Grain Drying Weight Reconciliation for African Farms

A drying intake ticket and a storage intake ticket can show different grain weights even when no kernels have gone missing. Water removed during drying accounts for part of the change. Cleaning, spillage, samples, transfers and measurement differences may account for other parts. A useful reconciliation identifies each movement before treating the remaining difference as a loss.

Use the Grain Storage Loss Calculator after establishing the quantity actually entering storage. It models storage losses using built-in assumptions; it does not measure moisture, calculate drying shrink or diagnose a missing load. Keep the drying reconciliation in a separate record, then use the tool to explore storage options with its stated limits.

Sources reviewed: October 8, 2026. This guide uses current access to primary FAO technical references, Farm Africa's October 2025 maize training manual for Uganda and Purdue University's PICS instructions. The older FAO references explain measurement principles, not current buyer contracts. The checklist below is editorial working guidance, not a grading certificate, an equipment operating procedure or a universal storage-moisture standard.

Define the lot and the measurement boundary

Start with one identifiable batch of the same commodity and processing state. Shelled maize, maize on the cob, paddy and milled rice are different materials. Do not compare a weight containing cobs or husks with a later weight of cleaned grain and call the entire difference drying shrink. Record what was weighed at each stage, including any material subsequently removed.

Give the lot a reference that appears on the intake slip, moisture record, drying-service sheet and final stock entry. Record the date, location and person responsible for each handoff. If several lots are combined, retain the component references and measurements. A combined batch needs its own reconciliation; one moisture reading from one original lot cannot explain every component.

Decide where the exercise begins and ends. A comparison from harvested crop to bagged grain includes more operations than a comparison from cleaned grain at dryer intake to the same grain at dryer discharge. Write those boundaries at the top of the worksheet. Record subsequent household withdrawals or sales separately so they do not appear as unexplained stock losses.

Put gross, tare and net weights on the same record

Gross weight includes the container or vehicle. Tare is the weight deducted for that container or vehicle. Net weight is the amount remaining after the deduction. Retain all three figures where available, rather than copying only the final net quantity. A later reviewer should be able to check how the grain quantity was obtained.

Identify the scale and the unit on each ticket. Kilograms and tonnes must be converted consistently before calculation. Ask the weighing operator how tare was established, particularly where sacks, pallets or a vehicle have changed between measurements. Do not replace an observed bag weight with the nominal capacity printed on the sack.

Keep drying, cleaning and transport tickets together. A receipt describing a bag count can support a handling record, but it cannot by itself establish net grain mass. If a scale result or tare record is missing, mark the reconciliation incomplete. An estimate can help planning, provided its basis stays visible; it should not be presented as a verified quantity.

Record the moisture basis before using a percentage

FAO's food-loss training reference distinguishes moisture expressed against total wet material from moisture expressed against dry matter. It also separates water removed during drying from food loss. Label measurements as wet basis or dry basis rather than leaving a bare percentage beside a weight.

For this worksheet, both moisture values must use the wet basis. If an instrument, laboratory report or supplier uses another basis, ask for a confirmed conversion before proceeding. Do not combine unlike measurements in the equation. Keep the original reading alongside any converted value and name the person or method responsible for the conversion.

A moisture entry should include the lot reference, sampling time, test method and instrument identifier. Ask the operator to document crop settings, calibration checks and any temperature correction required by the instrument instructions. These record fields make the evidence reviewable; they do not turn a handheld reading into an official laboratory result.

Connect the sample to the grain that was weighed

A moisture sample and a weight ticket should describe the same lot at the same processing stage. A reading taken before cleaning should not silently accompany a weight taken after cleaning. If grain is added or removed between tests, identify the movement. If the drying operator samples at a different point, record that point explicitly.

FAO's grain handling chapter calls for representative sampling because moisture can vary within a batch. Follow a sampling plan accepted by the buyer or a qualified local adviser. Preserve the sample identifiers and individual results so that an average remains traceable to actual observations.

Ask how samples are protected between collection and measurement, and how repeat readings are handled. Record disagreement rather than selecting the reading that produces the preferred result. Where a commercial dispute depends on moisture, agree the retest and reference method with the counterparty. An editorial worksheet cannot decide which party's test is binding.

Calculate the weight change attributable to water

FAO's batch and continuous drying reference gives the relationship between starting weight, starting moisture and final moisture. With both moisture readings on the wet basis, and with dry matter held constant:

Expected final weight = starting net weight × (100 − starting moisture %) ÷ (100 − final moisture %).

The difference between starting weight and expected final weight is calculated water removal. This is a mass-balance estimate. It assumes the material being compared has not lost or gained dry matter. Cleaning out impurities, removing kernels for samples or spilling grain changes that assumption and requires separate records.

