Intelligent Irrigation System and Control Method for Dual Control of Water and Salt in Rice-Crab Symbiotic Mode

Abstract

A water and salt dual-control intelligent irrigation system and control method for a rice-crab symbiotic mode, belonging to the technical field of agricultural irrigation. The irrigation system includes an automatic soil profile solution collection module, a remote control module, a Raspberry Pi development board module, a field transpiration, evaporation and leakage module, a water quality monitoring module, and an irrigation and drainage control module. According to the water level data of the crab-raising paddy field monitored in real time by the transpiration, evaporation and leakage module, the irrigation and drainage control module is regulated to carry out irrigation and drainage treatment; through the water quality monitoring module, the water body salt data and conductivity of the crab-raising paddy field are monitored in real time, and the irrigation and drainage control module is regulated to carry out water change and salt control to achieve dual control of water and salt; the system can also realize layered sampling and monitoring of the water body and soil profile of the crab-raising paddy field. The present invention realizes the tracking record and decision-making management of the water cycle and salt environment of the rice-crab symbiotic system, supports cloud monitoring and manual control, and realizes the intelligence and automation of water management and nutrient regulation in the rice-crab symbiotic mode.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural irrigation, and particularly relates to a water-salt dual-control intelligent irrigation system and a control method for a rice-crab symbiotic mode. Background Art

[0002] The rice-crab symbiotic mode is an efficient three-dimensional ecological mode that supplements the traditional rice cultivation with the cultivation of river crabs, with rice as the main body, river crabs as the supplement, soil as the foundation, mutual benefit between species, and complementary ecological advantages. Due to large market demand and policy support from government departments, the rice-crab symbiotic system has become a typical integrated farming mode in China, especially in the Northeast region. However, due to the high sensitivity of crabs to water and salt and the relatively rough management of water and salt, it has caused negative impacts such as low survival rate and unstable yield of river crabs: on the one hand, during the growth process of crabs, they are extremely sensitive to changes in water quality and soil salinity (Khoshnevisan et al., 2021). After fertilizing the paddy field and during the tillering water control period, the high-concentration nutrients in the water and soil environment will directly cause poisoning to the crabs, affecting the survival rate and yield stability of the crabs. On the other hand, the rice-crab symbiosis has formed a production mode with brand characteristics, such as Panjin river crabs, etc. However, most of these areas are saline-alkali areas with a relatively high degree of soil salinization. It is necessary to ensure the normal life activities of crabs through frequent drainage and irrigation, which not only causes serious waste of water and fertilizer resources but also has a series of important impacts on the physiological growth of rice. In addition, due to the higher ecological water demand of crabs, the field leakage amount is much higher than that of traditional paddy fields, resulting in a large amount of nutrient leaching and directly causing groundwater pollution (Wang Ang et al., 2019). Therefore, finding effective ways, rationally using science and technology, real-time monitoring the water and salt conditions in the paddy field, and timely taking effective measures to alleviate the poisoning effect of high water and salt concentrations on crabs and efficient water management meet the major needs of the country's "scientifically and reasonably utilizing paddy field resources and steadily developing integrated rice-fishery farming", and have important practical significance for realizing the green and efficient development of the rice-crab symbiotic farming industry. Summary of the Invention

[0003] In view of the above existing technical problems, the present invention provides a water-salt dual-control intelligent irrigation system and a control method for a rice-crab symbiotic mode. The irrigation system is an intelligent interaction system integrating data collection, monitoring, transmission, and remote control, which realizes real-time cloud monitoring of data such as field evapotranspiration, leakage, and nutrient leaching, and combines the obtained field water level, salinity, and conductivity data with the irrigation and drainage control module through an ultrasonic water level gauge and a water quality detector to maintain the appropriate state of water level and water quality through automatic control of paddy field irrigation and drainage.

