Agricultural irrigation method based on leaf area index and environmental parameters

Abstract

The invention provides an intelligent irrigation method based on a leaf area index and environmental parameters, and the method comprises the steps: calculating a crop coefficient through obtaining the leaf area index of a crop, then measuring the growth environmental parameters of the crop in a breeding shed, and further calculating the transpiration of the crop, and enabling the ratio of the actual water demand of the crop to the transpiration of the crop to be the crop coefficient. The actual water demand of the crops can be obtained through the product of the crop coefficient and the transpiration of the crops, the transpiration of the crops is influenced by factors such as solar radiation, environment temperature and wind speed, and the minimum value and the maximum value of the actual water demand of the crops are obtained through calculation. By comparing the actual irrigation amount with the minimum value of the actual water demand of the crops and comparing the actual soil humidity with the preset soil humidity of the crops, the actual irrigation amount can be controlled to achieve precise irrigation of the crops in different growth periods, and meanwhile the purpose of saving agricultural water is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of intelligent agricultural irrigation, and in particular to an agricultural irrigation method based on leaf area index and environmental parameters. Background Art

[0002] With today's technological innovation, modern agricultural irrigation has made great progress. At present, water-saving agriculture mainly adopts drip irrigation, sprinkler irrigation, micro-irrigation and other water-saving irrigation measures. Compared with flooding, these irrigation methods have achieved higher water use efficiency. However, sprinkler irrigation and drip irrigation can only be preset by humans at the start and end time of irrigation. In this case, it is impossible to carry out precise irrigation in a timely and appropriate manner according to the different growth cycles of crops, so as to meet the actual water demand of crops and the water demand of soil. Therefore, according to the water demand of crops, irrigation is carried out in a timely and appropriate manner. At the same time, intelligent technology is combined to monitor the irrigation system of crops, complete data collection and optimize water distribution after computer processing to achieve the purpose of saving water resources. This has become a new development trend of intelligent irrigation.

[0003] For example, Chinese patent application No. 202210296570.4, with a publication date of June 17, 2022, discloses an agricultural irrigation control method based on multi-environmental factor analysis, including the following steps: judging the environment in which the crop is located, selecting the crop irrigation area, and setting the irrigation cycle; obtaining soil parameters in the crop irrigation area; obtaining environmental parameters of natural dates within the irrigation cycle according to coordinates; obtaining crop growth parameters; calculating soil evaporation in the irrigation area; estimating crop evaporation; and obtaining irrigation water consumption within the set irrigation cycle. This method determines the environment in which the crop is located, obtains corresponding soil parameters, growth parameters, historical meteorological data, environmental parameters, etc. for open planting and greenhouse planting, and calculates soil evaporation, crop evaporation and other data in combination with relevant parameters, and finally calculates the irrigation water consumption, so as to reasonably irrigate while meeting the growth of crops and avoid waste of water resources.

[0004] The above-mentioned literature determines the water requirement through soil evaporation and crop transpiration, but soil evaporation cannot represent the actual evaporation of crops, and it estimates crop evaporation through environmental parameters and growth parameters. Its growth parameters mainly consider the current growth stage of the crop and do not consider the leaf area index. At the same time, during the irrigation process, the actual soil moisture conditions are not considered and the irrigation is not adjusted to meet the irrigation requirements of the crop in real time. Summary of the invention

[0005] The purpose of the present invention is to provide an agricultural irrigation method based on leaf area index and environmental parameters. By combining the leaf area index and environmental parameters, the actual water requirement of crops can be obtained, and then the crops can be accurately irrigated. The method has high reliability.

[0006] To achieve the above object, the present invention provides an intelligent irrigation method based on leaf area index and environmental parameters, comprising the following steps: S1 preset soil moisture for crops RH' and when to start irrigation of crops; S2 obtains crop leaf area index and crop growth environment parameters; S3 calculates the crop coefficient based on the crop leaf area index; S4 calculates the crop transpiration based on the parameters of the crop growth environment in step S2 ; S5 based on crop coefficient and crop evapotranspiration Calculate the actual water requirement of crops and the minimum actual water requirement of crops over a period of time ET min and maximum value ET max ; When the preset irrigation start time is reached, the central processor in the irrigation system controls the solenoid valve on the irrigation pipe to open to irrigate the crops, and the flow meter on the irrigation pipe monitors the actual irrigation volume. Q , and then compare the actual irrigation amount Q Minimum value of actual water requirement of crops ET min , actual soil moisture RH With preset crop soil moisture RH' , and controls the solenoid valve to open or close according to the comparison value.

