Drip irrigation System - Service

Drip irrigation. Irrigation system maintenance.

Drip irrigation systems, including underground drip irrigation systems (UDI), are becoming more widespread. An important aspect of such systems is reliability. This applies to both surface and underground drip irrigation systems. Since the pipes of the underground irrigation system are located directly in the soil, the reliability of the operation of such a system is decisive.

Drip irrigation systems are potentially very reliable, however, such systems often operate for a short time. The main reason for the failure of drip irrigation systems is clogging of the droppers. Mechanical blockage is easy to avoid. It is necessary to use a reliable and efficient filtration system, but unfortunately, often the main reason for the failure of the drip irrigation system is chemical and bacteriological clogging.

Routine maintenance is critical to prevent problems with poor system performance, irrigation uniformity, and to ensure the longest possible system life. The problem of the reliability of the operation of drip irrigation systems was seriously approached precisely with the beginning of the introduction of underground drip irrigation systems. In such a system, it is very difficult and expensive to replace the drip tube and at present such systems have been successfully operated for more than 15 years after their installation.

How to achieve this?
The first step to maintaining the effective and long-term operation of the system is the selection of the water source that will be used for irrigation and the development of a system of measures related to adaptation to water sources and system maintenance techniques. This information will assist you in determining the requirements for maintaining the system in good condition and in developing ways to flush the system.

Note: All of the above can be attributed to sprinkler systems, especially to systems with a fine spray of water.

Water quality
Initially, you need to be very careful when choosing a water source that must provide the required quantity and quality of water. The ability to irrigate the required areas and the determination of technical solutions to ensure the reliability and methods of maintaining the system depend on this.

There are three types of clogging hazards in the IV and the system. These potential hazards must be considered in design and operation. These are physical, chemical and biological factors.

Physical blockage by sand and silt.
Reliable filtration allows you to eliminate mechanical particles above the permissible size for a particular drip tube model. Typically, the size of mechanical impurities should not exceed one tenth the size of the smallest diameter of the dropper channel. This is due to the fact that larger particles can lead to clogging of the dropper, especially if the water used contributes to the formation of mucous biological plaque on the walls of the tube or in the droppers, to which mechanical particles can adhere.
Chemical clogging hazard:
- Bicarbonates in concentrations exceeding 2 meq / l and water pH above 7.5. Calcium carbonate causes deposits of insoluble calcium compounds to form deposits on the inner and outer surfaces of the droppers. This plaque, similar to the scale in a teapot, gradually gets thicker and eventually clogs up the droppers.
  Control measures - acidification of water to pH 7.0 and below.
- Calcium retained in water can cause precipitation when some phosphate fertilizers are used. To prevent the problem, special conditions for the addition of phosphorus fertilizers are necessary.
- High concentrations of sulfide ions can cause deposition on the tube walls and on the droppers of iron and manganese. These deposits are very persistent, even when the system is treated with acid.
  Constantly acidifying the water or using a pool to settle the water helps to solve this problem.
- Water containing more than 0.1 mg / L of sulphides can stimulate the growth of sulfur-feeding bacteria in the irrigation system. Continuous chlorination of the water may be required.
- If manganese salts are present in the water, chlorination should be used with caution, as this can lead to blockage of the droppers.
Not all of these factors are present in the water of a particular source. Therefore, it is very important to select the right water source and to do a chemical analysis of the water that is planned for use in the drip irrigation system. Table 1 summarizes the water quality requirements and describes the potential clogging threats to the irrigation system.
Biological hazards of clogging due to the development and growth of bacteria and algae in the drip tube and droppers. They, in combination with fine particles of silt and clay, can clog the droppers. Bacterial plaque and sulfur and iron deposits are also related to this problem.

Table 1. Water quality and factors affecting the reliability of drip irrigation systems.

