Grain silos are the mainstream storage equipment for grains nowadays. With their advantages of good sealing, small footprint, and stable storage, they are widely used in rural grain storage, grain purchase, and grain processing and other scenarios. However, many farmers are not aware that not all crops can be stored in silos.
Blindly storing crops in silos can easily cause grain agglomeration, heating, deterioration, and even damage to the silo equipment. This article, based on actual grain storage experience, thoroughly dissects the applicable crops, prohibited materials, storage methods, and selection techniques of grain silos, helping everyone avoid grain storage misunderstandings.
What is a Grain Silo
A grain silo is a closed storage equipment specifically designed for the centralized storage of granular and powdery grain crops. Currently, the most common type on the market is the prefabricated steel plate silo. Compared to traditional grain storage facilities, its structure is more regular, and its sealing and insulation properties are stronger.
This type of silo is generally in a vertical cylindrical shape, with a sturdy and sealed body. It is equipped with ventilation, temperature measurement, and discharge devices, enabling long-term stable storage of grains. The core advantage that distinguishes it from ordinary silos is the ability to isolate grains from humid air, pests, and rodents, minimizing the impact of the natural environment on grains.
At the same time, grain silos can achieve mechanized loading and unloading, eliminating the need for frequent manual grain turning and moving, significantly reducing labor costs, and meeting the storage needs of different scales of grain storage, such as family farms, large-scale planting bases, and grain processing plants.
What determines whether a crop is suitable for storage in a grain silo?
Moisture content
Moisture content is the core indicator for grain storage safety and is the primary criterion for determining whether a crop can be stored in a silo. The internal space of a silo is sealed, and the air circulation speed is slow. Once the moisture content of the grain exceeds the standard, the internal water vapor cannot be discharged in time.
A high-temperature and high-humidity environment will quickly promote the growth of mold, causing the grain to heat up, agglomerate, and mold, and in severe cases, even lead to local spontaneous combustion of the grain pile. The safe moisture content standards for different crops vary, and only grain that meets the standards can be stored for a long time.
Fluidity
Grain silos rely on gravity for discharge and mechanical transportation to complete the loading and unloading operations. This requires the stored crops to have good fluidity. Uniformly granular, dry, and loose materials can flow smoothly and will not clog the bottom discharge port and transportation equipment.
If the materials are sticky, prone to sticking together, during the flow process, they will adhere to the silo walls and pipeline interiors, not only making the discharge incomplete but also causing the residual materials to mold and deteriorate, polluting the subsequent grain entering the silo.
Material characteristics
Different crops have differences in particle size, hardness, density, and porosity. Crops with plump grains, hard texture, and uniform pores have better ventilation within the silo, allowing for uniform cooling and moisture removal throughout the grain pile, resulting in higher storage stability.
While fine, soft, and easily broken materials will compact the grain pile pores, hindering air circulation, creating ventilation dead zones within the silo, and causing local temperature and humidity imbalance, leading to grain storage problems.
Storage conditions
Each crop has different tolerances for temperature, humidity, and ventilation frequency. For example, oil crops have high oil content and are more prone to oxidation and deterioration, requiring higher temperature control requirements.
The ventilation and temperature control systems of grain silos can adapt to most dry grain storage, but they cannot meet the storage needs of preservation and fermentation materials. This is also the key reason why some crops cannot be stored in silos.
Which crops are suitable for storage in grain silos?
Corn
Corn has uniform grains and good fluidity. It is one of the most suitable grain crops for storage in silos. After reaching the drying standard, corn is hard in texture and not prone to breaking. The porosity of the grain pile is moderate, and the ventilation and heat dissipation effect is good. As long as the moisture content is controlled, corn can be stored in the silo for a long time with very low loss rate.
Wheat
Wheat has extremely strong storability and is a classic long-term storage grain crop. After drying, wheat is loose and does not stick together, is not prone to insect infestation or mold, and has a high adaptability to the storage environment. It is the main storage category for national reserve grains and can be stored in the silo for several years.
