The automotive sprinkler irrigation system is designed to reduce the costs of a sprinkler irrigation installation and eliminate the entire system of primary and secondary pipes within a farm. To eliminate these pipes, a set of mechanized equipment is created, based on the automatic movement of the emitters (sprinklers or micro-sprinklers).
Pivots and laterals are mechanized sprinkler irrigation systems that consist of moving an irrigation wing, thereby irrigating the entire crop area through a metal structure that supports the irrigation pipe and emitters. This structure is self-propelled and rotates around a point or follows the course of a PE pipe or channel, where it receives all the water, energy, and where the control elements are located.
Apart from the basic considerations in fertigation, we must consider the many limiting factors in the application of fertilizers through this irrigation system, which will involve a series of advantages and disadvantages.
Advantages:
- Application timing: Nutrient application can be carried out throughout the vegetative period of the plant.
- Types of fertilizers: Applying fertilizers with high mobility in the soil allows perfect regulation of its content in the soil profile.
- Uniformity of application: The uniformity of application will depend on the uniformity of the system’s irrigation.
- Cultivation tools: Many cultivation operations must be eliminated, especially mixing in chemical applications to avoid potential precipitation.
- Reduction of fertilizer doses: The possibility of applying fertilizers throughout the vegetative period, as well as their mobility in the soil, allows for a reduction in the doses applied, decreasing the risk of soil and groundwater contamination with proper timing of fertigation and irrigation.
- Reduction of mechanical damage to crops: The reduction of cultivation tasks performed with tractors reduces mechanical damage to crops.
- Possibility of foliar fertilization: Aerial application of fertilizers above the crop canopy makes foliar fertilization possible.
Disadvantages:
- Types of fertilizers: The mobility of different fertilizers in the soil is a limiting factor in the type of fertilizer to use. For example, potassium-rich mineral fertilizers with low soil mobility may not reach the plant’s root zone and thus be unusable.
- Solubility of fertilizers: Fertilizers must have very high solubility, avoiding precipitation issues. This increases fertilizer costs as cheaper options like ammonium anhydride cannot be used.
- Volatilization of fertilizers: The volatility of some fertilizers, such as those rich in ammonium, must be taken into account.
- Corrosivity of fertilizers: The possibility of many irrigation system components being in contact with fertilizers should be considered to avoid using materials that are not resistant.
Types of injection equipment:
Passive injection equipment
Using this type of equipment leads to reduced water pressure or water flow loss. Furthermore, calibration and flow adjustment are quite complicated. The use of such equipment is declining as modern irrigation systems are designed to operate at lower pressures. Moreover, automation is challenging with these systems due to the use of solenoid valves and pulse counters. In some cases, especially in small irrigation systems, proportional hydraulic injectors can be used, allowing the incorporation of one or two injection modules to dose one or two different products.
Active injection equipment
Most active injection systems used in agriculture use electric motors, which allow highly reliable injection control through frequency converters. Two main types of injection pumps are currently used:
Piston pumps
These allow selecting the nominal injection flow rate of the pump and safely adjusting the injection percentage by regulating the piston stroke or pump cycles per minute. It is also possible to incorporate multiple injection modules into a single pump for the application of more than one product simultaneously.
Membrane pumps
These injector pumps are mostly designed for low flow injections. In agriculture, they are generally recommended for chemigation in low-flow, low-pressure irrigation systems and for applying highly corrosive products.
Basic requirements for injection equipment:
- Manually or automatically adjustable.
- Made with materials resistant to the chemicals used.
- Availability of spare parts and easy maintenance.
- Ability to inject one or more products simultaneously.
- Capacity to adjust the injection flow up to 5%, with ranges of 1%.
- Correct dimensions considering maximum and minimum needs.