STORAGE OF AGRICULTURAL COMMODITIES

It is estimated that in the tropics each year between 25 and 40% of stored agricultural products is lost because of inadequate farm- and village-level storage.

Introduction

Storage losses Losses during storage may occur in many

ways: losses in weight due to insects, rodents or

birds eating the grain deterioration through fungus growth and

rotting loss in quality through biting damage, insect

and rodent excrement and fungus growth

Environmental influences on the stored product

loss of motivation in the farmer to grow more, because he is not able to store his harvest or part thereof in a safe way for any long period of time

damage to sacks, which causes waste during transportation

decline in germination capacity of stored seeds

Cereals and pulses When dried to moisture contents below the

safe moisture level, cereals and pulses can be stored for periods of a year or more under a wide range of temperatures, provided that during storage the moisture level does not rise, and precautions against insects are taken; insects may still develop at a relative humidity of approximately 35% and temperatures of around 15°C.

Storage of various groups of agricultural products

Often the products are dried in the field as much as possible. After cutting, cereals are tied into sheaves that are laid or hung on different kinds of racks or piled into stacks.

After harvesting, pulses are often left lying on the ground to let the leaves die off. The pulses are then dried with the foliage still attached on well-ventilated racks or platforms.

Drying

The following two factors determine the choice for the best storage method:

the moisture content of the product when it comes from the field

the relative humidity of the outside air during the storage period

Storage methods

Dry harvesting period and dry storage period

Dry harvesting and wet storage period. Wet harvesting and dry storage period Wet harvesting and wet storage period.

Depending on the weather during the harvesting period and the duration of storage there are four possible combinations:

Conditions for storage The main aim when storing sowing-seed is

the preservation of the seed viability. For that purpose the seed has to be stored within certain limits of temperature and humidity. These limits vary for seeds of different species and varieties.

Sowing-seed

For seeds with a moisture content between 5 and 14% every 1% decrease in moisture content doubles the possible storage time. Below 5% oxidation processes may play a role. Above 14% fungal growth causes rapid degeneration.

Every 5 °C decrease of the storage temperature doubles the possible storage time. For prolonged preservation of the seed viability the time of harvesting is very important. Seed that is harvested when still unripe loses its viability sooner than well-ripened seed.

Cool storage At a temperature below 10 °C it is possible to

store seeds with a moisture content (slightly) above the already mentioned safe limit.

Airtight storage (ambient temperatures).

The seeds have to be dried very well and, if possible, mixed with a moisture absorbing material and/or appropriate seed-protecting chemicals.

Storage methods for sowing seed

Fermentation: Fermentation is a cheap and energy efficient means of preserving perishable raw materials. When harvested, fruit and vegetables undergo rapid deterioration, especially in the humid tropics where the prevailing environmental conditions accelerate the process of decomposition.

Traditional Methods of Preservation and Storage of Farm Produce

Storage in Buckets: Pumpkin and amaranth leaves can be bunched up and dipped in a bucket of water, with the tips of the stems steeped in the water. Waterleaf and bush okra are not dipped but rather sprinkled with water. The leaves are then covered with a thin polythene sheet, tied to the bucket and kept in a cool place. Daily, the polythene sheet is removed temporarily and water sprinkled on the leaves. This method keeps the leafy vegetables fresh for about 6 days.

Storage in Clay Pots: In this method, clay pots of convenient sizes are washed clean and placed on a firm support. At the bottom of the pot is placed a layer of sterilized (boiled) wet jute bag and wire gauze on top of it. On top of the wire gauze, the washed vegetable leaves are placed and covered with another layer of wire gauze and a second jute bag. This bag is kept moist at all times.

Blanching: Fruits, fresh vegetables and root vegetable pieces can be immersed in a bath containing hot water (or boiling water) for 1 – 10 minutes at 91 – 99 Celsius, to reduce microbial levels, and partially reduce enzymatic activity that could lead to deterioration. This process can be termed as scalding or blanching.

It should provide adequate protection from rodents, birds, insects, mites etc.

It should permit aeration and fumigation when required.

It should prevent losses due to moisture and temperature etc.

It should permit easy inspection.

Requirement of Storage Structures

It should facilitate proper cleaning and should be self cleaning if it is silo.

It should be economical on unit storage cost basis.

It is, therefore, essential that grain be stored in structures of standard types which, after careful study, have been found suitable for different regions in the country.

Indigenous Storage Structures

These are generally used for the storage of wheat, gram, paddy, maize, and sorghum.

Their capacity varies from about 3.5 to 18 tonnes.

It is cylindrical in shape and its made of mud or combination of mud and split bamboos.

Bukhari Type Structure

These are used for the storage of paddy, maize, sorghum, wheat and barley.

Capacity ranges from 9 to 35 tonnes Very much like a timber placed on a raised

platform which is generally supported on pillars.

Kothar Type Structure

Used for the storage of paddy, maize, and sorghum in the rural areas of eastern and southern regions of India.

Capacity varies from 3.5 to 18 tonnes Shape of an inverted cone

Morai Type of Structure

Used for the storage of 25 to 500 tonnes of grain.

Cylindrical Grain Bin Used for storing different varieties of grain. The capacity may vary from 10 to 40

tonnes.

Bag Storage Structure

Proper disposal of rain water Repair of cracks, crevices and corners

where insects can hide Furnigation of storage space and

surroundings Protection from fire, pilfrage and rodent

attacks is essential

Measures of Good Storage

Using gunny bags of good quality, properly infested and so stacked that movements are not restricted for inspection and fumigation.

Preventing rats from interring the store by raising plinth or providing overhangs.

Grain moisture should be less than that recommended for safe storage.

Inspecting stock at least once a month is desirable

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