Study on Grain Storage and Loss Reduction Technology for Smallholder Farmers in China

This article is a translation of the paper titled"Study on Grain Storage and Loss Reduction Technology for Smallholder Farmers in China," which was published in the Chinese journal Grain Storage (《粮食储藏》), Volume 54, Issue 1, 2023. The original article was authored by Xu Shengwei, Lan Shengbin, Yan Xiaoping, and others from the Sinograin Chengdu Grain Storage Research Institute Co. Ltd. For the full Chinese version, please refer to the following link: 许胜伟 , 兰盛斌 , 严晓平 , 等 . 中国小农户储粮减损技术研究 [J]. 粮食储藏 ,2023,52(01):1-4+19.

Abstract

Household-level grain storage by smallholder farmers plays a critical role in China's national grain storage system. Based on systematic research into loss-reduction technologies specific to smallholder conditions, we have developed a series of optimized grain storage containers and integrated a range of technical processes covering the entire storage process. These measures are further enhanced by the application of chemical insecticides and the delivery of technical support services. These integrated measures have significantly reduced post-harvest losses at the household level, ensuring original grain quality and contributing to food safety in China.

In the vast rural areas of China, the rudimentary nature of traditional storage facilities used by smallholder farmers—combined with limited awareness of scientific grain storage practices—has resulted in considerable post-harvest losses at the household level. According to a sample survey conducted by the State Administration of Grain in 2008, the average household grain storage loss rate was approximately 8%. Of these losses, rodent infestation accounted for around 49%, mold development for 30%, and insect damage for 21%.

Grain storage among smallholder farmers in China also exhibits characteristics that differ significantly from practices in developed countries. On one hand, while the aggregate volume of grain stored is substantial, the amount retained per household is relatively small—particularly in southern regions, where storage is primarily intended for household consumption. On the other hand, the storage duration is generally long, typically exceeding six months. Therefore, it is imperative to establish a grain storage technology system tailored to the practical realities and needs of smallholder farmers in China.

1. General Requirements for Reducing Grain Storage Losses at the Household Level

1.1　Grain Quality Specifications

The grain to be stored by farmers should meet the criteria of being "dry, plump, and clean" and adhering to the principle of "two separations". Specifically, the moisture content of the grain should be within the safe moisture range. The grain should be harvested only after full maturity to ensure full grains. Additionally, impurities such as straw, weeds, and soil in the grain must be thoroughly cleaned out. The "two separations" mean that during storage, grain infested with pests should be separated from pest-free grain, and new grain should be separated from old grain.

1.2　Requirements for Grain Storage Bins and Containers

Since losses caused by rodent damage and grain mold account for 80% of post-harvest storage losses at the household level, it is essential that farmers' grain storage bins and containers not only meet the necessary structural strength requirements for safe grain storage but also provide protection against rodent and moisture.

1.3 Requirements for the Grain Storage Environment

The area surrounding the grain storage facility should be clean and tidy, free from accumulated debris, to minimize the risk of pests and rodents finding hiding places as much as possible. In addition, the grain storage facility should be placed in a well-ventilated and dry environment to prevent the moisture buildup in the grain due to dampness, which could compromise safe grain storage.

1.4 Management Requirements During Storage

During the storage period, regular inspections should be conducted on the grain storage containers and the surrounding environment. Any issues such as grain infestation by pests or damage caused by rodents should be promptly and properly addressed upon discovery.

2. Grain Loss Reduction Technologies for Smallholder Farmers

In accordance with the overall requirements for reducing grain storage losses among smallholder farmers, a holistic six-pronged technical approach integrating "storage containers, technologies, methods, insecticides, training, and service systems" was implemented. From 2004 to 2015, under the organization of the National Food and Strategic Reserves Administration, the Sinograin Chengdu Storage Research Institute Co. Ltd led a collaborative effort involving relevant universities, colleges, and research institutes to conduct systematic research on grain loss reduction technologies for smallholder farmers. achieving remarkable results. Statistics show that the average grain storage loss rate among demonstration farmers was reduced to approximately 1.06%.

