Die Bodenkultur - Journal for Land Management, Food and Environment
W. Opitz v. Boberfeld, M. Sterzenbach and H. Laser:
Accumulations of N, P and K in Soil in Different Systems of Outdoor Keeping during Winter with Cattle
In pasture systems with winter grazing, the release of urinary nitrogen, limited nitrogen removal by plants, and sward damage increase the risk of nutrient accumulation in soil. Depending on feeding practice and the nutrient utilization by plants, considerable accumulations may occur in form of ammonia, nitrate and potassium. With focus on these features, soils of winter pastures, arable land folds and straw bedding corrals were analysed regarding amounts of mineral N, soil pH, and plant available phosphate and potassium amounts. The results can be summarized as follows: High amounts of ammonia N were found in layer 0–60 cm at the center of stationary feeding places on winter grazed pastures (on average 194 kg N ha-1). However, the amounts were similar on summer grazed pastures (= control).
The ammonia concentration in soil decreases with an increasing distance from the center of the feeding places. A decrease by already >75 % was found in a distance of 25 m. The situation was similar for potassium, since the amounts decrease from >25 mg K 100 g-1 soil in the center to approximately 12 mg K 100 g-1 soil in a distance of 25 m. The amounts of nitrate N (<20 kg N ha-1 in layer 0–60 cm) were significantly lower than amounts of ammonia N. Nitrate concentrations at feeding places were similar to the concentrations in a distance. In arable land folds, amounts of ammonia N, nitrate N, and potassium were influenced by the stock density. The proportion of nitrate N is much higher than in pastures. Concerning phosphate the load into soils is negligible. Total P averages 3 mg P 100g-1 soil (layer 0–30 cm) on winter grazed pastures and 5 mg P 100g-1 soil in arable land folds. However, the feeding of supplemental preserves on winter pastures and arable land folds should be arranged decentralized by using mobile feeding equipment to avoid high peaks of N and K close to feeding places. Stock keeping in straw bedding corrals is an alternative to avoid nutrient loads into soils, but it requires high amounts of litter material (> 20 kg GV-1day-1). Otherwise the high stock densities and long folding periods within this system cause the highest nutrient accumulation in soil, reaching peak values up to 700 kg N ha-1. Savings of litter material are possible by using the right kind of straw, but no reduction is possible by a mechanical straw treatment.
Key words: Arable land folds, straw bedding corrals, winter pastures, beef cattle, K accumulation, N accumulation.