Soil Chemistry in Long-Term Livestock Camping Areas in Pyrenean Summer Pastures

- Livestock management may be an important variable controlling the distribution of soil chemistry in grazed summer pastures. Flocks congregate in some areas, produce spatial segregation of excretion. The study goal was to quantify the temporal variation (at the beginning and end of a summer grazing period) and the spatial variation in soil chemical properties in long-term livestock camping areas. In six linear transects, five topsoil sample points were obtained at 1, 20, 40, 60, and 80 meters from the centre of the camping areas to the surrounding Nardus stricta-dominant pasture that has been grazed for centuries. Soil available nutrients, total nitrogen (N), and organic carbon (C) increased linearly from 60 in towards the centre of the camping area as a result of stock concentration. Available N (nitrate, ammonium), phosphorus, potassium, and calcium were at least three times greater at the centre compared to surroundings. At the end of the grazing period, cations (potassium, ammonium, magnesium) and organic C and N increased significantly at the centre in contrast with the mobile anions (nitrates and phosphates) easily lost or absorbed by plants. Long-term livestock grazing with permanent camping areas resulted in significant lateral and temporal increases of available nutrients in higher quantities than ecosystem can recycle. A reduction in stocking rate by paddock or rotation among different camping areas would aid in managing soil nutrients more effectively.