[0004] The object of the present invention is achieved by the following technical solutions:

[0005] A control method for a water-salt dual-control intelligent irrigation system for a rice-crab symbiotic mode of the present invention

[0006] When the actual water level L of the paddy field > the upper limit of water storage L max2 , the system will automatically activate the drainage solenoid valve to drain the actual water level of the paddy field to the upper limit of water control L max1 , and then close the drainage solenoid valve;

[0007] When L ≤ L min , or when the conductivity TDS ≥ TDS max or the total salt content EC ≥ EC max , and , that is, when the salt content exceeds the standard at low water level, the system will automatically activate the irrigation solenoid valve to fill the paddy field water level L to L max1 , and then close the irrigation solenoid valve;

[0008] When TDS ≥ TDS max or EC ≥ EC max , and , that is, when the salt content exceeds the standard at high water level, the system will automatically open the drainage solenoid valve to drain the paddy field water level L to half of the current water level (L / 2), then close the drainage solenoid valve, and open the irrigation solenoid valve to fill the paddy field water level L to L max1 ;

[0009] Among them, L is the current paddy field water level; L min is the lower limit of water control; L max1 is the upper limit of water control; L max2 is the upper limit of water storage; TDS is the current paddy field conductivity; TDS max is the conductivity threshold; EC is the current paddy field water salt concentration, that is, salinity; EC max is the salinity threshold.

[0010] The rice-crab symbiotic mode water-salt dual-control intelligent irrigation system adopting the above control method of the present invention includes a remote control module, a Raspberry Pi development board module, and a soil profile solution automatic collection module, a field surface transpiration evaporation and leakage module, a water quality monitoring module, and a paddy field irrigation and drainage control module which are respectively connected thereto. The remote control module includes a PC terminal with a control program, which communicates with the Raspberry Pi development board module, remotely transmits the water level data and salinity data obtained by the field surface transpiration evaporation and leakage module and the water quality monitoring module to the PC terminal, and displays the water level value, salinity value, water temperature value, and conductivity value with or without leakage in real time through the PC terminal; according to the field water level height and water quality salinity detection data detected by the field surface transpiration evaporation and leakage module and the water quality monitoring module, combined with the "Water-salt Dual-control Irrigation Standard for the Rice-crab Symbiotic Mode in the Cold Region of Northeast China", it controls the irrigation, drainage or water change of the paddy field irrigation and drainage control module to ensure that both rice and crabs are in a suitable field environment; controls the automatic collection of the soil profile solution by the soil profile solution automatic collection module through the remote control module and the Raspberry Pi development board module.

[0011] Further, in the case of no external drainage in the paddy field, the field surface transpiration, evaporation and leakage module includes a bottomed infiltration bucket, ultrasonic water level gauges A and B, and a dual-channel Raspberry Pi RS485 expansion board. Ultrasonic water level gauges A and B are respectively arranged inside and outside the bottomed infiltration bucket. The leakage flux is obtained from the water level difference inside and outside the bottomed infiltration bucket. The water level data obtained by ultrasonic water level gauges A and B are respectively transmitted to the Raspberry Pi development board module for data storage through the two serial ports ttySC0 and ttySC1 of the dual-channel Raspberry Pi RS485 expansion board.

[0012] In the case of lateral leakage during external drainage in the paddy field, the field surface transpiration, evaporation and leakage monitoring module includes a bottomed infiltration bucket, a non-bottomed infiltration bucket, ultrasonic water level gauges A and B, and a dual-channel Raspberry Pi RS485 expansion board. Ultrasonic water level gauges A and B are respectively arranged inside the bottomed and non-bottomed infiltration buckets. The leakage flux is obtained from the water level difference inside the bottomed and non-bottomed infiltration buckets. The water level data obtained by ultrasonic water level gauges A and B are respectively transmitted to the Raspberry Pi development board module for data storage through the two serial ports ttySC0 and ttySC1 of the dual-channel Raspberry Pi RS485 expansion board.

[0013] Further, the water quality monitoring module includes a water quality detector and an RS485 module communication converter. The detection probe of the water quality detector is placed in the water to monitor the salinity, conductivity and temperature of the water body in real time, and transmits the obtained values to the RS485 module communication converter equipped with a CH340 chip. The RS485 module communication converter conducts USB serial communication with the Raspberry Pi development board module and transmits data such as the salinity, conductivity and temperature of the water body read to the Raspberry Pi development board module for storage.

