CN106804414A - Closed soilless culture automatic irrigation control method and system - Google Patents

Abstract

The invention discloses a closed soilless cultivation automatic irrigation control method: a. set V _th , V _D0 , wherein V _D0 = 0.2V _th , T _max , EC _Dth ; irrigate the soilless cultivation substrate for the first time The amount of liquid is V _IR1 = V _th + V _D0 ; b. Calculate V _C1 , ec ₁ , SR; c. With the change of time t, when t<T _max , judge whether SR=IR ₁ ·V _th Established, if not established, continue to judge whether SR=IR ₁ ·V _th is established with the change of time t, if SR=IR ₁ ·V _th is satisfied within the time less than T _max , start the second irrigation, the second Secondary irrigation amount V _IR2 =V _IR1 ·(1+μ), where u<0.4; if T _max time is reached, SR<IR ₁ ·V _th , then start the second irrigation, and the irrigation amount is equal to V _IR1 . The present invention comprehensively considers the crop transpiration and the salt enrichment in the matrix, and can not only realize the irrigation of the nutrient solution according to the needs of the crops, but also adjust the irrigation amount according to the salt enrichment in the matrix, and rinse the matrix to prevent the infiltration of the matrix. Excessive salt content affects the growth of crops.

Description

A closed soilless cultivation automatic irrigation control method and system

technical field

The invention relates to the field of agricultural irrigation, in particular to a closed soilless cultivation automatic irrigation control method and system.

Background technique

At present, soilless cultivation is developing rapidly. Soilless cultivation is a cultivation method that replaces soil with solid substrates such as peat, rock wool, perlite, and vermiculite, and uses nutrient solution for water and nutrient supply. Soilless cultivation was mostly used for seedling cultivation before, but because the substrate used in soilless cultivation is clean and hygienic, it avoids the occurrence of soil-borne diseases that are most likely to occur in the soil cultivation mode, so it has developed rapidly in facility agriculture this year.

Different from soil cultivation, the substrate used in soilless cultivation does not contain or contains a very small amount of nutrient elements. The nutrients needed for crop growth need to be supplied by nutrient solution, so the irrigation of nutrient solution is an important part of soilless cultivation. . In the current soilless cultivation technology, the irrigation control is basically in accordance with the irrigation control mode in soil cultivation: or regular irrigation, that is, the irrigation schedule is specified in advance, and the timing starts and ends regularly; or irrigation is performed according to sensor data, that is, The humidity sensor inserted or embedded in the substrate detects the change of the substrate humidity in real time, irrigates when it reaches a certain set value, and determines the irrigation stop time according to the detection data of the sensor; or performs irrigation according to the transpiration of the crop, that is, according to a specific The calculation formula calculates the transpiration of crops, and when it reaches a certain set value, irrigation is performed, and the amount of irrigation is determined according to the calculation data.

The various irrigation control modes mentioned above are all implemented according to the irrigation idea of soil cultivation, that is, the controller performs irrigation control according to the schedule, sensor or transpiration calculation model. They all ignore an important problem: different from soil cultivation, The substrate used in soilless cultivation is placed in a fixed container, or a cultivation tank, or a substrate bag, or a flower pot. The substrate is in a closed environment with limited capacity; the nutrients needed for crop growth need to rely on Provided by the nutrient solution, the crop loses water into the air in the form of steam through transpiration, and the nutrients that it cannot absorb will remain in the matrix, resulting in the accumulation of salt. When the salt accumulates to a certain extent, it will affect the growth of the root system of the crop. Respiratory and metabolic activities, resulting in affected crop growth. Therefore, in the process of soilless cultivation, the irrigation of nutrient solution needs to be dynamically adjusted according to the growth of crops, changes in the environment and the accumulation of salt in the substrate. However, the current automatic irrigation control method or system used in soilless cultivation This issue is rarely considered.

Contents of the invention

The purpose of the present invention is to provide a closed soilless cultivation automatic irrigation control method system to solve the problem that the existing soilless cultivation irrigation methods or systems are all implemented according to the irrigation idea of soil cultivation, which will affect the respiration and metabolic activities of crop roots , leading to the problem that crop growth is affected.

