Biogas slurry, water and fertilizer integrated irrigation system and pressure control method

Abstract

The invention relates to the technical field of agricultural irrigation, in particular to a biogas slurry, water and fertilizer integrated irrigation system and a pressure control method. Obtaining a water seepage capability coefficient and a transpiration capability coefficient of the soil; adjusting the aperture of the filter valve according to the water permeability coefficient of the soil and the ratio of adjusted biogas slurry to unadjusted biogas slurry to obtain the adjusted aperture of the filter valve of the irrigation system; acquiring a fertility weakening coefficient of the soil; according to the fertility weakening coefficient, the adjusted chemical fertilizer proportion, the adjusted biogas slurry proportion and the adjusted moisture proportion, the chemical fertilizer proportion, the biogas slurry proportion and the moisture proportion of water and fertilizer in next irrigation are obtained; and controlling the irrigation system to carry out next irrigation. Under the conditions that soil in an irrigation area is affected by historical irrigation fertility deposition and the aperture of the filter valve is not suitable, the irrigation area can still be effectively and scientifically irrigated, and the irrigation effect is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural irrigation, and particularly relates to a biogas slurry integrated water and fertilizer irrigation system and a pressure control method. Background Art

[0002] "Biogas slurry integrated water and fertilizer irrigation" is an innovative technology that combines organic waste (such as biogas slurry generated from biogas digesters) with water and fertilizer and applies it to agricultural irrigation. This technology not only improves the utilization efficiency of water resources but also effectively provides crops with essential nutrients such as nitrogen, phosphorus, and potassium. The organic substances and microorganisms in biogas slurry can improve soil structure, increase soil fertility, reduce the use of chemical fertilizers, and lower the risk of environmental pollution. In recent years, with the advancement of agricultural modernization, biogas slurry integrated water and fertilizer irrigation technology has gradually been applied in agricultural production, especially in areas where aquaculture is combined with farmland irrigation, demonstrating significant economic and environmental benefits.

[0003] When the biogas slurry integrated water and fertilizer irrigation system irrigates an irrigation area, it is necessary to adjust the biogas slurry ratio, chemical fertilizer ratio, and water ratio of the water and fertilizer used for irrigation to ensure that while preventing eutrophication and salinization of the soil in the irrigation area, the purpose of irrigation can be achieved and the purpose of fertilization can also be achieved. Existing methods only irrigate the irrigation area at a fixed ratio without considering the influence of the historical irrigation fertility accumulation on the soil in the irrigation area and the influence of the filter valve aperture of the irrigation system on the filtration of biogas slurry, resulting in ineffective and unscientific irrigation in the irrigation area and poor irrigation effects. Summary of the Invention

[0004] To solve the above problems, the present invention provides a biogas slurry integrated water and fertilizer irrigation system and a pressure control method.

[0005] The biogas slurry integrated water and fertilizer irrigation system and pressure control method of the present invention adopt the following technical solutions:

[0006] An embodiment of the present invention provides a biogas slurry integrated water and fertilizer irrigation pressure control method, which includes the following steps:

[0007] Obtain the initial water content sequence of all layer depths when the soil was not irrigated last time, the first-time water content sequence and the second-time water content sequence of all layer depths at different times after irrigation; obtain the water ratio, biogas slurry ratio, and chemical fertilizer ratio of the water and fertilizer used for the last irrigation; obtain the filter valve aperture of the irrigation system for the last irrigation; obtain the third water content sequence of all layer depths of the soil after several historical irrigations and the first initial water content sequence of all layer depths before each historical irrigation;

[0008] Obtain the first water content change value at each soil depth according to the initial water content sequence and the first-time water content sequence; obtain the second water content change value at each soil depth according to the initial water content sequence and the second-time water content sequence; obtain the third water content change value at each soil depth after each historical irrigation according to the first initial water content sequence and the third water content sequence; obtain the surface area and the bottom area of the soil according to the first water content change value; obtain the water seepage capacity coefficient of the soil according to the second water content change values corresponding to the surface area and the bottom area of the soil; obtain the transpiration capacity coefficient of the soil according to the change rate of the second water content change value corresponding to the surface area of the soil;

[0009] Adjust the biogas slurry ratio according to the water seepage capacity coefficient and the transpiration capacity coefficient of the soil to obtain the adjusted biogas slurry ratio of the water and fertilizer; adjust the aperture of the filter valve according to the water seepage capacity coefficient of the soil and the biogas slurry ratios including the adjusted and unadjusted ones to obtain the adjusted aperture of the filter valve of the irrigation system; obtain the adjusted chemical fertilizer ratio of the water and fertilizer according to the adjusted biogas slurry ratio, the chemical fertilizer ratio and the water ratio; obtain the siltation degree of the soil fertility after each historical irrigation according to the depth values and the third water content change values at different depths within the surface area of the soil;

[0010] Obtain the soil fertility weakening coefficient according to the siltation degree; obtain the chemical fertilizer ratio, the biogas slurry ratio and the water ratio of the water and fertilizer for the next irrigation according to the fertility weakening coefficient, the adjusted chemical fertilizer ratio, the adjusted biogas slurry ratio and the water ratio; control the irrigation system to conduct the next irrigation according to the adjusted aperture of the filter valve, the chemical fertilizer ratio, the biogas slurry ratio and the water ratio of the water and fertilizer for the next irrigation.

[0011] Further, the step of obtaining the first water content change value at each soil depth according to the initial water content sequence and the first-time water content sequence includes the following specific steps:

[0012] Take the difference between the a-th water content value in the first-time water content sequence and the a-th initial water content in the initial water content sequence as the first water content change value at the a-th soil depth.

[0013] Further, the step of obtaining the surface area and the bottom area of the soil according to the first water content change value includes the following specific steps:

[0014] Take the absolute difference between the first water content change value at the a-th soil depth and the first water content change value at the (a + 1)-th soil depth as the water content change characteristic value at the a-th soil depth, obtain the layer depth value corresponding to the maximum value of the water content change characteristic value, denoted as the stratification depth value, take the area from the first soil depth layer to the depth layer where the stratification depth value is located as the surface area of the soil, and take the area from the depth layer where the stratification depth value is located to the last soil depth as the bottom area of the soil.