[0014] Further, ultrasonic shields are provided outside the ultrasonic water level gauge A and the ultrasonic water level gauge B. The ultrasonic shield is an opaque tube with a longitudinal slit. The slit ranges from the ground to 35 - 55 cm below the ground, the width of the slit is 8 - 10 mm, and the soil-entering end is in a wedge shape, frustum shape or conical shape.

[0015] Further, the paddy field irrigation and drainage control module includes the ultrasonic water level gauge B, water quality detector, ultrasonic intelligent water meter, water level control valve, irrigation pipeline, drainage pipeline, irrigation solenoid valve, drainage solenoid valve and relay. The ultrasonic water level gauge B is placed in the paddy field to be measured and communicates with the Raspberry Pi development board module through a dual-channel Raspberry Pi RS485 expansion board, and transmits the current field water level situation to the Raspberry Pi development board module in real time. The detection probe of the water quality detector is placed in the water to monitor the salinity, conductivity and temperature of the water body in real time, and transmits the obtained values to the RS485 module communication converter equipped with a CH340 chip. The RS485 module communication converter communicates with the Raspberry Pi development board module through USB serial port and transmits the salinity, conductivity and temperature of the water body in the current state to the Raspberry Pi development board module in real time. The ultrasonic intelligent water meter is installed on the irrigation pipeline to observe and measure the real-time flow rate during the entire rice growth period, and is connected to the Raspberry Pi development board module to transmit signals for monitoring the irrigation events during the entire rice growth period. The irrigation solenoid valve and the drainage solenoid valve are normally closed solenoid valves when powered off, and the potential control ends of the solenoid valves are respectively connected to the Raspberry Pi development board module through relays. According to the real-time situation of the paddy field water level and water body salinity, combined with the "Water and Salt Dual-Control Irrigation Standard for the Rice-Crab Symbiotic Mode in the Cold Region of Northeast China", the paddy field irrigation and drainage control module controls irrigation, drainage and water change by energizing or de-energizing the relay. The water level control valve is set at the end of the irrigation pipeline close to the paddy field surface for forced water stoppage in case of failure.

[0016] The beneficial effects of the present invention are as follows:

[0017] 1. The present invention can realize real-time monitoring of the paddy field water level and water quality, and automatically control the opening and closing of the irrigation system according to the preset lower water control limit, upper water control limit and upper water storage limit. When the water quality affects the normal life of crabs, the system can also automatically improve the water quality and continue to process according to the specific reasons for irrigation or water change operations.

[0018] 2. The present invention can realize a fully automatic and precise irrigation function, and one person can easily manage hundreds of mu of paddy fields. Through remote control, operations such as irrigation, drainage and water change can be remotely controlled, and sampling can also be remotely controlled, eliminating the cumbersome process of traditional manual extraction of soil solution. At the same time, batch operations can be realized, saving time. Through high-end Internet of Things control and intelligent automation, the labor intensity is greatly reduced, and the labor cost is saved by about 70%.

[0019] 3. The present invention realizes real-time cloud monitoring of data such as transpiration and evaporation, deep percolation, daily water consumption, irrigation quota, irrigation time, water replacement quota, and drainage quota in the rice-crab symbiotic system, as well as data on water bodies and water quality and salinity in the soil profile. And based on the water cycle and water quality feedback information, through autonomous decision-making by the control module and data transmission, it realizes the full-automatic water and salt regulation of irrigation, drainage, water replacement, salt washing, and pollution reduction in the rice-crab symbiotic system, in order to provide a reliable guarantee for reducing the consumption of water and fertilizer resources, increasing the utilization efficiency of environmental resources, and ensuring the green and safe production of food.

[0020] 4. The present invention realizes the dynamic tracking function of in-situ paddy field leakage flux, which can improve the irrigation accuracy of paddy fields and contribute to the development of smart water conservancy. It has advantages such as rich functions, low cost, durability, and convenient maintenance, and has broad application prospects and market potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the control block diagram of the irrigation system of the present invention.

[0022] Figure 2 is the structural schematic diagram of the irrigation system of the present invention.

[0023] Figure 3 is the schematic diagram of the field surface transpiration, evaporation, and leakage monitoring module and water quality monitoring module of the present invention.

[0024] Figure 4 is the schematic diagram of the paddy field irrigation and drainage control module of the present invention.

