Successful conversion a simple
Converting existing farm buildings for crop drying and storage has its pitfalls.
Peter Hill reports from a Hampshire farm where a successful conversion has turned a large redundant structure into a simple but highly effective store
IT can be tempting to turn a building no longer needed for its original purpose into a crop store. And it can be an effective way to boost farm storage and drying capacity, agrees Hampshire dealer Les Parker.
"But there are pitfalls," he warns. "There are simple considerations, such as whether there is sufficient height for trailers to tip or for roof conveyors to fill the store to capacity. And more fundamental ones like whether the existing structure can take the thrust loads imposed by heaped grain.
"A steel- or concrete-framed cattle shed, for example, is designed simply to hold itself together and support a roof, it is not designed to take sideways pressure," he points out.
The answer is to install thrust-bearing walls that relieve the frame of such forces. That was the route taken when Tom Parker Farms took on Broom Farm and the adjoining Hoe Cross Farm at Soberton, Hants, and decided the old grass drying plant would make an ideal crop store.
The steel-frame building is basically sound with plenty of height and width and a fibre cement roof and side cladding that will see out another few years.
"But the 1.5m block walling would simply not be strong enough to withstand having grain piled against it," notes Mr Parker. "Digging out the foundations and installing independent galvanised steel thrust walls would have been the more expensive of two solutions, so self-shedding timber walling was chosen instead."
No conveyors or augers
Simplicity is a keynote of the design – there are no conveyors or augers to complicate things – but no corners have been cut to save costs. The result is a 1300t store and drying plant that will not only take the good yields achieved from the farms 120ha (297 acres) of arable but provide sufficient spare capacity for future acreage and yield growth.
"When you are making this sort of investment it is as well to look to future requirements," comments Tom Parker junior.
Extending the 18m (60ft) wide, 27m (90ft) long building was the first task, two extra bays pushing overall length to 36.5m (120ft). A block fan house on the end of the extension houses a dry air generator, twin fans and electrical controls. At the other end roller shutter doors in taller openings improve access and help keep out vermin. Solid sheets in place of roof lights keep the place dark to discourage birds.
Grain, oilseeds and pulses are handled in and out by telescopic handler, so the floor clearly needs to be capable of taking a fair bit of punishment.
Longer service life
The Flach and Leroy flooring has structural grade, pressure-treated bearers with hardwood top boards. That, says Mr Parker, should give a longer service life than a cheaper but lower specification installation.
Structural grade timber is also used for the self-shedding grain walling main frames which are bolted to the main concrete floor.
"The self-shedding walling costs about 20t in lost capacity," notes Mr Parker. "But over 1300t that is a very small proportion and worth it for the drastic reduction in shovelling needed to empty the store compared with standard L-shaped walling."
Storage flexibility is provided by slot-in partitions in each of the two main storage areas, using vertical support posts built into the side walls and air tunnel. Central support is provided by removable posts that slot into sockets in the grain floor.
"They are hellish heavy panels, but the arrangement gives us useful storage flexibility for crop and/or variety separation," notes Tom Parker.
Main considerations in designing the fan house were to provide plenty of space around the equipment and to keep noise levels to a minimum.
"It doesnt cost much to extend the fan house by a couple of blocks in each direction and yet it makes such a difference to be able to get around the equipment easily," suggests Mr Parker. "Insulating the roof and building, an earth wall screen has also made all the difference to noise levels.
The drying system was designed taking the 100cfm/t norm (for half the total storage capacity) assuming ambient air but trimmed to 78cfm/t to account for the dried air produced by the 14kW DAG.
Broom Farm/Hoe Cross Farm cropping ha (acres)
Brigadier feed wheat65 (162)
Dry peas55 (135)