Nitrogen: cost, efficiency and return
CY26 Annual Summary | Case Study
Nitrogen is one of the primary drivers of yield in rice production once the crop foundation is in place and it is also one of the most significant input costs. So, it is important to have a considered approach to nitrogen use which ensures that the rate of application matches crop and soil requirements, the method of application is the most effective for the system and that the timing of application is aligned with crop growth and seasonal conditions.
Applying extra nitrogen doesn’t necessarily make a difference to yield; what is important is applying the right amount of nitrogen at the right time and getting the basics right from the start. That means addressing soil constraints, planting and carrying out operations on time, achieving even crop establishment, keeping weeds under control and managing irrigation well.
On average, growers spent around $400/ha on nitrogen in CY26*. If all applied nitrogen contributed to yield, this investment is justified. However, the yield results show that the correlation between additional nitrogen and yield is not always clear cut. This season there was a 2.6 T/ha yield difference between the top and bottom yielding third of all Matilda crops. The previous two seasons had a 4 T/ ha yield gap. In all seasons there has been minimal difference in nitrogen applications (20–30kg urea) between the yield categories.
So, the key questions remain:
→ Are we achieving a return on all nitrogen applied?
→ Can efficiency be improved to maximise profitability?
* Based on CY26 prices, per kilogram of nitrogen, urea is $1.74/kg nitrogen and GranAm is $2.67/kg nitrogen.
Nitrogen application efficiency
Nitrogen efficiency varies significantly depending on application timing and method. The methods below are listed in order of efficiency:
1. Urea drilled or applied prior to permanent water: Urea drilled to 10 cm deep, aerial sown or broadcast onto dry soil followed by permanent water is the most efficient strategy. For drill sown crops, uptake efficiency improves as plant size and root development increases.
2. Panicle initiation (PI) applications: Urea applied at PI is the next most efficient. At this stage, crops have high demand and can rapidly take up nitrogen. However, PI nitrogen will only increase yield if the crop is deficient (low nitrogen uptake). While high rates (up to 250 kg/ha urea) can recover some yield in deficient crops, they cannot restore full yield potential. In most cases, applications above ~130 kg/ha at PI provide limited economic return.
3. Mid-season applications (into water): Broadcasting urea into standing water is relatively inefficient but can improve yield if earlier nitrogen was insufficient.
4. Between flush applications: Applying nitrogen (urea or GranAm) between flushes in drill sown systems is the least efficient because significant losses occur as soils dry out again and most nitrogen is lost as nitrogen gas.
GranAm and sulphur considerations
Benchmarking data shows that many of the high yielding crops had GranAm applications between flushes. However, so did many of the lower yielding crops and there was no clear yield benefit to applying GranAm as a nitrogen source between flushes. This additional application added to direct costs of growing the crop. For instance, there were 60 paddocks that used GranAm between flushes (at around 130 kg/ha), adding $70/ha in direct costs for no clear yield benefit.
Sulphur is an essential crop element for healthy growth and aids in the uptake of nitrogen in the plant. If a crop needs sulphur, then GranAm (21%N and 24%S) will provide a very rapid response and will contribute directly to yield. If it has been identified prior to planting that your soil may be limiting sulphur, gypsum (at 18%S) at 500kg/ha prior to rice planting is a more economical alternative.
It will also provide enough sulphur for all rotational crops for multiple seasons, plus added soil structural benefits. Soil testing is the most accurate method for determining sulphur requirements.
Are additional nitrogen applications economic?
Overall, early (between flushes) and late (greater than 10 days post PI) nitrogen applications are unlikely to deliver a profitable response, particularly where crop demand has already been met. The highest returning approach is to apply appropriate rates of starter fertiliser and urea at pre-PW for both economic efficiencies and yield results. Looking at past imagery can help to identify areas that need more or less nitrogen, as pre-PW applications are also the best time to use variable rate application.
Using imagery and the Rice Management Dashboard to identify areas that are not likely to reach the PI nitrogen uptake target can determine if a mid-season application is warranted. Monitoring the crop response following any mid-season application is crucial in ensuring the appropriate PI top dressing rate, providing a better return on applied nitrogen.
Key learnings
Nitrogen is one of the largest input costs and a primary driver of yield, and return on investment will be based on efficiency, not total application. Well-timed, targeted nitrogen applications are critical to maximising both yield and profitability.
For more information on benchmark results or to develop a tailored nitrogen program, contact Rice Extension.