Seed security is key to the attainment of household food security among resource poor farmers in developing countries (Wambugu et al, 2009). Good storage helps ensure household and community food security until the next harvest and commodities for sale can be held back so that farmers can avoid being forced to sell at low prices during the drop in demand that often follows a harvest. While considerable losses can occur in the field, both before and during harvest, the greatest losses usually occur during storage. Therefore the basic objective of good storage is to create environmental conditions that protect the product and maintain its quality and its quantity, thus reducing product loss and financial loss.
There are two reasons for food storage: domestic security and maintaining value prior to sale. Farmers may not accept improvements, which incur costs when storing primarily for home consumption because an improvement in the quality of a food produced for home consumption does not achieve a higher monetary value for the farmer.
In order to reduce the amount of food lost, the environment in the store needs to be controlled so as to lower the possibility of:
- Biological damage by insects, rodents and micro-organisms
- Chemical damage through acidity development and flavour changes
- Physical damage through crushing and breaking
Good storage thus involves controlling the following factors: temperature, moisture, light, pests and hygiene. Table 1 offers of an ovewview of the storage condition requirements of some food commodities.
Table 1: Storage characteristics of selected food commodities
|Cereals and pulses||Can be stored below their safe moisture level for periods of a year or more. Do not raise moisture levels.||Under a wide range of temperatures.||n/a|
|Seed for growing|
Moisture levels need to be low. 1 per cent decrease in moisture content below 14 per cent double storage time. Maximum drying temperatures of 35°C. Full sun drying is not recommended.
|Cool storage is necessary. A 5°C decrease in temperature doubles storage time.||Seed harvested when not fully ripe will lose its viability sooner than mature seed.|
|Oil-bearing products||Keep moisture below 7% because fungal growths above that level.||High temperature and exposure to light accelerates rancidity||-|
|Root and tuber crops||Keep humidity low to avoid rotting|
Ventilation is needed to avoid rotting. Yams can be stored for four months at normal temperatures (25-35°C). Potatoes for only five weeks as they are sensitive to sunlight. Chill rooms for storage on a large scale. Store should be ventilated during coolest part of the day and isolated during hottest time.
To increase storage life, use special treatment called ‘curing’ which consists of letting tubers grow layers of cork cells around the surface
|Fruit and vegetables||n/a||Keep better when cooled but damaged by freezing. Simple evaporative air-cooled cabinets allow small farmers to store them. Underground storage in pits and cellars is used.||Surface waxing or wrapping prevents the spread of rot from one fruit to another. Keep in CO2 rich atmosphere|
Source: based on IT Publications and UNIFEM, 1995
Most developing countries are in the tropics.They are often in areas of high rainfall and humidity, which are ideal conditions for the development of micro-organisms and insects, causing high levels of deterioration of crops in store.Thus, an assessment of different storage methods has to be undertaken before investing in one.Existing local methods are usually low-cost so adapting what is already there, rather than introducing new technology, is often a more realistic economic option for households. Traditional and improved storage techniques are presented in Table 2.
Table 2: Traditional and improved storage methods
|Suitable for||Capacity/Storage time||Cost/materials|
|Traditional storage methods|
|Earthenware pots and gourds||Cereals, beans, groundnuts, dried fruit and vegetables and seed material|
5-30 litres, Up to 1 year
|Leaves||Dried fruits, vegetables and treacle||Variable, up to 1 year if unopened||Low, banana leaves, string of sisal or other plant material|
|Bark||Cereals, particularly paddy and shelled maize||100kg, up to 3 months||Labour|
|Baskets||Cereals, pulses, oilseeds, potatoes||Variable, up to 9 months||Low but considerable labour involved. Reeds, grasses, palm leaves, bamboo|
|Sacks||Cereals, pulses and dried fruit||Up to 60kg, up to 1 year||Low. Jute, sisal and cotton|
|Basket silos||Cereals and pulses||Up to a tonne, up to 1 year||Local material, time spent on construction. Elephant grass, reeds, sorghum stalks|
|Roof storage||Cereals||Variable, up to 1 year||Wood for platform and labour. Wood for platform|
|Maize cribs||Maize||Variable, up to 6 months||Labour and materials. Variable|
|Underground pits||Cereals, pulses and root crops||Variable, up to 1 year||Labour. Grass, straw, chaff and clay|
|Clamp storage||Tubers||Up to 500kg, up to 6 months||Labour. Grass, straw|
|Small storehouses||Cereals and pulses||Variable, up to 1 year||Labour and materials. Variable|
|Earth silos||Cereals and pulses||Variable, up to 1 year||Labour. Earth, straw|
|Improved Storage Techniques|
|Plastic bags||Sowing seed, cereals, pulses, groundnuts, copra|
Up to 60kg, 6 to 9 months
|45-gallon metal drums||Cereals, pulses and seeds||50-200 liters, up to 1 year||Low, depending on availability. Oil drums and water tanks|
|The Pusa bin||Cereals and pulses||400kg to 3 tons, 6-12 months for well dried crops||Medium/high, skill required. Mud, cement or concrete, wood, plastic|
|Metal silos||Cereals and pulses||Up to 5 tons, approx. 1 year||Medium/high. Sheet metal|
|Brick silo||Cereals and pulses||Up to 5 tons, up to 1 year||Medium/high. Bricks, cement, reinforcing rod, wood for moulds, sheet metal|
|Cement-stave silo||Cereals and pulses||Up to 10 tons, up to 1 year||Medium/high. Cement, sand, iron and wire|
|Thai ferro-cement silo||Cereals and pulses||4-6 tons, 9 to 12 months||Medium/high. Cement, sand, aggregate, mortar plasticiser, sealant for base, paint, chicken-wire, rod, water pipe.|
|Storage in ventilated huts||Cereals, pulses, root crops||Variable, variable||Medium/high. Local building materials|
|Improved pit storage||Cereals, pulses, root crops||Variable, up to 1 year||Medium. Metal sheet, mud/dung/straw or plastic or ferro-cement lining|
Source: based on IT Publications and UNIFEM, 1995
Grain storage has been established to prepare for droughts and hunger and malnutrition (UNEP, 2010; 36). Grain storage provides an adaptation strategy for climate change by ensuring feed is available for livestock and seed stock is available in the event of poor harvests due to drought (UNEP, 2010; 62). Efficient harvesting can reduce post-harvest losses and preserve food quantity, quality and the nutritional value of the product (FAO, 2010; 3). Innovations for addressing climate change include technologies for reducing waste of agricultural produce (BIAC, 2009). In fact, the establishment of safe storage for seeds and reserves of food and agricultural inputs are used as indicators of adaptive capacity in the agriculture sector (CARE, 2010).
