Improved pasture response to nitrogen applied in winter after application of urea in autumn

Abstract

Nitrogen fertiliser was applied as urea in autumn (2 April 1983) and late winter (14 July 1983) to a predominantly ryegrass-white clover pasture on a Manawatu dairy farm. Responses in terms of herbage production, botanical composition, and certain other sward characteristics were measured on 22 August. Residual responses from the autumn application were small and were not statistically significant. Spring responses were significant for herbage mass, tiller weight, sward leaf area index, herbage phosphorus (% P) and total P yield (kg P/ha), herbage dry matter content (% DM), and apparent stubble yield (kg DM/ha). There was a significant, positive interaction between autumn and late winter applications of urea in that herbage mass response to 30 kg N/ha in winter was 7, 12, and 19 kg DM/kg N for plots receiving 0, 30, and 60 kg N/ha in autumn respectively. Possible reasons for this interaction are briefly discussed.

Effect of high rates of nitrogen fertiliser on perennial ryegrass growth and morphology in grazed dairy pasture in northern New Zealand

“…2) and increased ryegrass plant density by 28%. Increased ryegrass tiller density in response to N has been reported for a range of mixed pasture systems under grazing including set-stocked and rotationally grazed sheep pastures (Curll et al 1985) and rotationally grazed dairy pastures (Matthew et al 1986). Wilman & Wright (1983) summarised results from several field trials where sown grasses were defoliated every 4-5 weeks and where high rates of N fertiliser increased tiller density.…”