[0015] Further, obtain the water infiltration capacity coefficient of the soil according to the second water content change value corresponding to the surface layer area and the bottom layer area of the soil; obtain the transpiration capacity coefficient of the soil according to the change rate of the second water content change value corresponding to the surface layer area of the soil. The specific steps are as follows:

[0016]

[0017] In the formula, h1 is the average value of the second water content change values of all layer depths in the surface layer area of the soil; h2 is the average value of the second water content change values of all layer depths in the bottom layer area of the soil; σ2 is the variance of the second water content change values of all layer depths in the bottom layer area of the soil; α1 is a hyperparameter to prevent the denominator from being 0; s is the water infiltration capacity coefficient of the soil;

[0018] Perform least squares fitting on the second water content change values of all layer depths in the surface layer area of the soil, and normalize the slope of the fitting line through the sigmoid function as the transpiration capacity coefficient of the soil.

[0019] Further, adjust the biogas slurry ratio according to the water infiltration capacity coefficient and the transpiration capacity coefficient of the soil to obtain the adjusted biogas slurry ratio of the water and fertilizer; adjust the aperture of the filter valve according to the water infiltration capacity coefficient of the soil and the biogas slurry ratios including the adjusted and unadjusted ones to obtain the adjusted aperture of the filter valve of the irrigation system. The specific steps are as follows:

[0020] C ′ =(1 + a×z×s)×C

[0021] In the formula, a is a preset adjustment ratio coefficient; z is the transpiration capacity coefficient of the soil; s is the water infiltration capacity coefficient of the soil; C is the biogas slurry ratio of the water and fertilizer; C ′ is the adjusted biogas slurry ratio of the water and fertilizer;

[0022]

[0023] In the formula, D is the aperture of the filter valve of the irrigation system; D ′ is the adjusted aperture of the filter valve of the irrigation system.

[0024] Further, obtain the adjusted chemical fertilizer ratio of the water and fertilizer according to the adjusted biogas slurry ratio, chemical fertilizer ratio and water ratio. The specific steps are as follows:

[0025]

[0026] In the formula, C ′ is the adjusted biogas slurry ratio; B is the chemical fertilizer ratio; A is the water ratio; B ′The chemical fertilizer ratio after adjusting water and fertilizer.

[0027] Further, obtaining the siltation degree of soil fertility after each historical irrigation according to the depth values and the third water content change values at different depths in the soil surface layer region includes the following specific steps:

[0028]

[0029] In the formula, K is the number of different depths in the soil surface layer region; d k is the normalized depth value of the k-th layer depth from the ground surface in the soil surface layer region; h i,k is the third water content change value of the k-th layer depth in the soil surface layer region after the i-th historical irrigation; sigmoid() is the sigmoid function; Y i is the siltation degree of soil fertility after the i-th historical irrigation.

[0030] Further, obtaining the soil fertility weakening coefficient according to the siltation degree includes the following specific steps:

[0031]

[0032] In the formula, I is the total number of historical irrigations; g is the preset plant absorption coefficient; Y j is the siltation degree of soil fertility after the j-th historical irrigation; X is the soil fertility weakening coefficient.

[0033] Further, obtaining the chemical fertilizer ratio, biogas slurry ratio and water ratio of water and fertilizer for the next irrigation according to the soil fertility weakening coefficient, the adjusted chemical fertilizer ratio, the adjusted biogas slurry ratio and the water ratio includes the following specific steps:

[0034] When the soil fertility weakening coefficient is greater than the preset weakening threshold, adjust the adjusted biogas slurry ratio, the adjusted chemical fertilizer ratio and the water ratio according to the soil fertility weakening coefficient to obtain the chemical fertilizer ratio, biogas slurry ratio and water ratio of water and fertilizer for the next irrigation; when the soil fertility weakening coefficient is less than or equal to the preset weakening threshold, use the adjusted biogas slurry ratio, the adjusted chemical fertilizer ratio and the water ratio as the chemical fertilizer ratio, biogas slurry ratio and water ratio of water and fertilizer for the next irrigation;

[0035] Adjusting the adjusted biogas slurry ratio, the adjusted chemical fertilizer ratio and the water ratio according to the soil fertility weakening coefficient to obtain the chemical fertilizer ratio, biogas slurry ratio and water ratio of water and fertilizer for the next irrigation, the specific steps are as follows:

[0036] B ″ =(1 - X)×B ′ , in the formula, X is the soil fertility weakening coefficient; B′ A″ is the chemical fertilizer ratio after adjusting water and fertilizer; B″ is the chemical fertilizer ratio of water and fertilizer during the next irrigation;

[0037] C″ = (1 - X) × C ′ , where X is the soil fertility weakening coefficient; C ′ is the biogas slurry ratio after adjusting water and fertilizer; C″ is the biogas slurry ratio of water and fertilizer during the next irrigation;

[0038] A ′ = 1 - C″ - B″, where C″ is the biogas slurry ratio of water and fertilizer during the next irrigation; B″ is the chemical fertilizer ratio of water and fertilizer during the next irrigation; A ′ is the water ratio of water and fertilizer during the next irrigation.

[0039] The present invention also provides an integrated biogas slurry water and fertilizer irrigation system, including a memory and a processor. The processor executes the computer program stored in the memory to implement the steps of the foregoing method.

