Storing Rice
If possible, rice should be stored as paddy (unhusked) because of its greater resistance to insect damage and grain moisture fluctuation than milled rice (Labadan 1974, Xuan and Ross 1972. The moisture content of dried grains often increases during storage, causing bacterial and fungal diseases. Rice is a living biological organism that continually gives off carbon dioxide, gas, water vapor, and heat. Thus it gives an ideal environment for mold and bacterial growth. The grain continues to respire, a process of deterioration and decay, which chemically is oxidizing carbohydrates into carbon dioxide, water, and heat. Respiration and mold growth should therefore be minimized through drying of grains to remove excess moisture.
A moisture content of paddy above 14% will result in rapid deterioration and an increase in number of stored grain insects. The same insects are unable to survive and reproduce in grains with moisture content below 9%. For a storage period of about 6 months, 12–14% moisture will suffice; for 1 year, it should be about 10–11%. Grain at 12% moisture content could absorb moisture if exposed continuously to air with high relative humidity for 45 days. All these strongly suggest the storing of grains in proper containers to avoid extreme increases in moisture content once the equilibrium point at 14% moisture is reached. This condition stabilizes at an average humidity of about 78%.
Bulk storage
For many farmers, storing paddy in small bulk is a convenient way of keeping the grain. It eliminates expenditure for bags and saves on space. It can be utilized for temporary stocking of wet paddy if aeration is adequate. Usually, a particular room inside the farmer’s house is reserved for bulk storage.
The storage facility should provide protection against rats and insects, grain deterioration, and microbial activities. All these can be accomplished by storing grains at 13% moisture content and ensuring good air circulation. Proper sanitation and chemical control are part of good management. The more important factors to consider, which affect the rate of increase in pest population in stored grains, are food supply, temperature, moisture, and competition with other living organisms.
Storing in containers
A small quantity of paddy for household consumption and seed stock is usually stored in sacks, wooden or metal containers, clay jars, plastic drums, or bags.
This seed stock is given extra care because of its importance to the farmer. A space is provided for passage of air between the floor and the stock stored in containers; this will prevent heating of the grains, thus avoiding invasion of insects and organisms. In the absence of other kinds of storage facilities, mixing sand with seeds to irritate the insects and to lower the moisture content or placing ash at the bottom of containers are found effective.
Storage management practices
Losses due to insects, rats, birds, microbial organisms, and pilferage are major storage problems all over Asia. Good housekeeping practices, combined with other control measures, are suggested.
1. Dry the grains properly to the desired moisture content level.
2. Follow sanitation practices; clean storage facilities before use.
3. Follow manufacturers’ recommendations in the use of chemicals for spraying and/or fumigation of insects.
4. Provide a way of aerating the stored grains; keep seeds in moisture-proof containers; protect the grains in the storehouse from insect and rodent attack.