In order to solve the above technical problems, the invention adopts the following technical solutions:

The present invention is a closed soilless cultivation automatic irrigation control method,

a. Set crop water consumption threshold V _th , excess irrigation value V _D0 , where V _D0 = 0.1～0.3V _th , the maximum actual interval T _max between two consecutive irrigations, and the threshold EC of the conductivity of excess nutrient solution discharged from the substrate _Dth ; the amount of nutrient solution that is controlled by the irrigation actuator to irrigate the soilless culture substrate for the first time is V _IR1 =V _th +V _D0 ;

b. Detect the volume V _D1 of the nutrient solution discharged from the soilless culture substrate after the first irrigation, and the electrical conductivity EC _D1 ; calculate the actual volume of the nutrient solution obtained by the soilless culture substrate after the first irrigation V _C1 =V _IR1 -V _D1 , and the ratio of the difference between the conductivity value EC _D1 of the nutrient solution discharged for the first time and the threshold value EC Dth of the conductivity threshold value EC _Dth of the discharged nutrient solution ec ₁ =(EC _D1 -EC _Dth )/EC _Dth ; detection of solar radiation in the greenhouse total solar radiation According to the volume of nutrient solution actually obtained from the soilless culture substrate and the total amount of solar radiation, the ratio of crop transpiration with solar radiation is calculated IR ₁ =SR/V _C1 ;

c. With the change of time t, when t<T _max , judge whether SR=IR ₁ ·V _th is established, if not, continue to judge whether SR=IR ₁ ·V _th is established with the change of time t, If SR=IR ₁ ·V _th is satisfied within the time less than T _max , start the second irrigation, the second irrigation amount V _IR2 =V _IR1 ·(1+μ), where u<0.4; if the time T _max is reached , still SR<IR ₁ ·V _th , then start the second irrigation, and the irrigation amount is equal to V _IR1 ;

d. Calculate the time point and amount of the third irrigation compared to the time point and amount of the second irrigation Repeat the above steps to calculate the time point and amount of the second irrigation compared to the time point and amount of the first irrigation, and then irrigate Calculation of time point and quantity can be deduced by analogy.

Further, in the determination of the parameter u in step c, when the difference ratio ec ₁ between the conductivity value EC _D1 of the discharged nutrient solution and the set threshold value EC Dth of the conductivity threshold value EC _Dth of the discharged nutrient solution in this irrigation is less than 0.1, μ=0; When ec ₁ =0.1, μ=0.1; when 0.1<ec ₁ ≤0.2, μ=0.2; when 0.2<ec ₁ ≤0.3, μ=0.3.

Still further, in step a, V _D0 =0.2V _th

A closed soilless cultivation automatic irrigation control system, which is equipped with an optical radiation sensor to measure the amount of solar radiation R in the greenhouse, an EC value sensor to measure the conductivity value EC _Di of the nutrient solution discharged from the soilless culture matrix, and a displacement sensor to measure the Discharge the volume V _Di of nutrient solution in the soil culture matrix; Described optical radiation sensor, EC value sensor and displacement sensor are electrically connected with controller, and the measured parameter is transmitted to controller; Controller according to claim 1 or 2 According to any one of the methods described above, the irrigation actuator is controlled to irrigate the soilless cultivation substrate according to the time and quantity.

Compared with the prior art, the beneficial technical effects of the present invention are as follows:

The current irrigation control systems and methods used in the closed soilless cultivation mode basically seldom consider adjusting the irrigation amount according to the salt enrichment in the substrate. The amount of transpiration is used to supplement and irrigate the nutrient solution. The "closed soilless cultivation automatic irrigation control method and system" described in the present invention flexibly and effectively realizes variable irrigation according to crop transpiration and salt accumulation in the substrate; according to the EC value of the excess nutrient solution discharged from the substrate , reflecting the salt enrichment in the substrate, and adjusting the irrigation amount according to this value; calculating the crop transpiration according to the solar radiation, and determining when irrigation is required according to the accumulated solar radiation; that is, taking into account the crop transpiration and the substrate It can not only realize the irrigation of nutrient solution according to the needs of crops, but also adjust the irrigation amount according to the salt enrichment in the substrate, and wash the substrate to prevent the growth of crops from being affected by excessive salt content in the substrate.

Description of drawings

The invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is the control flowchart of closed soilless cultivation automatic irrigation control method of the present invention;

