Long-term studies of molybdenum applied to pasture

Abstract

The main effects of lime and molybdenum and their interactions with North African, Nauru, and Christmas Island rock phosphates and superphosphate applied to pasture were investigated over a five-year period on a molybdenum-deficient soil. Marked responses followed the application of oz sodium molybdate/ac and a dressing in excess of 2 tons of lime/ac was necessary to give equal yield responses. The response acted through an increase in total clovers, particularly white clover (Trifolium repens L.). All phosphate treatments responded markedly to molybdenum and 2 tons of lime/ac, with superphosphate giving the highest yields and North African the highest of the rock phosphate treatments. In the presence of applied molybdenum no significant yield response followed the application of 2 tons compared with 5 cwt/ac of lime on the superphosphate treatment, and it is suggested that there is no benefit in raising the soil pH beyond 5.8. Rock phosphate yields were slightly depressed by the application of 2...