Wednesday, August 10, 2022
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Proper Post-Harvest Handling Key To Household Food Security

by Harvest Money Editor
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It is unfortunate that farmers in Uganda lose about 30% of their harvested crops in the post-harvest value chain. The main causes of on-farm post-harvest losses (PHL) are wrong harvesting time, poor harvesting methods, improper methods of drying, poor storage, un favourable transportation and distribution systems among others. These losses do not only rob farmers of the investments made to produce the grains, but also impact negatively on their household income and food security.

In order for farmers to have high quality grains and hence better offer from markets, they must be able to do post-harvest handling in a timely and proper manner. The extra care taken at this stage is far more cost effective than attempting to upgrade produce quality later in the post-harvest chain, for example in the trader’s warehouse.

Here are some tips to help farmers prevent or reduce post-harvest losses of their crops and   achieve high quality grains for better markets.

Impact of the losses

According to Ministry of agriculture Animal industry and Fisheries (MAAIF) statistics, most farmers in Uganda lose between 30-40% of their farm produce due to poor post-harvest handling methods. This largely cuts across all farm produce, including cereals like maize and soya to milk, coffee etc.  Because profits in agriculture are largely slim, this is why many farmers get frustrated out of practicing agriculture. The losses largely occur due to lack of knowledge in proper harvest handling or even lack of the required storage facilities to effectively store their product.  When a farmer plants a crop or gets an animal, he expects to get profits from it on harvest.

This does not matter where a farmer is growing the crop for domestic usage, or he is keeping it for commercial purposes. If a farmer plants maize for example, he expects to harvest at least 2.5tons or 25, 100kg sacks from an acre.

However, this is not the case for most farmers in Uganda. The average actual yield for most cereals like maize is just 8bags, which over 70% below the expected harvest. This scenario cuts across most cereals. One of the reasons actual harvests are too low has got to do with the way harvests are carried out and thereafter, the manner in which the produce is stored.

Most of the harvest is done rudimentarily. Apart from the large scale emerging farmers in Nwoya and Amuru in northern Uganda and Kapchorwa in the east who have mechanized harvesters, most farmers harvest by hand. Because of this, a lot of the produce is left in the fields. Additionally, a big percentage of the product is also stolen by the casual workers hired to carry out the harvests.

 According to research by the Grain Council of Uganda and MAAIF, less than 10% of cereals farmers in Uganda have any effective storage system for their produce. In the north and north-east, they traditionally used to store produce in granaries. Because the granary is hoisted off the ground, pests and rodents found it difficult to access the produce.  However, most of these are no longer considered safe due to rampant thievery.  This is why most farmers sell off their produce at very low prices immediately after harvest, hence making losses. 

Some groups have set up storage facilities-for example in Amuru and Nwoya, in Kibaale, Masindi, Luwero and Mubende but the stores are still small and cannot accommodate everybody.

In addition to actual storage, there are cases where produce like cereals and coffee is dried on the bare ground. Again, this affects the quality hence drawing a low price on final sale. Across the country, there is therefore a very strong need to intervene in order to solve this challenge. 

-Harvest on time

Farmers should harvest their crops on time, as soon as they have reached physiological maturity. Crops have maturity indicators which show that they are physiologically mature. However, on reaching physiological maturity, some crops e.g. cereal grains are still too moist and soft to be threshed or shelled, and so most smallholder farmers leave them to dry naturally in the field for several weeks before harvest. This approach is generally not recommended as the crop left to dry in the field becomes vulnerable to agents of losses such as infestation by insect pests and damage by birds, wild animals and losses due to theft.  The insects that attack crops at maturity may be carried over into storage and cause serious damage to produce. For many cereals and legume crops, there is an additional danger of late harvesting as the grain may start to scatter in the field. This is especially the case for paddy rice, cowpea and beans. On the other hand, immature harvesting should be avoided as the grains will not have fully filled up and hence will have low weight and low nutrients and will also shrink during drying. It is important for farmers to be able to recognize when crops are mature in the field.

-Dry produce immediately

Immediately following harvest, farmers should transfer their crops to the homestead and commence drying; avoid heaping harvested produce in one place for days as they provide favourable conditions for the growth of moulds that lead to fungal contamination e.g. aflatoxin. During drying, the crop should never be placed in direct contact with the soil. Rather spread to dry on a clean surface e.g. tarpaulins, concrete platform, drying racks, a layer of woven sacks, etc. and should be kept away from farm animals.

