Long-term nitrogen fertilizer replacement value of cattle manures applied to cut grassland

摘要: Manures supply nitrogen (N) to crops beyond the year of application. This N must be taken into account for agronomic and environmental reasons. From 2002 2006 we conducted a field experiment on sandy soil in The Netherlands (52°03″N, 6°18″E) better quantify this residual effect. Treatments comprised different time series mineral fertilizer or cattle manures compositions, all applied at rate 300 kg total ha−1 year−1, whilst compensating differences available potassium phosphorus. Dry matter yields cut grassland responded positively (P < 0.05) both current manure applications previous years, whereas affected application only. could reasonably well predicted with simple model, adopting an annual relative decomposition organic 0.10–0.33 year−1 during 0.10 following years. Subsequent model calculations indicated that value (NFRV) injected undigested slurry rises from observed 51–53% when is first time, approximately 70% after 7–10 yearly applications, it took two four decades raise NFRV surface farm yard similar level initial 31%. relatively high (e.g. anaerobically digested slurry) had small effect, low manure) partly compensated by showing larger effects. Given long manuring history most agricultural systems, rethinking seems justified. results also imply term consequences reduced rates may underestimated if histories are insufficiently account.