			Hazard level
			Low	Moderate	High
рН			<7,0	7 - 8	> 8,0
Bicarbonates	HCO ₃	meq / l	<2,0	> 2,0	> 2,5
Iron	Fe	mg / l	<0,2	0,2 - 1,5	> 1,5
Manganese	Mn	mg / l	<0,1	0,1 - 1,5	> 1,5
Hydrogen sulfide	H ₂ S	mg / l	<0,2	0,2 - 2.0	> 2,0
Total dissolved substances	ТДС	mg / l	<500	500 - 2000	> 2000
Solids		mg / l	<50	50 - 100	> 100
Bacteria		quantity / ml	<10,000	10,000 – 50,000	>50,000

Methods to Avoid System Blockage
Methods to remedy a variety of water quality problems are listed below.

Problem	Options and Solutions
Carbonate precipitation (white bloom)	Continuous acid addition: pH must be maintained between 5 and 7. Periodic acid addition: pH around 4.0 at final watering daily.
Iron deposits (brown deposits)	Aeration to oxidize iron (Best for high iron salt concentrations of 10 mg / L or more) Chlorine precipitation. Add chlorine for accelerated precipitation of iron . Add chlorine at the rate of 1 mg / L chlorine for 0.7 mg / L iron Add before the filter in order to speed up filtering of the precipitate Lowering the pH to 4 or less at the final watering daily. A settling pond in front of the water intake. Additional aeration of water is very effective.
Manganese (black bloom)	Injection of 1 mg / l chlorine based on 1.3 mg / l manganese in front of the filter.
Iron bacteria (brown slimy plaque)	Chlorine injection in the amount of 1 mg / l free chlorine continuously, or from 10 to 20 mg / l, at the final watering daily. The pH must be no more than 7.0 for the chlorination to be effective.
Sulfur bacteria (white fibrous plaque on the inside of the tube)	Chlorine injection is constant in the amount of 1 mg / l, at 4-8 mg / l, hydrogen sulfide (pH must be up to 6.0 for chlorination to be effective), or Chlorine injection 1 mg / L free chlorine at final watering daily. (pH must be up to 6.0 for effective chlorination).
Bacterial sediment and algae	Chlorine injection at 0.5 - 1 mg / L continuously or 20 mg / L for 20 minutes at the end of each irrigation cycle.
Sulfurous iron (black sand)	Dissolve iron by adding acid continuously to lower the pH between 5 and 7.

Monitoring and preventive maintenance

For reliable operation of the drip irrigation system, you must follow the recommendations that we give below in this article.

Use reliable water filtration systems to minimize the amount of sand, dirt, silt and debris in your irrigation water. When using water from natural sources, such as rivers, canals, etc., it is desirable to use sedimentation ponds.
Check the irrigation system regularly to identify and correct problems that arise.
Periodically, it is necessary to check the quality and condition of the water at the ends of individual drip lines for the presence of dirt, sediments, bacterial mucus. It is advisable to take samples of contaminants for chemical and bacteriological analysis. This will help you pinpoint the cause of the contamination and find the most effective solution to the problem.
Conduct periodic analyzes of irrigation water.
Clean the system periodically in accordance with its technical condition.
Check the water flow on the meter. If there is a decrease in water flow per unit time, check if the filtration system or drip pipes are clogged. Flush the system if necessary.
Clean the entire system periodically, starting from the water supply pump. It is also necessary to flush the collectors, main and distribution pipelines.
In some cases, when flushing the system, it is necessary to increase the water pressure to ensure the rate of water flow in the pipes for reliable flushing of the system.
If using a fertigation system, use only soluble fertilizers. it is imperative to add fertilizers or other additives to the irrigation water before the filter. Use a fertigation system to acidify the water and normalize the pH.
For underground irrigation, use only dedicated, compensated anti-siphon drip tubing, and always use special tubing such as RootGuard®
On soils prone to cracking, use cultivation or loosening to close cracks. This will prevent the tubes from penetrating the soil through cracks in rodents and damaging the tubes.
Periodically check the water pressure at the most distant points of the system to monitor its condition.
Use quality materials and equipment for the irrigation system. Pay special attention to underground irrigation systems, as these systems are installed for a long period and require significant investments.
When operating the system, follow the recommendations of the equipment manufacturer or supplier to ensure optimum system performance.

