module 03 Drying
 lesson 01 1 The importance of drying
 obj 1 To define drying and to explain its importance

What is drying?
Dry before storage

Drying is when you reduce the moisture of the grain to a level where it becomes safe to store the grain.

Poor drying gives low quality grain

Why is drying so important?

  • If you wait too long before drying
  • if you don't dry long enough, or
  • if you dry the grain in a poor way

--> The quality of the grain will decrease fast

Wet grain is more vulnerable to pests, discoloration etc.

If the grain quality is less good, you will have less profits.

The purpose of storage



Before proper storage you need proper drying

The purpose of storage is to provide the dried grain with protection against insects, molds, rodents and birds, and to prevent moisture from re-entering the grain.

BUT if the drying is not done properly, you will have losses no matter how good the storage is.

Sometimes drying and storing are done together in one operation, called in-store drying.

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Why is grain with a high moisture content a problem?


What happens if the moisture content is high?

At harvest, the rice grain still contains a lot of moisture.

  1. High moisture gives natural respiration in the grain that causes deterioration of the rice.
  2. High moisture promotes the development of insects and molds that are harmful to the grain.
  3. High moisture in grain also lowers the germination rate of rice that is intended for seed.



Therefore, drying of rice is very important to prevent insect infestation and quality deterioration of grain and seed.



Drying for storage
Dry harvested grain within 12 hours! It is important to dry rice grain as soon as possible after harvesting. This means within 12 hours!

You must know how long you want to store the grain.
The longer you want to store the grain, the more you have to dry it first!

Moisture Content = MC The following table shows the best moisture content (MC) for storage of paddy grain and seed, and possible problems when the moisture content is not right:
Longer storage =lower MC
Storage period Required MC for safe storage Possible problems
2-3 weeks 14-18% Molds, discoloration, respiration loss
8 to 12 months 13% or less Insect damage
More than 1 year 9% or less Loss of viability

Dry and protect grain! Three conditions to store grain longer

So, safe storage of paddy grain for longer periods is possible if 3 conditions are met:
  1. Grain is dried down to 14% MC or lower.
  2. Grain is protected from insects and rodents.
  3. Grain is protected from re-wetting by surrounding air or rain.
Next lesson

In this lesson you learned the importance of drying grain, in the following lesson you will learn how drying can be done.



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