How is fresh produce stored after harvest in Northern Nigeria?

Nigeria faces a significant challenge with food loss, with an estimated 40% of its total food production being wasted annually. This loss directly affects the livelihoods of farmers, who lose up to 25% of their income due to inefficient storage and handling practices. Beyond farmers, end consumers are also affected as food loss leads to food scarcity and price increases, with food inflation at 39.84% in December 2024. Improved storage methods for fresh produce is therefore crucial to address food loss. 

This article takes a closer look at how fresh produce is stored after harvest in Northern Nigeria, exploring the creative solutions farmers are using, and what it will take to build a more sustainable system for the future.

How has fresh produce been stored traditionally in Northern Nigeria?

For generations, farmers in Northern Nigeria have relied on indigenous storage methods to preserve fresh produce and reduce spoilage. These methods, rooted in local knowledge and resourcefulness, have proven effective in the past. They include: 

Mud Rhombus.

• Rhombus Structures: These cylindrical structures with thick walls that insulate against the region's extreme temperature fluctuations. Usually made of mud, and ash, they provide a naturally temperature-controlled environment for grain storage. It is elevated on stone pillars to prevent rodent attacks and has a conical thatched or mud roof. This structure is commonly used for storing maize. However, it is prone to cracks, leakage, and fire hazards. Thatched Rhombus constructed from woven grass stems supported by wooden frames, is used to store sorghum in unthreshed forms. Although it provides ventilation, it lacks proper moisture and rodent-proofing. 

Straw huts storing onions.

• Huts: made from materials like straw, millet stalks, and wood, these huts are commonly used for storing fresh produce such as grains, onions, tomatoes, peppers, and leafy vegetables. These huts provide shade, ventilation, and protection from direct sunlight and rain, making them an effective short-term traditional storage method. For example, straw huts are widely used for onion storage, reducing spoilage compared to bagging in jute sacks. However, these huts are not adequately temperature-controlled, which is a significant concern for storing temperature-sensitive produce like tomatoes, peppers, and leafy vegetables. Tomatoes, for instance, should ideally be stored at around 55-70°F (13-21°C), while peppers and leafy vegetables are best kept at slightly cooler temperatures, between 45-50°F (7-10°C). Additionally, huts are not pest-proof or airtight, leaving produce vulnerable to spoilage, rodents, insects, and fungal infections.

Baskets storing tomatoes.

• Storage Baskets:  made entirely of plant materials such as bamboo, reeds, or timber, are designed for both storage and drying. They are often used for storing cowpea, tomatoes and millet. However, baskets do not provide protection against moisture, pests, and have limited capacity for storage. They can only provide short term storage at best.

Earthen pots.

• Earthen Pots and Underground Pits:  Earthen pots and jars are small-capacity containers used primarily for storing cowpeas and millet seeds. These containers are sealed with clay or cow dung to make them airtight. They can be effective short term for preserving seeds. However, they are fragile and can absorb moisture from the ground. Underground pits are used for storing millet and cowpeas. The pits, which range in depth from 1 to 3 meters, are lined with straw and padded with corn husks to provide insulation. This method allows for long-term storage of up to five years, it is prone to termite attacks, wall collapse, and difficulties in emptying and cleaning. 

Jute bags storing grain.

• Bags and Sacks: Farmers often use jute, hemp, or cotton sacks to store various grains, including maize, millet, and cowpeas and vegetable produce such as onions and potatoes. Jute bags are majorly preferred for their breathability. This method is convenient but is highly susceptible to insect infestation and mold growth. 

While these storage solutions have sustained communities for generations, they fall significantly short of guaranteeing long-term food safety and security in contemporary Northern Nigeria. They struggle to meet the demands necessary for commercial agriculture or to bridge longer food insecurity gaps. 

Pest infestation remains a persistent challenge. The region's grain losses to insects, rodents, and birds is as high as 20-30% despite traditional repellent techniques, compared to well controlled environments (without exposure to pests, temperature variation, and moisture) where only 1% of grains are lost. Climate change has exacerbated this problem by altering pest lifecycles and creating more favorable conditions for their proliferation. 

Traditional storage methods are also unable to protect against mycotoxins, a kind of toxin caused by fungus growth on produce. Alarmingly, studies have found dangerous levels of aflatoxins in up to 40% of grain samples from these traditional storage structures. These aflatoxins are a type of mycotoxins that can cause liver damage or cancer if consumed in high quantities over time.

The region's heat significantly reduces the shelf life of fresh produce, necessitating cold storage. Many fruits and vegetables, with shelf lives ranging from 3 days to a month, decompose rapidly under high temperatures. This accelerated spoilage, evident in tomatoes, onions, and carrots, is due to increased respiration rates and microbial activity. Notably, tomato respiration rates increase with temperature, directly contributing to early spoilage of about 45% in Nigeria.

Innovations for a Sustainable Future

To address these limitations, innovative storage solutions are emerging in Northern Nigeria.

Solar-powered cold rooms represent a promising development, particularly in states like Kano and Kaduna. These facilities harness the region's abundant sunshine to power refrigeration units that can operate independently of the grid. Organizations like ColdHubs have established pay-as-you-store models that allow smallholder farmers to access refrigeration services at affordable rates.

Hermetic storage bags, airtight containers that create modified atmospheres that eliminate pests without chemicals, are increasingly popular for grain storage. This simple intervention builds upon traditional storage principles while addressing their limitations. Companies like PICS Global have made significant inroads in Northern Nigeria with their hermetic bags that have demonstrated effectiveness in reducing aflatoxin contamination and increased shelf life compared to traditional sacks. 

Improved traditional structures incorporate modern materials while maintaining the basic design principles of indigenous storage. For instance, the Zero Energy Cool Chamber (ZECC) adapts the evaporative cooling principle of traditional clay pots but scales it up using bricks, sand, and water to create cooling chambers that can reduce ambient temperatures by 10-15°C without electricity.

The adoption of modern storage techniques is influenced by both demand and supply-side factors, but the relative impact of these factors varies by technology. Specifically, studies indicate that demand side issues like low education and awareness, financial constraints and deeply rooted cultural practices limit uptake.

For instance, this study found that factors militating against the full adoption of hermetic storage bags in Minna, Nigeria were unavailability (88.18%), farmers fearfulness (5.7%) and lack of proper education on the technology (3.04%).  

Supply-side issues, such as infrastructure gaps, credit access, and proximity to storage technology affected adoption.

For example, this study on cold storage in Nigeria, attributes the low uptake to the significant distances farmers must travel to access cold storage facilities and the chronic unreliability of the national electricity grid, compounded by limited access to solar power solutions.

To significantly improve food security and reduce post harvest losses, targeted interventions from both the government and private sector is vital. The government should focus on improving infrastructure, enhancing agricultural extension services, providing accessible financial incentives, and supporting research and development. The private sector can contribute by investing in and managing storage technologies, ensuring their availability and accessibility to farmers. A collaborative approach that addresses both infrastructural needs and socioeconomic realities is crucial to transforming post-harvest management, reducing food spoilage and enhancing supply chain efficiency.