2.1 A Series of New Grain Storage Bins Suitable for Different Grain Varieties Designed for Smallholder Farmers

High-quality grain storage containers are one of the most effective means of reducing losses caused by rodent damage and are crucial for minimizing storage losses at the household level. For southern regions of China, storage bins suited for storing grain at safe moisture levels have been developed, primarily featuring colour steel panel modular silos. In northern regions of China, steel-frame rectangular bins with steel mesh structures and natural ventilation have been adopted for storing high-moisture maize ears.

To facilitate the wider adoption and application of these newly developed grain storage bins for smallholder use, an industry standard titled Technical Standard for the Construction of Small-Scale Household Grain Storage Bins (LS/T 8005-2009) was established. This standard not only defines the technical specifications for various types of small grain storage bins, categorizing them into four major types: steel sheet bins, steel mesh bins, polymer material bins, and brick-concrete bins, but also standardizes the principles for naming and determining the model numbers of small grain storage bins, making their construction more consistent and regulated. For example, JWSG-120 represents a steel-frame rectangular bin with steel mesh structures, a storage capacity of 12 m³.

2.1.1 Color-coated Steel Panel Modular Bin

The color-coated steel panel modular bin was developed based on the grain storage ecological conditions in the North China Plain and the Middle and Lower Yangtze River Plain, where harvest seasons are characterized by relatively high temperatures. This type of bin is a form of steel sheet storage bin, made from color-coated steel panels. It is designed as a small household grain bin composed of multiple interlocking rings that can be stacked for use and collapsed for storage when empty. The thickness of the color-coated steel plates is about 0.4mm, making it suitable for storing raw grains such as rice and wheat and other unprocessed grains at safe moisture levels for smallholder farmers. The typical bin has a diameter of approximately 1.2 meters and a height of around 1.36 meters, consisting of three interlocking rings. Each ring features 2 to 10 corrugations. The total storage capacity is about 1.5 cubic meters, which can hold roughly 1 metric ton of grain (see Figure 1).

Figure 1 Color-coated Steel Panel Modular Bin

This bin has three main features. Firstly, it can be produced in a standardized and large-scale manner. Secondly, it is collapsible when not in use, with a collapsed height of approximately 0.5 meters, saving storage space. Thirdly, the bin is visually appealing, made of rust-resistant materials, durable, and easy to clean. If the bin has previously stored infested grain, exposing it to sunlight can effectively kill insect eggs. This type of bin has been the most widely promoted in China and is the most favoured among smallholder farmers.

There are three key points to note when using the color-coated steel panel modular bin:

1. The bin should not exceed three layers in height, with an optimal height of around 1.36m.

2. A moisture-proof pad should be placed under the bin. It is recommended to use a rigid polystyrene foam board as the moisture-proof pad. This pad not only prevents moisture but also protects the bin from damage caused by uneven ground surfaces, thereby extending its service life.

3. When loading grain into the bin, avoid placing heavy grain-filled objects against the bin walls, as this may cause deformation of the cylindrical structure.

2.1.2 Steel-frame Rectangular Bin

The steel-frame rectangular bin is a key bin type developed based on the ecological conditions of grain storage in Northeast China. In this region, grain is harvested in autumn and winter, characterized by relatively low temperatures, with the entire winter being cold and dry. In response to these climatic conditions, a steel mesh-structured bin was designed to allow direct storage of high-moisture maize ears. The exterior of the bin is supported by a section steel framework, with dimensions approximately 4m in length, 1.5m in width, and 2m in height, providing a storage capacity of about 12m³. It can store high-moisture corn ears with a moisture content below 25%. Through natural ventilation, the moisture content of the grain can be reduced to a safe level before temperatures rise in the following spring, ensuring safe grain storage. Moreover, the quality of the stored grain in this way is often superior to that of mechanically dried maize. The 1.5-meter width of the bin is a critical design parameter—if the bin exceeds this width, the maize cannot be adequately dried (see Figure 2).

Figure 2 Steel-frame Rectangular Bin

When using this type of bin, the following three aspects require attention:

1. The ground surface must be level and capable of bearing the full load of the filled bin. Failure to do so may cause direct damage to the bin or even lead to its collapse.

