Effect of phosphates on flooded rice
1987
Badrinath, A.M.K. | Krishnappa, A.M. | Patil, B.N. | Gowda, N.A.J. | Herle, P.S. | Rao, K.B. (Agricultural Research Station, Bangalore (India))
Superphosphate (SP), Mussoorie rock phosphate (MRP) and Mussoorie rock phosphate plus superphosphate (MRP + SP) and diammonium phosphate (DAP) in the midland soils of coastal Karnataka were evaluated during the 1984 and 1985 wet seasons. Soil was sandy clay loam, Ustoxtropept with pH 5.0, electrical conductivity 0.2 dS/m at 25 degrees Celsius, 1.26% organic C, 56 kg P/ha, and 83 kg K/ha. Available micro nutrients (in ppm) were Zn 0.25, Cu 1.86, Mn 0.38, Fe 57.7 and B 0.50. The experiment was in a split plot design with P sources in main plots and P levels in subplots, including a no-P control. Three 27-d-old IET 2911 (medium duration) seedlings/hill were transplanted at 15- x 15-cm spacing. All plots received 100 kg N and 88 kg K/ha. Half the N was applied at transplanting, 25% at tillering, and 25% at panicle initiation. P was applied at transplanting. The field was flooded from transplanting to maturity and the crop protected from insects, diseases, and weeds. Fertilizer sources gave significantly different yields in both years. The higher yield with SP alone or DAP were comparable to that with MRP + SP (25% + 75%). Yield with 26.4 kg P/ha was significantly higher than with other levels. The interaction effects were also significant in 1985-86. Locally available MRP is an inexpensive source of P.
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