Fig. 2 is a schematic structural view of the closed soilless cultivation automatic irrigation control system of the present invention;

detailed description

In the closed soilless cultivation mode, a very important irrigation principle is to consider the salt enrichment in the cultivation substrate to avoid affecting the normal growth of crops due to excessive salt content. In general, the salt content in the soil or matrix is reflected by the electrical conductivity value EC, so detecting its EC value is an important condition for the application of closed soilless cultivation. The existing EC sensors directly measure the EC value in the matrix with relatively poor accuracy. High, and the EC value of a single position cannot fully reflect the salt accumulation of the substrate as a whole; in the closed soilless cultivation mode, in order to fully supply the nutrients needed for crop growth and avoid the enrichment of salt in the substrate, the general irrigation method It is to oversupply the nutrient solution required for crop growth according to a certain proportion. In this way, part of the salt accumulated in the substrate can be washed out, and the excess nutrient solution discharged from the substrate can be recycled. Therefore, the accumulation of salt in the matrix can be reflected by detecting the EC value of the discharged nutrient solution. In addition, closed soilless cultivation is generally used in greenhouse planting. The consumption of crop nutrient solution is mainly realized through transpiration, and the most important parameter affecting crop transpiration in the greenhouse environment is the intensity of solar radiation. Therefore, according to the intensity of solar radiation To control the implementation of irrigation behavior.

As shown in Figure 1, a specific implementation of the closed soilless cultivation automatic irrigation control method.

The present invention controls when to irrigate according to the accumulated amount of solar radiation intensity, and controls the irrigation amount according to the volume and EC value of the nutrient solution discharged from the matrix. The specific control process is as follows:

1. Set crop water consumption threshold V _th , excess irrigation value V _D0 , where V _D0 =0.2V _th , maximum actual interval T _max between two consecutive irrigations, and threshold EC _Dth of conductivity of excess nutrient solution discharged from the matrix.

2. According to the formula (1), the first irrigation amount is V _IR1 , and after the irrigation is over, measure the capacity V _D1 of the discharged nutrient solution and the conductivity EC _D1 ; calculate the actual nutrients obtained in the matrix after the irrigation is over according to the formula (2) Liquid volume V _C1 , calculate the ratio ec ₁ of the difference between the conductivity value EC _D1 of the discharged nutrient solution and the set conductivity threshold value EC _Dth of the discharged nutrient solution according to the formula (3), and calculate the total solar radiation according to the formula (4) SR, according to the formula (5), calculate the change ratio IR ₁ of crop transpiration with solar radiation.

V _IR1 =V _th +V _D0 (1)

V _C1 =V _IR1 -V _D1 (2)

ec ₁ =(EC _D1 -EC _Dth )/EC _Dth (3)

IR ₁ =SR/V _C1 (5)

3. Judging whether SR=IR ₁ ·V _th is true, if not, continue to calculate SR according to formula (4) and judge again, if SR=IR ₁ ·V _th is satisfied within the time less than T _max , start the second irrigation , the irrigation amount is obtained according to formula (6), when ec ₁ <0.1, μ=0, when ec ₁ =0.1, μ=0.1, when 0.1<ec ₁ ≤0.2, μ=0.2, when 0.2<ec ₁ When ≤0.3, μ=0.3, under this control method, ec ₁ is not greater than 0.3; if T _max time is reached, SR<IR ₁ ·V _th , then start the second irrigation, and the irrigation amount is equal to V _IR1 . After the irrigation, measure the capacity V _D2 and the conductivity EC _D2 of the discharged nutrient solution; calculate the actual amount of nutrient solution V _C2 obtained in the matrix after the irrigation is completed according to the formula (7), and calculate the discharged nutrients according to the formula (8) According to the ratio ec ₂ of the difference between the liquid conductivity value EC _D2 and the set discharge nutrient solution conductivity threshold value EC _Dth , the total solar radiation SR is calculated according to the formula (4), and the crop transpiration is calculated according to the formula (9). Change ratio IR ₂ .

V _IR2 ＝V _IR1 ·(1+μ) (6)

V _C2 =V _IR2 -V _D2 (7)

ec ₂ =(EC _D2 -EC _Dth )/EC _Dth (8)

IR ₁ =SR/V _C2 (9)

4. By analogy, judge whether SR=IR _i ·V _th is true, if not, continue to calculate SR according to formula (4) and judge again, if SR=IR _i ·V _th is satisfied within the time less than T _max , start the first i irrigation, the irrigation amount is obtained according to formula (10), when ec ₁ <0.1, μ=0, when ec ₁ =0.1, μ=0.1, when 0.1<ec ₁ ≤0.2, μ=0.2, when 0.2 When <ec ₁ ≤0.3, μ=0.3, under this control method, ec ₁ is not greater than 0.3; if T _max time is reached, SR<IR ₁ ·V _th , then the i-th irrigation will be started, and the irrigation amount will be equal to _VIRi-1 . After the irrigation is over, measure the capacity V _Di and the conductivity EC _Di of the discharged nutrient solution; calculate the actual amount of nutrient solution V _Ci obtained in the substrate after the irrigation is completed according to the formula (11), and calculate the nutrient discharge this time according to the formula (12) The ratio ec _i of the difference between the liquid conductivity value EC _Di and the set discharge nutrient solution conductivity threshold value EC _Dth , the total solar radiation SR is calculated according to the formula (4), and the crop transpiration is calculated according to the formula (13). Change ratio IR _i .

