Fertilizer studies on Basaltic red loam soil form the Lismore District, NSW.

Abstract

A pot-culture study was made -to examine the effects of nutrient elements on the growth of white clover (Trifolium repens L.) and Paspulum dilatutum Poir. on a basaltic red loam soil known to contain a high percentage of phosphorus and free iron vide. The response of paspalum to phosphorus was limited by deficiency of nitrogen. The results indicate that the native phosphorus in the soil is of very low availability, but that the added phosphate is not rapidly converted in the soil to unavailable forms. They suggest also that the response to superphosphate on this soil is restricted by other deficiencies rather than by phosphate fixation. The paspalum responded most to nitrogen on the soil where the lowest yields occurred without added nitrogen. However, the percentage nitrogen in the stunted untreated plants on this soil was higher than in less responsive plants on other soils. The results indicate that the percentage total nitrogen in paspalum is not a satisfactory index of the likely response of the plants to nitrogen. High levels of manganese were found in the paspalum plants which were examined. In an experiment with white clover, molybdenum, deficiency was induced by a light dressing of manganese sulphate. Responses of clover to phosphorus, molybdenum, and sulphur were obtained, and some evidence of calcium and magnesium deficiency is presented. The importance of elements concerned in protein formation in plants in relation to the general problem of pasture improvement on these soils is discussed.