Air supported boom sprayer.
Protect your crop 3:
Choose between trailed, hitch or self-propelled sprayers I
n the previous issue we discussed different spray nozzles and the importance of making the right choice. Another choice must be made between models being drawn by a tractor, models carried on the hitch and self-propelled sprayers, but first some more information on the interesting method of using air-supported boom sprayers. Air supported boom sprayers Air-supported boom sprayers appeared in South Africa in the nineties, although the principle had already been launched abroad earlier. The principle of operation The tractor drives a fan, and the airstream is blown into a strong PVC bag or stocking. This airstream is then forced out through a series of holes at the bottom of the bag. Air speed at the outlets is approximately 50 m/second. The air volume and air speed are the same at each outlet across the length of the bag. The spray boom is mounted under the bag. The spray nozzles on the boom are placed 250 mm apart and are mounted at an angle of 30° to the vertical airstream. The airstream pushes the spray droplets to the plants or the soil. The air movement also ensures that the spray reaches the bottoms of the leaves efficiently. The outstanding features of the spray are that, instead of high volumes of water (250 litres/ha and more) and large droplets such as in conventional boom sprayers, the air supported boom
sprayer uses lower volumes (30 to 75 litres/ha) and smaller droplets being pushed by a strong vertical air stream towards the soil. Some of the farmers who purchased the sprayers are satisfied that they apply herbicides and pesticides very effectively. They particularly emphasised the following beneficial properties of the sprayers and the spraying principles:
Air supported sprayer (75 â„“/ha) = 37 500 litres for 500 hectares Conventional sprayer (250 â„“/ha) = 125 000 litres for 500 hectares The savings in the quantity of water to be supplied in the field are therefore obvious, especially where water needs to be transported over long distances to fields.
Less water At 30 to 75 litres of water per hectare commonly used by air supported boom sprayers, the cost and effort to transport clean water to the fields are immediately alleviated. Comparing the water needs of an air supported boom sprayer and a conventional sprayer for 500 hectares, the results are:
Tractor hitched sprayer.
ProAgri Botswana / Namibia / Zimbabwe 15
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