Fertilization of Sorghum Based on Modified Mitscherlich-Bray Equation Under Semi-Arid Tropics

For quantitative evaluation of the efficiency of soil tests and fertilizer response to post-rainy sorghum crop through a Mitscherlich-Bray equation under ustic moisture regimes of Vertisols, field experiments were conducted at the Dry Farming Research Station, Solapur for three years. The Mitscherlich-Bray equation viz., log (A-y) = log A - c₁b - cx is basedon the principle that the native and added nutrients comprehend different efficiency factors. However, as the nutrient availability, both from soil and added nutrients, is a function of existing available moisture in the soil, original Mitscherlich-Bray equation was modified as log (A - y) = log Ac₂/M (c₁b + cx). The c₂ is the efficiency coefficient for stored available soil moisture and M is stored available soil moisture at seeding (mm mol soil depth). The validity of the modified equation was tested through follow-up trials for two years which indicated that the modified Mitscherlich-Bray equation (MMB) was significantly superior in nutrient (N and P) uptake and biomass production of sorghum followed by Mitscherlich-Bray, six tier, farmer's practice and control. On the basis of soil moisture and soil test values through a MMB equation, the fertilization schedule for dryland crops particularly for sorghum has been worked out.