Recently, ECHO Community member Brad Ward asked on our online forum about metal silo construction. “I'm going to be building a 3.5 cubic meter metal silo. I have come across a couple of good resources online that cover the topic pretty well, but I would love to hear from those of you who have built and/or implemented silos at the household or community level. Are there some construction tips you could share? What has your experience been with using the silos? If they were used by more than one household, do you have some recommendations for helping to avoid future conflict? Thanks!!”
Brad received feedback from several network members.
Dr. Joel Matthews encouraged a community-first approach. “First, you will want to investigate traditional grain storage techniques. Do local farmers build their own silos? If so, does their traditional design utilize clay or other locally available building materials? Do local farmers believe that their traditional design fails? Are they interested in phasing in a new design? If so, what are the limitations of their technology that have been voiced by the farmers, and how can your design address those concerns? What is the cost/benefit ratio of traditional design vs. your proposed design?”
[Brad responded that these considerations have been taken into account in the community to which he referred.]
Nate Gray from Agri-Plus in Ghana responded, “I've been working on a similar project in Northern Ghana for the last couple years. We made and tested several prototypes inspired by the model that was at ECHO Florida. Our challenge was to adapt it in a way that could easily be reproduced here in Ghana using locally available materials, tools, and skills, while still being affordable to a smallholder farmer. So here is a brief explanation of what we have found...
Figure 11. Grain outlet spout and outlet locking lid. Source: Edward Martin
“Currently we have some confidence in a model that measures about 46 inch tall by 46 inch in diameter using a 0.8mm to 1mm thick galvanized sheet metal. The joints are made simply by folding the seams in the same fashion as a tin can, a method that is already used by tinsmiths here in constructing water drums and other locally made sheet metal products. The seams are then sealed with some sort of sealant. One sealant that we've tried is a putty made from shea butter (very common here), cement and oil paint. This type of sealant can last a couple years if mixed properly and if the bin is not moved around much after sealing. More recently, though, we have been using a polyurethane caulk that has become available here. It is a bit more costly, but is much more reliable and longer lasting. For the inlet and lid, they made it wide enough for somebody to fit through to clean out the bin, and they fashioned it from sheet metal and then lined it with PVC. This is done by cutting a length of 1 inch PVC pipe lengthwise, then slightly heating it to press it out flat till it cools. It is then used to line the metal inlet and lid. The outlet spout and cap is made from a piece of 6 inch PVC riveted onto the opening of the bin. We've also added a fumigation chamber at the top using a 2 inch piece of PVC attached to the bin in the same way as the outlet pipe, with the exception that there is a perforated piece of sheet metal over the bin opening that allows air to flow but nothing more. This way when using fumigation tablets that are common here (such as aluminum phosphate tablets), there is very little risk of direct contact with the grain held inside, in case the tablets are not properly wrapped. We used PVC for all the openings because it makes it much easier to get a nice tight fit than with metal on metal.
“Concerning the question of use even by more than one household.... We have started to help organize the forming of what we have called Food Management Groups here.
Figure 12. Food management group depositing grain into metal silo. Source: Edward Martin
These groups are made up of about 10 people per silo that agree to contribute an equal amount of corn and store it in a locked bin until 'hunger season,' the last couple months of the growing season before new harvests come in (Figure 12). One silo can adequately serve 10 people, each representing an average size family, for about two months. Each year every member pays a small fee to use the silo. That money is saved and used to pay for the silo, purchase additional silos so the group can grow to include more of their community members, and possibly build some capital so that eventually they can use the extra funds to invest in grain to store and resell at a higher price. Each group is formed with a chairman/woman, secretary, and technician who is trained in proper fumigation and silo handling/maintenance. The fee is enough for a group of 10 to be able to buy a silo in two years, and low enough that it is less than half the value increase of their grain, so it still makes financial sense to use a bin. While we are still in the infant stages of forming these groups, so far we have seen them work together very well. Some members have testified that they have never experienced being able to feed their families debt-free through the hunger season with quality grain that is free of insect infestation. As a group, they are learning to better manage their food resources so that they still have food in the highest time of need, rather than selling their grains early in the year and needing to buy back at a higher price (often on credit), to be able to feed their families till the new harvest comes in.
Figure 13. Finished metal silos roofed to protect them from the elements. Source: Edward Martin
“I was concerned that the improvements we made after our original prototypes added too much cost to make them affordable to individual families, but so far we have still sold some to individual families that are using them.”
Figure 14. Peter Namba (left) in front of his silo. Source: Edward Martin
Edward Martin from Agri-Plus added, “Last fall when I was in Ghana, I interviewed Peter Namba, the man on the left in Figure 14. I asked him what he likes about the Agri-Plus program and the metal storage silos. He replied, “I had grain left over at the end of the ‘hunger’ season. This has never happened before.” Mr. Namba shares these two silos with several other families.”
Brad was also encouraged by members to reach out to specific individuals who have experience in grain storage or who work in his region.
Join the conversation and get connected at http://edn.link/metalsilo.
For more resources about metal silos, visit ECHO’s Grain Storage page at http://edn.link/grainstorage.
Cite as:
ECHO Staff 2018. Metal silos for grain storage. ECHO Development Notes no. 140