[0040] The beneficial effects of the technical solution of the present invention are as follows: According to the present invention, even when the irrigation area soil is affected by historical irrigation fertility sedimentation and the filter valve aperture is inappropriate, effective and scientific irrigation can still be carried out in the irrigation area, improving the irrigation effect, ensuring that the irrigation area soil will not be eutrophicated and salinized, and achieving the purpose of fertilization while achieving the irrigation purpose. When adjusting the ratio of water and fertilizer used for irrigation, the ratio of biogas slurry is adjusted by analyzing the soil water seepage capacity coefficient and transpiration capacity coefficient to determine the ratio of biogas slurry after adjusting water and fertilizer, improving the scientificity, accuracy and objectivity of adjusting the ratio of biogas slurry. By analyzing the adjusted ratio of biogas slurry, chemical fertilizer ratio and water ratio, the chemical fertilizer ratio after adjusting water and fertilizer is determined, improving the scientificity, accuracy and objectivity of adjusting the chemical fertilizer ratio. When determining the sedimentation degree of soil fertility after each historical irrigation, the sedimentation degree is determined by analyzing the depth values and the third water content change values at different depths in the soil surface layer area, improving the scientificity, accuracy and objectivity of the sedimentation degree of fertility, and providing a data basis for subsequent fine adjustment. Finally, the soil fertility weakening coefficient is obtained through the sedimentation degree; according to the fertility weakening coefficient, the adjusted chemical fertilizer ratio, the adjusted biogas slurry ratio and the water ratio, the chemical fertilizer ratio, biogas slurry ratio and water ratio of water and fertilizer during the next irrigation are obtained; and then the irrigation system is controlled to carry out the next irrigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0042] Figure 1 The flowchart of the steps of a biogas slurry water and fertilizer integrated irrigation pressure control method provided by an embodiment of the present invention;

[0043] Figure 2 The schematic diagram of layered irrigation provided by an embodiment of the present invention. Detailed implementation manners

[0044] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following, in combination with the accompanying drawings and preferred embodiments, details the specific implementation manners, structures, features, and effects of a biogas slurry water and fertilizer integrated irrigation system and pressure control method proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0046] The following specifically describes the specific solution of a biogas slurry water and fertilizer integrated irrigation pressure control method provided by the present invention in combination with the accompanying drawings.

[0047] Please refer to Figure 1 , which shows the flowchart of the steps of a biogas slurry water and fertilizer integrated irrigation system and pressure control method provided by an embodiment of the present invention. The method includes the following steps:

[0048] Step S001: Obtain the initial water content sequence of all layer depths when the soil was not irrigated last time, the first-time water content sequence and the second-time water content sequence of all layer depths at different times after irrigation; obtain the water ratio, biogas slurry ratio, and chemical fertilizer ratio of the water and fertilizer used in the last irrigation; obtain the aperture of the filter valve of the irrigation system last time; obtain the third water content sequence of all layer depths of the soil after several historical irrigations and the first initial water content sequence of all layer depths before each historical irrigation.

[0049] It should be noted that the main purpose of this embodiment is to adjust the proportion of the constituent components of the irrigated water and fertilizer according to the fertilizer retention capacity of the irrigation area to ensure reasonable irrigation of the soil. The water and fertilizer components for irrigation mainly include water, biogas slurry, and chemical fertilizers. The proportion of biogas slurry in the water and fertilizer for irrigation is controlled by a filter valve. Before starting the analysis, relevant data is collected first.

[0050] It should be noted that the irrigation system in this embodiment is a layered irrigation system. Please refer to Figure 2 , Figure 2 which is the schematic diagram of the layered irrigation in this embodiment. Figure 2 It contains multiple irrigation outlets, and the interval between the irrigation outlets is 20 cm, which can be adjusted specifically. Each irrigation outlet corresponds to a soil layer at a certain depth, which are soil layer 1, soil layer 2, soil layer 3, and soil layer 4 from top to bottom in sequence. The water volume in the soil layer in this embodiment is collected by water volume sensors, and the distribution of the water volume sensors is in a grid pattern, that is, there are multiple water volume sensors in the soil layer at the same depth.

[0051] Specifically, obtain the initial water content sequence of all layer depths when the soil has not been irrigated for the last time, the first-time water content sequence and the second-time water content sequence of all layer depths at different times after irrigation, as follows:

[0052] Collect the water content of the soil layers at different depths when the soil has not been irrigated through the water volume sensors installed at different depths. There are multiple water volume sensors in the soil layer at the same depth. Take the average value of the water volume values measured by the multiple water volume sensors in the soil layer at the same depth as the water content of the soil layer at that depth, and obtain the initial water content sequence of all depths of the soil when the soil has not been irrigated.

[0053] Ten minutes after a watering, collect the water content of the soil layers at different depths again through the water volume sensors installed at different depths. There are multiple water volume sensors in the soil layer at the same depth. Take the average value of the water volume values measured by the multiple water volume sensors in the soil layer at the same depth as the water content of the soil layer at that depth, and obtain the first-time water content sequence of all depths of the soil after irrigation.

[0054] Twenty-four hours after the same watering, collect the water content of the soil layers at different depths once again through the water volume sensors installed at different depths. There are multiple water volume sensors in the soil layer at the same depth. Take the average value of the water volume values measured by the multiple water volume sensors in the soil layer at the same depth as the water content of the soil layer at that depth, and obtain the second-time water content sequence of all depths of the soil after irrigation.

[0055] Specifically, obtain the water proportion, biogas slurry proportion, and chemical fertilizer proportion of the water and fertilizer used for the last irrigation. It should be noted that obtaining the proportions of different components of the water and fertilizer is an existing method, which will not be elaborated in this embodiment.

[0056] Specifically, obtain the aperture of the filter valve of the irrigation system for the most recent time.

[0057] Specifically, obtain the third water content sequence of all soil layer depths after several historical irrigations and the first initial water content sequence of all layer depths before each historical irrigation.

[0058] It should be noted that each historical irrigation corresponds to a third water content sequence, multiple irrigations correspond to multiple third water content sequences, each third water content sequence corresponds to a first initial water content sequence, and the third water content sequence is obtained 24 hours after each historical irrigation.

[0059] So far, the initial water content sequence, the first-time water content sequence, the second-time water content sequence, the water proportion, biogas slurry proportion, chemical fertilizer proportion of the water and fertilizer used for irrigation, the aperture of the filter valve, and several historical third water content change values are obtained.

[0060] Step S002: According to the initial water content sequence and the first-time water content sequence, obtain the first water content change value of each soil layer depth; according to the initial water content sequence and the second-time water content sequence, obtain the second water content change value of each soil layer depth; according to the first initial water content sequence and the third water content sequence, obtain the third water content change value of each soil layer depth after each historical irrigation; according to the first water content change value, obtain the surface area and bottom area of the soil; according to the second water content change values corresponding to the surface area and bottom area of the soil, obtain the water seepage ability coefficient of the soil; according to the change rate of the second water content change value corresponding to the surface area of the soil, obtain the transpiration ability coefficient of the soil.

