What is the best way to ventilate and dry grain?

Sometimes grain has to be harvested while it is not dry out of necessity . In the Netherlands this often happens that we bring in grain with an average moisture content of around 18% and a temperature of 20 ° C.

How fast do you ventilate grain? Does putting a stove in front help?

On a short term there is no direct risk. Grains of 18% moisture and 20 ° C will not go moldy even without ventilation within 3 weeks. So immediate action is not always necessary.

What can you do?

First of all an explanation. Mold is dependent on moisture and temperature. When the grain is dry, it is best to be warm. However if the grain is damp, it is important to bring the temperature down as quickly as possible.

Cold nights are ideal for chilling. If you cool the grain to 10ºC with ventilation, it can remain at 18% moisture until the end of the year.

Cooling grain further down than 10ºC could cause the outside of the grain to  absorb moisture when the temperature rises outside in the spring. There are still people who think that grain should be stored as cold (5 ° C) as potatoes, but that is not correct.

Of course you know that some fungi are responsible for the formation of DON.

When can you dry grain outside?

There are a few rules here. The most logical is that if grain does not dry on the field, it will not dry in the shed either, because it is basically the same with air. Cold air can contain little moisture and how warmer the air gets, how much more moisture it will contain

The most efficient is to blow outside air, heated or not, through the grain. Cold air is heated by the grain, which allows it to absorb moisture and thereby the grain dries. The evaporation of water requires heat, which is why the grain cools down.

The most suitable air has a relatively low moisture content and is about four degrees colder than the grain. To bring grain to 15% moisture, the air must be drier than 67% RH (RH).

Unfortunately, this type of air is not very common in our climate and if you do not have an automatic control, you often have to check when you can turn on the fans.

Dry grain at what temperature?

The higher the temperature, the more water air can hold. An example:

Air from 5ºC and 80% RH heated to 10ºC → 1.4 g / m3 more water absorption / m3

Air from 15ºC and 80% RH heated to 20ºC → 2.5 g / m3 more water absorption / m3

Drying is therefore more efficient at higher temperatures. You can choose to start drying immediately after harvesting. This requires the least number of operating hours of the fan (s).

Be careful when using a stove. The temperature should not rise more than a few degrees, otherwise the drying will move too fast and condensation zones will form in the grain. Condensation zones can be broken through with a stirring system and with this it is possible to work with larger temperature differences.

Drying grain: final words

For those who want to know more, we have an extensive instruction booklet “Sensible grain storage” available. If you are interested, please send us an email and we will be happy to send it to you.

Our website contains a number of useful and affordable measuring instruments such as our moisture meters, penetration thermometers, sample drills and hygrometers.

We can help you with simple thermostats to extensive, automated controls on your fans. And if you do not have aeration yet and you still want to cool: take a look at our aeration pear. An affordable and effective solution.

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