Influence of Improved Pastures and Grazing Animals on Nutrient Cycling within New Zealand Soils

The improvement of New Zealands pastures over the last 150 years has increased the nutrient status of the soil as a result of the application of fertiliser, an increased soil organic matter content and increased biological activity. The grazing animal has also influenced the nutrient status of the soil by increasing the rate at which nutrients cycle between the soil, plants and animals. However, the grazing animals also cause losses of nutrients from the soil through concentrating nutrients into small volumes of soil under dung and urine patches, redistributing nutrients around the farm and removal of nutrients in the form of animal products. If these losses are not replaced by fertiliser applications then reductions will occur in both the amount of nutrients in the soil and in pasture production. Research directed toward maximising the cycling of nutrients originating from animal excreta is required in order to develop strategies to minimise fertiliser inputs.