[0007] In the above method, crops are planted in a breeding shed. By obtaining the crop leaf area index, the crop coefficient can be calculated through the formula, and then the growth environment parameters of the crops in the breeding shed are measured, and then the crop transpiration can be obtained through the formula. Since the ratio of the actual water requirement of the crop to the transpiration of the crop is the crop coefficient, the actual water requirement of the crop can be obtained by multiplying the crop coefficient and the transpiration of the crop. Since the transpiration of the crop is affected by factors such as solar radiation, ambient temperature, and wind speed, the minimum and maximum actual water requirement of the crop can be obtained by calculation. In the process of irrigating the crops, by comparing the actual irrigation amount with the minimum actual water requirement of the crop, the actual soil moisture with the preset crop soil moisture, the actual irrigation amount can be controlled to achieve precise irrigation of crops in different growth periods, and at the same time achieve the purpose of saving agricultural water.

[0008] Furthermore, the step S6 includes: S6.1 to S6.3, S6.1 If the actual irrigation volume QLess than the minimum water requirement of crops ET min , then open the solenoid valve and continue irrigation until the actual irrigation volume Q Equal to the minimum actual water requirement of the crop ET min When the solenoid valve is closed, irrigation is stopped; S6.2 If the actual soil moisture RH Equal to the preset crop soil moisture RH' , then close the solenoid valve and stop irrigation; S6.3 If the actual soil moisture RH Less than the preset crop soil moisture RH' , then open the solenoid valve and continue irrigation until the actual irrigation volume Q Equal to the maximum actual water requirement of the crop ET max .

[0009] The above method can determine the soil moisture while detecting the irrigation amount.

[0010] Furthermore, the formula of the crop leaf area index in step S3 is as follows: (1) In formula (1), is the crop coefficient, is the crop leaf area index.

[0011] With the above settings, the company can derive the crop coefficient based on the crop leaf area index.

[0012] Furthermore, the calculation formula of the actual water demand in step S5 is as follows: (2) In formula (2), The actual water requirement of crops, Crop transpiration.

[0013] The above settings can be used to calculate the actual water requirement of crops based on crop transpiration and crop coefficient.

[0014] Furthermore, in step S2, the crop leaf area index is measured by a leaf area index measuring instrument.

[0015] The above settings make it easy to measure the crop leaf area index.

[0016] Furthermore, in step S2, the parameters of the crop growth environment include the net radiation on the surface of crop leaves in the breeding shed, atmospheric pressure, wind speed, temperature and humidity, soil heat flux and soil humidity.

[0017] The above settings, by obtaining the environmental parameters of the crops, facilitate the subsequent calculation of the crop transpiration through the environmental parameters.

[0018] Furthermore, in step S2, the net radiation on the surface of crop leaves in the breeding shed is measured by a radiation sensor, the atmospheric pressure in the breeding shed is measured by a pressure sensor, the wind speed in the breeding shed is measured by an anemometer, the temperature and humidity in the breeding shed are measured by a temperature and humidity sensor, the soil moisture in the breeding shed is measured by a soil moisture sensor, and the soil heat flux in the breeding shed is measured by a soil heat flux transmitter.

[0019] The above settings make it easy to measure the parameters required for calculating crop transpiration through different sensors.

[0020] Furthermore, in step S4, the crop transpiration The calculation formula is as follows: (3) In formula (3), ET0 represents crop transpiration, in mm / d; Δ represents the slope of the saturated water vapor pressure temperature curve in the breeding shed, in kPa / ℃. R n It indicates the net radiation on the surface of crop leaves in the breeding shed within one hour, in units of MJ / (m 2 d), G represents soil heat flux, with the unit of MJ / (m 2 d), γ represents the trend coefficient of air density in the breeding shed, with the unit of kPa / °C. T h It indicates the average temperature in the breeding shed within one hour, in degrees Celsius. v h It represents the average wind speed at a height of 2m within one hour, in m / s. e s Indicates the saturated water vapor pressure in the breeding shed, in kPa. e a Indicates the actual water vapor pressure in the breeding shed, the unit is kPa.

[0021] The above settings make it easy to calculate crop transpiration .

[0022] Furthermore, the calculation formula of the slope Δ on the saturated water vapor pressure temperature curve in the breeding shed is as follows:

[0023] The above settings make it easy to calculate the slope of the saturated water vapor pressure temperature curve in the breeding shed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of the working method of the present invention.

[0025] Figure 2 It is a structural schematic diagram of the irrigation system used in the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1 As shown, an agricultural irrigation method based on leaf area index and environmental parameters, In this embodiment, crops are taken as an example for explanation, and the specific steps are as follows: S1 preset soil humidity in crop breeding shed RH' and when to start irrigation for crops.

