Effects of salt and other fertilizers on yield and mineral composition of forage crops. III.—herbage

Salt did not increase the yields of herbage in four experiments, two of which were responsive to muriate of potash. There were, however, consistent negative interactions between salt and potash. Salt in finely powdered form may scorch clover severely if applied in dry weather. Salt and ammonium sulphate, providing the nitrogen, increased yields, greatly increased sodium contents of both grass and clover, whilst muriate of potash markedly depressed sodium contents. Salt did not alter the potassium concentrations in either grass or clover but muriate of potash had consistently large incremental effects. Repeated application of ammonium sulphate reduced potassium concentrations. Fertilisers did not in any way alter calcium contents of either grass or clover and, apart from superphosphate, there were no effects on phosphorus concentrations. Three cwt. of ammonium sulphate increased the percentage concentration of magnesium by an average of 14% for grass and 4% for clover, while 2 cwt. of muriate of potash or 4 cwt. of salt depressed the grass and clover magnesium contents by 7.5% and 4% respectively. Much the greatest reductions in herbage magnesium due to muriate of potash were in the late‐season samples. A small dressing of magnesium sulphate increased herbage magnesium in one of two experiments.