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Storage of Grains – Overview, Importance, Affecting Factors

Last Updated : 31 Jul, 2022
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Man has been storing grains and other products for a long time. It is ever worry for man to hold food supply to mitigate hunger in the time ahead. Storage of grain and control of quality happen in three areas; the farm area, the collection point area, and the terminal point area where grain is processed or handled or pushed ahead in bigger masses. There are expenses required for stacking and dumping of grains at each phase of capacity, for transportation among stockpiles, and for stockpiling itself. Extra expenses are engaged with maintaining grains, for the most part, cleaning, and drying, and for the control of quality. Post-harvesting losses represent around 10% of all out-food grains because of improper storage, bugs, rodents, microorganisms, and so on. Ordinary capacity strategies utilized for the capacity of grains, appear to be absolutely lacking for the protection of the quality and anticipation of their wastage. storage of food grains and oilseeds in the traditional storage or in jute packs doesn’t give a longer storage period. Appropriate logical strategies for their storage and furthermore controlling bug pervasion in these grains are imperative needs. Safe storage of agriculture items is fundamental to keep away from misfortunes or losses because of rodents, bugs, and illnesses and to keep up with great quality for a more extended period.

Importance and Need for Storage

In India, yearly storage losses have been assessed at 14 – million tons worth of Rs. 7,000 crores which insect damages alone record for almost Rs. 1,300 crores. The major financial misfortune brought about by insects; pests aren’t dependably by utilization yet additionally by contamination. Around 600 types of insects have been related with put away grain items. Almost 100 types of pests of stored items cause economic loss. As per World Bank Report (1999), post-gather misfortunes in India add up to 12 to 16 million metric lots of food grains every year, a sum that the World Bank specifies could take care of 33% of India’s poor. Out of these post-handling loss capacity – pests alone record 2.0 to 4.2 percent followed by rat’s 2.50 percent, Birds at 0.85 percent, and moisture at 0.68 percent. It is important to prevent losses during storage and to increase economic growth. Therefore, there is a need for storage of grains for the following:

  • To Feed over growing population
  • Changes in sudden costs and high demand in the market.
  • At the time of natural calamities such as shortages, droughts, famines, etc.
  • Requirement of storing agricultural products from season to season and yearly demand.
  • When there are off-season requirements.
  • When there is a requirement in the production of a particular commodity.
  • Requirement for large-scale processing
  • Preventing the extinction of original varieties (Germ Bank)
  • Conservation of wholesome quality.

Factors affecting the storage of Food Grains

Duration of Storage

Classified in terms of duration of storage:

  • Short Term Storage – storage for up to 6 months.
  • Medium Term Storage – storage up to 12 to 18 months.
  • Long Term Storage – storage up to 5 years or greater. 

Size or Scale of Storage

Classified in terms of size or scale of storage as:

  • Small Scale Storage – capacity of storage ranges up to 1ton
  • Medium Scale Storage – capacity of storage ranges from 2 to 50 tonnes.
  • Large Scale Storage – capacity of storage ranges from 100s to 1000s.

Principle of Storage

Classified in terms of the principle of operation. These include:

  • Physical Storage: It works on physical principles and controlling atmospheres to prevent deterioration and to achieve storage of grains. Example: Cold storage.
  • Chemical Storage: It works on using chemicals in storage systems to prevent insect infestations and to achieve storage. Example:  Methyl bromide.
  • Biological Storage: It works by using biological agents such as microorganisms to stop the activities of deterioration and increase the storage life.

Factors that are greatly affecting grain storability and quality

Moisture content

The moisture content of grains is an important factor for storing. It affects the quality and reduces the shelf life. Moisture helps the growth of many various microorganisms such as bacteria, molds, fungi, pests, and insects. Therefore, grains should be maintained at recommended moisture contents and temperatures and moisture migrations should be controlled to keep the grain from spoiling. The recommended moisture content of many grains is below 13%.

Grain temperature

Grain temperatures should be constrained by moving air through the grain mass. Whether holding wet grain for a brief timeframe or putting away dry grain for longer periods, air circulation is expected to keep the grain cool and slow shape development. Appropriately circulated air through grain can for the most part be securely held quite a bit longer than non-circulated air through the grain. Contrasts in grain temperatures make convection flows which can move and cause moisture concentration in the top of the container. Issues brought about by this moisture development or moisture migration, frequently become clear in the spring when outside air temperatures start to warm.

Initial Grain conditions

To keep and assure that only high-quality grain goes into storage, the following is recommended:

  • Cleaning the bin site area. Eliminate any old grain, grass, weeds, and other flotsam and jetsam.
  • Eliminate all hints of old grain from the storage and handling equipment.
  • Appropriately change the join to limit grain harm.
  • Clean the grain as it is placed into the bin, ideally utilizing a rotating grain cleaner.
  • Cool the grain to the overall external air temperature when it is placed into the bin.

