A new critical level of soil potassium for wetland rice [in Bangladesh]
1992
Bhuiyan, N.I. | Saha, P.K. | Saleque, M.A. | Nuruzzaman, M.
The present critical level of 0.2 meq exchangeable K/100 g soil appears to be too high for wetland rice. Twenty four field trials on potassium rates (0, 30, 60, 90 and 120 kg K/ha) were conducted during the 1990 T. Aman (wet) season at different locations of Bangladesh, using BRII rice variety as a test crop. Potassium soil test values, determined by neutral 1.0 N NH4OAc method (KAA), ASI method (KAS) and I.0 N HNO3 (boiled) method (KNA) were calibrated with the relative grain yields of wetland rice obtained from the twenty four field trials. The three K extraction methods were significantly correlated to each other, the highest correlation co-efficient being between KAA and KAS (r=0.967** ). The critical deficiency level of soil K for each test method was determined. These values were 0, 10, 0.075 and 1.125 meq/100 g soil by graphical procedure for 1.0 N NH4OAc, ASI and 1.0 N HNO3 methods, respectively. But by statistical procedure, these values were 0.075 and 0.640 meq/100 g soil for 1.0 N NH4OAc, ASI and 1.0 N HNO3 methods respectively.
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