Utilization of nitrogen from injected and surface-spread cattle slurry applied to grassland

Abstract

The utilization of nitrogen (N) from cattle slurry following injection into grassland was assessed in 4 field experiments at different sites in the Netherlands for 3-5 years. In two experiments, surface application of slurry was included; all slurry applications were made in the spring. In each experiment three rates of slurry application were used, the maximum rates were 40 t ha-1 yr-1 and 80 or 90 t ha-1yr-1 for the surface-spread and injected treatments, respectively. In all experiments 0, 200, 400 or 600 kg fertilizer N ha-1yr-1 was applied, both in combination with the slurry applications or alone. newline˜ Averaged over all experiments the mean apparent recoveries of N (ANRs) from surface-spread slurry, injected slurry and the lowest rate of fertilizer N were 23%, 49% and 90%, respectively. The corresponding mean apparent efficiencies of N (ANEs) were 6.0, 11.5 and 27.4 kg dry matter (DM) per kg N applied. In the experiments enabling direct comparison with surface spreading, injection consistently resulted in higher ANR and ANE values; the average increases were 2.3 fold and 1.9 fold, respectively. Injection had a relatively greater effect on N uptake than on DM yield; causes and consequences of this are discussed.