Daily operation questions about drip irrigation
Author:
Release time:
2020-09-14
1: What is drip irrigation technology? Drip irrigation technology refers to the technique of using pressurized water to irrigate crops in a dripping state through water-dissipating devices such as drippers, drip arrows, drip irrigation pipes, and drip irrigation tapes.
2: In which country did the intelligent water-fertilizer integrated drip irrigation technology originate?
It originated in Israel.
3: Compared with traditional irrigation technologies, what are the advantages of drip irrigation technology? Why?
1) Labor saving: Completely breaks through the traditional irrigation model, one person can easily take care of hundreds or thousands of acres of crops. Whether it is intelligent automation or semi-automatic control, it is simply opening valves and pressing buttons, greatly reducing labor intensity and saving about 70% of labor.
2) Fertilizer saving: Through the drip irrigation system, combined with the currently popular fully soluble water-soluble fertilizers, water and fertilizer integration is easily achieved, accurately applying fertilizers to the roots of crops. The high utilization rate of drip irrigation water also leads to a high utilization rate of fertilization, saving more than 50% of fertilizers, and the nitrogen fertilizer utilization rate can be as high as 70%.
(3) Water saving: Changes the traditional disadvantage of flooding irrigation that waters the land instead of the crops. According to the water requirements of the crops, timely, appropriate, and controllable precise irrigation is achieved, avoiding deep seepage and surface runoff, and saving 40-70% of water. Drip irrigation is local irrigation, only moistening the crop root zone, and it is not easy to produce ineffective irrigation; frequent irrigation is easily implemented using drip irrigation technology, excessive irrigation is easily controlled; irrigation automation is easily implemented, and intelligent and precise irrigation is implemented; compared with sprinkler irrigation, it is not affected by wind and has no drift loss; evaporation loss is small.
(4) Peace of mind: The system is simple to operate, and the fully automatic intelligent control system can easily realize timed, fixed-point, and quantitative water and fertilizer supply. Irrigation and fertilization can be completed by simply opening valves and pressing buttons, which is very convenient.
(5) Electricity saving: The operating pressure of the dripper can be around 1 kg, while the operating pressure of sprinkler irrigation is often above 2 kg. Therefore, under the same irrigation area, the head operating pressure of the drip irrigation system is often lower than that of the sprinkler irrigation system; the water consumption of drip irrigation is small, and the total electricity consumption is smaller than that of sprinkler irrigation.
6) Land saving: Water is transported through pipes, and pipes are often buried underground, without occupying farmland. More importantly, drip irrigation is the most dependent irrigation method for three-dimensional cultivation. Easy and accurate water and fertilizer management solves the great inconvenience of manual operation at high altitudes, greatly improving the number and height of cultivation layers, making large-scale three-dimensional cultivation possible, and saving a large amount of land resources.
7) Increased yield: Based on the comprehensive effect of the drip irrigation system, the yield per unit area of crops can be effectively increased, generally increasing by 30%-60%, and some can even double.
8) Increased income: In addition to the huge benefits of increased yield, benefits can also be obtained from the savings of various resources mentioned above. In addition, using the drip irrigation system, the time to market for crops is advanced, thus obtaining extra high additional income.
(9) High quality: Because the water and fertilizer supply is timely and scientifically reasonable, the crops grow well, the fruits are full, the nutrients are sufficient, the shape of the fruits is beautiful, and the color is attractive.
(10) Environmental protection: Avoids a large amount of fertilizer being washed into rivers in traditional fertilization, reducing groundwater pollution; after using drip irrigation, the soil moisture is small, the humidity is low, the growth of weeds, pests and diseases is reduced, and the amount of pesticides is reduced.
4: What are the disadvantages of drip irrigation?