[0025] In the figure: 1. Automatic soil profile solution collection module, 2. Raspberry Pi development board module, 3. Field surface transpiration, evaporation, and leakage module, 4. Water quality monitoring module, 5. Irrigation and drainage control module, 6. Remote control module;

[0026] 7. Irrigation solenoid valve, 8. Water level control valve, 9. Sampling probe, 10. Ultrasonic water level gauge A, 11. Ultrasonic water level gauge B, 12. Water quality detector, 13. Liquid collection bottle, 14. Drainage pipeline, 15. Drainage solenoid valve, 16. Control module, 17. Bucket with bottom, 18. Bucket without bottom; 19. Protective cover, 20. Gap; 21. Water meter, 22. Irrigation pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present invention will be described in detail below with reference to the drawings and embodiments.

[0028] Embodiment: A control method for a water-salt dual-control intelligent irrigation system in a rice-crab symbiotic mode of the present invention,

[0029] Based on the water and salt control standards for the rice-crab symbiotic mode in the cold regions of Northeast China (as shown in Table 1), the specific irrigation and drainage methods of the rice-crab symbiotic system according to the growth period of rice are as follows:

[0030] When the actual water level L of the paddy field > L max2 , the drainage solenoid valve 15 is activated to start drainage until the water level reaches L max1 , and then the drainage solenoid valve 15 is closed;

[0031] When L min < L ≤ L max2 , this interval belongs to the beneficial water layer for rainwater resources, and the rainwater resources can be fully utilized without taking any measures;

[0032] When L ≤ L min , or when the conductivity TDS ≥ TDS max or the total salt content EC ≥ EC max , and at this time, that is, when the salt content exceeds the standard at low water level, the salt can be reduced directly by irrigation. The irrigation solenoid valve 7 is activated, and the water level of the paddy field is irrigated to L max1 , and then the irrigation solenoid valve 7 is closed;

[0033] When TDS ≥ TDS max or EC ≥ EC max , and at this time, that is, when the salt content exceeds the standard at high water level, then water replacement is required to reduce the salt; the system automatically opens the drainage solenoid valve 15, and the water level L of the paddy field is drained to half of the current water level, that is, L / 2, then the drainage solenoid valve 15 is closed, and the irrigation solenoid valve 7 is opened, and the water level L of the paddy field is irrigated to L max1 ;

[0034] When TDS < TDS max and EC < EC max , there is no need to consider the salt control requirements, and the irrigation and drainage operations can be completely carried out according to the water control standards;

[0035] Among them, L is the current water level of the paddy field; L min is the lower limit of water control for each growth stage; L max1 is the upper limit of water control for each growth stage; L max2 is the upper limit of water storage for each growth stage; TDS is the current conductivity of the paddy field; TDS max is the conductivity threshold for each growth stage; EC is the salt concentration of the current paddy field water, that is, salinity; EC max is the salinity threshold for each growth stage.

[0036] Table 1 Irrigation Standards for Dual Control of Water and Salt in the Rice-Crab Symbiotic Mode in the Cold Region of Northeast China

[0037]

[0038] The water-salt dual-control intelligent irrigation system for the rice-crab symbiotic mode includes a remote control module 6, a Raspberry Pi development board module 2, and a soil profile solution automatic sampling module 1, a field surface transpiration, evaporation and leakage module 3, a water quality monitoring module 4, and a paddy field irrigation and drainage control module 5 that are respectively connected to the Raspberry Pi development board module 2 and are arranged in the paddy field. The remote control module 6 includes a PC terminal with a control program, which communicates with the Raspberry Pi development board module, remotely transmits the water level data and salinity data obtained by the field surface transpiration, evaporation and leakage module 3 and the water quality monitoring module 4 to the PC terminal, and real-time displays the water level value, salinity value, water temperature value and conductivity value with or without leakage through the PC terminal; the remote control module 6 and the Raspberry Pi development board module 2 control the opening and closing of the irrigation solenoid valve 7 and the drainage solenoid valve 15 of the paddy field irrigation and drainage control module 5 according to the real-time water level and water quality salinity data detected by the field surface transpiration, evaporation and leakage module 3 and the water quality monitoring module 4, in combination with the "Water-salt Dual-control Irrigation Standard for the Rice-crab Symbiotic Mode in the Cold Region of Northeast China", so that the paddy field is irrigated, drained or exchanged with water, ensuring that both rice and crabs are in a suitable field environment; the remote control module 6 and the Raspberry Pi development board module 2 control the automatic sampling of the soil profile solution by the sampling probe of the soil profile solution automatic sampling module 1 and store it in the liquid collecting bottle 13 at the corresponding height.

