Impacts of winter/early spring nitrogen fertiliser use on pastoral farms

Recognising that winter/early spring is characterised by very different climate and pasture growing conditions across the length of New Zealand, it is also a period of potential feed shortages for grass fed farm systems.

The New Zealand Fertiliser Association has commissioned a science-based assessment of the impacts of tactical nitrogen fertiliser use to address this feed shortage, when applied following accepted good practices. The science review findings are supplemented by scenario modelling.

Relative to the primary growing seasons, the volumes of nitrogen fertiliser applied during this winter/early spring period are small, but never-the-less, available evidence suggests that a feed shortage in early spring is probably best met by supplementary feeding or by N applications when growing conditions (soil temperature and moisture) allow for a pasture response.  Calendar timing will vary from region to region. No-Winter applications in the modelling scenario resulted in minimally changed simulation outputs – none were statistically or practically significant. Modelled leaching loss was similarly unaffected.