Nitrogen use and farm performance on Wairarapa sheep and beef farms

Abstract

Seventy-eight sheep and beef farms on the east coast of the North and South Islands were surveyed in August/September 1991 on the use and benefits of nitrogen (N) fertiliser. The survey covered the years 1987/88-1990/91 and included 16 sheep and beef farms in Wairarapa. Farms with high N use (>5 kg/ha/year on average over the whole farm area in pasture and crop) received 20 (Wairarapa) or 28 (other east coast regions) kgN/ ha/year on 83 or 53% of the farm area respectively. Diammonium phosphate (DAP) was the major form of N used in Wairarapa. Urea and DAP/ammonium sulphate mixes were the major forms used in other east coast regions. Most of the N was applied from May to August in all regions. High use of DAP in Wairarapa was associated with higher rates of phosphorus but lower rates of sulphur applied compared with other regions. Survey farmers identified feed demand as the major factor influencing amount of N applied and the timing of application. Soil moisture and temperature at application were ranked as the major factors affecting the response to N. Benefits of N were listed as lower susceptibility to drought, higher calf weaning weights, longer winter grazing rotation and greater pasture cover at lambing. Over the whole survey, N use was associated with significantly higher animal and financial performance. N use on easy land on the North Island survey farms was associated with a significantly lower presence of browntop, other perennial grasses (mainly Yorkshire fog and crested dogstail), white clover, annual legumes (mainly suckling and cluster clover) and flatweeds. On steep hills, N use was associated with a significantly lower presence of other perennial grasses and annual legumes. Keywords: animal performance, financial performance, nitrogen fertiliser, pasture species, sheep and beef farms