[0039] In the case of no external drainage in the paddy field, the field surface transpiration, evaporation and leakage module 3 includes a bottom leakage measuring barrel 17, an ultrasonic water level gauge A 10, an ultrasonic water level gauge B 11, and a dual-channel Raspberry Pi RS485 expansion board. The ultrasonic water level gauge A 10 and the ultrasonic water level gauge B 11 are respectively arranged inside and outside the bottom leakage measuring barrel 17. The leakage flux obtained from the difference between the water levels inside and outside the bottom leakage measuring barrel 17, and the water level data obtained by the ultrasonic water level gauge A 10 and the ultrasonic water level gauge B 11 are respectively transmitted to the Raspberry Pi development board module 2 for data storage through the two serial ports ttySC0 and ttySC1 of the dual-channel Raspberry Pi RS485 expansion board;

[0040] In the case of lateral leakage during the external drainage of paddy field water, the field surface transpiration, evaporation and leakage monitoring module 3 includes a dual-channel Raspberry Pi RS485 expansion board, a bottomed infiltration bucket 17, a bottomless infiltration bucket 18, an ultrasonic water level gauge A10, and an ultrasonic water level gauge B11. Ultrasonic water level gauges A10 and B11 are respectively arranged in the bottomed infiltration bucket 17 and the bottomless infiltration bucket 18 to monitor the water levels in the bottomed infiltration bucket 17 and the bottomless infiltration bucket 18, while ensuring that the rice planting density and the water and fertilizer management methods in the bottomed infiltration bucket 17 and the bottomless infiltration bucket 18 are the same; after deducting the precipitation, the daily water level difference in the bottomed infiltration bucket 17 is the in-situ paddy field transpiration evaporation amount, and the daily water level difference in the bottomless infiltration bucket 18 is the water consumption of the in-situ paddy field. The leakage flux obtained from the water level difference between the bottomed infiltration bucket 17 and the bottomless infiltration bucket 18, and the real-time water level values obtained by the ultrasonic water level gauges A10 and B11 are respectively transmitted to the Raspberry Pi development board module 2 through the two serial ports ttySC0 and ttySC1 of the dual-channel Raspberry Pi RS485 expansion board.

[0041] The water quality monitoring module 4 includes a water quality detector 12 and an RS485 module communication converter. The detection probe of the water quality detector is placed in the water to monitor the salinity, conductivity, and temperature of the water body in real time, and transmits the obtained values to the RS485 module communication converter equipped with a CH340 chip. The RS485 module communication converter conducts USB serial communication with the Raspberry Pi development board module 2, and transmits data such as the salinity of the water body, the conductivity of the water body, and the temperature of the water body read to the Raspberry Pi development board module 2 for storage.

[0042] The structures of the ultrasonic water level gauge A10 and the ultrasonic water level gauge B11 are the same as those in the invention patent with the patent number 2021115878485 and the name of an intelligent irrigation and drainage and soil profile solution collection and monitoring system for paddy fields, and an ultrasonic shield is provided outside; the ultrasonic shield is an opaque tube with a longitudinal slit. The slit ranges from the ground to 35 - 55 cm below the ground, the width of the slit is 8 - 10 mm, and the soil-entering end is in a wedge shape, a frustum shape or a conical shape. To ensure recording the actual water layer changes, when there is no water layer, record the groundwater layer changes. The ultrasonic water level gauge transmits data to the data recording module and the irrigation and drainage decision-making system every hour for data tracking records and the calculation of transpiration evaporation and leakage flux.

[0043] In this example, the ultrasonic water level gauge A10 and the ultrasonic water level gauge B11 transmit data to the data recording module of the Raspberry Pi development board module 2 every hour for data tracking records and the calculation of transpiration evaporation and leakage flux.