V _IRi =V _IR1 ·(1+μ) (10)

V _Ci =V _IRi -V _Di (11)

ec _i =(EC _Di -EC _Dth )/EC _Dth (12)

IR _i =SR/V _Ci (13)

As shown in Figure 2, a closed soilless cultivation automatic irrigation control system is installed with an optical radiation sensor to measure the amount of solar radiation R in the greenhouse, and an EC value sensor is installed to measure the conductivity value EC _Di of the nutrient solution discharged from the soilless cultivation matrix , installing a displacement sensor to measure the volume V _Di of the nutrient solution discharged from the soilless culture substrate; the optical radiation sensor, the EC value sensor and the displacement sensor are connected to the controller with electrical signals, and the measured parameters are transmitted to the controller. In the controller, the program is used to calculate according to the above-mentioned method, and the irrigation actuator is controlled according to the time and quantity to irrigate the soilless cultivation substrate.

The above-mentioned embodiments are only to describe the preferred mode of the present invention, not to limit the scope of the present invention. Without departing from the design spirit of the present invention, those skilled in the art may make various Variations and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (4)

1. a kind of closed soilless culture automatic irrigation control method, it is characterised in that：

A. crop wager requirements threshold value V is set_th, excess irrigation value V_D0, wherein V_D0=0.1~0.3V_th, it is double to irrigate maximum Actual interval T_max, the unnecessary nutrient solution conductivity threshold EC discharged from matrix_Dth；Control irrigates actuator for the first time to without soil The amount that cultivation matrix irrigates nutrient solution is V_IR1=V_th+V_D0；

B. after detection is irrigated for the first time, soilless culture substrate discharges the volume V of nutrient solution_D1, electrical conductivity EC_D1；Calculate for the first time The nutrient solution volume V that soilless culture substrate is actually obtained after irrigation_C1=V_IR1-V_D1, and discharge nutrient solution conductivity value for the first time EC_D1With the discharge nutrient solution conductivity threshold EC of setting_DthDifference ratio ec₁=(EC_D1-EC_Dth)/EC_Dth；In detection greenhouse Solar radiation amount calculates solar radiation total amountThe nutrient solution volume that is actually obtained according to soilless culture substrate and Solar radiation total amount calculates changing ratio IR of the crop transpirstion amount with solar radiation₁=SR/V_C1；

C. the change of t over time, works as t<T_maxWhen, judge SR=IR₁·V_thWhether set up, if invalid, over time The change of t, continuation judges SR=IR₁·V_thWhether set up, if less than T_maxIn time, SR=IR is met₁·V_th, start Irrigate for second, second irrigation volume V_IR2=V_IR1(1+ μ), wherein u<0.4；If reaching T_maxTime, still SR<IR₁· V_th, then starting second irrigation, irrigation volume is equal to V_IR1；

D. third time irrigation time point and amount repeat above step second compared to the calculating of second irrigation time point and amount Irrigation time point and amount compared to first time irrigation time point and amount calculating, the calculating of irrigation time point and amount is with such later Push away.

2. closed soilless culture automatic irrigation control method according to claim 1, it is characterised in that：Join in step c The determination of number u, as discharge nutrient solution conductivity value EC in this time irrigation_D1With the discharge nutrient solution conductivity threshold EC of setting_Dth's Difference ratio ec₁<When 0.1, μ=0；Work as ec₁When=0.1, μ=0.1；When 0.1<ec₁When≤0.2, μ=0.2；When 0.2<ec₁≤ When 0.3, μ=0.3.

3. closed soilless culture automatic irrigation control method according to claim 1, it is characterised in that：In step a, V_D0 =0.2V_th。

4. a kind of closed soilless culture automatic irrigating control system, it is characterised in that：Light radiation sensor is set and determines greenhouse Interior solar radiation amount R, sets the conductivity value EC that EC values sensor determines discharge nutrient solution in soilless culture substrate_Di, set Draining quantity sensor determines the volume V of discharge nutrient solution in soilless culture substrate_Di；The light radiation sensor, EC value sensors It is electrically connected with the controller with draining quantity sensor, measured parameter is transferred to controller；Controller is according to such as claim Any one method described in 1-3, control irrigation actuator is irrigated soilless culture substrate according to quantity on time.