(1) Easy to clog: Because the flow path section of the dripper is small and the water outlet is small, it is easily blocked by organic and inorganic impurities in the water. This blockage is called physical blockage; if the water contains high levels of cations such as calcium and magnesium, it is easy to crystallize in the flow path and block the dripper. This blockage is called chemical blockage; in addition, green algae may sometimes grow in the flow path of the dripper, blocking the dripper. This blockage is called biological blockage. Using a filter can prevent physical blockage; acid washing can prevent chemical blockage; using chlorination can prevent biological blockage.
(2) High management requirements. IMG_0987.JPG
5: What are the types of drippers? How are they usually selected?
(1) On-pipe drippers, in-line drippers
The so-called on-pipe drippers refer to drippers that can be installed on capillaries and PE pipes on site. In-line drippers refer to drippers that can be directly embedded in polyethylene pipes during production.
On-pipe drippers are flexible to use, and the dripper installation spacing can be adjusted on site according to the irrigation requirements of crops to better meet the water requirements of crops. The disadvantage is that installation is time-consuming, labor-intensive, and inefficient.
On-pipe drippers are usually used to irrigate fruit trees, potted plants, trees, shrubs, flowers, etc.
In-line drippers are installed on the production line at a certain interval at the time of leaving the factory. During field installation, only a special connector (bypass, pipe fitting, etc.) is needed to connect the in-line drip irrigation pipe to the water supply branch pipe. This greatly saves installation costs and labor intensity, and improves installation efficiency. It is often used to irrigate fruit trees, vegetables, flowers, windbreak forest belts, etc. 6: What is drip irrigation tape? What is drip irrigation pipe? How to choose?
Drip irrigation soft tubes with a wall thickness of less than 0.6 mm are usually called drip irrigation tapes. When not filled with water, their shape is a soft tape. Huawi has a clear distinction: the finished product of drip irrigation tape is tape-shaped, and the embedded dripper is sheet-shaped;
while the finished product of drip irrigation pipe is tube-shaped, and the embedded dripper is cylindrical. Drip irrigation tapes are low in cost but have a short lifespan. The service life varies from one season to 5-8 years. The thinner the physical life, the shorter. Currently, the thinnest drip irrigation tape has a wall thickness of 0.1 mm. It can only be used for one season. Drip irrigation tapes are often used to irrigate densely planted crops such as vegetables, cotton, potatoes, corn, and flowers.
Drip tapes come in many forms. Some have independent drippers embedded in the tape, some have embedded inlets and continuous plastic strips for water outlets, and some are double-walled plastic films with water inlets and outlets pressed into the upper layer. The effects vary. Drip tapes with multiple inlets usually have good anti-clogging performance. Tapes with slit outlets usually have a certain anti-negative pressure soil suction capacity. Drip tapes have lower manufacturing costs, and thinner walls result in lower transportation costs. Multi-water outlet continuous patch-type drip tapes have good anti-clogging performance, and the price is irrelevant to the dripper spacing, making them very suitable for densely planted ridge-planted vegetables. Columnar drip pipes have higher strength, but higher cost and higher transportation costs. Drip pipes can be selected for crops with wide row spacing and high value. Orchards, high-value vegetable fields, and windbreak belts can use drip pipes.
7: What factors determine the lifespan of drip tapes and drip pipes?
Wall thickness, material, anti-clogging ability, water quality, filtration system, insect pests, rodent pests, soil stone content and sharpness, laying and recovery methods, and daily management and maintenance level, etc.
The thicker the wall, the stronger the resistance to physical damage and the longer the lifespan, but the initial cost is also higher. For multi-season use, the drip tape wall thickness must exceed 0.2 mm. After each season of use, some drip tapes are always damaged and must be cut off, and then reused with glue or connectors, or by heat fusion.
Drip pipes and tapes made of new materials have high tensile strength, wear resistance, and anti-aging ability, and a long lifespan. Currently, some drip irrigation products on the market add recycled materials multiple times, resulting in extremely poor tensile strength and anti-aging ability. Users should have the ability to identify them.
