Soil Test Crop Response & Targeted-Yield Dose
Doses nitrogen
Enter your target yield and soil-test N, P and K to get a fertiliser dose tuned to that yield — N, P₂O₅, K₂O and the urea, SSP and MOP per hectare.
Soil-test targeted yield
Next: top up with 58.3 kg urea, 0 kg SSP and 32 kg MOP per hectare, split N across growth stages.
STCR coefficients are region- and lab-specific; these are illustrative for rice/wheat. Use your own state STCR equations and a recent soil test for exact rates.
STCR — key facts
- Approach
- dose tuned to target yield
- Equation
- FN = a×target − b×soil-test
- Soil credit
- subtracts nutrients in soil
- Inputs
- target yield + soil-test N,P,K
- Soil-test unit
- kg/ha
- Outputs
- N, P₂O₅, K₂O per ha
- Fertilisers
- urea, SSP, MOP
- Privacy
- Runs in your browser; nothing uploaded
Fertilise for the yield you want, credit the soil you have
Blanket fertiliser recommendations treat every field the same, ignoring how much nutrient the soil already holds — so rich fields get over-fed and poor ones under-fed. STCR flips that: it works from a target yield and your soil-test values, using calibrated equations of the form FN = a × target − b × soil-test. The first term is what the target needs; the second credits what's already there, so the dose is matched to both your goal and your ground.
This tool gives the fertiliser N, P₂O₅ and K₂O per hectare and the urea, SSP and MOP to apply, from your target yield and a recent soil test in kg/ha. By crediting soil nutrients it cuts waste and balances the dose. Pair it with the Fertilizer (NPK) and NPK-from-Grade calculators to fine-tune the product mix once you know the nutrient targets.
Hit a target yield
Dose calibrated to the yield you aim for.
Credit the soil
Subtract nutrients the test already shows.
Cut waste
Stop over-applying on fertile fields.
Buy the right bags
Get urea, SSP and MOP per hectare.
Frequently Asked Questions
What is STCR?+
Soil Test Crop Response (STCR) is an approach that prescribes a fertiliser dose tuned to a specific TARGET yield and your actual soil-test values — not a one-size-fits-all blanket recommendation. It uses calibrated equations so the dose credits the nutrients already in your soil and supplies only what's needed to hit the target.
How does the STCR equation work?+
For each nutrient the dose follows FN = a × target − b × soil-test value, with separate a and b coefficients for N, P and K. The first term is the total nutrient the target yield needs; the second subtracts a credit for what the soil test shows is already available. The result is the fertiliser nutrient to apply per hectare.
How is STCR different from a blanket recommendation?+
A blanket recommendation gives every field the same kg/ha regardless of its fertility. STCR instead reads your soil test and target yield, so a rich field gets less and a poor field gets more. That precision cuts waste, balances the nutrients and lines the dose up with the yield you're actually aiming for.
What inputs do I need?+
A recent soil test reporting available N, P and K (commonly in kg/ha), and the target yield you want for the crop. The tool combines them through the STCR equation to give the fertiliser N, P₂O₅ and K₂O, then converts those into bags of urea, SSP and MOP per hectare.
Why does STCR cut fertiliser waste?+
Because it credits the nutrients the soil test already shows are present, you stop paying for and applying nutrients the crop doesn't need. On fertile fields the saving can be large; on poor fields it ensures you actually apply enough. Either way the dose is matched to the target rather than guessed.
What does the calculator output?+
It gives the fertiliser requirement as nutrients — N, P₂O₅ and K₂O per hectare — and converts those into straight fertilisers: urea for N, single super phosphate (SSP) for P₂O₅ and muriate of potash (MOP) for K₂O. That tells you exactly how many kilograms or bags of each to buy and apply.
Why is the soil test in kg/ha?+
STCR equations are calibrated against soil-test values expressed as available nutrient in kg/ha, so the credit term lines up correctly. If your lab reports in ppm or another unit, convert to kg/ha first (ppm × 2.24 for a standard furrow-slice) so the equation gives a sensible dose.
Can I use it for different target yields?+
Yes — that's the point. Raise the target and the required nutrient rises through the a-coefficient term; lower it and the dose drops. This lets you plan fertiliser for an ambitious or a conservative yield goal and see the cost trade-off before you commit.
Does it replace a soil-testing lab?+
No — it depends on a lab soil test for the N, P and K credits. The calculator turns that test plus your target yield into a dose; it can't measure your soil for you. Use a recent, properly sampled soil report, ideally with STCR coefficients calibrated for your region and crop.
Are the results exact?+
They're a calibrated prescription, but real response varies with soil type, climate, crop variety, management and the accuracy of the soil test and coefficients. Treat the dose as a strong starting point, split applications sensibly, and refine against your own yield and soil-test history over seasons.