The process of separating the grains or seed from the ears in case of cereal crops or pod in case of oilseed and pulse crops is called ‘Threshing’. The process of threshing helps to make the clean produce for the use in future.
Threshing is done by different methods as follows:
(1) Threshing Manually:
Threshing is done manually for threshing of some crops such as cereal crops and few pulse crops. Hand beating method is normally used for threshing paddy (Oryza sativa L) that easily shatters.
The different hand threshing methods are as follows:
(i) Threshing Rack:
The farmer holds the crop by hand and beat it against slanting bamboo or wooden platform or any other hard object. It is slow and labor consuming process.
Trampling involves the bare feet of animal to thresh some crops such as cereal crop, pulse crops and oilseed crops. The crops are spread over a mat or canvas or platform made with bricks and workers trample the crop with their own feet or use their animal for treading the crops. In case of trampling by bullock, a strong pole is fixed in the center of threshing space in which bullocks are tied in lines one after another.
The harvested crops are spread on threshing space and bullocks are made to move round the pole and trample the harvest materials continuously till the grains are completely separated from the straw. Crop spread in a circular path on the threshing floor. A man drives the bullocks from the back.
In some areas, animals have been replaced by tractor. Because threshing is also done by tractor. It is most expensive method. After animal treading, the straws are separated from the grain and cleaning of grain is done by winnowing with the help of wind and with the aid of electric fan.
The threshing is done by the use of sticks. This method is useful for threshing small quantity of crops. But this method is not popular for threshing of Paddy (Oryza sativa L).
(2) Threshing Mechanically:
The crops are threshed mechanically by using some threshing machine. As for example, Olpad thresher is used. It is most improved method of threshing. Paddy (Oryza sativa L) Wheat (Triticum sp), Oat (Avena sativa), Barley (Hordeum vulgare L) etc., are threshed by using Olpad thresher.
Japanese paddy thresher is used for threshing paddy (Oryza satire L). It consists of threshing drum, driving mechanism and supporting frame. The main part of the machine is the wooden drum having peg-teeth all around its circumference. The thresher is operated one or two labors.
Threshing is followed by winnowing. Winnowing is the method of separating grain or seed from chaff.
Paddy winnower is a machine used for cleaning the seeds of paddy.
The seeds or grains contain moisture. The content of moisture above permissible limit hampers the storage life of grains or seeds. The moisture content of grains or seeds of crops at the time of harvesting is about 18-20 percent. The moisture content for safe storage for most the crop is 14 percent. The seeds or grains should be dried in sun or by artificial heating to reduce their moisture.
High moisture in the grains as well as high humidity in the atmosphere causes sprouting and molding of grain. In case of sun drying, the grains or seeds are spread on hard floor or threshing yard or on polythene sheets and are allowed to dry by the sunlight. The grains or seeds for uniform drying are stirred occasionally at the interval of one hour. Sun drying needs more area and labors for spreading, stirring and collection of grains or seeds.
The agricultural produce must be stored properly for the continuous supply and consumption as well as to get the higher market price. Because the market price is generally remains low at harvesting time. Generally the food grains, oilseeds, pulse crops etc., are stored for future use.
Factors Affecting the Storage of Food Grains:
The factors that influence the storage of food grains are as follows:
(1) Moisture Content of the Grains:
The seeds that contain high Percentage of moisture are subjected to the attack of insect pests and microorganisms. Moist seeds are amenable for easy biting of insects. Sometimes, moist grains or seeds may even germinate and become unfit for consumption.
(2) Climatic Condition:
Grains or seeds are hygroscopic and absorb moisture from the atmosphere. Under moist climate, the seeds are subjected to the attack of insect pests and microorganisms Moist climatic condition is favorable for the growth and development of insect pests and microorganisms.
(3) Quality of the Produce:
The crops that are harvested early contain more ill-filled and shriveled grains. The shriveled and broken grains/seeds are predisposing causes for the insect attack.
(4) Storage Condition:
The produce is generally stored in gunny bag which is more prone to insect infestation of the produce. The storage condition should be such to provide the protection of produce from the attack of insects. The ill storage condition result in loses quality of good grains.
(5) Method of Storage:
Food grains and oilseeds are stored either in bags or in bulk (i.e. without bagging). Pusa bins may also be used for storage of food grains. Godowns are most common structure for above ground bag storage. The godowns should be made free of insect pests and microorganism by fumigation using EDB (Ethylene di bromide).
Several insect pests attack the produce during storage which can be controlled by Spraying Malathion 50 EC or Dichlorovos 18 EC.
The following points are important to remember for storing of agricultural produce:
(1) The stores should be at least 0.5 km. away from the place which are a source of infection like kilns, flour or bone crushing mills, garbage dumping grounds, slaughter houses and tanneries. It should be constructed, as far as possible, away from dwelling houses.
(2) The stores should be, as far as possible, situated near a transport head room or main road.
(3) There should not be any tree near the stores. Otherwise birds will be a nuisance.
(4) The walls of the stores should be made smooth and the cracks and crevices and rat burrows should be filled up completely. The plinth should be kept 0.75 meters above the ground level.
(5) The floors of the stores should be constructed of either cement concrete or stone slab with a slope of 4 cm from the walls or its outer edge to prevent rain water from getting inside the godown through the door.
(6) The ventilators and windows need to be filled in such a manner that the store is open to air and made air tight for desired period.
(7) The floor and loose matters of katcha store should be scrapped annually in the month of April and re-plastering should be done. The store should be rat proof.
(8) The roof of the godown should be water proof.
(9) The debris of the godown should be collected and burnt before storing the new agricultural produces.
(10) The old grains from the store should be disposed of or removed and the store should be thoroughly cleaned before storing the new produce. White washing the walls and ceiling of pucca godown should be done.
(11) The store should be disinfected with Malathion 50 EC s@ 3 liters per 100 sq. meters after cleaning the store. The store may be fumigated with Aluminum phosphate @ 25 tablets (3 gm. each) pr 100 sq. meters in place of Malathion spraying.
(12) The bags should be disinfected by dipping in 0.5 percent Malathon 50EC (Dilution: 1 :50) or boiling water for a minute in case of bag storage.
(13) The completely dried grains (moisture content ranging from 12-14 percent) should be stored.
(14) The grains meant for seeds should be treated with Malathion 50EC.
(15) The new and old stock should not be kept in same godown.
(16) The dunnage comprising timber pallets, timber squares, palm matting or still better, a layer of polythene sheet and the dunnage should be sprayed with Malathion 50 EC to avoid insect infestation.
(17) The bags should be stacked 60-70 cm. away from the walls with proper alleys around for inspection and other operations (i.e. fumigation, spraying etc.)
(18) It is essential to inspect the store fortnightly for insect pests infestation and rodent damage and also for taking necessary measure to avoid the losses.