The establishment of safe, long-term storage facilities ensures that grain supplies are available during times of drought (UNEP, 2010; 36). It is important to be able to store food after harvest so as not to be compelled to sell at low prices. Appropriate storing techniques can prolong the life of foodstuffs, and/or protect the quality, thereby preserving stocks year-round.
The cleaning and drying of grain for storage are essential measures. However, difficulties in achieving the desired freedom from excess moisture and foreign matter are frequently encountered. Failure to adequately clean and dry grain can lead to pest infestations. Over-drying of grains can also negatively impact seed quality. Losses of seeds from insects, rodents, birds and moisture uptake can be high in traditional bulk storage systems. Controlling or preventing pest infestation may require chemical sprays. Some markets will not accept seeds and grains treated with these chemicals.
Table 2 sets out the relative costs of traditional and modern storage technologies. Costs requirements vary between storage methods. If the produce is for consumption, rather than sale, then investing large amounts in a new technology will not prove cost-efficient. On the other hand, if the amount of food for sale increases, then the investment can be paid back over time. Calculating the existing profit and potential profit with new technology is useful for businesses to estimate this payback period. The amount people are prepared to invest in new technology may depend partly upon who owns the equipment and facilities. In some cases, farmers will invest in a new technology if they have total ownership of it while in other cases, storage may be collectively owned and so costs can be shared. Access to credit is often dependent on where people live, educational levels and on being able to raise collateral. Adopting new storage methods for low-income farmers will be possible if they are given assistance with literacy and numeracy, and possibly some kind of group training.
Health and safety regulations and quality control guidelines should be elaborated by the relevant national authority. Standardised training and inspections may also be undertaken by a government agency. Adopting new storage methods is likely to require technical training. For example, in addition to constructing a new silo, training or advice on maintenance, health and safety regulations, quality control and seed storage behaviour (sensitivity to light and moisture) could be needed. It is important to monitor progress, in order to resolve problems, build on developments, and record successes and failures. Socio-economic impacts should be considered, such as who benefits and how additional income or time is distributed between and within households or businesses.
A common constraint is that produce has to be sold off immediately to pay off debts to landowners or creditors. This is the most widespread reason for deciding that investing in new storage technology is impossible. It has to be considered also that additional time input for constructing and maintaining storage facilities will be perceived as worthwhile only if the increase in income is sufficient.
Before initiating technology development work, it is important to assess the need for improvements. IT Publications and UNIFEM (1995) suggest an opportunities assessment checklist that can be usefully discussed with producers during a preliminary appraisal:
- Problems with existing storage techniques
- Disadvantages of existing storage techniques greater than advantages
- Possibility of improved storage of reducing the loss of produce/possibility of increase on quality of produce for sale or consumption by better storage
- Possibility to keep surplus produce stored away rather than having to sell any extra produce immediately
- Possibility to sell any extra produce
- Increased profit through improved storage
- Time for learning improved techniques for collecting materials and making the new equipment/money for storage materials
- Access to new technical knowledge and skills required for producing, maintaining and using the new technology
- Benefits against investment on time, money and effort in improving storage
BIAC (Business and Industry Advisory Committee to the OECD) (2009) Agriculture and climate change, Issues for consideration. November 2009, Paris, France
CARE (2010) Toolkit for Integrating Climate Change Adaptation into Development Projects - Digital Toolkit – Version 1.0 CARE International, with technical input by the International Institute for Sustainable Development (IISD), July 2010.
FAO (2010) “Climate-Smart” Agriculture - Policies, Practices and Financing for Food Security, Adaptation and Mitigation, FAO, Rome, 2010.
IT Publications (Intermeditate Technology Publications) and UNIFEM (United Nations Development Fund for Women) (1995) Storage in Food Cycle Technology Source Books, IT Publications, UK, 1995
UNEP (2010) Connecting the Dots Biodiversity, Adaptation, Food Security and Livelihoods, Nairobi, 2010
Wambugu, P. W., P. W. Mathenge, E. O. Auma and H. A . van Rheenen (2009) Efficacy of Traditional Maize (Zea Mays L.) Seed Storage Methods in Western Kenya, in African