What is the relationship between flower cultivation and meteorological conditions? An analysis of greenhouse tidal irrigation systems
I. Overview of the tidal irrigation system
The tidal irrigation system is a highly efficient water-saving irrigation system designed on the principle of tidal ebb and flow. It is suitable for the cultivation and management of various potted plants and can effectively improve the utilization efficiency of water resources and nutrient solution. Tidal irrigation is mainly divided into two types: floor-type and bench-type. The floor-type tidal irrigation system involves building a water-storing seedling tray pool on the ground surface, in which several outflow holes and return holes are distributed; the bench-type tidal irrigation system involves building a large-area water-storing seedling tray on the bench, with outflow and return holes reserved in the tray. During application, irrigation water or a properly proportioned nutrient solution overflows from the outflow holes, causing the water level in the entire bench to rise slowly and reach a suitable liquid level height (called the flood tide), submerging the cultivation bed to a depth of about 2-3 cm; after maintaining this for a certain period (sufficient absorption by the crop roots), about 10-15 minutes, the nutrient solution rises to the surface of the medium in the pot through capillary action. At this point, the return opening is opened to discharge the nutrient solution back to the nutrient solution tank (called the ebb tide), and the nutrient solution is sent out again when another cultivation bed needs water. The tidal irrigation system has equipment for adjusting the pH value of the nutrient solution and various nutrient concentrations, as well as a filtration system and disinfection system to prevent the nutrient solution from becoming excessively turbid. Bench-type tidal irrigation systems all require elevated specially made cultivation benches, so the corresponding equipment costs are also relatively higher.
II. Advantages and features of the tidal irrigation system
Tidal irrigation is a mature agricultural irrigation technology that has been widely used in developed countries. It effectively resolves the contradiction between irrigation and oxygen supply, and irrigation basically does not destroy the "three-phase" composition of the substrate. It is a highly efficient and high-energy agricultural technology, and in China it is also in a stage of widespread development and application.
1. Water-saving and efficient, with a completely closed system circulation that can achieve a utilization rate of 90%;
2. Plants grow faster; the seedling age per week can be 1 day earlier than with traditional seedling-raising methods, improving facility utilization;
3. It avoids the formation of a water film on plant leaf surfaces, allowing leaves to receive more light for photosynthesis and promoting transpiration pull to absorb more nutrient elements from the roots;
4. Stable water and air content in the root medium, preventing capillary roots from dying due to drought near the edges and bottom of containers;
5. Relative humidity is easy to control, keeping leaf surfaces dry and reducing the amount of chemical agents used;
6. No weed growth under the bench, reducing fungal breeding, because the area under the bench is very dry;
7. Lower management costs; whether operated manually or assisted by a microcomputer controller, one person can complete the irrigation of 0.2~0.5 ha. of plug seedlings within 20-30 min;
8. It can be used at any time, without restrictions on variety, specification or time.
9. With general sprinkler irrigation methods, each plant absorbs fertilizer and water unevenly, causing the finished product rate to decline, whereas the tidal irrigation finished product rate is 100%, and production achieves standardization, with uniform height for each plant and guaranteed quality.
10. With tidal irrigation, fertilizer is absorbed directly by the roots, water does not contact the leaf surface, and the leaves are glossy, allowing a higher selling price. Calculating on the basis of producing 25 pots per sq m, if quality is improved so that each pot sells for 5 to 10 yuan more, the income per sq m can increase by as much as 125 to 250 yuan, making the return on investment considerable.
III. Description of the tidal irrigation system
Flood tide: On both sides of each cultivation bench there are delivery pipes, with a water pump installed at the front end of the pipe. An automatic irrigation controller controls the nutrient solution being sent from the fertilization system through to the cultivation bench. This ensures that the flood tide is completed within a certain time.
Ebb tide: When the flood tide water pump stops working, after the plants have been irrigated, the automatic irrigation controller controls the return water pump to start and send the nutrient solution back to the return liquid tank.