Table 2. Recommended types of work for the maintenance of the PKO system.

Before installing the system

Water quality analysis

Before the first irrigation season (and any change in system parameters such as water pressure or flow)

1. Filtration system adjustment

cleaning the filters
adjusting the washing system
adjusting the washing frequency
adjusting the washing duration

2. Check pressure, total water flow, and irrigation uniformity.

Before the start of the irrigation season:

1.Testing and checking the system for pressure, total water flow, and irrigation uniformity.

2. Inspect and check the pumping station, pumps, motors, power supply, and automation.

3. Check water intake and pump.

4. Check all components and accessories. Replace faulty ones.

5. Inspect and check the coarse and fine filters.

6. Clean the system

During the watering season

1. Every day

bypassing the irrigated area and repairing any malfunctions that occur.
checking the filters.
checking the pressure and flow of water in the system.

2. Once a week

check for clogging of individual droppers
checking and cleaning filters
flushing the system

3. Once a month

checking and flushing the filters;
measuring the pressure in the distribution network of pipelines and comparing with the pressure in a clean system;
measuring the output of water from the droppers at individual points of the system and comparing with the technical parameters of the tubes;
check the pH of the water during flushing - keep the pH not higher than 6.5.

If necessary

1. Add acid

2. Add Chlorine

Annually before turning off the system

1. Complete thorough flushing of the system

2. Chlorination

Chlorination

Chlorination should be used regularly to kill algae and bacteria and reduce the harmful effects of other negative organic factors. Chlorination does not in any way affect the amount of lime or calcium carbonate deposits in the system. Liquid sodium hydrochloride is recommended as a chlorine source. It is usually introduced into the system using fertigation equipment if it is chlorine resistant. Chlorination is carried out either continuously (in small doses) or intermittently (in large doses).

The chlorine injection point should be located as close as possible to the treated area of the system since the concentration of residual chlorine decreases depending on the distance from the injection point.

Table 3. Recommended doses of chlorine

The task of chlorination	Chlorination method	Required concentration (mg / l)
		System start	End of the system
Precipitation warning	Constant	3 - 5	> 1
Precipitation warning	Intermittent	10	> 3
System cleaning	Constant	5 - 10	> 3
System cleaning	Intermittent	15 - 20	> 5

To check the quality of chlorination, it is advisable to use laboratory methods for determining active chlorine in irrigation water at the beginning and at the end of the system during the chlorination period to ensure the required concentration. Chlorine is more effective in acidic environments. High pH or alkaline water requires acidification so that the pH does not exceed 6.5 and chlorine works efficiently.

WARNING: Active chlorine is very dangerous. Follow all safety instructions for its use and do not allow it to come into contact with any fertilizer. Direct contact of chlorine and fertilizers can lead to an explosive chemical reaction.

Acid

Acid treatment should only be used to remove chemical deposits (carbonates, hydroxides, and phosphates). The acid is not effective for organic deposits. The purpose of using acid is to lower the pH of the water to a level where these chemical deposits become soluble and can be removed from the system. There are several technical acids that can be used for this purpose. These are hydrochloric, sulfuric, nitric, and orthophosphoric acids.

Preference is given to nitric and orthophosphoric acids. These acids are additionally also fertilizers since they contain nitrogen or phosphorus.

For periodic processing, the acidity of the solution can be of the order of pH 4.0. Knowing the water consumption per unit of time, you can calculate the required amount of acid. It is convenient to use fertigation equipment for working with acids, especially if it is equipped with a Ph.

The acid solution is injected for a period of 10 to 12 minutes. Check the pH level at the end of the system to make sure you have reached the desired value. After acid treatment, continue watering with clean water and thoroughly flush the system.

The acids are very corrosive to steel, cement, and aluminum. Polyethylene and PVC are acid-resistant. Ensure that the acid supply pump or dosing unit is acid-resistant and calibrate to the desired concentration.

WARNING: acids are very dangerous - always follow all operating instructions and safety precautions. Always add acid to water, NEVER add water to acid as this can cause dangerous chemical reactions.