Influence of stock camping behaviour on the soil microbiological and biochemical properties of grazed pastoral soils

The size and activity of the soil microbial biomass in grazed pastures was compared on the main grazing area and on stock camp areas where animals con gregate. Two sites were on hill country and three on gently sloping border- dyke irrigated land. Due to the transfer of nutrients and organic matter to the camp areas via dung and urine there was an accumulation of soil organi c C, organic and inorganic P and S and soluble salts in the camp areas. Soi l pH also tended to be higher in camp areas due to transfer of alkalinity b y the grazing animals. Water soluble organic C, microbial biomass C and bas al respiration were all higher in soils from camp areas but the proportion of organic C present as microbial C and the microbial respiratory quotient were unaffected. Microbial activity as quantified by arginine ammonificatio n rate and fluorescein diacetate (FDA) hydrolysis was higher in camp than n oncamp soils but dehydrogenase activity remained unaffected. Activities of protease, histidase, urease, acid phosphatase and aryl-sulphatase were all higher in stock camp soils. The activities of both histidase and aryl-sulph atase were also higher when expressed per unit of microbial biomass C, indi cating that the increased activity was the result of increased enzyme produ ction by the microbial community. Prolonged regular applications of dairy s hed effluent (diluted dung and urine from cattle) to a field had a similar effect to stock camping in increasing soil organic matter content, nutrient accumulation and soil biological activity. It was concluded that the stock camping activity of grazing animals results in an increase in both the fer tility and biological activity in soils from camp areas at the expense of t hese properties on the main grazing areas.