Boron Application & Borax for a Target B Rate
Feeds cauliflower
Enter your target boron rate and area to get the borax product needed — boron has a narrow safe margin, so dose carefully and apply it evenly.
Boron application rate
Next: apply 9.52 kg/ha of product (19.05 kg total). Spread it evenly and well-diluted — never band concentrated boron near seed.
Boron is the classic narrow-margin nutrient. Even crops vary: brassicas need it, beans burn easily. Confirm with a soil test.
Boron application — key facts
- Borax boron
- ≈ 10.5% B
- Product needed
- target B ÷ 0.105
- Total product
- product per ha × area
- Safe margin
- Narrow — excess is toxic
- Corrects
- Hollow stem, fruit cracking
- Poor seed set
- Cauliflower, groundnut, cotton
- Apply
- Evenly; bulk small doses
- Privacy
- Runs in your browser; nothing uploaded
A tiny nutrient with an outsized effect — and a narrow safe margin
Boron is needed in only tiny amounts, but a shortage wrecks the parts of a crop that matter most: it causes hollow stem, fruit cracking and poor seed set in crops like cauliflower, groundnut and cotton. Because boron drives cell-wall formation, flowering and pollination, a deficiency shows as deformed, corky, empty growth even when everything else is right. The fix is a measured dose of borax, which is about 10.5% boron.
This tool turns a target B rate into the borax product per hectare and total product for your area. The catch is that boron has a narrow safe margin — too much is toxic — so weigh accurately, bulk small doses with sand or soil, and spread evenly. Pair it with the Micronutrient Spray and Crop Nutrient Removal calculators to build a complete, balanced nutrition plan.
Hit the right rate
Convert target boron straight to borax.
Stay below toxic
Respect boron's narrow safe margin.
Fix deficiency signs
Stop hollow stem and fruit cracking.
Buy the right amount
Total product for your whole field.
Frequently Asked Questions
What does a boron application calculator do?+
It converts a target boron (B) rate into the amount of borax product you need to apply, for your area. You enter the B rate you want to supply and the field size, and it gives the borax per hectare and the total product to buy — so you hit the right boron dose without guesswork.
Why is boron important for crops?+
Boron corrects deficiencies that cause hollow stem, fruit cracking and poor seed set in crops like cauliflower, groundnut and cotton. It is vital for cell-wall formation, pollination, flowering and the movement of sugars, so a shortage shows up as deformed growth, cracked or corky fruit, and empty pods or heads.
How much boron does borax contain?+
Borax is roughly 10.5% boron by weight, so about 10 kg of borax supplies a little over 1 kg of actual boron. The calculator uses this content to work back from your target B rate to the borax product needed — apply more product to get more elemental boron.
Why does the dose need to be so careful?+
Boron has a narrow safe margin — the gap between enough and too much is small, and excess boron is toxic to plants, causing leaf-tip scorch and stunting. Always weigh and spread borax accurately, distribute it evenly, and never apply a heavy band near seeds or roots.
Soil application or foliar spray?+
Both work. Soil-applied borax corrects a season-long deficiency and is what this calculator sizes; a dilute foliar spray gives a quick boost at flowering. For foliar use, dissolve a small amount fully and spray in cool conditions — and still respect the narrow safe margin.
How do I know my crop is boron deficient?+
Watch for the classic signs: hollow or browned stems in cauliflower and brassicas, cracked or corky fruit and tubers, poor pod and seed fill in groundnut and pulses, and dying growing points. A soil or tissue test confirms it before you commit to a corrective dose.
How do I apply borax evenly over a small dose?+
Because the rate per hectare is small, mix the borax with dry sand, soil or another fertiliser to bulk it up, or dissolve it for spraying. Bulking spreads the tiny quantity uniformly and avoids hot spots where over-application could turn toxic.
How often should boron be applied?+
Boron does not persist long in soil, especially light, leached or high-pH soils, so it is usually applied each season for responsive crops rather than building a reserve. Re-test periodically and only repeat the corrective dose where deficiency is confirmed.
Are the figures precise?+
They are solid planning figures based on borax being about 10.5% boron. Real boron needs vary with crop, soil type, pH and leaching, so confirm with a soil or tissue test, apply evenly, and treat the result as a careful starting dose rather than an exact prescription.