[0044] The paddy field irrigation and drainage control module 5 includes the ultrasonic water level gauge B11, water quality detector 12, ultrasonic intelligent water meter 21, water level control valve 8, irrigation pipeline 22, drainage pipeline 14, irrigation solenoid valve 7, drainage solenoid valve 15 and each solenoid valve relay. The ultrasonic water level gauge B11 is placed in the paddy field to be measured and communicates with the Raspberry Pi development board module 2 through a dual-channel Raspberry Pi RS485 expansion board for serial communication, and transmits the current field water level situation to the Raspberry Pi development board module in real time. The detection probe of the water quality detector 12 is placed in the water to monitor the salinity, conductivity and temperature of the water body in real time, and transmits the obtained values to the RS485 module communication converter equipped with a CH340 chip. The RS485 module communication converter communicates with the Raspberry Pi development board module 2 through USB serial communication and transmits the salinity, conductivity and temperature of the water body in the current state to the Raspberry Pi development board module 2 in real time. The ultrasonic intelligent water meter 21 is installed on the irrigation pipeline 22 to observe and measure the real-time flow rate during the entire growth period of rice, and is connected to the Raspberry Pi development board module 2 to transmit signals for monitoring the irrigation events during the entire growth period of rice. The irrigation solenoid valve 7 and the drainage solenoid valve 15 are normally closed solenoid valves when powered off. The potential control ends of the solenoid valves are respectively connected to the GPIO.0 and GPIO.2 ports of the GPIO signal end of the Raspberry Pi development board module 2 through relays. According to the paddy field water level situation and water quality situation, combined with the "Water and Salt Dual-Control Irrigation Standard for the Rice-Crab Symbiotic Mode in the Cold Region of Northeast China", the paddy field irrigation and drainage control module 5 performs irrigation, drainage or water exchange operations by energizing or de-energizing each relay, so as to ensure that the water level is suitable for rice growth and the water quality is suitable for the survival and development of crabs. The water level control valve 8 is set at the end of the irrigation pipeline 6 close to the paddy field surface to forcibly stop the water in case of a failure to prevent accidents and flooding of the paddy field.

[0045] A manual control button is also set on the control interface of the Raspberry Pi development board module 2 to control the energization or de-energization of the relays connected to the irrigation solenoid valve 7 and the drainage solenoid valve 15 through the manual control button, so as to realize irrigation, drainage and one-key water exchange control.

[0046] The Raspberry Pi development board module 2, the Raspberry Pi RS485 communication expansion board, the RS485 module communication converter, the relay, etc. are all purchased components. The remote control module 6 is developed through the "WeChat Developer Tools" third-party development platform to implement a WeChat mini-program; among them, the Raspberry Pi RS485 communication expansion board has two serial ports for communication, which are respectively connected to the ultrasonic water level gauge A10 and the ultrasonic water level gauge B11. The RS485 module communication converter is equipped with a CH340 chip, which enables the water quality detector 12 to communicate with the USB port of the Raspberry Pi development board module 2 in a serial port manner. There are three relays, namely Relay I, Relay II, and Relay 1. Relay I and Relay II are respectively connected to the irrigation solenoid valve 7 and the drainage solenoid valve 15, and Relay 1 is connected to the positive and negative pressure pumps of the automatic acquisition module 1. The PC communicates with the Raspberry Pi development board module 2. The data generated by the rice-crab symbiotic mode water-salt dual-control intelligent irrigation system, such as daily transpiration evaporation, seepage, and total field water consumption data, irrigation time, irrigation quota, irrigation frequency, and total irrigation volume data, soil solution extraction time and frequency data, drainage time and drainage volume, are directly stored in the Raspberry Pi development board module 2.

[0047] The bottomed bucket 17 and the bottomless bucket 18 of the present invention have the same height, diameter, and buried depth; their structural parameters are the same as those of the invention patent with the patent application number 2020111240076 and the name of an apparatus for automatically collecting multi-layer solutions in a paddy field soil profile. Here, it will not be elaborated.