The use of multiple inlets for water intake and drippers with good flow turbulence performance results in high anti-clogging performance. If this aspect is poor, a carefully selected filtration system can prevent clogging.
When the water quality is poor (high sand content or high organic impurity content), a carefully designed and selected filter system should be used to extend the service life of the drip irrigation system. Filtration is the life of drip irrigation technology!
If thin-walled drip tapes (wall thickness less than 0.3 mm) are used, insects such as mole crickets in the soil will bite the drip tapes. An investigation should be carried out before laying. If found, measures should be taken to kill the insects.
8: What are the factors affecting the uniformity of water dripping in the system? In order to achieve high-yield and high-quality crops, irrigation uniformity is very important. Uniform irrigation is the only way to ensure uniform fertilization during drip irrigation. The factors affecting the uniformity of water dripping in the system are:
(1) Dripper manufacturing factors: To ensure uniform irrigation in the drip irrigation system, the water output of a single dripper must first be uniform. The parameter reflecting whether a single dripper is uniformly discharging water is the manufacturing deviation, denoted by Cv. The magnitude of the manufacturing deviation reflects the manufacturing precision of the manufacturer. The smaller the manufacturing deviation, the better the uniformity of a single dripper.
(2) Sensitivity of dripper flow rate to pressure changes: The flow index is usually high at the head of the capillary tube on flat ground and decreases towards the end. If the sensitivity is high, the water output will be lower towards the end, affecting yield and quality. The relationship between dripper flow rate and working pressure is expressed by the following formula: q=k×hx.
Where:
q—Dripper flow rate (liters/hour);
h—Working pressure (meters);
k—Flow parameter;
x—Flow index.
The flow index x reflects the sensitivity of the dripper flow rate to pressure changes:
- When the water flow in the dripper is fully laminar, the flow index x is equal to 1, i.e., the flow rate is proportional to the working head;
- When the water flow in the dripper is fully turbulent, the flow index x is equal to 0.5;
- When the flow index x is equal to 0, the water output is not affected by pressure changes. This state is called full pressure compensation. The flow index of various other types of irrigators varies between 0 and 1.0.
(3) Pressure compensation and non-compensation performance
Drippers can be divided into pressure-compensating drippers and non-pressure-compensating drippers. Pressure-compensating drippers have a flow regulating diaphragm inside. When the pressure is high, it reduces the flow cross-section to reduce the water output. When the pressure is high, it increases the flow cross-section to increase the water output. Pressure-compensating drippers have uniform water output. They can extend the laying length of the drip pipe, improve drip irrigation uniformity, and better meet the water and fertilizer requirements of plants.
Non-pressure-compensating drippers have no diaphragm in the flow path. The water output varies with the pressure at the dripper. The irrigation uniformity is low.
If the capillary tube is short and the dripper pressure does not change much, non-pressure-compensating drippers can be considered to save investment. In mountainous areas where pressure changes are large, pressure-compensating drip pipes are best used.
9: What equipment is typically configured at the head of a drip irrigation system?
As shown in the figure below:
The check valve in the figure prevents the irrigation water from flowing back; the valve between the upstream and downstream connecting pipes of the fertilization device creates a pressure difference to facilitate fertilizer injection into the system.
The two pressure gauges upstream and downstream of the filter are used to monitor the degree of filter clogging. The greater the pressure difference, the more severe the clogging. The management personnel control the filter flushing according to the pressure difference.
The third pressure gauge from the top is used to monitor the allowable pressure of the irrigation system; the flow meter is used to monitor the irrigation flow rate of each irrigation area in the system. If it is not within the normal range, it indicates that there is a problem with the system operation. Too high indicates leakage, and too low indicates dripper clogging or valve failure to open. Management personnel must learn to observe whether the irrigation system is operating normally through flow and pressure gauges.
The inlet and exhaust valves at the head are used to eliminate the vacuum in the pipeline and protect the safety of the head equipment.
