How Much Moisture Loss Is Costing You at the Weighbridge
Every point of moisture your grain loses in storage comes off the tonnage you're paid for. Here's how to work out what over-aeration is costing you.
SiloSense IQ ·
Grain is sold by weight, and part of that weight is water. When grain dries out in the silo — usually because aeration fans have run on air that was drier than the grain needed — that water leaves, and so does the tonnage you’re paid for.
Most growers know this in principle. Fewer have put a number on it.
The arithmetic
When grain loses moisture, the dry matter stays the same and only the water goes. So the new weight is:
new tonnes = old tonnes × (100 − old moisture %) ÷ (100 − new moisture %)
Take 100 tonnes of wheat stored at 12.5% moisture that comes out at 11.5%:
- 100 × 87.5 ÷ 88.5 = 98.87 tonnes
- That’s 1.13 tonnes gone — from one percentage point of moisture.
Scale it to a site:
| Stored | Moisture lost | Tonnes lost |
|---|---|---|
| 100 t | 1 point | 1.13 t |
| 1,000 t | 1 point | 11.3 t |
| 1,000 t | 2 points | 22.7 t |
At an illustrative $350 a tonne, a single point of moisture across 1,000 tonnes is roughly $3,950 off the cheque. Put in your own price — the shape of the answer doesn’t change.
Where the moisture goes
Grain and the air around it are always trading water. If the air pushed through the silo is drier than the grain is “comfortable” with at that temperature, the grain gives up moisture. Run fans for days on warm, dry afternoon air and you’re slowly drying the whole silo — and paying for the electricity to do it.
That’s fine if the grain went in too wet and you want to dry it. It’s a straight loss if the grain was already at a safe, saleable moisture.
Aeration isn’t the enemy
None of this means “don’t aerate”. Cooling grain is the single most effective thing you can do to slow insects and moulds, and aeration is how you do it. The goal is to aerate on the right air:
- Cool air that brings grain temperature down.
- Air that won’t strip moisture from grain that’s already at target.
- Never humid air that puts moisture back in.
The difference between “fans on a timer” and “fans on the right air” is exactly the moisture — and tonnage — you keep.
Know what’s happening inside
You can’t manage what you can’t see. A moisture reading at the weighbridge tells you what you lost after it’s gone. Sensor cables through the grain tell you each layer’s temperature and humidity every day, so you can see moisture moving while you can still do something about it.
How SiloSense helps
Aeration Manager checks outside temperature and humidity before running fans in automatic modes, using the winter and summer limits you set for each silo. Fans run when the air helps, and wait when it doesn’t.
Paired with SiloSense IQ monitoring, you see moisture at every level of the silo, every day — and with SiloSense IQ+, a moisture guard stops fans running on any air that would push moisture back into the grain.
Protecting a single point of moisture across a season usually covers the system. Request a demo and we’ll run the numbers for your site.