How to Work Out Gross Margin Per Hectare

At the end of a season the whole-farm figure tells you whether the year worked. It doesn’t tell you which of the six things you grew paid for the others.

Gross margin per enterprise answers that, and the denominator you divide by determines whether the answer is useful.

Gross margin, not net profit

Gross margin is enterprise output value less its variable costs. Variable costs are the ones that change with the scale of that enterprise: seed, fertiliser, sprays, casual labour, contract operations, and for livestock, feed and veterinary costs.

Fixed costs — machinery depreciation, rent, permanent labour, insurance, finance — are shared across the whole farm.

The reason gross margin is the comparison figure is that allocating fixed costs between enterprises is arbitrary. Does the tractor cost belong to the maize or the vegetables? Any split is a convention, and different conventions produce different rankings.

Gross margin sidesteps that entirely. It compares enterprises on costs genuinely attributable to each, which makes the comparison fair. Net profit answers a different, whole-farm question.

Divide by the limiting resource

Per hectare is the default because land is usually what’s scarce. But it’s a choice, and the right denominator is whatever actually constrains you.

Land-limited? Margin per hectare.

Water-limited? Margin per cubic metre of irrigation water. Under irrigation restrictions this can rank enterprises completely differently — a crop with a lower margin per hectare and much lower water use may be the better choice.

Labour-limited at a specific point? Margin per hour of labour in the peak week. Many horticultural enterprises are constrained by harvest labour availability rather than by land, and per-hectare figures hide that entirely.

Capital-limited? Margin per unit of working capital tied up.

The default per-hectare comparison quietly assumes land is the constraint. When it isn’t, the ranking it produces is the wrong one.

Get the variable cost list right

The classification errors that distort the figure:

Own labour. If family labour isn’t costed, enterprises that consume a lot of it look artificially good. Cost it at what it would cost to hire, or at least record the hours.

Own machinery operations. Fuel and repairs vary with use and are properly variable; depreciation is fixed. Splitting these correctly matters for machinery-intensive enterprises.

Stored inputs. Fertiliser bought last season and used this one should be costed at what it cost, not at today’s price, unless you’re doing a replacement-cost analysis deliberately.

By-products. Straw, cull animals, and second-grade produce are output and belong in the enterprise’s revenue.

Common mistakes to avoid

• Allocating fixed costs between enterprises and treating the result as comparable.
• Not costing family labour, which flatters labour-intensive enterprises.
• Comparing per hectare when water or labour is the actual constraint.
• Ignoring by-product revenue.
• Comparing a single season, when weather variation between years often exceeds the difference between enterprises.

How to do it with Farm Profit Tracker

The Farm Profit Tracker records income and variable costs per enterprise.

1. Record income and variable costs separately for each enterprise.
2. Cost own labour and own machinery operations properly.
3. Divide by your actual limiting resource, not automatically by area.
4. Compare across at least three seasons, since one year’s weather dominates a single figure.

Other farm tools are in the tools directory.

Frequently asked questions

Why gross margin rather than net profit?

Because fixed costs are shared across the whole farm and allocating them between enterprises is arbitrary. Gross margin compares enterprises fairly; net profit answers a whole-farm question.

What counts as a variable cost?

Costs that change with the scale of that enterprise: seed, fertiliser, sprays, casual labour, contract operations. The tractor payment is fixed even though it feels variable at harvest.

Should I always maximise margin per hectare?

Only if land is your binding constraint. Where irrigation water, seasonal labour or capital is scarcer, margin per unit of that resource is the right measure.

Final thought

Work out what actually limits you before choosing the denominator. Per hectare is the habit; the constraint is the question.

Try the free Farm Profit Tracker