IV. Tidal irrigation system configuration
Tidal irrigation system configuration is divided into floor-type bench irrigation system configuration and seedling bench-type irrigation system configuration. The floor-type bench irrigation system is suitable for cultivating larger plants, while the seedling bench-type irrigation system is suitable for cultivating smaller plants.
Floor-type irrigation bench design
According to the size of the greenhouse and the owner's requirements, the cultivation bench is built. Water flow channels of different depths are built on the cultivation bench in both the north-south and east-west directions. During the flood tide, the deep channels running north-south distribute the incoming water across the cultivation bench. Because the water level rises continuously, the shallow channels running east-west deliver water to the bottom of the flower pots, and a splash guard cover is installed at the water inlet. The water on the cultivation bench reaches the bottom of the flower pots almost at the same time. During the ebb tide, the water flowing out of the flower pots passes through the east-west shallow channels and directly collects into the north-south deep channels, and then the north-south deep channels send the excess liquid back to the return liquid tank.
Seedling bench irrigation system design
Beneath the end of each cultivation bench there is a nutrient solution supply tank, and a submersible pump is installed inside the tank to send the nutrient solution from the tank through the liquid delivery pipe to the cultivation bench. The pump flow rate should ensure that the flood tide is completed within a certain time. A buffer device is installed at the top of the liquid delivery pipe to avoid wetting the plant leaves. When the water pump stops working, the remaining liquid returns to the liquid tank through the same pipe and pump, so that the same pipe can be used for both irrigation and recovery.
Except that the bench surface uses a tidal inflow and drainage tray, which differs from the floor-type tidal irrigation system, the seedling bench-type tidal irrigation system configuration is basically the same as the floor-type tidal irrigation system configuration in other respects.
The irrigation schedule can be transmitted by a substrate tension meter on each cultivation bench to the greenhouse environment control computer, and the computer controls the water pump through the controller. When the computer receives a value below the set tension value, the program starts the water pump, and the working time is a fixed value. The substrate moisture tension meter consists of a highly flowable ceramic tip plus a sensitive pressure sensor controlled by the computer environment control, and the tension meter will respond instantly to changes in moisture tension in the substrate.
1. Fertilizer machine system setup
The fertilizer machine contains 4 nutrient solution tanks, 1 acid tank and 1 mixing tank.
It is mainly composed of the following 4 parts.
① The injection pump and three-way flow valve from the feed liquid tank to the mixing tank according to the nutrient ratio.
② The mixing tank that combines water, nutrients and acid liquid under normal pressure.
③ The main pump that delivers the liquid in the mixing tank to the irrigation area.
④ The fertilizer machine's hardware integration board is composed of EC value, pH value and flow input terminals, as well as acid pump, nutrient pump, solenoid valve and main pump output ports.
2. Computer control system
The fertilizer machine can continuously provide water and nutrient solution to plants according to the optimal growth conditions of the plants. The fertilizer machine has 5 separate fertilizer injectors, controlled by the same environment control computer in the greenhouse. Software programs control the water flow and the nutrient ratio of each valve. The entire system is composed of software, hardware, transmission equipment, sensors, environment control, irrigation control and nutrient control.
3. System operation
The fertilizer machine uses a solenoid three-way valve to achieve precise feeding from the feed liquid tank to the mixing tank. According to the nutrient ratio requirements, the solenoid valve can supply liquid to the mixing tank or return it to the original liquid tank.
The computer can monitor and alarm the pH value and EC value of the liquid flowing out of the mixing tank and adjust the flow rate. The mixing ratio of the mixed liquid can be pre-set by the grower, and this monitoring is only to ensure the normal operation of the system, not a form of real-time control. Due to system or ratio sensor faults, when the ratio of the mixed liquid exceeds the set limit, the system alarms and takes necessary measures.
Because the number of opened irrigation valves differs, when the system output flow changes, the computer automatically controls the feeding amount of the nutrient solution through the solenoid valve to ensure the set ratio and flow rate.
