To find out whether your input stock matches the record, count one group of inputs by hand and write the count beside the recorded amount, item by item. What you end up with is a stock count sheet: one row per item, with what you counted, what the record has, and the difference between the two. The record of what came in and went out is not a count. It holds only what someone wrote down, so it drifts: it has no line for the bag that tore, the drum emptied in a hurry, or the jug a neighbor brought back without a word.
On many farms that record is kept from memory, or not at all. Buying then runs on a guess, and a surplus or a shortage shows up only when an input runs out in the middle of an operation, or turns up expired in a corner of the shed. With a count beside the record, that surprise becomes a number you see before an operation starts instead of halfway through it.
Why does the record drift without anyone noticing?
Because a record of movements holds only the movements someone wrote down. Hanson, Johnson and Lesley, who wrote the University of Maryland Extension guide to farm records, explain that an inventory is a count taken at one moment, only valid for that point in time, because stock keeps changing. The in-and-out record is a different thing: it follows the movements over the year.
If you keep a field log, a line for each operation with the input and the amount used, most of the going-out side comes from there. The record can add up perfectly and still be wrong about the shed, because a torn bag or a returned jug changes the stock without anyone picking up a pen.
When the record slips, you cannot see it on the page. Destro and colleagues (2023), who studied warehouses, not farms, report, citing Hachem and colleagues (2016), that once a record starts to drift, the gap can keep growing like a snowball while nobody notices. The count is your only check, because you take it from what is in the shed, not from what was written down.
Which way does the difference run, and why does it matter?
Work out each difference as the record minus the count, so every row carries a plus or a minus. A plus means the record has more than you found: something went out without being written down. A minus means you found more than the record has: something came in or came back without an entry. Each sign leads to a different mistake.
| Which way the difference runs | What happened | What it is about to cost |
|---|---|---|
| Plus: the record is higher than your count | Stock went out without an entry | You reorder too late and run short in the middle of an operation |
| Minus: the record is lower than your count | Stock came in or came back without an entry | You buy what you already have, and it sits, ages or expires in the shed |
On the sheet, each row has its own sign, and you act on each row by that sign. A plus on the crop-protection line means a spray job may stop halfway because a jug you were counting on is not there. A minus on the fertilizer line means the next load you order may be fertilizer you already have, and it will sit in the barn.
Is the count the same job as keeping the record?
No. The count is a separate sheet, made walking through the shed, not a correction typed into the record. Kenkel, in an Oklahoma State University Extension guide for farm-supply cooperatives, describes counting part of the stock on a set cycle so the records can be reconciled to reflect the actual physical count; his guide is for a store, not a farm, but the step carries over.
On a farm, the count is one person with a notebook walking through the shed. The Maryland authors write that to take an inventory you count and assign value to your resources. You keep the record at a desk, from what people remember to write down; you take the count in the shed, from what is there. Only when you set the two side by side do you see how far the record has drifted.
When is the difference real, and when does it come from how you counted?
A difference means something only if you count the same way every time. The Maryland authors write that once you decide how to measure a resource, you should be consistent from year to year. A half-used bag counted as full, fuel read off the tank gauge one time and measured with a dipstick the next, a count taken before spraying one month and after it the next: each creates a difference that has nothing to do with the stock. Keep the counting method the same, and what is left on the sheet is the real gap.
A record that does not match is common, not the exception. In the stores of one global retailer studied by MIT researchers, records matched the shelf exactly for only about half of the items; those were shops, not farms, but they show how far a record nobody checks can drift. The drift comes from many small slips, with no one making a big mistake, so the count is less about catching one big error than about giving you a date on which the record and the shed agree again.
What can you decide from the difference, and what not?
Use the difference when you decide what to restock, and name the person who checks it before any input is reordered: you, the manager, or whoever does the buying. From the difference you cannot work out how much to buy or when; that stays your decision. Nor can you work out how to store an input better, which is for you and your agronomist. What you learn is that the record is off, by how much and in which direction, so buying no longer rests on the record alone. Once you have gone through the rows, correct the record to the counted figures, date the sheet, and name who does the next count.
The count is worth most right before a busy stretch. If you keep a calendar of operations, a written plan of when each field operation should happen, count the inputs those operations need before they start, so you find a missing input then and not on the morning the job is due.
The difference can also become a number you follow from one count to the next. Another guide in this library, one operational number worth tracking, shows how to choose one figure from the farm’s work and decide in advance where it comes from and how often you check it; the difference fits if the same person counts it on a set date each time.
Where to start
An hour, with the record open to one group of inputs and a notebook in the shed. Not the whole shed at once.
After the count and the correction, your record is right as of that date. From then on, every figure in it is an estimate until someone walks through the shed with a notebook again. Checking what you wrote down against what is really there is worth doing for every record the farm keeps, and in the farm management guide you will find the rest of running a farm.