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Leveraging on Storage Systems for Price and Supply Stabilization of Ware Potatoes

Potato growing in Kenya plays a crucial role in supporting rural livelihoods and ensuring food security.  Potato crop is the second most cultivated crop in Kenya, grown by over 800,000 farmers. Approximately 83-90% of farmers sell their potatoes directly to traders or local markets immediately after harvest. The main potato markets are urban areas of Nairobi, Mombasa, Thika, Garissa, Nakuru and Kisumu. Potato prices are, however, volatile, swinging between the extreme ends based on either harvest season or off-harvest season. The volatility in potato prices complicates marketing efforts, as farmers face the dilemma of when to sell and the ideal market conditions for recouping their investment. Storing potatoes comes with the risk of spoilage. Agricultural prices are important for an economy, since they influence the level of farm incomes, the welfare of consumers and export earnings. Government interventions in pricing of farm products are aimed at improving the welfare of primary producers by stabilizing prices, and consequently stabilizing incomes.  Government interventions may also be aimed at improving allocation of resources, increasing self-sufficiency in food, and safeguarding consumer welfare.

Low potato prices due to oversupply negatively affects the financial security of farmers while high potato prices in off-season affect consumer welfare.  Between 2019 and 2021, for instance, the highest wholesale market prices for Red Irish and White Irish potatoes were Ksh 162 and Ksh 153 per kilogramme, respectively, and the lowest market wholesale market prices were Ksh 16.18 and Ksh 9.24 for Red Irish and White Irish, respectively. The high difference in prices serves as evidence on the variations of prices across various species. This blog explores ways of utilizing cold storage to stabilize supply and prices of ware potato during low seasons.

Figure 1: Red Irish and White Irish wholesale commodity prices (2019-2022)

Data Source: Ministry of Agriculture and Livestock Development Wholesale Commodity Prices

Storage-based Measures to Ensure Price Stability and Supply of Ware Potatoes in Kenya

One of the price stabilization strategies is a buffer stock scheme, which operates by buying excess supply of the commodity when the market is oversupplied, and then releasing it (off-loading) into the market when supply falls short.  Kenya has been running a Strategic Grain Reserve (SGR) through the National Cereals and Produce Board (NCPB) with the aim of cushioning cereal farmers and grain consumers from the effects of supply and price shocks, and to provide a first line of defense for coping with food deficits. However, to ensure more resilience to shocks, there is a proposal to transform the Strategic Grain Reserve (SGR) into a Strategic Food Reserve (SFR) by including other critical foodstuffs appropriate to local conditions. The proposal entails the establishment of a National Food Reserve and Trading Corporation with the aim of managing the National Strategic Food Reserve. The National Strategic Food Reserve will keep reserves of maize, rice, wheat, dried cassava, beans, green grams, Irish potatoes, powdered milk, canned meat, dried fish, and other pulses. Some of these foods such as Irish potatoes are perishable, requiring modern potato storage techniques.

There are several storage options to extend the ware potatoes shelf life, including both traditional and modern storage systems. Both modern and traditional storage systems rely on maintenance of low temperatures to extend potato shelf life. Traditional storage systems rely on lower temperatures and ambient air, while modern storage systems rely on lower temperatures, ambient and/or mechanical cooling systems.

Traditional storage systems include pit storage, heap storage, diffused light stores, wooden brick structures, and ventilated rooms. In pit storage, the potatoes are stored in pits dug in cool, shaded areas. The pits are lined with materials such as neem leaves, dry grass, or sugarcane trash. Potatoes are loaded into the pits, leaving a gap at the top, followed by a layer of dry grass. A thatched covering is used for protection from rain and sunlight to maintain suitable storage conditions. In heap storage, potatoes are stacked in a conical or pyramid-shaped heap in an area with good ventilation. Regular inspections are conducted to remove rotting or sprouting potatoes. Diffuse light storage, commonly used for seed potatoes, combines reduced light exposure with specific humidity and temperature control measures to preserve seed quality. Traditional storage systems do not achieve lower temperatures of about 5 Celsius, and therefore are not suitable for long storage.

There are several different types of improved cold storage systems available, including conventional refrigerated rooms, ventilated cold rooms, jacketed storage, and controlled atmosphere (CA) storage systems. Conventional refrigerated rooms provide temperature-controlled environments, ideal for preserving potato quality. However, the refrigerated rooms can be expensive to operate and maintain, especially for long-term storage because they require continuous cooling. Ventilated cold rooms use a ventilation system to force air circulation, which helps to cool the room and maintain the right humidity levels. This is a more energy-efficient option than conventional refrigerated rooms, but it can be less effective at controlling temperature and humidity. A slight change in the optimal temperature and humidity required for potato storage may cause loss of the stored produce.

Jacketed storage involves surrounding the storage area with insulation and a temperature-regulating jacket. The jacketed storage system is a more energy-efficient option than conventional refrigerated rooms, as it does not require the continuous operation of a compressor. However, it is expensive to install. Controlled atmosphere (CA) storage systems function by modifying the gas composition within storage rooms to control respiration rates and reduce spoilage. This is the most effective way to store potatoes for long periods of time, but it requires specialized equipment and careful monitoring.

There is no perfect cold storage system, and their challenges range from high initial investment, operational and maintenance costs. Cold storage systems can be expensive to install and maintain. There is also risk of spoil and/or quality loss if temperature and humidity are not properly controlled. Another challenge is linked to the potato varieties grown in Kenya. Shangi potato variety is the most dominant variety in Kenya but has a short dormancy period of between 30-60 days, implying that potatoes must be sold just 30 days and the objective of supply stabilization may not be achieved. There are potato varieties with relatively long dormancy periods such as Dutch Robin, Kenya Mpya and Unica but are not popularly grown. The best performing varieties in the world, such as Amish Cobbler, Bintje and Yukon cold can be stored for up to 8 months.

Conclusion and Recommendations

The development of potato cold storage facilities in Kenya is crucial for achieving price and supply stabilization in the potato market. The current marketing system, characterized by volatile prices and inconsistent supply, poses challenges for farmers and consumers. Improved cold storage is a valuable investment for the potato industry and to the achievement of supply and price stabilization. However, the cost of installation and maintenance is a barrier for potato industry stakeholders.

To address the pressing challenges surrounding potato storage in Kenya, it is important that agricultural research institutions research and develop new potato varieties with extended dormancy periods, surpassing the current 120-150 day. Farmers can also be encouraged to diversify from the Shangi potato, which has the shortest dormancy period, to other varieties with relatively longer storage durations. Even as the National Food Reserve and Trading Corporation is being established, it is important to ensure the Corporation adopts more cost-effective and energy-efficient cold storage technologies.

Farmers groups and cooperatives with interest in constructing cold storage can be supported by developing appropriate financing mechanisms. These can be done by commercial banks and development corporations inclined to agricultural investment. Developing quality standards and safety requirements and offering training and technical support to farmers and National Food Reserve and Trading Corporation on the proper use and maintenance of these facilities is crucial in ensuring the effectiveness of the storage facilities.

Authors: Elvis Kiptoo, KIPPRA Young Professional

Meshack Omega, KIPPRA Young Professional

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