2. There should be a minimum distance of 1.5 meters between the bin and any surrounding structures to ensure adequate ventilation.

3. The longer side of the bin should be oriented facing the prevailing wind direction. Installing the bin in a well-ventilated location will further enhance moisture reduction through natural airflow.

The steel-frame rectangular bin has been widely promoted in Northeast China due to its reliable grain storage performance, simple operation, moisture and rodent resistance, and attractive, durable design. It is important to note, however, that this bin was specifically designed based on the grain storage ecological conditions of Northeast China and may not be suitable for use in other regions.

2.2 Integration of a Series of Grain Storage Technology Models for Smallholder Farmers

To support the use of newly developed grain storage bins for smallholder farmers, a series of optimized and integrated grain storage technology models have been developed based on the ecological conditions and characteristics of wheat, maize, and rice in different regions. These include eight technical models tailored to smallholder needs: safe-moisture rice storage, slightly high-moisture rice storage, natural hypoxia storage for wheat, and hermetic heat storage for wheat, among others. Building upon the Technical Standard for the Construction of Small-Scale Household Grain Storage Bins, the General Design Drawings for Small-Scale Household Grain Storage Bins, and these eight technical processes, a comprehensive grain storage technology system for smallholder farmers in China has been essentially established.

2.3 Development of Specialized Insecticides for Household Grain Storage

While high-quality grain storage containers can effectively eliminate rodent problems, they cannot completely prevent insect infestations. Since aluminium phosphide fumigants, commonly used in large-scale grain depots, are strictly prohibited for use in smallholder grain storage, it is essential to develop insect prevention and control agents specifically for farmers’ grain storage. The specialized insect repellents developed for smallholder farmers are broad-spectrum, highly effective, and low in toxicity, meeting national health standards. These agents utilize microencapsulation slow-release technology, which significantly extends the duration of efficacy. In addition, plant-based insect prevention measures have been introduced, such as the use of natural repellents like Sichuan pepper (Zanthoxylum), Chinese toon leaves, sweet flag (Acorus calamus), and mugwort (Artemisia argyi).

2.4 Establishment of a Three-Tier Technical Service System

To ensure the effective promotion of grain storage loss reduction technologies for farmers, the National Food and Strategic Reserves Administration coordinated the establishment of a three-tier technical service system for scientific household grain storage, with leading national grain research institutes and universities as the core, provincial-level grain research institutions as the supporting network, and key grain storage equipment enterprises and grassroots grain depots as the operational foundation. This system has provided strong support for the smooth implementation of the national household scientific grain storage special program.Bottom of Form

2.5 Information Technology Provides Convenience for Farmers

By fully leveraging internet and information technology, the “Expert Consultation System for Household Grain Storage” has been developed, including a multifunctional multimedia inquiry terminal and a portable inquiry device. This system consists of eight functional modules: storage equipment consultation, grain quality sensory inspection, grain storage methods consultation, seed storage methods consultation, pest identification consultation, pest control methods consultation, rodent identification consultation, and rodent control methods consultation, enabling farmers to easily access knowledge related to safe grain storage.

In addition, China Grain Reserves Group Ltd. Company (Sinograin) has launched the “Hui San Nong” Grain Sales Reservation App, which has been widely adopted. The app provides functions such as grain policy inquiry, grain sales reservation, reservation status inquiry, on-site check-in, grain payment estimation, and sales record inquiry. Farmers can use their mobile phones to select nearby grain depots and schedule grain delivery appointments, significantly improving the efficiency of grain sales and receiving unanimous praise from farmers.

The “One-Card System” is a grain procurement system developed by Sinograin, representing a key initiative to strengthen the management of policy grain procurement through digital means. Grain sellers are issued an IC card during the grain intake process, which is used to complete all business operations, including registration, quality inspection, weighing, warehousing, settlement, and payment. This ensures that the entire grain procurement process operates in a standardized, transparent, and traceable information platform. The direct result of using the “One-Card System” is to make grain payment transactions more transparent and timely, while ensuring more timely settlement of payments to farmers.

