Hay Drying System Under Study

Press, Volume CVI, Issue 31239, 10 December 1966, Page 9

Hay Drying System Under Study

To winter the greatly increased sheep numbers that are expected on farms in the next few years farmers are going to have to place greater emphasis on conserving hay and artificial drying could be a worthwhile aid in a fickle climate in the spring.

With the period about 197072 in view Mr C. J. Crosbie, farm advisory officer (machinery) of the Department of Agriculture in Christchurch, told farmers attending a field day at the Wincbmore irrigation research station this week that be was looking into the Dutch system of hay drying—he was not advocating use of drying at this stage but was looking into how this system might fit into New Zealand farm practice. Farmers at the field day saw two stacks of bales of hay being dried under this system. In one case a stack of 600 bales in a hay shed had been dried down to a moisture content of 18 to 22 per cent—--20 per cent is regarded as a safe storage level for hay. The hay in question was baled four days after mowing and was brought into the shed at 28 to 30 per cent moisture content To allow air to pass through the bales the tension was slackened off at baling and a soft type of bale was produced not weighing more than 621 b. For this exercise the stack was made in the form of an 18ft square. As the bales tend to shrink as drying goes on, a wooden framework is erected to hold the stack in place and Mr Crosbie said that the timber members needed to be at not more than 6ft centres around a suitable square base. In this case the stack was 14ft high to contain 600 bales. The bales in each layer are placed around the outside of the square first and then are laid in towards the centre. The bales are placed in the manner of a brick wall so that joints are sealed to stop air leaks.’ In the bottom. two layers of the stack a 2ft square hori-

zontal tunnel or duct was left extending into the centre of the stack. This was roofed with long lengths of 6in by 2in timber to prevent it from collapsing. At the centre of the stack a metal sheathed bung unit was used. It is 6ft tall and 2ft square and sheathed for sft of its height and has a 4ft square cap fitted on the top. As the building of the stack proceeded this unit was hoisted upwards towards the roof leaving a 2ft square vertical duct or plenum, and when the stack was completed the unit was firmly pressed back into the top of the stack sealing the top part of the duct When the fan is started, the air is blown through a canvas duct into the centre of the stack and then the air passes up the vertical duct. The air passes radially out through the hay in the lower layers of the stack and vertically up through the top layers in much the same manner as when wheat is dried in a radial grain drier. The fan unit used here was built up by the New Zealand Agricultural Engineering Institute using a backward tipped centrifugal fan (non overloading), a secondhand baler engine and appropriate belts and pulleys. It has been constructed so that by shutting a door in the air intake, waste heat from the engine can be used to correct the humidity under damp conditions. The unit has been Constructed on a trailer base so that it can be easily shifted from the hay barn to the granary for drying grass seed and grain. It is a dual-purpose type of fan unit. It provides more than 8000 cubic feet of air a minute at five inches water gauge and more than 10,000 cubic feet at two and a half inches water gauge a s when used for drying hay.