Rice
The outer shell of rice is hard, which can protect the internal grains from moisture and easy damage. After drying and reaching the moisture content standard, the rice is stable for storage in the silo. It is important to note that the pores of rice are relatively small, and regular ventilation is required during storage to avoid local heat accumulation.
Soybeans
Soybean grains are round and have excellent fluidity, which is suitable for mechanized storage and unloading in silos. Soybeans have a high protein and oil content. As long as the moisture content entering the silo is strictly controlled and a high-temperature environment is avoided, they can effectively prevent oil seepage and spoilage, and are suitable for large-scale batch storage.
Sorghum
Sorghum grains are compact and hard, which is suitable for storage and does not easily mold. It has a low requirement for storage environment. After conventional drying, sorghum can be directly stored in the silo and is widely used for batch storage of raw materials for brewing.
Soybean meal
Soybean meal is a commonly used feed raw material. It has loose grains and good fluidity, which is suitable for centralized storage in silos. Soybean meal has a slightly stronger water absorption ability. During storage, it is necessary to do a good job in sealing and moisture prevention to avoid the formation of lumps due to external moisture entering the silo.
Rapeseed
Rapeseed grains are small and have uniform density. They can be safely stored in silos. As an oil crop, rapeseed is afraid of high temperature and high humidity. Before entering the silo, it must be thoroughly dried. During storage, keep the silo at a low temperature and ventilate to prevent oil oxidation.
Sunflower seeds
After drying, the grains of sunflower seeds are loose, have no viscosity, and do not easily form lumps, which is suitable for storage in silos. Due to its high oil content, the core of storage is to control temperature and moisture prevention to avoid the deterioration of the seed kernels and the production of odors over a long period of time.
Which crops are not suitable for storage in grain silos?
Not all agricultural products can adapt to the sealed and dry storage environment of the silo. The following types of materials, once stored in the silo, are prone to deterioration, equipment malfunctions, etc., and are strictly prohibited from being placed in the grain silo.
Crops with high moisture content
Unwashed wet corn, wet rice, fresh grains, etc., with excessive moisture content, must not be stored in the silo. The sealed environment of the silo cannot quickly remove the moisture inside the grains, and they will heat up, mold, sprout, and breed a large amount of mycotoxins, resulting in the complete destruction of the grain in the silo.
Fresh fruits and vegetables
Fruit and vegetable crops require a ventilated, fresh-keeping, and moisture-retaining environment, and they will continuously breathe, release water vapor and heat. Grain silos are mainly dry and sealed, and do not have a preservation function. After being stored in the silo, fruits and vegetables will quickly rot and ferment, and the produced odors and molds will contaminate the silo equipment.
Silage feed and fermented materials
Silage corn, silage grass, etc., are fermented materials that require an anaerobic sealed storage environment. These materials themselves contain a large amount of moisture and organic acids, and continuous fermentation will produce acidic gases and moisture. Storing them in the grain silo will not only cause rapid deterioration but also the acidic substances will corrode the steel plates of the silo, shortening the service life of the equipment.
Special materials prone to agglomeration or adhesion
Wet wheat bran, fine wet feed, sticky powder materials, etc., have extremely poor fluidity and are prone to adhering to the silo walls and discharge pipes. These materials will cause residual discharge, agglomeration and blockage after being stored in the silo. The residual materials will accumulate and mold over time, causing overall silo contamination and also causing discharge equipment blockage and failure.
How to store grains correctly
Control the moisture content of the grain before storage
All grains must be dried or sun-dried before storage to reach the safe moisture content standard. The moisture content of corn and rice should be controlled at 14% or less, that of wheat and soybeans at 13% or less, and the moisture content of oil crops should be even lower to prevent mold from occurring at the source.
Do a good job in ventilation and temperature management
According to the seasonal temperature changes, the ventilation system of the silo should be opened reasonably. In cold and dry weather in autumn and winter, regular ventilation and heat dissipation can be carried out to remove moisture; in hot and humid weather in summer, open ventilation should be reduced to prevent outside moisture from entering the silo and maintaining a stable temperature inside the silo.