The pressure regulator and solenoid valve at the head of the branch pipe are not essential components. If automatic control is used, a solenoid valve must be installed. If the pressure in the branch pipe may exceed the pressure level of the pipe or drip pipe/tape, a pressure regulator should be installed to reduce the pressure to the design level. If the pressure at the head of the branch pipe is not high, it is not necessary to install it. Generally, when installing a drip irrigation system in mountainous areas, the system safety should be fully considered, and sufficient pressure regulators, inlet and exhaust valves, and pressure relief valves should be installed.
10: What are the different types of drip irrigation filters used to prevent clogging, and how to choose them?
Generally divided into:
(1) Gravel filter: Also known as a sand media filter. It consists of quartz sand filled in a steel tank. Impurities are filtered through the sand medium. Gravel filters must be flushed alternately. Automatic backwashing is preferred.
Gravel filters are best for filtering organic impurities from river water and lake water. They are often installed as primary filters at the head of the drip irrigation system.
(2) Centrifugal filter: When irrigation water passes through this type of filter, the water flow is centrifugal, separating larger sand particles and entering the sand collection tank. After a certain period of accumulation, the sediment is manually or automatically discharged.
Centrifugal filters are most suitable for filtering well water. They are often used as primary filters in well water drip irrigation stations.
(3) Mesh filter: A filter that filters impurities through a screen.
When the water quality is good, the mesh filter can be used alone. It is generally used as a secondary filter in conjunction with gravel filters and centrifugal filters.
(4) Disc filter: A disc filter is a device in which grooved plastic discs are stacked together, and water passes through the channels formed by the grooves, intercepting impurities to achieve filtration.
Similar to mesh filters, they can be used alone when the water quality is good. Generally used as a secondary filter in conjunction with gravel filters and centrifugal filters.
Common filter combination schemes
River water and lake water rich in organic impurities:
Gravel filter + mesh filter or disc filter;
Well water rich in sand:
Centrifugal filter + mesh filter or disc filter;
Good water quality:
Use mesh filter or disc filter alone.
11: What are the different types of filter flushing? How to choose?
Filters generally have: hydraulic direct flushing, hydraulic backwashing, and suction backwashing. Hydraulic backwashing is the traditional flushing method. Backwashing is generally considered better than direct flushing. Suction backwashing is a recently developed flushing method with very good results, but it is currently only implemented on mesh filters.
Automatic filter flushing is best. However, the Price of automatic flushing filters is much higher than that of manual flushing. Automatic flushing has two control modes: pressure difference control and time control. Pressure difference control is better than fixed-time control.
12: What are the different control methods for drip irrigation systems? How to choose?
Drip irrigation systems can use three control methods: manual control, semi-automatic control, and fully automatic control. Manual and semi-automatic control are often used in agricultural drip irrigation.
Manual control equipment is simple and can use gate valves, ball valves, butterfly valves, etc. to control according to experience or a prepared irrigation schedule. Manual control is very common in agriculture.
Semi-automatic control equipment includes: timers (or metering), solenoid valves, and wires. Irrigation managers program irrigation on the controller according to experience or a prepared irrigation schedule.
A fully automatic irrigation system is controlled by a computer. It has a high level of intelligence and makes it easier to achieve precise irrigation, fully meeting the water requirements of crops. The computer sends commands to the field controller. The controller starts the water pump, controls the valve opening, controls the filter flushing, and controls the fertilization system, etc. Various sensors can be connected to the controller, such as: soil moisture sensors, soil temperature sensors, conductivity sensors, PH sensors, flow sensors, rain sensors, etc., used to monitor the crop growth environment and automatically adjust.
Fully automatic irrigation systems are the future trend. However, due to the complexity of design, installation, debugging, and management, it requires high-level, well-trained excellent design, installation, and management personnel. At present, it is not suitable for large-scale promotion in agriculture in China.
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