[0028] S2 obtains the leaf area index of the crop and the parameters of the crop growth environment. In this embodiment, the leaf area index is measured by a leaf area index meter, and the parameters of the crop growth environment include the net radiation on the surface of crop leaves in the breeding shed, atmospheric pressure, wind speed, temperature and humidity, soil heat flux, and soil humidity. The net radiation is measured by a radiation sensor, the atmospheric pressure is measured by a pressure sensor, the wind speed is measured by an anemometer, the temperature and humidity are measured by a temperature and humidity sensor, the soil humidity is measured by a soil humidity sensor, and the soil heat flux is measured by a soil heat flux transmitter.

[0029] like Figure 2 As shown, the leaf area index meter 5, the radiation sensor (not shown in the figure), the pressure sensor 3, the anemometer 2, the temperature and humidity sensor 4, the soil moisture sensor 6 and the soil heat flux transmitter (not shown in the figure) are all connected to the central processor 1 in the irrigation system, so that the parameters required for calculating the crop transpiration can be measured by different sensors and the measured parameters can be transmitted to the central processor 1.

[0030] S3 calculates the crop coefficient based on the crop leaf area index, the formula is as follows:

[0031] In formula (1), is the crop coefficient, is the crop leaf area index.

[0032] S4 calculates the crop transpiration based on the parameters of the crop growth environment in step S2 , The calculation formula is as follows:

[0033] In formula (3), ET0 represents crop transpiration, in mm / d; Δ represents the slope of the saturated water vapor pressure temperature curve in the breeding shed, in kPa / ℃, and the calculation formula is as follows:

[0034] T h It indicates the average temperature in the breeding shed within one hour, in degrees Celsius. R n It indicates the net radiation on the surface of crop leaves in the breeding shed within one hour, in units of MJ / (m 2 d), G represents soil heat flux, with the unit of MJ / (m 2 d), γ represents the trend coefficient of air density in the breeding shed, with the unit of kPa / °C. v h It represents the average wind speed at a height of 2m within one hour, in m / s. e s Indicates the saturated water vapor pressure in the breeding shed, in kPa. e a Indicates the actual water vapor pressure in the breeding shed, in kPa. Calculate crop transpiration .

[0035] S5 based on crop coefficient and crop evapotranspiration Calculate the actual water requirement of the crop using the following formula: (2) In formula (2), is the actual water requirement of the crop, is the crop transpiration. Since the ratio of the actual crop water requirement to the crop transpiration is the crop coefficient, the actual crop water requirement can be obtained by multiplying the crop coefficient and the crop transpiration. Since the crop transpiration is affected by solar radiation, ambient temperature, wind speed and other factors, the crop growth environment parameter values ​​measured over a period of time will fluctuate within a certain range, and then the minimum value of the actual crop water requirement over a period of time can be obtained by calculation. ET min and maximum value ET max .

[0036] S6 When the preset irrigation start time is reached, the central processor 1 in the irrigation system controls the electromagnetic valve 9 arranged on the irrigation water pipe 8 to open, so that the water in the water tower 11 flows into the irrigation water pipe 8 to irrigate the crops, and the actual irrigation amount in the irrigation water pipe 8 is monitored by the flow meter arranged on the irrigation water pipe 8 Q , and then compare the actual irrigation amount Q Minimum value of actual water requirement of crops ET min , actual soil moisture RH With preset crop soil moisture RH' In this embodiment, the actual irrigation amount Q The calculation is performed by a flow meter 10, which is arranged on the irrigation water pipe 8 and is connected to a central processor 1 in the irrigation system. S6.1 If the actual irrigation volume Q Less than the minimum water requirement of crops ET min , then open the solenoid valve and continue irrigation until the actual irrigation volume Q Equal to the minimum actual water requirement of the crop ET min When the solenoid valve is closed, irrigation is stopped; S6.2 If the actual soil moisture RH Equal to the preset crop soil moisture RH' , then close the solenoid valve and stop irrigation; S6.3 If the actual soil moisture RH Less than the preset crop soil moisture RH' , then open the solenoid valve and continue irrigation until the actual irrigation volume Q Equal to the maximum actual water requirement of the crop ET max When the water level drops to 0, the solenoid valve is closed to stop irrigation.