Insect and Mold Control

Pests and insects are not an issue in that frame of mind for under 10 months or a year. in the event that grain is to be put away for longer than this, or on the other hand in the event that a container has had a bug issue previously, extraordinary safety measures ought to be taken. These include:

  • Spraying within the storage container with defensive insecticides 2 to 3 weeks before the new grain is added.
  • Treat the grain with approved insecticides as the container are filled.
  • Top-dress the grain with a supported insecticide after the container has been filled and the grain surface has been evened out.

Environmental Conditions

Really look at the grain temperature and condition no less than one time each month. Circulate air through depending on the situation to keep up with grain temperatures somewhere in the range of 35˚ and 40˚F. During the colder time of year, the air circulation framework should be worked exclusively on a support timetable to control limited temperature increments. Actually, take a look at the grain temperature and condition at regular intervals, and depending on the situation screen the cooling zone and warming zone progress. Try not to work the fan on warm days. At the point when air temperatures are hotter than grain temperatures, fan activity can bring about moisture consolidating and perhaps freezing on the grain. Insect movement is top throughout the summer, and successive checking is required assuming that invasions are to be controlled before they form into serious issues.

Monitoring Grain Conditions

Few areas and conditions to be checked and to monitor grain quality include:

  • The surface area of grain for build-up, crusting, wet regions, molds, and bugs.
  • The rooftop of the bin for condensation and breaks.
  • Grain mass for non-uniform temperatures, moisture pockets or layers, molds, and bugs.

Exhaust air for any off-smells

On the off chance that issues are recognized, they should be assessed and adjusted quickly. This might incorporate cooling with air circulation, further drying, or fumigation for a bug or pest control.

Methods of Storage

Traditional Storages


Bukhari is a traditional storage structure and they are cylindrical in shape. These cylindrical shape traditional structures are made of mud alone or mud and bamboo. These structures are raised above from ground by wooden and masonry platforms. Bukhari storage type structures are used for the storage of paddy, wheat, Bengal gram, maize, and sorghum. These cylindrical storages have a capacity of 3.5 to 18 tonnes. Even though smaller capacity structures are also available.


Morai storage structures are generally used in the rural areas of the eastern and southern regions of India. The morai structures are placed on a raised platform and are very similar to the shape of an inverted cone. This type of storage structure is supported on wooden or masonry pillars. It has a storage capacity of 3.5 to 18 tonnes. Morai structures are suitable for grain storage of sorghum, paddy, and maize.

Mud Kothi

Mud Kothi are common storage structures in rural regions. These structures are made from mud mixed with dung and straw in a rectangular shape. They have 1 to 50 tonnes of capacity. Mud bins or Mud Kothi is suitable for grains and other seeds storage.


This storage structure is shaped like a box made of wood.  The walls and floors of kothar are made of wooden planks, it is raised on the pillars and a thatched or tiled roof is placed over them to protect them from sun or rain. It has a storage capacity of 9 to 35 tonnes. Kothar storage structure is suitable for the storage of paddy, maize, sorghum, and wheat.

Modern storages

In India, bulk storage systems are used for the storage of larger volumes of grains in silos and conventional godowns (sheds) designed for bagged storage. The modern storage structures should be selected on the basis of first quality and then cost considerations. There are the following types of modern storage structures.


The modern structures used for storing the grains in bulk are silos. Silos are constructed from steel or reinforced concrete. These silos are generally circular with conical bottom. Bulk storage bins for storing grains can be made from reinforced concrete, plain or corrugated galvanized sheet, mild steel black sheet, aluminum sheet, fiberglass, brick, Ferro cement, asbestos sheet, etc.  But in India, mild steel bins and R.C.C. bins are quite common. 

Silos/bins are classified into two groups depending upon the relative dimensions of the container.

The following terminology is useful for the design of storage structures

Plane of rupture

The plane of rupture is that surface down which a wedge of material bounded by one wall face, the free surface, and the plane of rupture would start sliding if the bounding wall were to move.

Angle of repose

When a granular product is dumped through a circular opening on a level horizontal surface, the product takes a shape of an inverted cone. The angle between the horizontal and inclination of the heap is called the natural angle of repose. It indicates the product’s ability to flow. The cohesive materials have a higher angle of repose than non-cohesive materials. The natural angle of repose is approximately equal to the maximum angle of internal friction of the product.

The silos are classified as, 

  • Shallow bins: A bin whose relative dimensions are such that the plane of rupture meets the grain surface before it strikes the opposite side. A Squat silo is an example of a shallow bin.
  • Deep bin: A bin in which the plane of rupture meets the opposite side before it emerges from the grain. Vertical silos are examples of deep bins. Vertical silos can be circular, hexagonal, or rectangular.

Sheds or Warehouses

A horizontal shed has been used to provide low-cost, large-volume storage. Very large volume sheds have also been constructed by the Food Corporation of India (FCI) for storing grains and other products. Sheds are usually made of steel or corrugated sheet construction with flat concrete floors. Grain loads on the walls have to be supported by girts and heavy vertical buttresses designed to resist their loads in bending. Roofs have to be supported on a network of purlins and rafters. For larger sheds having 50,000-60,000 tonnes capacity a suspended drag-chain conveyor is used.

