Compiled by JP le Roux
Protect your crops 1:
What makes a good sprayer? O
ne of the most important weapons in the farmer’s arsenal is a good herbicide. However, this will do the farmer no good if he cannot apply it to his crops effectively. Having the right tools for the job is of the utmost importance to ensure that you can protect your crops against weeds that can easily diminish your yields. There is a strong correlation between the efficiency of the herbicide and the efficiency of the mode of application. It is therefore important that the farmer uses effective spraying equipment and to calibrate the sprayer correctly. It is essential that the farmer has adequate technical knowledge of all the parts of a sprayer before he decides which one to buy. It will save a lot of time and money, and minimise wastage if the farmer understands the sprayer and knows how to operate it effectively.
Sprayer tank
The tank must be made of a material that cannot corrode easily. The inside of the tank should have a smooth surface to make easy and thorough cleaning and rinsing possible.
A tank with a recessed opening will limit spillage when it is refilled. The opening of the tank should be at least 250 mm wide to allow easy access to the working parts inside the tank. It is essential that the tank must have an outlet on the bottom to allow easy cleaning after use.
Filters
The quality of the filters will play a major role in limiting maintenance time and costs on the sprayer nozzles. The filters will prevent any particles from clogging the nozzles that can lead to uneven application in the field. A minimum of two good-quality filters is recommended to ensure smooth operation; one can be a suction filter and the other a flow-through filter. A screen should also be added to the inlet of the tank to catch any larger particles that may be in the water or crop protection product. Suction filters with screens finer than 100 mesh (around 200 mesh) can limit the flow of certain wettable powders, but is essential when smaller sprayers are being used. Although screens from 150 to 200 mesh can cause problems and uneven spraying by getting blocked partially without the operator noticing it in time, it is still better to use them and clean them regularly. It is easier to clean screens than blocked nozzles. Effective filters are essential for the effective operation of the spray system. Therefore, they must be cleaned regularly and inspected for damage. Use a filter that is easy and quick to clean, without having to take it apart. Certain filters only have a screw top than can be removed for cleaning.
Mixing
The sprayer’s main and mixing tank must be rust resistant.
A mixer in the spray tank is essential to distribute the chemicals evenly through the water and to keep the solution in suspension, preventing the chemicals from settling at the bottom
ProAgri Botswana / Namibia / Zimbabwe 13
and causing fluctuations in application quantities. For proper mixing in tanks holding less than 1 000 litres, there should be a separate pipe between the pump and the closing valve, situated in such a way that it continuously mixes the content of the tank. The open end of the pipe should be close to the bottom to prevent material from settling down on the bottom. For spray tanks larger than 1 000 litres a special mechanical mixer is recommended. It is essential for any tank holding more than 2 000 litres.
The pump determines the effectiveness of the sprayer and is therefore one of the most important components. The main tank and mixing tank should be corrosion and rust resistant. 39
