Store chemical-free crops with airtight PICS bags

Store chemical-free crops with airtight PICS bags
Store chemical-free crops with airtight PICS bags

Africa-PressUganda. James Mugerwa, a National Agriculture Advisory Services (Naads) extension worker based in Buvuma District, is aware of the postharvest challenges. As a mixed farmer, the harvest period brings a lot of pressure as farmers brace for pests and thieves.

He explains that farmers can lose as much 17.6 per cent for about 2.8 million metric tonnes (MT), 12.4 per cent of about 214,000 MT and 13.5 per cent of 230,000 MT of maize, millet and rice produced in the country respectively. Mugerwa usually stores his grain harvest in stacked bags safe from contamination with cattle and chicken.

He sometimes sells immediately when he anticipates good prices. But he still has to battle attacks by weevils, termites and fungi as well as exposure to aflatoxins.“I still suffer losses because to keep the crops longer, I have to apply pesticides which increase the costs of production,” Mugerwa explains.

Improved storageScientists are recommending a cheap technology which is chemical free, improves income and food security, in form of storage bags commonly known as Purdue Improved Crop Storage (Pics).In South of the Sahara, postharvest maize losses are at 14 per cent minimum and 36 per cent maximum. In Uganda, on farm postharvest maize losses is about 6 per cent of the quantity stored and increases in some instances up to 100 per cent.

According to experts, the quality of crops depends largely on storage as poor storage causes contamination. In Uganda, this problem is aggravated by the fact that smallholder farmers continue to use traditional methods that increase the losses.Traditionally, people use old jerrycans, sacks, cribs, fire places, pots and granaries, to prolong the life of their cereals and legumes. But these have limitations that lead to significant post-harvest losses.

According to the Food and Agriculture Organisation (Fao), moisture, pests, and temperature are three significant threats to stored grains. But grain losses can be prevented with simple technologies.Smallholder farmers usually store their crops to earn money, food consumption, and planting. The decision to sell immediately after harvest is prompted by inadequate storage, need for money, high storage costs and prevailing prices.

The Pics project was globally launched in 2007 but rolled out in Uganda in 2014 and scientists at the National Agricultural research Organisation (Naro), are using it as an alternative to using chemical pesticides on stored grain or simply losing it to pests.Evidence suggests that hermetic technologies such as Pics bags could be effective against key legume storage pests.

The Pics bag works like other hermetic containers, by limiting the supply of oxygen to insects living in stored grain. After Pics bags are closed, insects in stored grain use up much of the oxygen left inside the bag. When oxygen becomes too low, the insects cease feeding, and stop growing and reproducing; this prevents serious damage to the grain. Once you choose to use Pics bags, you will not have to use any pesticides.

Up to 98 per cent of all insects can be eliminated from stored grain within a month of depositing it in the bag, significantly cutting losses.Dr Charles Lwanga Kasozi, a senior research officer of Naro has endorsed the bags as a proven technology for cutting losses after harvest.

“Any attempts that don’t help in managing post-harvest losses are not helpful to farmers and with Pics bags they can achieve more from their sweat,” Dr Kasozi said.According to Dr Kasozi, small-scale farmers in Uganda often have fewer options to prevent losses after harvest.

“Climate change may induce what were previously minor storage pests to become new (serious) pests, or even enable introduction of new pests,” he noted.“Pics bags can enable farmers to effectively protect their seeds and prevent storage losses,” he added.The bags are distributed by several agro supply shops in Uganda including Bukoola Chemical Industries and cost about Shs7,000. They are available in 50 and 100kg capacity.


By dramatically reducing the threat of pest destruction of stored crop, Pics bags reduce the need for insecticides. Decreased reliance on insecticides also translates to lower costs for small farmers.

The bags are economical for many farmers costing Shs7,000. Although they are more expensive compared to traditional bags, farmers can use them for up to four years, as long as they don’t have any holes.Another benefit is that they alleviate the need for farmers to sell harvests immediately to avoid risking losing the crop during storage.

In addition to bolstering the income potential of small farmers, Pics bags are practical for farmers as they serve as an easily-accessible source of food during times of shortage. Farmers can open them for consumption at any point.The bags are portable enough for farmers to keep them on-farm, or even in their homes.


In 2014, the Pics team received the third grant from the Gates Foundation for a five-year project to commercialise the bags in Sub-Saharan Africa to improve market access and food security among smallholder farmers. The bags are being promoted in seven countries including Uganda, Kenya and Rwanda in East Africa.

Storage types in Uganda

Old jerrycans. Although this is a cheap method where an old jerrycan can be used, crops can still be damaged and the closed container can encourage the growth of mould.Sacks. Bags are cheap and easy to obtain. Most shops sell them between Shs1,000 to Shs1,500. But bags are easily attacked by rats and pests.Closed cribs. These are made out of locally-available material including poles, nails and iron sheets. Cribs are prone to attacks from termites and thieves.

Above the fire. Some farmers construct table-like platforms above the cooking place to keep their crops, especially maize, so that rising smoke and heat keeps drying the maize. But smoke affects the colour and can only be used for planting.Pots. This is a traditional technology in Uganda. The pot’s mouth is closed with a smaller pot and is usually smeared with cow dung to keep away pests and deter rat penetration. But pots are fragile and can easily be broken.

Granaries. Granaries are made of local materials such as grass, reeds or small sticks, poles, stones, mud, clay and water. Some farmers smear granaries with cow dung. A granary offers easy access to termites, pests and rats.


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