The advantages of modem storage bins are, 

  • Low cost, easier handling, and quality control.
  • low space area requirement
  • The cost of bags is saved.
  • Availability of modern automatic and mechanization technology for easy and fast handling requirements.
  • Protection from birds, rodents, and environmental conditions.

Preventive measures for the loss of grains in storage

Heating: pests can be killed at 60 for more than 10 min or 50 for 2hrs.

Radiation: Beta or gamma rays are used that cause physical disorders, loss of reproductive power, and loss of life in pests. Gamma rays have more penetration power and are also a costly method.

Aeration: Aeration is the process of moving air through processed grain at low flow rates to maintain and improve the quality. It cools the grain and slows down the insect activity and prevents storage odor, reduces moisture accumulation, and changes temperature and RH. The application of fumigation with aeration is effective.

Fumigation: Fumigation is the process of spraying or dusting chemicals. Insects are controlled by exposing grains to lethal concentrations of a toxic gas for a long enough time. The three types of fumigants are:

  1. Ethylene bromide is a liquid fumigant with a higher boiling point.
  2. Methyl bromide is a gas fumigant with less boiling, used for quick killing, and requires aeration.
  3. Phosphite tablets are solid fumigants that react with atmospheric moisture to form hydrogen phosphide gas which is lethal to pests and microbes.

Frequently Asked Questions

Question 1: What are the instructions followed by the storage?


To limit the grain misfortunes in the storage, legitimate directions and steps ought to be followed. Here are the steps for best storage performance:

  1. The produce should be totally cleaned and reviewed.
  2. Dried to the protected stockpiling moisture level of 10-12 % for food grains and 7-9% for oil seeds (on wet reason) for a protected stockpiling time of 6 a year.
  3. Capacity designs ought to be appropriately fixed, cleaned, and sanitized.
  4. Designs ought to bear the heap of grain put away and don’t allow contact/trade with outside moist air.
  5. Designs ought to be built in the coolest place of the house.

Question 2: What are the direct and indirect damages?


If the grains are not put away as expected, or not dealt with, it will prompt different harms which will influence the advancement of the farmer as well as the country. These harms can be direct or indirect.

  • Direct Damages: These are the harms brought about by insects, pests, etc. They eat the grains from inside and make them empty, hence diminishing the weight of the grains, staining of grains, and foul smell. These are immediate harms.
  • Indirect Damage: This incorporates the harm that is caused by consuming contaminated grains. Such utilization can cause food contamination and different worm diseases in people.

Question 3: What are the types of storage losses?


Storage structures are used for the storage of grains, seeds, and other food products. But during the storage, there will be losses in stored products due to pests, insects, rodents, and by other aspects. Types of storage losses:

  1. Quantitative loss.
  2. Qualitative loss.
  3. Loss of seed viability.
  4. Damage to storage structures.

Question 4: What are the storages used by farmers?


Storage structures used by the farmers are:

  • Gunny bags with different capacities (35, 50, 75, and 100 kg).
  • Mud bins have a capacity of 100 – 1000 kg.
  • Baked earthen containers with 5- 100 kg capacity.
  • In heaps, on a flat floors in the corner of houses.
  • Bamboo structures.
  • Wooded bins.
  • Underground structures.

Question 5: What are the quantitative losses?


Quantitative misfortunes are the misfortune that influences the weight and thickness of grains during the stockpiles. Feeding on stored grains of insects causes a loss in weight. A rice weevil will eat 14 mg out of 20 mg of a rice bit during its formative period. Be that as it may, the entire grain is lost. A female weevil, through three ages each year, has the biotic potential to imitate 1,500,000 offspring which will consume 1,500,000 bits of rice kernel (producing 30 kg of rice) A gravid female of Sitotrogacerealella can obliterate 50 g of rice totally in 3 ages.

Question 6: What are the advantages of fumigants?


Chemical substances are applied straightforwardly to the grain to forestall harm by storing insects. Presently their utilization is confined exclusively to seeds and grains implied for animal feed. These grain protectants can be applied as splash/dust on the uninfected grain. Here are some of the benefits of fumigants:

  • Utilized as a prophylactic treatment
  • Can be powerful when the grains are put away in free compartments where fumigation is unimaginable.
  • Less perilous than fumigants.
  • Doesn’t influence germination antagonistically.
  • One application at reap time is adequate for one year.

Question 7: What is Qualitative loss?


Qualitative loss is the effect that occurred by deteriorating the quality of grain during storage. Here are the losses-Feeding on the grain, Chemical changes in grain content, Defilement of grains with shed skin and body parts, Spreading the pathogenic micro living organisms, Loss of seed practicality, Bugs, pests were found to make the deficiency of practicality of seeds a degree of 3.6 to 41 % in paddy.

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