Nitrogen fertiliser promotes growth in plants and is the easiest and often the cheapest way to increase pasture growth.  Plants deficient in nitrogen look pale green, stunted and yellow compared to their lush, green nitrogen rich counterparts.

Nitrogen is found in various fertilisers, including urea, ammonium sulphate, di-ammonium phosphate and mono-ammonium phosphate.

Urea is very soluble and contains only nitrogen  (46-0-0-0) while ammonium sulphate, also very soluble, also contains sulphur (21-0-0-24). 

Di-ammonium phosphate is a compound fertiliser containing phosphorus, sulphur and nitrogen (18-20-0-2). Mono-ammonium phosphate differs from di-ammonium in that it has a different combination of the chemicals used (11-22-0-1).

Nitrogen should be used “strategically” – or when you are guaranteed to get a response and when soil is sufficiently moist and warm. The best response is in spring and early summer with 80-100%, 60-80% response in late winter and early spring, 20-40% in autumn when rainfall is low and 50-70% when rainfall was high.

It is important to remember the concern for the environment and limits suggested by regional councils: for grazed pasture 20-40 kg N/ha (45-90 kg urea/ha)  while for  silage and hay 30-60 kg/ha (65-130 kg urea/ha).

Higher levels will result in leaching into the soil and the soil water and this will be worse in winter.

The best time to apply nitrogen is when you have pasture regrowth.  Cut for silage or hay 5-6 weeks after application. Stock can graze about 4-5 weeks after application if growth has been good.

When applying fertilisers be vigilant with animals to be sure they don’t ingest fertiliser with the pasture. Do not ignore the manufacturer’s warnings and recommendations and keep well away from waterways and drains when spreading.

It’s very important to wait until all fertiliser is washed off the leaves of the grass before grazing.   Keep a few breaks ahead of the herd clean until a decent rain has washed the grass clean. The composition of fertilisers is always in the order of N-P-K-S-Mg.