Sheep urine affects soil solution nutrient composition and roots: differences between field and sward box soils and the effects of synthetic and natural sheep urine

摘要: Abstract Urea-N in sheep urine returned to soil is an important component the N-cycle of extensively managed grassland soils but relatively little known its effects on P and C cycling. Previous studies using sward boxes sown with Agrostis capillaris mixed from Ah AB horizon a brown ranker showed that application synthetic (SSU) increased pH solution concentration dissolved organic (DOC) inorganic forms N P. To extend information field, we compared SSU addition field rate corresponding upper value range found patches (500 kg urea-N ha−1). For 50-mm deep cores taken at intervals up 56 d after treatment, magnitude change concentrations nutrients were less lagged behind time boxes. The difference was attributed larger mass roots, existence discrete greater moisture content able buffer effects. Synthetic urine, prepared according published formulae, may provide than natural (NSU) hill and, additionally, does not contain minor components such as hippuric acid influences nitrification changes associated presence NH3/NH4+. compare NSU used applied equal volumes (9.97 g l−1 urea-N) or (4.04 g l−1 ewes fed grass. Natural increases disproportionately for SSU. toxic roots increasing proportion dead decomposing, especially study highlights differences chemistry root dynamics between box NSU, demonstrating need caution extrapolating results field.