[0061] It should be noted that when conducting irrigation, it is necessary to dynamically adjust the proportion of the composition components of the water and fertilizer according to the fertilizer retention ability of the land. If the water seepage ability coefficient of the land is too high, it will cause the water-containing nutrients to seep into the ground, resulting in a low retention degree of chemical fertilizers in the soil; if the evaporation rate of the land is too high, it will cause the chemical fertilizers not to be absorbed by plants along with the water, that is, the chemical fertilizers accumulate in the soil, leading to soil eutrophication and hardening, and ultimately causing salinization of cultivated land. Therefore, it is necessary to analyze the water seepage ability coefficient and transpiration ability coefficient of the current irrigation area after a period of time after irrigation, and then use them for irrigation control to conduct reasonable irrigation. The water seepage ability coefficient and transpiration ability coefficient of the soil can be analyzed through the change of water content.

[0062] Furthermore, it should be noted that within a certain period of time after irrigation, the water and fertilizer will penetrate into different layer depths of the soil. The water volume on the ground surface will seep into the bottom layer and decrease, and the water content of the bottom layer will change little due to being replaced by the upper layer. Therefore, obvious changes will occur between certain levels.

[0063] Specifically, according to the initial water content sequence and the first-time water content sequence, the first water content change value of each soil layer depth is obtained as follows:

[0064] Take the difference between the a-th water content value in the first-time water content sequence and the a-th initial water content in the initial water content sequence as the first water content change value of the a-th soil layer depth.

[0065] Furthermore, according to the initial water content sequence and the second-time water content sequence, the second water content change value of each soil layer depth is obtained.

[0066] It should be noted that the method for obtaining the second water content change value of each soil layer depth is the same as that for obtaining the first water content change value of each soil layer depth, which will not be elaborated in this embodiment.

[0067] Furthermore, according to the first initial water content sequence and the third water content sequence, the third water content change value of each soil layer depth after each historical irrigation is obtained.

[0068] Specifically, according to the first water content change value, the surface area and the bottom area of the soil are obtained as follows:

[0069] Take the absolute difference between the first water content change value of the a-th soil layer depth and the first water content change value of the (a + 1)-th soil layer depth as the water content change characteristic value of the a-th soil layer depth, obtain the layer depth value corresponding to the maximum water content change characteristic value, denoted as the stratification depth value, take the area from the first soil layer depth to the depth layer where the stratification depth value is located as the surface area of the soil, and take the area from the depth layer where the stratification depth value is located to the last soil layer depth as the bottom area of the soil.

[0070] Specifically, according to the second water content change values corresponding to the surface area and the bottom area of the soil, the water infiltration capacity coefficient of the soil is obtained as follows:

[0071]

[0072] In the formula, h1 is the average value of the second water content change values of all layer depths in the surface area of the soil; h2 is the average value of the second water content change values of all layer depths in the bottom area of the soil; σ2 is the variance of the second water content change values of all layer depths in the bottom area of the soil; α1 is a hyperparameter to prevent the denominator from being 0, and in this embodiment, α1 = 0.1 is described; s is the water infiltration capacity coefficient of the soil.

[0073] It should be noted that h1 - h2 represents the average difference in the change value of the water content between the surface layer area and the bottom layer area of the soil. The greater the difference, the more the water on the surface penetrates downward. Although the water in the bottom layer penetrates to a deeper level, due to the replenishment of the surface water, its change is not significant, and the water infiltration capacity coefficient of the soil is relatively high; σ2 represents the fluctuation of the change value of the water content at different depths within the bottom layer area of the soil. If the water and fertilizer applied by irrigation do not penetrate into the ground, the water in the bottom layer will accumulate, that is, the difference in the change value of the water content between different layers is relatively large. The smaller the difference, the better the infiltration.

[0074] It should be noted that since soil evaporation is affected by factors such as environmental temperature, wind speed, and soil structure, when the evaporation amount in the irrigation area is larger, the water content on its surface will change more significantly with the increase in depth. Therefore, the transpiration capacity coefficient of the soil can be reflected by obtaining the slope through fitting the change value of the water content on the surface layer.

[0075] Specifically, according to the change rate of the second water content change value corresponding to the surface layer area of the soil, the transpiration capacity coefficient of the soil is obtained as follows:

[0076] Perform least - squares fitting on the second water content change values at all layer depths within the surface layer area of the soil. After normalizing the slope of the fitted straight line through the sigmoid function, it is used as the transpiration capacity coefficient of the soil.

[0077] It should be noted that since the change value of the water content becomes smaller with the increase in depth, the slope of the fitted straight line is less than 0. In this embodiment, the result obtained by normalizing the slope reflects the transpiration capacity coefficient of the soil.

[0078] So far, the water infiltration capacity coefficient and the transpiration capacity coefficient of the soil have been obtained.

[0079] Step S003: Adjust the biogas slurry ratio according to the water infiltration capacity coefficient and the transpiration capacity coefficient of the soil to obtain the adjusted biogas slurry ratio of the water and fertilizer; adjust the aperture of the filter valve according to the water infiltration capacity coefficient of the soil and the biogas slurry ratios including adjusted and unadjusted to obtain the adjusted aperture of the filter valve of the irrigation system; obtain the adjusted chemical fertilizer ratio of the water and fertilizer according to the adjusted biogas slurry ratio, chemical fertilizer ratio, and water ratio; obtain the degree of siltation of soil fertility after each historical irrigation according to the depth values and the third water content change values at different depths within the surface layer area of the soil.

[0080] It should be noted that the advantage of the biogas slurry integrated water and fertilizer irrigation system compared with the traditional water and fertilizer irrigation system is that biogas slurry is added. As an organic fertilizer, biogas slurry is more likely to remain in the soil, and the release of its fertility follows the passage of time. It is more suitable for irrigation areas with a high infiltration capacity coefficient. When biogas slurry is untreated, it presents as a viscous liquid. After being filtered by a filter valve, large particles and sediments in it will be filtered out. And the smaller the aperture of the filter valve, the better the filtering effect. However, when the aperture is too small, the difference between the filtered fertilizer solution and chemical fertilizer will decrease, that is, biogas slurry is also more likely to penetrate into the ground along with the water. Therefore, it is necessary to adjust the aperture size of the filter valve of the irrigation system to ensure the balance among water, chemical fertilizer, and biogas slurry.

