Nitrogen economy of cattle slurry aeration and spreading on to grassland

Slurry aeration processes were followed in private dairy farms. Nitrogen losses during 3–6 weeks of aeration were 10% of the total nitrogen (Ntot) and the proportion of NH4 + from Ntot increased from 48% to 51%. No changes in NO3 −concentration were observed. The average dry matter reduction was 16%. The fertilizer values of aerated and non‐aerated cattle slurry on grassland did not differ significantly. In most cases, band‐spread slurry gave a higher yield than did the injected slurry. Water dilution improved N recovery slightly, but not significantly. The N recovery of mineral slurry N in the next harvest varied considerably, although in most cases it did not significantly differ from that of the mineral fertilizer. In general, the results obtained encourage the use of cow slurry as a grassland fertilizer.