Urea as a nitrogen fertilizer for grass cut for silage

Abstract

SUMMARYForty-one experiments were carried out in England and Wales between 1983 and 1985 to compare ammonium nitrate and urea as N top dressings for multicut silage.The results showed that relative dry matter yields from the two fertilizers differed considerably between sites. However, compared with ammonium nitrate, there was a mean yield decrease with urea of 2% at the first cut and 5% at the second cut. Mean herbage N contents and apparent N recoveries were lower with urea than with ammonium nitrate at both the first and second cuts. It appeared, at least for first-cut dressings applied in early spring, that urea effectiveness increased with the amount of rain falling within 3 days of fertilizer application. The effect was much less obvious at the second cut.Urea effectiveness was not markedly reduced on soils of high pH or light texture, where higher ammonia volatilization losses might have been expected.