3. Emergency Storage Technologies for High-Moisture Grain

3.1 Emergency Storage Technology for High-Moisture Paddy Rice and Wheat

When grain is harvested with high moisture content, bag-type drying technology can be used. Each drying bag can hold 500 kg to 700 kg of grain, and the drying capacity ranges from 1 to 20 bags per batch. Grains of different varieties, moisture contents, and quality levels can be placed in separate bags and dried simultaneously. Each bag requires 24 to 48 hours for drying. Once a bag is dried, it is replaced with another, allowing for continuous batch drying. This method does not increase the grain breakage rate, and the cross-breaking rate of paddy rice increases by no more than 1%. After drying, the grain can be stored in prefabricated silos made of color-coated steel panels. This approach is well-suited for smallholder farmers. For larger volumes of grain, mechanical dryers are recommended (see Figure 3).

Figure 3 Bag-type Drying Technology

3.2 Short-Term Emergency Storage Technology for High-Moisture Corn Ears

To address the issue in Northeast China where some newly harvested high-moisture corn cannot be dried in time and requires temporary storage, a modular short-term storage silo for high-moisture corn ears (commonly referred to as the “ground-stacked grain” silo) has been developed. This type of silo is composed of multiple freely combinable standardized square units, each measuring 2m × 2m × 1.1m, with a total storage capacity of approximately 35 m³. It is suitable for the short-term storage (within 3 months after harvest) of newly harvested corn ears with moisture content below 30%, and provides a low-cost solution for safe temporary storage. The side and bottom frames of the silo are made of 2.0 mm thick steel plates, and the steel mesh has an aperture size of 40 mm × 60 mm to ensure effective ventilation and cooling. Its main features include: ① Good ventilation performance; ② Quick and time-saving installation; ③ Convenient grain loading and unloading. This type of silo has been applied and promoted in Northeast China. As of November 2016, over 20,490 units have been deployed (see Figure 4).

Figure 4. Modular Short-Term Storage Silo for High-Moisture Corn Ears

The difference between this silo and the steel-frame rectangular bin are as follows: the steel-frame rectangular bin relies on natural ventilation to reduce the moisture content of corn to a safe storage level before temperatures rise in the following year, thereby enabling the safe storage of high-moisture corn ears. The key design parameter for this type of bin is its width. In contrast, the modular short-term storage silo for high-moisture corn ears utilizes cold air during the corn harvest season and relies on natural ventilation to rapidly lower the temperature of the corn ears inside the silo. This allows the corn kernels to freeze within a short period of time, facilitating subsequent threshing and drying. For this type of silo, the key design parameter is that the grain loading height should not exceed 1 meter, and sufficient clearance from the ground must be maintained to ensure effective ventilation.

4. Achievements in Household Grain Storage in China

Since 2004, with support from national science and technology projects as well as the Special Program on Scientific Grain Storage for Farmers led by the National Development and Reform Commission and the National Food and Strategic Reserves Administration, China has widely promoted and applied technologies for reducing post-harvest losses in household grain storage. In 2007, pilot projects were carried out in the Northeast Plain, North China Plain, and the Middle and Lower Yangtze River Plain—major grain-producing regions in China—establishing 32,000 demonstration households. In 2009, another 572,000 demonstration households were set up across 14 provinces nationwide. In 2010, the demonstration scope had expanded to 23 provinces, encompassing 1.38 million demonstration households.

Starting in 2011, a nationwide Special Program on Scientific Grain Storage for Farmers was implemented, with the Sinograin Chengdu Storage Research Institute Co. Ltd serving as the national technical lead. Following the principle of "voluntary participation and joint funding" (60% funded by central and local governments and 40% by farmers), smallholder grain loss reduction technologies were promoted across the country. By the end of 2017, over 9.5 million sets of new smallholder grain storage facilities had been constructed in 26 provinces (autonomous regions and municipalities). These facilities help reduce household grain storage losses by approximately 976,000 tons annually. The program has achieved remarkable results in reducing losses and increasing farmers' income, providing strong technical support for ensuring national food security.

Related Links:

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2.Corn Storage Equipment Types and Applicability

3. Corn Storage in Open-air Structures: Common Methods, Technical Requirements, and Considerations

4. China’s Post-harvest Grain Loss Reduction Policies and Practices