[0081] Furthermore, it should be noted that because biogas slurry fertilizer contains organic matter and microorganisms, the fertilizer efficiency of biogas slurry fertilizer is relatively slow and continuous. It can gradually release nutrients, improve soil health and structure, and long-term use can enhance the water retention capacity and air permeability of the soil. The fertilizer efficiency of chemical fertilizer is rapid and can usually provide the nutrients required by plants in a short period. However, due to the lack of organic matter, long-term use will lead to problems such as soil fertility decline, soil acidification, and nutrient loss. The integrated water and fertilizer irrigation adjusts the proportion of chemical fertilizer and biogas slurry, and thus irrigates different irrigation areas, which can effectively and scientifically improve the irrigation efficiency.

[0082] Furthermore, it should be noted that on the one hand, when the evaporation rate in the irrigation area is very high, it will lead to a decrease in the water content in the soil, resulting in that after the chemical fertilizer is irrigated into the soil, it cannot be dissolved in the water and absorbed by the plants, causing problems such as soil acidification due to the accumulation of inorganic substances; on the other hand, when the infiltration capacity coefficient of the irrigation area is very high, the chemical fertilizer will penetrate downward along with the water, that is, before the crop has absorbed all the nutrients in the irrigation water, the nutrients have already been lost, resulting in ineffective fertilization and pollution. There are a large number of organic matter and microorganisms in biogas slurry, and when irrigating, the thicker the biogas slurry, the residues that have not been fully fermented will continue to ferment in the soil, thereby improving the soil structure and reducing the infiltration capacity coefficient of the soil. Therefore, it is necessary to adjust the proportion of biogas slurry in the water and fertilizer composition and the aperture size of the filter valve according to the current infiltration capacity coefficient and evaporation rate.

[0083] Specifically, the proportion of biogas slurry is adjusted according to the infiltration capacity coefficient and transpiration capacity coefficient of the soil to obtain the adjusted proportion of biogas slurry in the water and fertilizer, as follows:

[0084] C ′ =(1 + a×z×s)×C

[0085] In the formula, a is a preset adjustment ratio coefficient, and in this embodiment, a = 0.1 is described; z is the transpiration capacity coefficient of the soil; s is the infiltration capacity coefficient of the soil; C is the proportion of biogas slurry in the water and fertilizer; C ′It is the proportion of biogas slurry after adjustment of water and fertilizer.

[0086] It should be noted that when the transpiration capacity coefficient and seepage capacity coefficient of the irrigation area are larger, the water content in the soil is less, and the retention of biogas slurry in the soil is poor. Therefore, it is necessary to increase the proportion of biogas slurry so that the residues that have not been fully fermented in the biogas slurry will continue to ferment in the soil.

[0087] Specifically, the aperture of the filter valve is adjusted according to the seepage capacity coefficient of the soil, the proportion of biogas slurry including adjusted and unadjusted ones, and the adjusted aperture of the filter valve of the irrigation system is obtained as follows:

[0088]

[0089] In the formula, D is the aperture of the filter valve of the irrigation system; s is the seepage capacity coefficient of the soil; C ′ is the adjusted proportion of biogas slurry; C is the proportion of biogas slurry; D ′ is the adjusted aperture of the filter valve of the irrigation system.

[0090] It should be noted that when the adjusted proportion of biogas slurry is larger, the water and fertilizer used for irrigation are thicker, and the aperture of the filter valve should be adjusted to increase. At the same time, the better the seepage capacity coefficient of the soil, the more biogas slurry is required, and the aperture of the filter valve should also be adjusted to increase to optimize the ability of the soil to retain organic matter.

[0091] Specifically, according to the adjusted proportion of biogas slurry, the proportion of chemical fertilizer and the proportion of water, the adjusted proportion of chemical fertilizer after adjustment of water and fertilizer is obtained as follows:

[0092]

[0093] In the formula, C ′ is the adjusted proportion of biogas slurry; B is the proportion of chemical fertilizer; A is the proportion of water; B ′ is the adjusted proportion of chemical fertilizer after adjustment of water and fertilizer.

[0094] It should be noted that when the adjusted proportion of biogas slurry is less, the proportion of chemical fertilizer should be increased, and vice versa, the proportion of chemical fertilizer should be reduced to ensure that the soil has sufficient water and fertilizer. At the same time, considering that there is also a proportion of water when forming water and fertilizer, so considering the proportion of water, is used as a basic value for adjustment, and finally the adjusted proportion of chemical fertilizer after adjustment of water and fertilizer is obtained.

[0095] It should be noted that after adjustment based on the transpiration capacity coefficient and the water infiltration capacity coefficient, it is also necessary to consider the fertility remaining in the soil after previous irrigation. For example, when the evaporation in the irrigation area is too large, the chemical fertilizer has not been absorbed by the plants after being dissolved in water, and it is precipitated due to the too low soil water content. Since the plants cannot directly absorb the chemical fertilizer crystals, the plants lack water and fertilizer. If additional fertilizer is applied due to the lack of fertilizer in the plants, it will cause excessive accumulation of fertilizer in the soil, which will further cause soil compaction and the like. Therefore, it is necessary to make a further adjustment according to the water infiltration capacity coefficient and the transpiration capacity coefficient of the soil.

[0096] Furthermore, it should be noted that the accumulation of fertilizer in the soil is manifested as the degree of decrease in water content. The water content decreases due to evaporation, and the nutrients are not lost but remain in the soil. Therefore, it is necessary to increase the subsequent irrigation water volume so that more fertilizer is dissolved in the water, making it easier for the plants to absorb. And with multiple irrigations, the chemical fertilizer precipitated in the soil will show a stacking effect, that is, more and more is precipitated. If no dilution treatment is carried out, a large amount of chemical substances will dissolve in the water after irrigation, causing seedling burning.

