A. The simple answer is DON’T!!
All of the Nitrogen in these fertilisers is present in the slower acting Ammonium form which needs time to convert to faster-acting Nitrate N before the plant can pick it up. The bugs that convert it (Nitrification)® are very slow-acting at soil temperatures below 10°C and still slow at 15°C.
% nitrification of fertiliser NH4-N to NO3-N time in weeks


Solution: Simple… use a fertiliser that contains both N Forms + Sulphate Sulphur i.e. ASN Cold Start®.
ASN (Ammonium Sulphate Nitrate) Cold Start® has consistently outperformed Ammo on Canterbury Dairy farms over the past seven seasons by producing 33-96% more grass over the August-September periods at similar rates of N. viz.
(ASN 41.5kgN /ha vs 45kgN/ha with Ammo36).
ASN may cost a little more, but it produces the goods where the alternatives struggle.
An extra 10kg DM / ha @12 ME = 122ME/ha/day= an extra $29,328/100ha!!! (122x100x28days=341600 MJME. 70 MJME to make 1 Milk Solid= extra4880MS @$6.50/kg MS).
The difference in cost is nothing compared to the results gained, or the cost of supplementary feed because you haven’t grown enough grass.
I bet your fertiliser rep didn’t tell you about the different forms of N and the effect of cool soil temperature on Nitrification (probably because they don’t know!).
Contact ViAg today to secure your order and get your pastures pumping.
ASN Cold Start® is the registered trademark of Agri NZ Ltd Tauranga.