Recirculating air below the crop
More productive tomato plants with less energy
Henk van de Velde grows tomatoes in two different glasshouses and has been trying to create a better humidity environment using two methods. The first method involves recirculating air above the crop in one of his glasshouses, while the second involves recirculating air below the crop in the other glasshouse. Data from the 2007 – 2008 growing season have shown that positioning the recirculation fans below the crop has resulted in healthier and more productive plants. What is remarkable about these results is that they were achieved using less energy (because of a lower pipe temperature) and less electricity to operate the fans.
Henk van Velde’s glasshouse is 6m high and is equipped with a gutter mounted 75cm from the ground. The recirculation fans are attached to the gutter using specially-designed hinge brackets, allowing the fans to be secured flat underneath the gutter when the crop is cleared. At first, one time the glasshouse volume of air was recirculated per hour. Now, the free outflow of air, without the need for air hoses, has enabled sufficient air movement to be created at the bottom the crop using the same number of fans at a lower speed. As a result, the fruit are showing fewer swelling cracks and the crop is responding more favourably to pipe heating in the early morning. Crop transpiration has also increased from 58% to 75%. Another interesting fact is that this recirculation method requires a pipe heating temperature of only 38°C.
HortiMaX fans, model MRVL, were used for this application.
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14 - 16 February 2012
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