[0048] The present invention combines the concentration data of solutes such as soil solution nutrients, salts, heavy metals, and pesticides collected by the soil profile solution automatic collection module 1 with the seepage data of the field surface transpiration evaporation and seepage module 3 and the water quality monitoring module 4 to calculate the leaching loss of different solutes. Taking ammonium nitrogen and nitrate nitrogen as examples, the calculation formulas for the leaching flux and total leaching amount of ammonium nitrogen and nitrate nitrogen are as follows:

[0049] Ammonium nitrogen leaching flux (mg·m -2 ·d -1 ):

[0050]

[0051] Nitrate nitrogen leaching flux (mg·m -2 ·d -1 ):

[0052]

[0053] Total ammonium nitrogen leaching amount (mg·m -2 ):

[0054]

[0055] Total nitrate nitrogen leaching amount (mg·m -2 ):

[0056]

[0057] In the formula, L 桶内,0 represents the water level of the internal water level gauge of the leakage observation device during this sampling, in mm; L 桶内,0 represents the water level of the internal water level gauge of the leakage observation device during this sampling, in mm; L 桶外,0 represents the water level of the internal water level gauge of the leakage observation device outside the plot during the next sampling, in mm; L 桶外,0 represents the water level of the internal water level gauge of the leakage observation device outside the plot during the next sampling, in mm; T is the time interval between two samplings, in d; respectively represent the ammonium nitrogen and nitrate nitrogen concentrations of the samples collected by the multi-layer solution automatic sampling device in the 20 - 40 cm rice paddy soil profile, in mg·L -1 .

[0058] It can be understood that the above specific description of the present invention is only for explaining the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced to achieve the same technical effect; as long as it meets the usage requirements, it is within the protection scope of the present invention.

Claims

1. A control method for a water and salt dual-control intelligent irrigation system in a rice-crab symbiotic mode, characterized in that: When the paddy field water level L > the upper limit of water storage L max2 , the system will automatically activate the drainage solenoid valve to drain the actual water level of the paddy field to the upper limit of water control L max1 , and then close the drainage solenoid valve; When L ≤ L min , or when the conductivity TDS ≥ TDS max or the total salt content EC ≥ EC max , and when, that is, when the salt content exceeds the standard at low water level, the system automatically activates the irrigation solenoid valve to fill the paddy field water level L to L max1 , and closes the irrigation solenoid valve; When TDS ≥ TDS max or EC ≥ EC max , and when the high water level has exceeded the salt standard, the system automatically opens the drain solenoid valve, drains the paddy field water level L to half of the current water level, that is, L / 2, closes the drain solenoid valve, and opens the irrigation solenoid valve to fill the paddy field water level L to L max1 ; Among them, L is the paddy field water level; L min is the lower limit of water control; L max1 is the upper limit of water control; L max2 is the upper limit of water storage; TDS is the current conductivity of the paddy field; TDS max is the conductivity threshold; EC is the current salt concentration of the paddy field water, that is, salinity; EC max is the salinity threshold.

2. The intelligent irrigation system for dual control of water and salt in the rice-crab symbiotic mode adopting the control method as described in claim 1, characterized in that: It includes a remote control module, a Raspberry Pi development board module, and a soil profile solution automatic collection module, a field surface transpiration, evaporation and leakage module, a water quality monitoring module, and a paddy field irrigation and drainage control module respectively connected thereto. The remote control module includes a PC terminal with a control program, which communicates with the Raspberry Pi development board module, remotely transmits the water level data and salinity data obtained by the field surface transpiration, evaporation and leakage module and the water quality monitoring module to the PC terminal, and displays the water level value, salinity value, water temperature value and conductivity value with / without leakage in real time through the PC terminal; according to the field water level height and water quality salinity detection data detected by the field surface transpiration, evaporation and leakage module and the water quality monitoring module, combined with the water and salt dual-control irrigation standard for the rice-crab symbiotic mode in the cold region of Northeast China, control the irrigation, drainage or water change of the paddy field irrigation and drainage control module to ensure that both rice and crabs are in a suitable field environment; control the automatic collection of the soil profile solution by the soil profile solution automatic collection module through the remote control module and the Raspberry Pi development board module; the water and salt dual-control irrigation standard for the rice-crab symbiotic mode in the cold region of Northeast China is:

