Fertiliser guides
Direct answers first, then the working. Every figure links to its source, and anything we could not verify is flagged. Written by the Fert Directory editorial team; not yet reviewed by a qualified agronomist.
General information only. Check with your agronomist or local advisor. More
Nitrogen
How much urea per hectare for wheat? A worked rule of thumb
About 40 kg N per t/ha of wheat yield, minus soil nitrogen, divided by 0.46. A worked urea example with the assumptions stated and the limits spelled out.
Updated 17 October 2026
Costs and prices
How to calculate the cost per kg of nitrogen (with examples)
Turn a price per tonne into dollars per kg of N with one formula, then adjust for N lost to the air. Worked table using 17 Oct 2026 urea listings.
Updated 17 October 2026
Soil testing
How to read a soil test: pH, phosphorus, potassium, sulphur and mineral N
Plain-English soil test basics: pH (water vs CaCl2), Olsen P, PBI, potassium, sulphur and mineral N, with Victorian pasture ranges and GRDC sampling tips.
Updated 17 October 2026
Nitrogen
Nitrogen budget for wheat: a step-by-step worked example
Follow GRDC’s published wheat nitrogen budget from rainfall to soil test to a urea rate (311 kg/ha in the example), and see where the method can go wrong.
Updated 17 October 2026
Nitrogen
Urea volatilisation: how much nitrogen do you really lose?
Australian field data on ammonia loss from surface urea: an 8% national median, a 0–48% range, what drives it, and how drilling or timely rain cuts it.
Updated 17 October 2026
Nitrogen
Urea vs ammonium sulphate: which is cheaper per kg of N?
Compare urea (46% N) and ammonium sulphate by nitrogen per tonne, sulphur, nitrogen loss and acidification, with a cost-per-kg-N example and the lime caveat.
Updated 17 October 2026