kilogram per hectare
Mass per areaexact by definition
The kilogram per hectare is the working unit of metric agronomy: 1 kg/ha is 10⁻⁴ kg/m², exact, since a hectare is exactly 10,000 square metres. Seeding rates, fertiliser rates and nutrient removal are all written this way outside the United States.
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The hectare was created in 1795 as a hundred ares, and survives as one of a handful of non-SI units the metric system agreed to keep because land is not usefully measured in square metres.
About the kilogram per hectare
Almost every agronomic recommendation in the metric world arrives as kilograms per hectare, and the reason is arithmetic convenience rather than tradition. A hectare is 10,000 m², so a rate in kg/ha divided by ten gives grams per square metre directly — 200 kg/ha is 20 g/m², which is a number you can picture in your hand.
The conversion that actually matters is to pounds per acre, because North American labels, drills and extension bulletins are written in those. The factor is 1.121: lb/ac × 1.121 = kg/ha, and going the other way, kg/ha × 0.892 = lb/ac. A 100 lb/ac nitrogen rate is 112 kg/ha. The two numbers are close enough that swapping them by accident does not look absurd, which is exactly what makes the mistake expensive.
One kilogram per hectare in every mass per area unit
| 1 | kilogram per hectare (kg/ha)this unit | |
| 0.001 | tonne per hectare (t/ha) | |
| 0.0001 | kilogram per square meter (kg/m²) | |
| 0.1 | gram per square meter (g/m²) | |
| 0.892179 | pound per acre (lb/ac) | |
| 0.00044609 | short ton per acre (ton/ac) | |
| 0.0204816 | pound per thousand square feet (lb/1000 ft²) | |
| 0.00294935 | ounce per square yard (oz/yd²) | |
| 0.00892179 | hundredweight per acre (cwt/ac) |