Grain losses and control measures

Reason for grain losses and control measures

1. Grain Losses and Control Measures

2. Grain losses occur not only in storage but also in transit By establishing proper norms, the transit losses can be considerably reduced The maximum permissible loss in transit is 0.1% for distances up to 1000 kms , 0.15% for distances up to 2,000 kms and 0.20% for distances over 2000 kms As to losses in storage, the norms developed relate to only natural losses of grain and grain products This would mean losses resulting from respiratory properties of the grain and also due to loss of fine dust in the grain There is also allowance made for losses resulting from rodents, insects, etc

3. The permissible loss for wheat, rye and barley stored in bulk in flat warehouses over one year, for example, is 0.12% and if stored in grain elevators 0.10%. Equivalent figures for paddy are 0.15% and 0.12 %. Insects and rats are the greatest enemy of human being in so far as the loss of food grain are concern Some of the well known insect causing damage to the stored grain are Rice weevil, Khapra beetle, Pulse beetle, Rice moth, Grain moth etc Their mere presence in grain renders the grain as low or heavy infested grain

4. Up to two live insects per kg of grain is low infested one whereas more than two insects per kg would make it heavily infested grain The following well tested method would prevent the infestation of grain by insects (a) Hygienic methods of insect and pest control. (b) Hermetic technology of insect and pest control. (c) Aeration technology. (d) Heat treatment methods. (e) Use of Chemicals.

5. T he chemical treatment methods have been accepted as the most popular method of controlling insects and pests. The insecticides commonly used for prophylatic treatment of stored food grain are Malathion and Dichlorvos . Malalthion acts as a contact insecticide. The Dichlorvos (DDVP) has both contact as well as fumigant action Pyretherum is the best known natural insecticide, the most important constituents of which are known as pyrethrine It is non-toxic to human beings and is considered quite safe for use in food grain. It can also be used for space treatment or as surface treatment on walls and floors etc.

6. Aeration & Fumigation

7. Aeration Aeration is the process of moving air through stored grain at low flow rates to maintain or improve its quality Aeration can provide three major benefits in the storage of grains. 1. It cools the grain and slows down insect activity. 2. By cooling the grain, aeration prolongs the effectiveness of pesticides. 3. It can provide an appreciable drying function

8. Benefits of Aeration It prevents storage odours. Grains stored for longer periods often develop objectionable odours. Aeration provides the grains a new, fresh smell It reduces moisture accumulation. Moisture condensation by changes in temperature and relative humidity can be reduced by aeration Application of fumigants through an aeration system is an easy and practical method for controlling insects in stored grains.

9. Aeration systems can be installed in both horizontal and vertical storages. The following set of basic design parameters are found suitable for cooling of dry grains by aeration

10. Before storing grain in bags, disinfecting of empty bags should be done by either dusting or smoking or fumigation During the process of dusting or fumigation, all the openings except one for the operator to get in and out are closed If smoking is to be done, a suitable formulation of Benzene Hexachloride which on ignition gives out smoke is used. About 10 kg of fumigant is required for 30 cu.m in space After filling, the remaining opening should also be closed and locked for about 48 h. After the expiry of this period, the structure should be opened carefully. Nobody should be allowed to come within a distance of 15 m from the storage structure for some time after opening the doors. After about 4 h, all the doors and openings should be opened, and should remain open for another 6h No one is allowed to enter the structure during this time. It should be remembered that above process is quite a dangerous one and it should be done under supervision of experienced and trained operators

11. Hermetic storage Hermetic storage (HS) technology has emerged as a significant alternative to other methods of storage that protect commodities from insects and moulds Also known as Sealed storage or airtight storage or assisted hermetic storage It is a form of bio-generated modified atmosphere It is based on principle of generation of an oxygen-depleted, carbon dioxide enriched interstitial atmosphere caused by the respiration of the living organisms within the ecological system of a sealed storage Advantage is the generation of a MA in an environmentally safe and sustainable manner, eliminating the need for chemical treatments, fumigants, and climate control

12. It creates Low oxygen modified atmosphere Creation of sufficiently low oxygen and elevated CO2 MA protects from insects, molds and oxidation effects This is done through a natural metabolic process of insect respiration and, in some cases the respiration of the commodity itself When a level of less than 2% oxygen is reached , mortality of all insect stages is achieved rapidly Preventing entry of moisture from surrounding atmosphere Protection from rodents Properly designed hermetic storage is highly rodent resistant Rodent resistance is provided in the case of large hermetic enclosurers such as Cocoons by using trough, slippery materials such as flexible PVC (typically 0.83 mm thick), and tensioning straps, which prevent rodents from getting a tooth hold

13. Applications of Hermetic Storage Long-term storage of cereal grains, primarily rice, corn, barley and wheat Long-term storage of a variety of seeds to preserve germination potential and vigor Quality preservation ofb high-value commodities, such as Cocoa and coffee Storage of specialized, difficult to store products such as brown rice, rice bran and basmati rice Prevention of growth of toxinogenic aflatoxins in corn and peanuts, or ochratoxins in coffee HS is also used to store oily commodities such as cottonseeds or peanuts to prevent the growth of free fatty acids (FFAs) and resulting rancidity

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