Nothing you record carries a price through to the block. You buy a chemical at one price, buy more of it later at another, and then spray a mixture of the two without knowing — or caring — which drum a particular litre came from.
So Intecrop does not try to follow the money through the store. It works the cost out afterwards, from the records you already keep, using a weighted average. That one choice explains most of what looks odd in the cost report.
A cost is never stored
There is no cost field on an application, and no price stamped onto a block. Every figure the cost report shows is worked out at the moment you ask for it, by replaying the chemical's records in date order.
That is worth having: correct the price on a receipt from three years ago and every report that depends on it comes right on its own. There is no stored total to go back and fix, and nothing can drift out of step with the records behind it.
One average per chemical, per period
For each chemical, over the period you asked for:
average cost per unit = (opening value + what you paid for stock received in the period) ÷ (opening quantity + quantity received in the period)
The opening position is what a replay of every record before the period leaves behind. So:
| Quantity | Value | |
|---|---|---|
| On hand at the start, carried at R120/L | 40 L | R4 800 |
| Received during the period at R150/L | 60 L | R9 000 |
| Total | 100 L | R13 800 |
The average is R13 800 ÷ 100 L = R138 per litre, and every litre applied during that period is costed at R138 — whether it came from the old drum or the new one. That single number is what the report's unit cost column shows.
What each kind of record does
- A receipt is a change in stock, and it is signed: a positive one is an intake, a negative one takes stock back out. A receipt with a price is what sets the cost — it is the only thing that puts new money into the average. A receipt without a price is carried at the average you already had, so it adds quantity without moving the cost.
- A correction sets the quantity to what you counted. The average carries over unchanged, so the value follows the new quantity.
- An application always reduces stock, at the average, and never returns anything to the store.
The excess is part of the cost
Almost every job mixes more than the blocks strictly need. What comes out of the store is therefore more than the sum of the doses that went onto the ground.
That difference is not dropped and it is not put in a bin of its own. The whole quantity deducted from the store is spread across the blocks on the application, in proportion to each block's dose multiplied by its area. So a block's cost — and its cost per hectare — carries its share of the excess.
That is deliberate. You paid for the excess, it was mixed for that job, and the blocks on that job are the only honest place to put it.
Changing the period changes the number
This is the cost of the design, and it catches people out.
The average is computed over the period you selected, so the same application can come out at two different costs in two reports run over two different periods. Neither is wrong. A cost per hectare only means something alongside the period it was worked out over — which is why every export prints the period on it.
The default period is the season, so the figure you get without touching anything is the one most decisions want.
If nothing was priced, nothing costs anything
If a chemical has no priced receipt in the period and no value carried in from before it, the average is zero and every application of it comes out free.
The report is not broken; it has nothing to work with. The fix is to put prices on the receipts — the cost report can only ever be as good as the prices you captured.
A shared store is one pool
Where two farms draw on the same store, they draw on the same stock, so the average is worked out over every record of that chemical rather than over one farm's share of them.
That is the right answer for one physical store. It is also a reason to think carefully about whether land that is run separately should be sharing a store at all — see Farms and production units.