Hermetic storage is a technology to store agricultural commodities in an airtight container such as a drum or a plastic bag to prevent air and water getting in to the stored grain from outside.
To maintain the original seed moisture content and reduce the pest damage by the lack of oxygen replaced by carbon dioxide.
The available oxygen in the internal ecosystem is reduced to lethal levels for any living organisms through the biological activity related to gas exchange of the respiration of grains and organisms.
Allowing the hermetic storage, a way to reduce the attack of insects and fungi on the stored food. Hermetic storage also allows for organic storage without chemical pesticides. The hermetic storage system can be used for cereal crops such as wheat, oil seed and pulses. 1/3rd of the food produced is loosed. Therefore, reducing grain losses and its quality preservation during storage is a global challenge.
The conventional methods of stored grain quality protection are based on periodic use of harmful residue leaving chemicals for consumer and environment. Hermetic storage is a technology to protect the quality of grain and seed at different post-harvest phases of storage to meet international standards. Humidity and managing moisture is a challenge.
The relative humidity of the enclosed air will reach an equilibrium with the moisture content in the grain. In general, an equilibrium relative humidity inside the bag, drum should be 65% or less. A relative humidity of 65% or less is considered a safe prevention against the development of aflatoxin.
Different types of grain moisture meters are used to measure grain moisture content. Seed must be dry before storage. High moisture contents in hermetically stored grain can lead to loss in germination and viability and thus dryness must be ensured. The direct effect of hermetic storage is that farmers can store more seed and maintain excellent quality.
The indirect effects that are part of a seed management theory of change are that as farmers become more aware of seed as distinct from grain, and begin accessing new varieties, and begin producing seed separate from grain, they manage seed carefully and avoid accidental mixing of varieties.
Safe moisture content for Hermetic Storage:
- Cereals (12-14%)
- Pulses (13-15%)
- Oil seeds (6-9%)
Key points for Hermetic Storage:
- Initial grain quality has profound effect on development and yield of crop. Storage conditions can significantly affect seed quality but do not affect genetic make-up of stored seed.
- Healthy, vigorous, full size grain, free from physical, pest and insect damage seed can successfully store for long term.
- Grain should be at preferred moisture content varying considerably by crop type before storage.
- Insects, pests and high humidity is greatly reduced before placing in hermetic storage.
- Place it in shade may reduce physical aging.
Benefits of hermetic storage which provide economic advantages to farmers:
- Reduced physical losses.
- Ability to sell seed (and grain) over a longer period and achieve a better price.
- Improved quality of seed leading to lower seeding rates.
- Improved plant vigor, and ultimately improved yields.
Financial and economic loss:
Assume a farmer has 100kg of seed and use a storage technology (conventional storage) that allow 5% weight loss and result in 15% lower price for remaining damaged seed.
- Quantity after storage loss: 100kg – 05kg [05%] = 05kg
- Price of loss seed: 35Rs/kg * 05kg = 175Rs
- Lower price of remaining damaged seed = 14.25 * 35 [15%] = 498.75Rs
- From every 3500Rs [100kg] you will loss 175 + 498.75 = 673.75Rs
Hermetic storage works by allowing the insects to naturally respire and exhaust oxygen level in an air tight environment to the point where they cannot survive. Insecticides or fungicides are not necessary. However, grains must be first dried properly to about 12-14% moisture to avoid loss germination and viability.
Authors: Ehsan Khalid* and Faryal Fatima
Seed Physiology Lab, Department of Agronomy, University of Agriculture, Faisalabad-38040, Pakistan