The most common method of fertilizer and plant protection delivery to plants for today is the spraying of working fluid droplets, although there may be another technical approaches.
Methods of spraying of the the active substance can be:
This approach is most known today. Using various spray nozzles (injection, mechanical) water jet, is transferred to the state of a drop suspension. Usually, a mechanism of accelerating of the working fluid relative to the environment is used. The liquid, under the influence of the sum of factors, is split up from the jet-filaments into separate droplets.
Further, under the influence of the forces of density, air movement and surface tension, droplets of various sizes of spherical shape are formed. Most sprayers generate droplets, with a certain range of size. To get predictable results, use sprayers from well-known companies. In this case, you get a predetermined size of the droplets, the speed of their flight and, as a result, the quality of the processing area.
It is usually «typical» for aviation way of applicating of the plant protection products and technologically difficult to implement in other conditions. The first grinding of the liquid flow into droplets occurs at the moment of spout from the spray nozzle. The second grinding occurs when high-speed droplets come into contact with stationary atmospheric air.
Obviously, without such conditions (high speed of movement of technology relative to the atmosphere), this mechanism is difficult to implement. Disadvantages - it is impossible to accurately set the rate of outflow per unit area. You can only set the total amount of liquid used over a given territory. The impact of wind drift on the quality of processing is very large.
The process of disintegration into droplets of films and liquid strands is called direct spraying. But at the same time the reverse process occurs - kinetic coagulation of the drops into larger ones when they collide while moving at different speeds. Turbulent air flow complicates the trajectory of the droplets, the latter are in contact with each other - turbulent coagulation occurs. Both of these mechanisms exist at the same time and must be taken into account when fertilizing.
This is an addition to the traditional technology of spraying the working solution. Spray drops are charged by a special installation using electron-ion technology. As a result, the drops are more actively attracted to the leaves of the plants, and not just settle down under the influence of gravity. This technology has certain limitations, since the charged drops more intensively settle on the edges of the leaves, which leads to an uneven coating of the plant surface.
To the working solution, substances are added which, when sprayed, polymerize in air, with the formation of threads on which droplets are strung. This contributes to a more rapid gravitational sedimentation of the drug on the leaves and soil.
In this case, aerosols are obtained by either grinding powders (granules) or by evaporating the liquid from the suspension, solution.
The mechanism is similar to the process of cloud formation. The pre-heated air stream contains a significant amount of liquid dissolved in it. Upon contact with colder ambient air, supersaturated vapor appears and condensation of the liquid into droplets begins.
The process of creating such an aerosol is two-phase. During the first, the working fluid (usually the solvent is mineral oil) is heated to 600° C, which causes the solvent to evaporate. The second phase begins immediately after exiting the nozzle — cooling the mixture begins the reverse process — condensation from supersaturated steam. Particles of the working substance and ash are also the nuclei of condensation. Such a thermomechanical aerosol is usually used for treating premises or trees from parasites.
This method provides several options for exposure:
Suitable for processing land, greenhouses, greenhouses, granaries, forests.
To protect the seeds from the spores of fungi they are heated in water. It maintains germination and destroys fungal spores. Although this method does not apply to the spraying of plant protection agents, it performs the same role - it protects the crop at the pre-sowing stage.
To protect the seeds from pathogens of various diseases at the stage of sowing, dressing is used. Allocate dry, wet and semi-dry dressing.
For dry dressing, the pesticide is sprayed over the seeds, which must be moistened beforehand. This contributes to the adhesion of the substance to the surface of the seed.
The wet method consists in applying a pesticide solution to the seeds. In this case, the shelf life before sowing is minimal, or the grain should be dried immediately.
As an intermediate option, the semi-dry method is used, in which the consumption of the working solution is not more than 15 liters per ton of grain. In this case, it is permissible to store the seeds without additional drying while waiting for sowing.
A variety of seed treatments - inlay. In this case, the polymerizing components are added to the solution of water and pesticide. The solution forms a film that covers the seed and fixes the active substance on the surface.
Even more advanced technology - dragee. In this case, several shells are fixed to the surface, each of which contains a different substance. In this case, each seed will be protected by a multilayer film with a «kit» of herbicide, pesticide, repellent, fungicide and other substances.
Regardless of the technology used to deliver the active substance to the place of use, the main goal when using plant protection products is to protect the crop from diseases and pests. The most widespread liquid forms of fertilizers and plant protection products, due to the simplicity of accounting and control of their use. Liquid fertilizers and plant protection products can be mixed in one tank without specialized equipment, a similar process for dry components is technologically much more difficult.
Fluid movement is easier to control, the speed of this process can be changed very quickly, which allows you to accurately maintain the rate of outflow, even with unstable speed of movement of equipment on the field. Liquid droplets adhere well to the surface of the leaves, as opposed to sprayed dry matter.
