The evaluation of supply parameter,a new index of zinc availability in Mollisols

A new zinc supply parameter taking into account the intensity, quantity and buffering capacity and also the relative competitive influence of Cu²⁺, Fe²⁺, Mn²⁺ on the availability of Zn²⁺ has been tested. The proposed parameter correlated significantly and positively to Bray's per cent yield and zinc concentration in some parts of rice plant. The critical limit of soil zinc, in terms of this parameter at 15° and 30°C for rice, were 0.51 and 0.97 respectively. The required zinc addition to the deficient soil was also calculated on the basis of the values of this parameter at 30°C.