By David Njagi
The purpose of any seed treatment is to improve its performance. If you are a farmer struggling to generate the right seed for planting M.A. Mushira of CIMBRIA takes you through the process of treating your seed from harvesting to planting.
After seed is harvested, there are equipments that do all operations required on that seed material to make it suitable for planting.
The first stage in seed processing is shelling or threshing the seed material. This is done with shelling machines. But the other seed material may not require shelling because they are threshed.
Normally, seed is harvested at moisture content that is a little bit higher than the required safety levels for storage.
Hence, material for shelling must be done on machines that are properly selected, set and adjusted, so that during shelling, the seed material is not damaged, either externally or internally.
After the seed is shelled, it has to be dried so that the moisture content of the seed material is safe for its subsequent storage and processing.
Drying is done either by exposing to the sun or by artificial driers. The sun can be used to dry seed but it is important to harvest it at the right moisture content.
This is because sun drying, if not carefully handled can lead to over-drying of the seed, which can be damaged during shelling.
The seed is harvested when it has a moisture content of around 18 percent. In such a case, a farmer requires artificial drying to reduce the moisture content after shelling.
In all the drying arrangements, temperature level is important. Grain is usually dried at low temperatures.
For maize and other cereal crops, the temperature range should be between 13 degrees Celsius and 13.5 degrees Celsius so that the grain is safe for storage.
But drying temperature alone is not important. What is most important is the kernel temperature during drying.
This is because if the temperature is too high, it can destroy the germination capability of the seed.
For example, for maize, the kernel temperature must not exceed 43 degrees Celsius. For wheat, it must not exceed 43 degrees Celsius to 49 degrees Celsius. For barley it must not exceed 49 degrees Celsius.
After grain is dried, the next operation in post harvest handling of grain is storage.
This is necessary so that the grain can be stored safely for subsequent operations. The store must be clean, safe and free from moisture.
The pre cleaned dry grain which is stored safely can now be drawn and processed into seed.
The most important operation that follows includes fine cleaning. This makes sure that the grain is free from any impurities.
Any dust or foreign material must be removed so that the seed is of very high purity. After the seed has been fine cleaned, it can then be sorted and graded.
Grading is separating the seed into different quality factions.
Separating of the seed depends on physical characteristics, like length, weight, thickness, colour, and specific weight, among others.
Seed treating and packaging
After the seed has been graded, sorted and fine cleaned, the next operation is seed treating and packaging.
Seed treating is where the cleaned seed is dressed with a chemical that helps to prevent disease and pest attack on the seed before planting.
There is a whole range of equipment for doing fine cleaning, grading and sorting.
For example for fine cleaning, farmers should use flat screen cleaners or the delta cleaners. These use screen and air.
The screens are also oscillating with the machine to make sure very fine precision cleaning is obtained for the seed.
For grading, equipments like gravity separator, cylindrical cylinders, destoners, among others, are used.
These are rather conventional machines for grading and sorting seed.
Nowadays, there are optical machines to help in grading and sorting. The optical machine is mainly a colour sorter which can also be used to separate seed according to either, colour, shade or shape.
There are conventional equipment for seed treating which are drum like with a screw conveyor for mixing the seed with the chemical.
The latest addition to this range of seed treating equipment is the centricoater.
The centricoater is a new invention which is good for all types of seed and can use all types of chemicals that are in slurry form, powder form, or even for pelleting or coating the seed.
The centricoater has the advantage in that it uses resources like water and chemicals very efficiently.
It is very accurate in its operations because it uses a Thin Layer Chromatography (TLC) based system for weighing, treating and discharging the seed from the seed treater.
It is the ultimate seed treater at the moment. It can do both bulge seed treating or continuous seed treating, meaning it can be a continuous line for seed production.
Where you can get equipment
CIMBRIA supplies a whole range of equipment for doing fine cleaning, grading and sorting.
Overall, CIMBRIA has the capacity for designing, manufacturing, and supplying seed plants on a timely basis, or individual machines for specific operations in the seed line.
The focus for all equipment supplied by CIMBRIA is to make sure that seed is handled gently with minimum wastage and dust emissions to the atmosphere in order to cause minimum impact to the environment.
CIMBRIA manufactures artificial driers, and this can be used either for shelled maize or for maize still on cob.
M.A. Mushira is the Area sales manager at CIMBRIA East Africa Ltd. His contacts are:
Mobile: +254 722 374 329