Fertilizer and stocking rates on two King Country soils

Abstract

Parent materials such as volcanic ash and sedimentary siltstone and sandstone form soils which differ markedly in their physical and chemical properties. In stocking x fertilizer rate trials on two families of soils, Te Kuiti-Tumutumu (volcanic ash) and Mahoenui-Mangatea (siltstonesandstone), the former showed marked response to increasing rates of superphosphate in terms of pasture availability and animal production but the latter showed negligible response above the lowest rate (250 kg/ha). Responses to superphosphate were apparent on Te Kuiti-Tumutumu only at the high stocking rate. Sward composition showed no measurable improvement with the application of superphosphate. Management practices were undoubtedly important in this respect. Differential ‘topdressing should be practised where feasible. When soil test levels for phosphate are medium to low, Te Kuiti-Tumutumu soils should receive at least 500 kg/ha/yr of superphosphate, Mahoenui-Mangatea soils 250 kg/ha/yr. Stocking rates and management practices must be such as to allow full utilization of the additional pasture grown.