3. The water and salt dual-control intelligent irrigation system in the rice-crab symbiotic mode according to claim 2, characterized in that: In the case of no external drainage in the paddy field, the field surface transpiration, evaporation and leakage module includes a bottomed seepage bucket, ultrasonic water level gauges A and B, and a dual-channel Raspberry Pi RS485 expansion board. Ultrasonic water level gauges A and B are respectively arranged inside and outside the bottomed seepage bucket. The leakage flux obtained from the difference in water levels inside and outside the bottomed seepage bucket, and the water level data obtained by ultrasonic water level gauges A and B are respectively transmitted to the Raspberry Pi development board module for data storage through the two serial ports ttySC0 and ttySC1 of the dual-channel Raspberry Pi RS485 expansion board; In the case of lateral leakage in the external drainage of the paddy field water, the field surface transpiration, evaporation and leakage monitoring module includes a bottomed seepage bucket, a bottomless seepage bucket, ultrasonic water level gauges A and B, and a dual-channel Raspberry Pi RS485 expansion board. Ultrasonic water level gauges A and B are respectively arranged inside the bottomed and bottomless seepage buckets. The leakage flux obtained from the difference in water levels inside the bottomed and bottomless seepage buckets, and the water level data obtained by ultrasonic water level gauges A and B are respectively transmitted to the Raspberry Pi development board module for data storage through the two serial ports ttySC0 and ttySC1 of the dual-channel Raspberry Pi RS485 expansion board.

4. The intelligent irrigation system for dual control of water and salt in the rice-crab symbiotic mode according to claim 3, wherein: The water quality monitoring module includes a water quality detector and an RS485 module communication converter. The detection probe of the water quality detector is placed in the water to monitor the salinity, conductivity and temperature of the water body in real time, and transmits the obtained values to the RS485 module communication converter equipped with a CH340 chip. The RS485 module communication converter conducts USB serial communication with the Raspberry Pi development board module and transmits the detected water body salinity, water body conductivity and water body temperature data to the Raspberry Pi development board module for storage.

5. The intelligent irrigation system for dual control of water and salt in the rice-crab symbiotic mode according to claim 4, characterized in that: An ultrasonic water level gauge A and an ultrasonic water level gauge B are provided with ultrasonic shields; the ultrasonic shields are opaque tubes with longitudinal slits, the slits extend from the ground to 35 - 55 cm below the ground, the width of the slits is 8 - 10 mm, and the soil - entering end has a wedge - shaped, frustum - shaped or conical structure.

6. The water-salt dual-control intelligent irrigation system for the rice-crab symbiotic mode according to claim 5, wherein: The paddy field irrigation and drainage control module includes the ultrasonic water level gauge B, a water quality detector, an ultrasonic intelligent water meter, a water level control valve, an irrigation pipeline, a drainage pipeline, an irrigation solenoid valve, a drainage solenoid valve and a relay. The ultrasonic water level gauge B is placed in the paddy field to be measured and communicates with the Raspberry Pi development board module through a dual - channel Raspberry Pi RS485 expansion board for serial communication, and transmits the current field water level situation to the Raspberry Pi development board module in real time. The detection probe of the water quality detector is placed in the water to monitor the salinity, conductivity and temperature of the water body in real time, and transmits the obtained values to the RS485 module communication converter equipped with a CH340 chip. The RS485 module communication converter communicates with the Raspberry Pi development board module through USB serial communication and transmits the salinity, conductivity and temperature of the water body in the current state to the Raspberry Pi development board module in real time. The ultrasonic intelligent water meter is installed on the irrigation pipeline to observe and measure the real - time flow rate during the entire rice growth period, and is connected to the Raspberry Pi development board module to transmit signals for monitoring the irrigation events during the entire rice growth period. The irrigation solenoid valve and the drainage solenoid valve are normally - closed solenoid valves when powered off, and the potential control ends of the solenoid valves are respectively connected to the Raspberry Pi development board module through relays. According to the real - time situation of the paddy field water level and water body salinity, combined with the water - salt dual - control irrigation standard of the rice - crab symbiotic mode in the cold regions of Northeast China, the paddy field irrigation and drainage control module controls irrigation, drainage and water change by energizing or de - energizing the relay. The water level control valve is set at the end of the irrigation pipeline close to the paddy field surface for forced water stop in case of failure.

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