SULPHUR FRACTIONS OF LEGUMES AS INDICATORS OF SULPHUR DEFICIENCY

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Abstract
A study of 157 locations, representing 18 soil series in west central Alberta, revealed that yield responses of alfalfa, alsike clover and red clover to applications of sulphur fertilizer were not confined to either specific soil series or definite geographical areas.Samples of the three legume crops from 74 of the test locations were analysed to determine the usefulness of three sulphur fractions and of the ratio total nitrogen:total sulphur as indicators of the need for sulphur fertilization. Extractable sulphur and extractable sulphate were present in considerably larger quantities in alfalfa and alsike clover grown on non-sulphur-deficient soils as compared with samples from soils deficient in that element. These determinations offer a possible means of detecting the need for sulphur fertilization with those two legume crops. While total sulphur and the total nitrogen-total sulphur ratio also showed differences, their magnitude was not of the same order as with these two fractions.Similar determinations for red clover showed the differences to be smaller than for alfalfa and alsike clover and they appear to be of doubtful value for predicting the need for sulphur fertilization.