The investigations were carried during 1978 and 1979 on the acid soils of Shillong and Simla to study the effects of Mg and P on the yield and composition of potato tubers. On acid soil of Shillong (pH 5.2) there was positive response to MgSO4 upto 20 kg/ha whereas on Simla soil (pH 6.6) the response to Mg was not significant. However, there were highly significant responses of potato to P on both the soil types. Mg and P had synergistic effect on the concentra tion of each other whereas the applications of both Mg and P had a depressing effect on the concentration of Ca in the plant. Mg and P improved the percentage dry matter in tubers.
