The interaction between liming and forms of nitrogen fertilizer on established grassland

Abstract

SummaryFour factorial experiments made in 1982 and 1983 tested the effect of 10 t CaCO3/ha, applied either in autumn 1981 or spring 1982, on the response of established grassland to 360 kg N/ha per year applied either as ammonium sulphate, calcium nitrate, urea or a mixture of ammonium nitrate and calcium carbonate.Lime did not increase yield in the short term. It also reduced herbage Mn and, to a lesser extent, herbage N, P and Mg. The mixture of ammonium nitrate and calcium carbonate gave about 0·5 t D.M./ha per year more herbage than did the other forms of N.Lime had no effect on the recovery in the herbage of N from calcium nitrate, but it reduced N recovery from the other three fertilizers in 1982, and from urea also in 1983. Soil pH, which initially ranged from 4·9 to 5·7 at the four sites, was raised by lime to almost 7·0 in the top 5 cm soil. This pH is probably not high enough to cause serious losses due to NH3-volatilization.Application of fertilizer prone to loss from NH3-volatilization is not recommended soon after liming. However, the practice is not likely to cause detectable yield loss in established grassland in Northern Ireland.