphate (MAP) and 4 rates of fertilizer phosphorus and 2) 2 consecutive field trials to investigate the effects on rice of fresh and residual P from fertilizers containing PP-34. Rice grown on acid sulfate soils in both pot and field experiments showed marked response to fresh and residual phosphates applied either in the form of PP-34 or MAP. In 3 consecutive field trials, the response to residual phosphate of the second rice crop was the highest. Averaging from the 3 crops, grain yield increase due to the added-P was about 30 percent. The effectiveness of fresh and residual PP-34 were comparable to those of P containing in Monoammonium phosphate. As a straight P fertilizer, PP-34 can be used for flooded rice in acid sulfate soils as an alternative source to highly water-soluble P fertilizer, MAP. Moreover, for the formulation of mixed fertilizers for rice, a fertilizer containing 40% available P derived from PP-34 and 60% deriving from Diammonium phosphate (DAP) was as agronomically effective as DAP. It is probable that PP-34 can be used to partially substitute other highly water-soluble P materials in the mixed fertilizer produce. |