[0037] The working principle of the present invention is as follows: the crop coefficient is calculated by obtaining the crop leaf area index, and then the growth environment parameters of the crop in the breeding shed are measured, and then the crop transpiration is calculated. Since the ratio of the actual water requirement of the crop to the transpiration of the crop is the crop coefficient, the actual water requirement of the crop can be obtained by multiplying the crop coefficient by the transpiration of the crop. Since the transpiration of the crop is affected by factors such as solar radiation, ambient temperature, and wind speed, the minimum and maximum values ​​of the actual water requirement of the crop are obtained by calculation. In the process of irrigating the crops, the actual irrigation amount is compared with the minimum value of the actual water requirement of the crop, and the actual soil moisture is compared with the preset crop soil moisture, so that the actual irrigation amount can be controlled to achieve precise irrigation of the crop in different growth periods, and at the same time achieve the purpose of saving agricultural water.

Claims

1. An intelligent agricultural irrigation method based on leaf area index and environmental parameters, Features: The following steps are involved: S1 preset soil moisture for crops RH' and when to start irrigation of crops; S2 obtains crop leaf area index and crop growth environment parameters; S3 calculates the crop coefficient based on the crop leaf area index; S4 calculates the crop transpiration based on the parameters of the crop growth environment in step S2 ; S5 based on crop coefficient and crop evapotranspiration Calculate the actual water requirement of crops and the minimum actual water requirement of crops over a period of time ET min and maximum value ET max ; When the preset irrigation start time is reached, the central processor in the irrigation system controls the solenoid valve on the irrigation pipe to open to irrigate the crops, and the flow meter on the irrigation pipe monitors the actual irrigation volume. Q , and then compare the actual irrigation amount Q Minimum value of actual water requirement of crops ET min , actual soil moisture RH With preset crop soil moisture RH' , and controls the solenoid valve to open or close according to the comparison value.

2. The intelligent agricultural irrigation method based on leaf area index and environmental parameters according to claim 1, characterized in that: The step S6 comprises: S6.1 to S6.3, S6.1 If the actual irrigation volume Q Less than the minimum water requirement of crops ET min , then open the solenoid valve and continue irrigation until the actual irrigation volume Q Equal to the minimum actual water requirement of the crop ET min When the solenoid valve is closed, irrigation is stopped; S6.2 If the actual soil moisture RH Equal to the preset crop soil moisture RH' , then close the solenoid valve and stop irrigation; S6.3 If the actual soil moisture RH Less than the preset crop soil moisture RH' , then open the solenoid valve and continue irrigation until the actual irrigation volume Q Equal to the maximum actual water requirement of the crop ET max .

3. The intelligent agricultural irrigation method based on leaf area index and environmental parameters according to claim 1, characterized in that: The calculation formula of the crop leaf area index in step S3 is as follows: （1） In formula (1), is the crop coefficient, is the crop leaf area index.

4. The intelligent agricultural irrigation method based on leaf area index and environmental parameters according to claim 1, characterized in that: The calculation formula of the actual water demand in step S5 is as follows: （2） In formula (2), is the actual water requirement of the crop, is the transpiration of crops.

5. The intelligent agricultural irrigation method based on leaf area index and environmental parameters according to claim 1, characterized in that: In step S2, the leaf area index of the crop is measured by a leaf area index measuring instrument.

6. The intelligent agricultural irrigation method based on leaf area index and environmental parameters according to claim 1, characterized in that: In step S2, the parameters of the crop growth environment include the net radiation on the surface of crop leaves in the breeding shed, atmospheric pressure, wind speed, temperature and humidity, soil heat flux and soil humidity.

7. The intelligent agricultural irrigation method based on leaf area index and environmental parameters according to claim 6, characterized in that: In step S2, the net radiation on the surface of crop leaves in the breeding shed is measured by a radiation sensor, the atmospheric pressure in the breeding shed is measured by a pressure sensor, the wind speed in the breeding shed is measured by an anemometer, the temperature and humidity in the breeding shed are measured by a temperature and humidity sensor, the soil moisture in the breeding shed is measured by a soil moisture sensor, and the soil heat flux in the breeding shed is measured by a soil heat flux transmitter.

8. The intelligent agricultural irrigation method based on leaf area index and environmental parameters according to claim 1, characterized in that: In step S4, the crop transpiration The calculation formula is as follows: In formula (3), ET0 represents crop transpiration, in mm / d; Δ represents the slope of the saturated water vapor pressure temperature curve in the breeding shed, in kPa / ℃. R n It indicates the net radiation on the surface of crop leaves in the breeding shed within one hour, in units of MJ / (m 2 d), G represents soil heat flux, with the unit of MJ / (m 2 d), γ represents the trend coefficient of air density in the breeding shed, with the unit of kPa / °C. T h It indicates the average temperature in the breeding shed within one hour, in degrees Celsius. v h It represents the average wind speed at a height of 2m within one hour, in m / s. e s Indicates the saturated water vapor pressure in the breeding shed, in kPa. e a Indicates the actual water vapor pressure in the breeding shed, the unit is kPa.

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