Description of main equipment configuration
1) Automatic irrigation and fertilization unit
The automatic irrigation and fertilization unit is controlled by a controller. It was specially developed for the greenhouse horticulture industry and is a proven stable and reliable controller. By installing the control panel on the irrigation unit, control of the irrigation unit can be achieved. The opening and closing of the solenoid valve can be controlled through pre-set start conditions, thereby controlling the progress of irrigation and fertilization. Start conditions can be set in combination with time, light intensity, accumulated light and external control conditions. The machine can accurately control EC and pH values, so each crop will receive a strictly quantified amount of fertilizer. In long-term practice, growers can easily and more fully grasp information about water and fertilizer usage for this crop, thereby being able to cultivate higher-quality products.
The components used in the automatic irrigation and fertilization system are all tested high-quality components to ensure that it can operate well. It can be used alone to control irrigation and fertilization in the greenhouse, and can also be used in combination with other automated control equipment in the greenhouse to achieve overall automated control of the greenhouse. As an additional service, we can design the most ideal overall irrigation and fertilization system for users according to their specific needs.
The fully automatic irrigation and fertilization control system brings customers multiple benefits:
- Efficient fertilization for all crops;
- Saves on expensive fertilizer and water usage;
- Accurate, stable and reliable;
- Simple stainless steel frame, with flexible and diverse options;
- Can be used as a "standalone" irrigation unit or as part of a complete greenhouse control solution
- Can record irrigation and fertilization data
- High cost-effectiveness
System configuration:
Stainless steel frame: outer packaging dimensions are 1.68mx1.40mx1.15m (hxlxb)
Mixing tank system: mixing tank volume is 0.2m3
Water pump: at a pressure of 3.5bar, the hourly water output can reach 12m3, 20m3 or 40m3
Float flow meter (one on each feed pipe)
2 EC and pH sensors
Electronic interface design conforms to international standards
Electronic flow meter
1x130Micron filter
3 readable pressure gauges
2) Computer irrigation control:
White electrical cabinet box, 8 buttons
Operated through universal symbols
Menu display (no need to remember any codes/encoding)
The display can show 2 lines of letters, with 40 characters per line
40 output signals to control external devices
20 input signals to connect various sensors
Can record and report irrigation data, and can view historical data
Automatic background light display function
Accurate, stable and reliable EC/pH control
Can control up to 8 feed pipes
10 start conditions control the opening and stopping of solenoid valves
Opening control of each solenoid valve, with one cycle every 24 hours
Chinese operation interface
3) The disinfection system has two types: ultraviolet disinfection device and ozone disinfection device, choose either one
Ultraviolet disinfection device
The ultraviolet disinfection device uses ultraviolet light with a wavelength of 225nm-275nm to strongly kill microorganisms, killing microorganisms in the raw water.
Product features
Fast sterilization speed, does not change the physical or chemical properties of water, does not increase the odor of water, does not produce harmful halogenated methane compounds, and has no side effects.
The water treatment cylinder is made of imported high-quality stainless steel, can withstand a working pressure of 1.2MPa, and has the advantages of rust prevention, high strength, no metal ion contamination, and easy cleaning of the equipment surface.
The ultraviolet lamp is a professional new product appraised by the national health department and epidemic prevention department, with a power of 30W and a main spectral line of 253.7nm. Ultraviolet light at this wavelength has the highest sterilization rate, reaching over 98%, with low energy consumption and a continuous service life of over 3000 hours, and is equipped with reliable ballast equipment.
Modular electronic control device, with complete functions and standard timing, adopts an integrated design with the water treatment cylinder, and has the features of convenient installation, simple operation, safety and reliability, and easy maintenance.
Ozone disinfection device
Ozone disinfection device 1 unit
Ozone output: 5g/h Product dimensions: 350*250*580mm (length*width*height)
Ozone concentration: air source 5-20g/m3 oxygen source 20-35g/m3
Cooling method: air cooling Power supply: 220V/50Hz
Power: 160W (power size adjusted according to actual needs)
Gas source type: dual-purpose type for air source and oxygen source, built-in oil-free air compressor, air compressor with independent control switch
Product configuration: dehydroxylated quartz structure ozone generator unit, all-stainless steel chassis, precision ammeter, fan, with ozone regulator (knob type), etc.