-Carry out proper threshing or shelling

Thresh or shell your crops in a proper way. It is important for farmers to minimize damage to grains during threshing/shelling as damaged grain is much more susceptible to attack by insects and fungi in storage.  Consequently, techniques that crush and damage grains such as beating with sticks are not recommended, except in commodities where beating poses no significant damage.  Also, the grain should be neither too moist (soft) nor too dry (brittle) at the time of threshing/shelling; it is best done when grain is around 14 to 16% moisture content, although paddy rice is commonly threshed at around 18-22%. Beans, cowpea, sorghum, and paddy rice can be threshed by hand and this can be done conveniently by beating the crop against a threshing platform e.g. tree log, metallic drum, etc.  However, this process is relatively slow and tedious.  A moderately expensive option would be motor-driven threshers which come in different models with outputs ranging from 600 to 5,000 kg/h.  Most models will also clean the threshed grain using shaking screens and/or blower fans.  In the case of paddy rice, pedal operated threshers are also commonly available. A simple hand-operated sheller is also available for shelling maize.

Clean product properly

Clean your threshed/shelled grain properly. Cleaning can significantly improve grain quality and hence its grade and price.  Cleaning involves the removal of foreign matter such as stones, husks, pods, broken grains and dust produced during threshing.  At the same time it is possible to remove insect-damaged and mouldy grains by hand picking.  Cleaning is most often done manually by winnowing.  This involves tossing the grain into the wind which carries off the lightest impurities, while the heavier grain falls onto a tarpaulin or other surface.  However, this method does not separate the heavier impurities.  For this a sieve is required, where the grain is retained on the sieve and smaller heavier impurities fall through it.  Such a sieve can be either single or double handed. 

-Dry to required moisture

Dry threshed or shelled produce until they attain recommended moisture content for storage. There are subjective and objective indicators which farmers can use to indicate safe moisture level for storage. Experienced farmers will know how to judge the safe moisture content evidenced by the fact that they have been storing grain safely all their lives. A more objective method for moisture content determination is to use the salt-bottle method.

-Use proper packaging       

Package dried produce in appropriate containers or bags and ensure good        storage at home.Grains may be stored for short-term (e.g. <3 months) before it is moved to the next link in the marketing chain, or medium to long-term (3-12 months)    where farmers keep it for household consumption or for sale at a later time when prices are more favourable. There are many options available for farmers to store their grain and protect against pest infestation. These are some of the storage methods:

Open weave sacks: This type of packaging is suitable for storing grains on-farm for a period of 3 months or less. Open weave sacks may be made of polypropylene, sisal or jute. Most farmers commonly use the polypropylene bag to store their produce as it is the most commonly used and cheap option available in the market. Its disadvantage is that the produce, if not treated with appropriate insecticide, can be easily attacked by insect pests while in storage. This is less likely in the case of millet, due to its small grain size and storage at moisture contents that are very limiting to insects (e.g. 10% or less), or in the case of paddy that has a seed coat that is difficult for insects to penetrate. To avoid such damage, maize, cowpea, sorghum and beans that are to be stored for more than 3 months should be admixed with a suitable insecticidal dust at the manufacturer’s recommended dosage rate.

Hermetic (airtight) bags: With hermetic bags, the bags have an inner layer(s) of polythene (kavera) that is airtight in addition to the outer polypropylene sack. Once grains are packaged in the bag and closed properly, the produce is isolated from the outside environment. Hermetic grain storage systems strive to eliminate all exchange of gases between the inside and the outside of a grain storage container. If the gas exchange is low enough, living organisms such as insects within the container will deplete oxygen and produce carbon dioxide until they die or become inactive due to the low oxygen. With this method, farmers can store their produce for more than a year, if they so require.

Plastic silos: These are specially made containers (can be metallic or plastic) that are designed to work on the same principle as hermetic bags, thus excluding packaged produce from the external environment.

Ensure you have a well-constructed storage facility

-Do not store on the floor

In storage, the sacks/bags and silos must be prevented from touching the floor and the wall of the store, from which they may absorb moisture, causing grain rot. To achieve this, the bags/silos should be placed on pallets away from the wall so that they are suspended at least 10 cm above the floor surface. The roof must also guarantee freedom from leakage of rainwater into the store.

It must be worthwhile to note that practicing timely and proper PHH is not the only solution for better markets for farmers’ produce. It must be combined with collective marketing through bulking the produce to attract and retain better markets.

Compiled by Joshua Kato and Francis Okori         

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