[0097] Furthermore, it should be noted that since evaporation only affects the soil surface, this embodiment only analyzes the soil surface layer, and the plants are usually rooted below the surface layer. That is to say, if the water content retained increases with the increase in depth, the less the fertilizer accumulates.

[0098] Specifically, according to the depth values and the third water content change values at different depths in the soil surface layer area, the degree of fertilizer accumulation in the soil after each historical irrigation is obtained, as follows:

[0099]

[0100] In the formula, K is the number of different depths in the soil surface layer area; d k is the normalized depth value of the k-th layer depth from the ground surface in the soil surface layer area, and the normalization method is carried out through the sigmoid function; h i,k is the third water content change value of the k-th layer depth in the soil surface layer area after the i-th historical irrigation; sigmoid() is the sigmoid function for normalization; Y i is the degree of fertilizer accumulation in the soil after the i-th historical irrigation.

[0101] It should be noted that as the depth increases continuously, if the water content retained is more, the less the fertilizer accumulates. The water content is reflected by the third water content change value. When the third water content change value is larger, it indicates that more water content is retained and less fertilizer accumulates.

[0102] It should be noted that if the evaporation amount on the surface layer is larger, then during the subsequent irrigation process, since almost no water can be stored in the surface layer, there will not be too much fertilizer component seeping downward, that is, it will not have an impact of burning the seedlings on the roots of the plants. And the deeper the layer, the less water there is, the greater the degree of siltation, and the impact of evaporation is relatively smaller compared to the surface, so it is more likely to have an impact of burning the seedlings.

[0103] Thus, the degree of siltation of soil fertility after each historical irrigation is obtained.

[0104] Step S004: Obtain the soil fertility weakening coefficient according to the degree of siltation; according to the fertility weakening coefficient, the adjusted chemical fertilizer ratio, the adjusted biogas slurry ratio and the water ratio, obtain the chemical fertilizer ratio, the biogas slurry ratio and the water ratio of the water and fertilizer for the next irrigation; control the irrigation system to perform the next irrigation according to the adjusted filter valve aperture, the chemical fertilizer ratio, the biogas slurry ratio and the water ratio of the water and fertilizer for the next irrigation.

[0105] It should be noted that the degree of siltation of soil fertility after each historical irrigation is obtained above, and by combining the impacts of multiple historical irrigations, the composition of the water and fertilizer is adjusted again to ensure that the soil water and fertilizer are appropriate.

[0106] Specifically, the soil fertility weakening coefficient is obtained according to the degree of siltation, as follows:

[0107]

[0108] In the formula, I is the total number of historical irrigations; g is the preset plant absorption coefficient, and in this embodiment, g = 0.5 is described; Y j is the degree of siltation of soil fertility after the j-th historical irrigation; X is the soil fertility weakening coefficient.

[0109] It should be noted that when the degree of siltation of soil fertility after historical irrigation is greater, the less fertility is required for the next irrigation, and the greater the fertility weakening coefficient.

[0110] It should be noted that if the value of the fertility weakening coefficient is larger, then the overall irrigation amount needs to be adjusted to avoid burning the seedlings due to a large amount of water being irrigated at one time and the chemical fertilizer in the soil dissolving in the water.

[0111] Specifically, the chemical fertilizer ratio, the biogas slurry ratio and the water ratio of the water and fertilizer for the next irrigation are obtained according to the fertility weakening coefficient, the adjusted chemical fertilizer ratio, the adjusted biogas slurry ratio and the water ratio, as follows:

[0112] When the fertility weakening coefficient is greater than the preset weakening threshold, the adjusted biogas slurry ratio, the adjusted chemical fertilizer ratio, and the water ratio are adjusted according to the fertility weakening coefficient to obtain the chemical fertilizer ratio, the biogas slurry ratio, and the water ratio of the water and fertilizer for the next irrigation; when the fertility weakening coefficient is less than or equal to the preset weakening threshold, the adjusted biogas slurry ratio, the adjusted chemical fertilizer ratio, and the water ratio are used as the chemical fertilizer ratio, the biogas slurry ratio, and the water ratio of the water and fertilizer for the next irrigation.

[0113] It should be noted that in this embodiment, the preset weakening threshold is described as 0.7.

[0114] Among them, adjusting the adjusted biogas slurry ratio, the adjusted chemical fertilizer ratio, and the water ratio according to the fertility weakening coefficient to obtain the chemical fertilizer ratio, the biogas slurry ratio, and the water ratio of the water and fertilizer for the next irrigation includes the following specific steps:

[0115] B″ = (1 - X) × B ′

[0116] In the formula, X is the fertility weakening coefficient of the soil; B ′ is the chemical fertilizer ratio after adjusting the water and fertilizer; B″ is the chemical fertilizer ratio of the water and fertilizer for the next irrigation.

[0117] C″ = (1 - X) × C ′

[0118] In the formula, X is the fertility weakening coefficient of the soil; C ′ is the biogas slurry ratio after adjusting the water and fertilizer; C″ is the biogas slurry ratio of the water and fertilizer for the next irrigation.

[0119] A ′ = 1 - C″ - B″

[0120] In the formula, C″ is the biogas slurry ratio of the water and fertilizer for the next irrigation; B″ is the chemical fertilizer ratio of the water and fertilizer for the next irrigation; A ′ is the water ratio of the water and fertilizer for the next irrigation.

[0121] It should be noted that the greater the fertility weakening coefficient, the more excessive the historical residual fertility accumulation, and the fertilizer ratio should be reduced during the next irrigation.

[0122] It should be noted that the aperture of the filter valve after adjusting the irrigation system, the chemical fertilizer ratio, the biogas slurry ratio, and the water ratio of the water and fertilizer for the next irrigation are obtained. The next irrigation is carried out by controlling the aperture of the filter valve of the irrigation system and obtaining appropriate fertilizer water.

[0123] Specifically, according to the adjusted aperture of the filter valve, the chemical fertilizer ratio, the biogas slurry ratio, and the water ratio of the water and fertilizer for the next irrigation, the irrigation system is controlled to carry out the next irrigation.

