Nitrogen fertiliser can be used to boost pasture growth. For nitrogen applications to be successful, the grass must be in a growing state. If the grass is not growing, the plants will not take up the nutrient. The response that can be obtained from applying nitrogen depends on numerous factors such as:


  • soil fertility      
  • soil temperature      
  • type of plants      
  • soil moisture      
  • sunlight


Each of these factors influences the growth rate of plants and hence the uptake of nitrogen.

Timing – when should it be put on prior to cutting silage / hay?

Fertiliser applications to increase yield need to be applied at least 4 weeks prior to cutting silage/ hay. Ideally after the paddock has been grazed, fertiliser is applied and then the paddock is shut up for hay/silage. It is essential this fertiliser application is timed with a rainfall event; 10 mm of rain is normally sufficient. Fertiliser timing for hay paddocks is  generally around the same time, although the shut up period will be greater than 4 weeks. If postponed too long the likelihood of sufficient rain is reduced.

What blend should I use?

If you have done autumn P & K topdressing or soil test results show adequate nutrient levels, Pasture Booster (24-4-13-5) may be sufficient. If nutrient levels are less than satisfactory or autumn topdressing was not done, a blend higher in P & K such as Pasture Promoter (16-8-13-7) may be required. If nutrient levels are high, the use of urea may be appropriate. If paddocks treated with nitrogen or a nitrogen blend are grazed prior to cutting silage or hay the yield will be significantly reduced. Do not re-admit stock to any areas treated with nitrogen for a minimum of 21 days.

Product Analysis Rate (kg/ha) Comment


16-8-13-7 200 – 300 Sources of N to boost production P, K & S to maintain soil nutrient levels.
Pasture Booster 24-4-13-5 150 – 200 Source of N, P & K to boost pasture or hay where normal Autumn topdressing has already been applied.
Urea 46-0-0-0 80 – 100 Nitrogen only.


Note: These are examples only – consult your local Roberts representative to tailor a fertiliser program to suit your specific needs.