The FAO reference's published example starts with 2,000 kg of corn at 25% moisture and ends at 15%. Applying the relationship gives 2,000 × 75 ÷ 85 = 1,764.71 kg. The calculated water removed is 235.29 kg. These are source example values, not a farm result, a buyer's deduction schedule or a recommended drying endpoint.

Keep the full calculation in the worksheet and round only the displayed result. Record the rounding rule used for settlement separately. A lower final weight is expected in this example, but the calculation alone does not prove that a real consignment has been correctly weighed, dried or handled.

Investigate the difference without guessing its cause

Place expected final weight beside measured final net weight. Review known removals, additions and measurement differences before naming the remaining variance. Link each adjustment to a ticket or contemporaneous record. Do not label a discrepancy theft, pest damage or operator negligence solely because the measured quantity differs from the estimate.

Cleaning removals

Record what was removed, when it was removed and whether it was weighed. Keep this separate from the water-removal estimate.

Samples and withdrawals

List quantities taken for testing, household use, sale or another destination, with their dates and lot references.

Transfers and additions

Identify any movement into or out of the batch. A mixed lot may require a revised calculation rather than a single adjustment.

Weighing differences

Check units, tare, scale identity and transcription against the original slips before seeking a physical explanation.

Where these records are absent, write down what is unknown and who needs to provide it. Retain both the raw evidence and the working calculation. A corrected worksheet should show which entry changed and why. The aim is an auditable explanation, including unresolved items, rather than a forced zero balance.

Check the drying-service and buyer terms separately

Ask the service provider to state the charging basis: intake weight, output weight, hours, a batch charge or another agreed unit. Record whether handling, cleaning, packaging, testing, transport and taxes are included. Obtain current written terms instead of copying a price from a technical manual or an old social-media advertisement.

Ask the buyer which moisture, impurity and quality conditions apply to the commodity and intended use. Request the sampling procedure, accepted measurement method and deduction schedule where relevant. Keep physical water shrink, service charges and contractual price deductions in distinct columns. They describe different things and should not be added together without a stated basis.

Before payment, compare the invoice with the accepted service scope and completed records. Seek an explanation for a quantity or deduction that cannot be traced to the agreed terms. A technically correct moisture calculation does not establish contractual entitlement, buyer acceptance or a legal remedy. Obtain appropriate local advice for a disputed transaction.

Confirm storage readiness independently of shrink

Farm Africa's October 2025 Uganda maize manual recommends drying maize to 13% moisture before storage. That recommendation has a crop and workflow context. It should not be replaced by the 15% endpoint in FAO's arithmetic example or applied indiscriminately to every grain, storage period and buyer specification.

Keep quality acceptance beside the quantity reconciliation, with a separate decision on whether the lot may enter the intended store. The Uganda manual describes inspection, sampling, testing and recording at reception. Ask the relevant extension service, store operator or buyer to resolve a failed or uncertain quality check. A weight balance does not certify food safety.

Purdue's PICS farmer instructions require dry, clean grain and intact inner liners, with each layer tied separately. Use the correct product instructions and verify the grain condition first. Hermetic packaging is a storage control, not a substitute for drying or a method of repairing an unexplained quantity discrepancy.

Use the confirmed intake in the storage plan

Enter the recorded storage-intake quantity into the Grain Storage Loss Calculator using tonnes, together with the selected crop, country, storage method, duration and price. Its built-in method rates produce a planning comparison. The current interface does not accept starting and ending moisture readings or a custom measured loss rate.

Save the inputs and date beside the planning result. Keep measured drying water removal outside the projected storage-loss figure. If the actual store later performs differently, retain the observation as evidence for a separate assessment rather than describing the tool's default as the loss measured on your farm.

The grain-storage loss planning guide covers the broader choice between storage systems. Use the harvest-date planning checklist to coordinate the operations leading into drying. Carry confirmed service costs into the Smallholder Farm Budget Planner, without assuming a future sale price or storage premium is guaranteed.

Close the lot with a short evidence packet

Keep the original intake and discharge tickets, moisture tests, sampling notes, movement records, accepted terms, invoice and final storage entry in one private folder. Use lot references in filenames. Share only the records needed by the operator, buyer or adviser, and remove unrelated personal details from a copy used for training.

The closing note should state the measurement boundary, calculated water removal, measured quantity, documented adjustments and any unresolved variance. Name the next action and its owner where evidence is missing. This creates a reusable process for the next lot while keeping the distinction between a calculation, a measured outcome and a commercial acceptance decision visible.