For large farms satellite observations can give data
https://www.aigorithm.com.au/farmer_operational.html
BoM, radar etc., gives improved accuracy of rainfall, etc., relevant to when/if to apply fertilizer.
Photos - and analysis thereof / machine learning -has a role.
Is the crop showing indications of water stress, nitrogen (or other) deficiency, disease?
Photos from drones ...
Spectral Reflectance and Heat Tolerance: UWA is involved in projects that use hyperspectral sensors (350–2500nm) to measure reflected light from wheat leaves and heads. This, along with imaging spectroscopy, helps in identifying stress-related traits (e.g., frost damage, drought).
Hyperspectral sensors measuring reflected light from wheat leaves and heads in the 350–2500nm range can detect nitrogen and other nutrient deficiencies, with nitrogen deficiency being a well-established application in precision agriculture due to its effect on chlorophyll and the "Red Edge" [1]. Deficiencies in phosphorus and potassium affect internal leaf structure and water regulation, changing how light scatters in the NIR range [1]. A Uniview article discusses UWA's use of hyperspectral imaging for crop health [1]. You can read more at UWA News.
https://www.uwa.edu.au/news/article/2025/march/uwa-technology-set-to-transform-agricultural-monitoring
Magic Wavelength
Communication. Timely info via internet from Departments of Agriculture ...
from LLMs run from Dept of Agriculture? https://arxiv.org/html/2507.21773v1
Farners sharing info through Ag. Depts. ...
And the computing environment evolves (and has fashions?)
One approach that gets some google hits is "fertilizer application" "Reinforcement Learning"
CropGym https://arxiv.org/abs/2104.04326
And, at an individual farm level, the old SYN package is now re-coded for iPad
https://nbroadacre.weebly.com
A lot of miscellaneous bits and pieces mostly not really relevant to the task at hand follow.
Numbers below from asking google:
In WA wheatbelt, the main N-fertilizer is urea, and as at Feb 2026 it is about $1000 per tonne.
Urea is often applied at seeding (often blended with other fertilizers) and top-dressed during the season (3 to 6 weeks after seeding).
The average wheat/sheep farm size in the Western Australian wheatbelt is now over 3,000 hectares.
And about 2000 ha will be under crop.
Yields about 2.5tonne/ha, and CBH pays, say $330 per tonne, say $750 per ha.
In the central and southern wheatbelt of Western Australia, urea fertilizer application rates generally range from 0.03 to 0.15 tonnes per hectare (30 kg/ha to 150 kg/ha), depending on soil type, rainfall, and target yield.
In many farming systems, variable rate technology is increasingly used, with average rates often falling around 0.07–0.08 tonnes per hectare (70–80 kg/ha).
So urea cost is $75 per ha. If one can get a 1% improvement in efficiency, say over whole farm it would be $15,000.
(Other costs P/K fertiliser, needed before Urea, $75 per ha; herbicides and fungacides $100 per ha;
seeding/fertilising etc. machinery cost, fuel, labour - might that be another $100 per ha; seed costs $50 per ha; harvesting costs machinery, fuel, labour $75 per ha.)
pricen and miscellaneous