[0124] It should be noted that the integrated biogas slurry water and fertilizer irrigation system can automatically adjust the proportion of different components of the fertilizer water and the aperture of the filter valve, and through the control system, each parameter reaches the adjusted aperture of the filter valve, the chemical fertilizer proportion, the biogas slurry proportion and the water proportion of the fertilizer water during the next irrigation for the next irrigation. Specifically, it is an existing method and will not be elaborated in this embodiment.

[0125] After the filtration aperture increases, the biogas slurry is relatively viscous, and it is necessary to correspondingly increase the magnitude of the pressure to keep the irrigation flow rate unchanged. Therefore, it is necessary to adjust the irrigation pressure, and the adjustment ratio is the change range of the biogas slurry concentration and the aperture of the filtration hole.

[0126] Through the above steps, a method for controlling the irrigation pressure of the integrated biogas slurry water and fertilizer is completed.

[0127] Another embodiment of the present invention provides an integrated biogas slurry water and fertilizer irrigation system, the system includes a memory and a processor, and when the processor executes the computer program stored in the memory, the following operations are performed:

[0128] Obtain the initial water content sequence of all layer depths when the soil was last not irrigated, the first-time water content sequence and the second-time water content sequence of all layer depths at different times after irrigation; obtain the water proportion, biogas slurry proportion and chemical fertilizer proportion of the water and fertilizer used in the last irrigation; obtain the aperture of the filter valve of the irrigation system in the last irrigation; obtain the third water content sequence of all layer depths of the soil after several historical irrigations and the first initial water content sequence of all layer depths before each historical irrigation; according to the initial water content sequence and the first-time water content sequence, obtain the first water content change value of each layer depth of the soil; according to the initial water content sequence and the second-time water content sequence, obtain the second water content change value of each layer depth of the soil; according to the first initial water content sequence and the third water content sequence, obtain the third water content change value of each layer depth of the soil after each historical irrigation; according to the first water content change value, obtain the surface area and the bottom area of the soil; according to the second water content change value corresponding to the surface area and the bottom area of the soil, obtain the water seepage ability coefficient of the soil; according to the change rate of the second water content change value corresponding to the surface area of the soil, obtain the transpiration ability coefficient of the soil; adjust the biogas slurry proportion according to the water seepage ability coefficient and the transpiration ability coefficient of the soil to obtain the adjusted biogas slurry proportion of the water and fertilizer; adjust the aperture of the filter valve according to the water seepage ability coefficient of the soil, including the adjusted and unadjusted biogas slurry proportions, to obtain the adjusted aperture of the filter valve of the irrigation system; according to the adjusted biogas slurry proportion, chemical fertilizer proportion and water proportion, obtain the adjusted chemical fertilizer proportion of the water and fertilizer; according to the depth values and the third water content change values of different layer depths in the surface area of the soil, obtain the siltation degree of the soil fertility after each historical irrigation; according to the siltation degree, obtain the soil fertility weakening coefficient; according to the soil fertility weakening coefficient, the adjusted chemical fertilizer proportion, the adjusted biogas slurry proportion and the water proportion, obtain the chemical fertilizer proportion, biogas slurry proportion and water proportion of the water and fertilizer for the next irrigation; control the irrigation system to perform the next irrigation according to the adjusted aperture of the filter valve, the chemical fertilizer proportion, biogas slurry proportion and water proportion of the water and fertilizer for the next irrigation.

[0129] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A biogas slurry water and fertilizer integrated irrigation pressure control method, characterized in that: The method comprises the following steps: Obtain the initial moisture content sequence of all layers of soil before the most recent irrigation, the first time moisture content sequence and the second time moisture content sequence of all layers of soil at different times after irrigation; obtain the water ratio, biogas slurry ratio and chemical fertilizer ratio of the water fertilizer used in the most recent irrigation; obtain the aperture of the filter valve of the most recent irrigation system; obtain the third moisture content sequence of all layers of soil after several historical irrigations and the first initial moisture content sequence of all layers of soil before each historical irrigation; According to the initial moisture content sequence and the first time moisture content sequence, obtain the first moisture content change value of each soil layer depth; according to the initial moisture content sequence and the second time moisture content sequence, obtain the second moisture content change value of each soil layer depth; according to the first initial moisture content sequence and the third moisture content sequence, obtain the third moisture content change value of each soil layer depth after each historical irrigation; according to the first moisture content change value, obtain the surface area and bottom area of ​​the soil; according to the second moisture content change value corresponding to the surface area and bottom area of ​​the soil, obtain the soil infiltration capacity coefficient; according to the change rate of the second moisture content change value corresponding to the surface area of ​​the soil, obtain the soil transpiration capacity coefficient; The biogas slurry ratio is adjusted according to the water infiltration capacity coefficient and the transpiration capacity coefficient of the soil to obtain the biogas slurry ratio after water and fertilizer adjustment; the filter valve aperture is adjusted according to the water infiltration capacity coefficient of the soil, including the adjusted and unadjusted biogas slurry ratios, to obtain the filter valve aperture after the irrigation system is adjusted; the chemical fertilizer ratio after water and fertilizer adjustment is obtained according to the adjusted biogas slurry ratio, chemical fertilizer ratio and water ratio; the siltation degree of soil fertility after each historical irrigation is obtained according to the depth values ​​of different layers in the soil surface area and the third water content change value; According to the degree of siltation, the soil fertility reduction coefficient is obtained; according to the fertility reduction coefficient, the adjusted chemical fertilizer ratio, the adjusted biogas slurry ratio and the water ratio, the chemical fertilizer ratio, the biogas slurry ratio and the water ratio of the water-fertilizer at the next irrigation are obtained; according to the adjusted filter valve aperture, the chemical fertilizer ratio, the biogas slurry ratio and the water ratio of the water-fertilizer at the next irrigation, the irrigation system is controlled to carry out the next irrigation.

2. According to claim 1, a biogas slurry water and fertilizer integrated irrigation pressure control method is characterized in that: The method of obtaining the first moisture content change value of each soil layer depth according to the initial moisture content sequence and the first time moisture content sequence includes the following specific steps: The difference between the ath water value in the first time water content sequence and the ath initial water content in the initial water content sequence is taken as the first water content change value of the ath soil layer depth.

