Soil phosphorus cycling is modified by carbon and nitrogen fertilization in a long?term field experiment

Background and aims: Phosphorus (P) is an essential element for crop growth. However, while links of P turnover in soils to carbon (C) nitrogen (N) availability have been described, it remains be clarified how combinations fertilizer C N additions affect stocks cycling distinct fractions at different soil depths. The objectives our study were (1) assess total are affected by organic amendments fertilization, (2) evaluate respond (3) verify whether fertilization increases biological cycling. Methods: We collected samples from a long-term field experiment established 1984 Rauischholzhausen, Germany. Haplic Luvisol received either no (NOF), farmyard manure (FYM) or combination mineral (OMF). Each treatment additionally three levels N: 0 kg ha?1 y?1 (N0), 100 (N100), 200 (N200). fertilizers applied spreader the (calcium ammonium nitrate) was spring as top dressing plot machine. estimated isolated sequential fractionation, assessed oxygen isotopic composition 1 M HCl-extractable phosphate (?18OP). Results: found that increased matter (OM) addition inputs caused significant decreases resin- NaHCO3-extractable topsoil (0–30 cm). Mineral alone resulted resin-, NaHCO3-, NaOH-extractable upper subsoil (30–50 These changes occurred both inorganic P. ?18OP values closer expected equilibrium fertilized with N, indicative more intensive than treatments without inputs. Conclusions: findings suggest OM promotes losses labile uptake enrichment these forms subsoil, overall increase top- horizons upon fertilization.