Regularly monitor grain temperature and moisture
Do not wait until the grain has problems before checking. Daily monitoring of the temperature and moisture at different positions of the grain pile is necessary. The center of the silo, the periphery of the silo wall, and the bottom of the silo are key areas prone to heat accumulation and moisture accumulation. If there is any abnormal temperature or moisture, ventilation treatment should be carried out promptly.
Prevent pests, mold, and cross-contamination
When the silo is empty, clean and disinfect the silo body in advance to kill residual eggs and molds. After the grain is stored in the silo, take strict sealing protection to block the entry channels of pests and rodents. When changing the stored crops, thoroughly clean the remaining materials in the silo to avoid cross-contamination between new and old grains.
How to select the appropriate grain silos for crops?
Choose the silo capacity based on storage scale
For small-scale family farmers and individual producers, a small silo with a capacity of several hundred tons to two thousand tons can be selected, suitable for storing their annual self-produced grains. For large-scale farms and grain purchasing stations, which need to store large quantities of grains, a large prefabricated silo with a capacity of five hundred tons to several thousand tons can be chosen to meet the requirements for bulk grain storage.
Select the silo bottom type based on discharge method
For corn, wheat and rice with good particle fluidity, conical bottom silos can be selected. They can be automatically discharged by gravity, which is simple to operate and leaves no residue. For fine powder materials and soybean meal and other materials prone to residue, a flat-bottom silo combined with cleaning equipment is suitable to thoroughly clean the materials inside the silo and avoid residue deterioration.
Configure ventilation systems based on storage requirements
For regular grain storage, a basic bottom ventilation system can meet the heat dissipation requirements. Oil crops and high-value-added grains have higher requirements for storage environments. Layered ventilation and intelligent temperature measurement systems can be installed to precisely control the temperature and humidity inside the silo, making it suitable for long-term storage.
FAQ: Common uuestions about grain silo storage of crops
Can all grains be stored in steel silos?
Grains that are dry and have good fluidity can be stored in steel silos. As long as the moisture and storage environment are controlled properly, the sealing and stability of steel silos are more suitable for long-term storage of grains than traditional grain silos. Only damp, fermented, and perishable materials are not suitable for storage.
Can different crops be stored together in the same silo?
It is not recommended to store different crops together. The particle size, moisture content, and storage stability of different crops are different. Storing them together will result in uneven ventilation and local overheating and moisture accumulation. At the same time, different uses of grains require different storage conditions. Mixing them together will affect the quality of the grains and their sale and processing.
How long can grains be stored in the silo?
Under the condition of meeting moisture standards and proper ventilation and temperature control, wheat can be stored for 3-5 years, corn and rice for 2-3 years, and oilseeds such as soybeans and rapeseed for 1-2 years. With proper daily maintenance, the storage time can be extended. Improper maintenance will cause deterioration within a few months.
Do oil crops need special grain silos?
No special silos are required, but the system needs to be upgraded. Oil crops are prone to oxidation and are afraid of high temperatures. There is no need to replace the silo structure. Just by combining more complete ventilation and low-temperature temperature control equipment to keep the silo dry and at a low temperature, the storage requirements can be met.
Why is moisture content tested before storage?
Moisture content is the core indicator for the safety of stored grains. Excessive moisture is the main cause of grain mold, heating, and insect infestation. Testing the moisture content before storage, screening out the qualified grains, can fundamentally avoid the damage of the entire silo of grains and minimize the loss of stored grains.
Conclusion
The suitable storage types for grain silos are very diverse. Dry and loose grain crops such as corn, wheat, rice, soybeans, oilseeds, and feed pellets can all be safely and long-term stored in silos. However, high-humidity fruits and vegetables, fermented silage, and sticky and lumpy materials are not suitable for the sealed storage environment of silos.
For growers, to do a good job in grain storage, they not only need to understand the crop compatibility, but also need to control key aspects such as the moisture content when entering the silo, ventilation and temperature control, and daily monitoring. At the same time, by combining their own storage scale and crop type, they should select suitable silo equipment and supporting systems to maximize the preservation of grain quality, reduce grain loss after harvest, and increase planting income.