3. The biogas slurry water and fertilizer integrated irrigation pressure control method according to claim 1, characterized in that: The step of obtaining the surface area and the bottom area of ​​the soil according to the first water content change value includes the following specific steps: The absolute difference between the first moisture content change value at the depth of the a-th soil layer and the first moisture content change value at the depth of the a+1-th soil layer is used as the moisture content change characteristic value at the depth of the a-th soil layer, and the layer depth value corresponding to the maximum moisture content change characteristic value is obtained, which is recorded as the stratification depth value. The area from the depth of the first soil layer to the depth layer where the stratification depth value is located is taken as the surface area of ​​the soil, and the area from the depth layer where the stratification depth value is located to the depth of the last soil layer is taken as the bottom area of ​​the soil.

4. The biogas slurry water and fertilizer integrated irrigation pressure control method according to claim 1, characterized in that: The method of obtaining the water infiltration capacity coefficient of the soil according to the second water content change values ​​corresponding to the surface area and the bottom area of ​​the soil; and obtaining the transpiration capacity coefficient of the soil according to the change rate of the second water content change value corresponding to the surface area of ​​the soil, comprises the following specific steps: Wherein, h1 is the average value of the second water content change value of all layers in the soil surface area; h2 is the average value of the second water content change value of all layers in the soil bottom area; σ2 is the variance of the second water content change value of all layers in the soil bottom area; α1 is a hyperparameter to prevent the denominator from being 0; s is the soil water infiltration capacity coefficient; The least squares method was used to fit the second water content change values ​​of all layers in the soil surface area, and the slope of the fitting line was normalized by the sigmoid function and used as the soil transpiration capacity coefficient.

5. The biogas slurry water and fertilizer integrated irrigation pressure control method according to claim 1, characterized in that: The biogas slurry ratio is adjusted according to the water seepage capacity coefficient and the transpiration capacity coefficient of the soil to obtain the biogas slurry ratio after water and fertilizer adjustment; the filter valve aperture is adjusted according to the water seepage capacity coefficient of the soil and the biogas slurry ratio including the adjusted and unadjusted biogas slurry ratio to obtain the filter valve aperture after the irrigation system is adjusted, and the specific steps include the following: C′=(1+a×z×s)×C In the formula, a is the preset adjustment ratio coefficient; z is the soil transpiration capacity coefficient; s is the soil water infiltration capacity coefficient; C is the biogas slurry ratio of water and fertilizer; C′ is the biogas slurry ratio after water and fertilizer adjustment; Where D is the filter valve aperture of the irrigation system; D′ is the filter valve aperture after adjustment of the irrigation system.

6. The biogas slurry water and fertilizer integrated irrigation pressure control method according to claim 1, characterized in that: The specific steps of obtaining the chemical fertilizer ratio after water-fertilizer adjustment according to the adjusted biogas slurry ratio, chemical fertilizer ratio and water ratio are as follows: In the formula, C' is the adjusted biogas slurry ratio; B is the chemical fertilizer ratio; A is the water ratio; B' is the chemical fertilizer ratio after water-fertilizer adjustment.

7. The biogas slurry water and fertilizer integrated irrigation pressure control method according to claim 1, characterized in that: The method of obtaining the siltation degree of soil fertility after each historical irrigation according to the depth values ​​of different layers in the soil surface area and the third water content change value includes the following specific steps: Where K is the number of different depths in the soil surface area; d k h is the normalized depth value of the kth layer from the ground surface in the soil surface area; i,k is the third water content change value of the kth layer depth in the soil surface area after the i-th irrigation in history; sigmoid() is the sigmoid function; Y i is the degree of siltation of soil fertility after the i-th irrigation in history.

8. The biogas slurry water and fertilizer integrated irrigation pressure control method according to claim 1, characterized in that: The specific steps of obtaining the soil fertility reduction coefficient according to the siltation degree are as follows: Where, I is the total number of irrigations in history; g is the preset plant absorption coefficient; Y j is the degree of siltation of soil fertility after the jth irrigation in history; X is the soil fertility weakening coefficient.

9. The biogas slurry water and fertilizer integrated irrigation pressure control method according to claim 1, characterized in that: The chemical fertilizer ratio, biogas slurry ratio and water ratio of water fertilizer in the next irrigation are obtained according to the fertility reduction coefficient, the adjusted chemical fertilizer ratio, the adjusted biogas slurry ratio and the water ratio, and the specific steps include the following: When the fertility reduction coefficient is greater than the preset reduction threshold, the adjusted biogas slurry ratio, the adjusted chemical fertilizer ratio and the water ratio are adjusted according to the fertility reduction coefficient to obtain the chemical fertilizer ratio, biogas slurry ratio and water ratio of the water fertilizer for the next irrigation; when the fertility reduction coefficient is less than or equal to the preset reduction threshold, the adjusted biogas slurry ratio, the adjusted chemical fertilizer ratio and water ratio are used as the chemical fertilizer ratio, biogas slurry ratio and water ratio of the water fertilizer for the next irrigation; The adjusted biogas slurry ratio, the adjusted chemical fertilizer ratio and the water ratio are adjusted according to the fertility reduction coefficient to obtain the chemical fertilizer ratio, biogas slurry ratio and water ratio of water fertilizer during the next irrigation. The specific steps are as follows: B″=(1―X)×B′, where X is the soil fertility reduction coefficient; B′ is the chemical fertilizer ratio after water and fertilizer adjustment; B″ is the chemical fertilizer ratio of water and fertilizer during the next irrigation; C″=(1―X)×C′, where X is the soil fertility reduction coefficient; C′ is the biogas slurry ratio after water and fertilizer adjustment; C″ is the biogas slurry ratio of water and fertilizer during the next irrigation; A′=1―C″―B″, where C″ is the ratio of biogas slurry to fertilizer in the next irrigation; B″ is the ratio of chemical fertilizer to water and fertilizer in the next irrigation; and A′ is the water ratio of water and fertilizer in the next irrigation.

10. A biogas slurry water and fertilizer integrated irrigation system, the system comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is executed by a processor, the steps of a biogas slurry, water and fertilizer integrated irrigation pressure control method as described in any one of claims 1 to 9 are implemented.

Images