A Precision Rotation Irrigation Method for Controlled Irrigation of Rice in Smart Irrigation Districts

Abstract

This invention discloses a method for precise rotational irrigation of rice in smart irrigation districts. This method takes into account the current water supply and service levels of traditional irrigation districts and constructs a complete solution for precise rotational irrigation of rice in smart irrigation districts. Through steps such as formulating technical standards for controlled irrigation of rice in irrigation districts, establishing controlled irrigation units, creating dynamic water condition maps of irrigation districts, dividing soil permeability identification zones in irrigation districts, and setting up water supply and service zones in irrigation districts, it completes various tasks including clarifying the threshold values ​​for paddy field moisture monitoring indicators at each growth stage of rice, collecting paddy field moisture information, compiling dynamic rotational irrigation groups, determining irrigation quotas, and implementing precise rotational irrigation. This provides a new method for the high-quality promotion of water-saving irrigation technologies for rice, such as controlled irrigation, rainwater harvesting irrigation, shallow wet irrigation, and intermittent irrigation, at the irrigation district scale. In particular, it provides a practical and feasible infrastructure for traditional irrigation districts to gradually realize automatic monitoring, intelligent water allocation, and precise irrigation water supply and service during the transformation to smart irrigation districts.

Description

Technical Field

[0001] This invention belongs to the field of irrigation district water supply and water service technology, and in particular relates to a method for precise rotational irrigation of rice controlled irrigation for smart irrigation districts. Background Technology

[0002] Rice irrigation areas are major agricultural water users and the main battleground for implementing water-saving irrigation technology research and development achievements to conserve irrigation water resources. However, unlike field-scale rice water-saving irrigation experiments or producers applying water-saving irrigation technologies in the field, irrigation area-scale water supply and service requires a comprehensive consideration of complex factors such as water resource volume, water distribution capacity of various levels of canals, water demand of rotational irrigation groups, and precision irrigation of paddy fields, rather than simply transferring the results of water-saving irrigation technology experiments. Controlled irrigation technology for rice refers to an irrigation technique in which, after the rice turns green, a water layer is no longer established on the field surface. Instead, irrigation time and quotas are determined based on the physiological and ecological water requirements of rice, using soil moisture content as a control indicator. Studies have shown that controlled irrigation technology for rice has many advantages, including water saving, energy saving, labor saving, high yield, high quality, low consumption, disease resistance, lodging resistance, and reduction of greenhouse gas emissions. Developing a precise rotational irrigation method for controlled irrigation of rice suitable for irrigation district scale can not only promote water saving at the irrigation district scale and maximize water saving benefits, but also play an important role in promoting the construction of smart irrigation districts and realizing the upgrading and transformation of rice production towards green, high-yield and high-efficiency.

[0003] At present, the following technical problems are faced in promoting rice controlled irrigation technology at the irrigation district scale: (1) If the rice field is irrigated according to the traditional controlled irrigation technology requirements, that is, no water layer is established on the field surface during each growth stage after the rice turns green, the water between the lower limit of soil moisture content control and the soil saturation moisture content can only maintain the short-term water demand of rice. The irrigation district will face frequent or even continuous water supply and water service work, the irrigation cost will rise, and the final water saving benefits will be insufficient.

[0004] (2) If a water layer is no longer established on the field surface during each growth stage after the rice turns green, the range of soil moisture variation between the lower limit of soil moisture control and the soil saturation moisture content is relatively small, making it difficult to distinguish the soil moisture stress suffered by the rice.

[0005] (3) Due to the differences in soil permeability in irrigation areas, if the same irrigation quota is used for irrigation, paddy fields with high soil permeability will usually reach the control limit earlier, and targeted measures are needed to adjust them.

[0006] (4) After each rotation irrigation, the distribution of paddy fields that have reached the lower limit of control in the irrigation area will be different. The traditional centralized grouping and interspersed grouping of irrigation canals makes it difficult to accurately respond to the water demand of paddy fields that have reached the lower limit of control inside and outside the rotation irrigation group.

[0007] Based on the above problems, the inventors have conducted in-depth research on water-saving irrigation methods at the irrigation district scale, hoping to design a precise rotation irrigation method for rice controlled irrigation in smart irrigation districts that can solve the above problems. Summary of the Invention

[0008] To overcome the aforementioned problems, the inventors have designed a precise rotational irrigation method for rice controlled irrigation in smart irrigation districts. This method takes into account the current water supply and service levels of traditional irrigation districts and addresses the upgrade needs of water supply and service in smart irrigation districts. It constructs a complete solution for precise rotational irrigation of rice in smart irrigation districts. Through steps such as formulating technical standards for controlled irrigation of rice in irrigation districts, establishing controlled irrigation units in irrigation districts, creating dynamic water condition maps of irrigation districts, dividing soil permeability identification zones in irrigation districts, and setting water supply and service zones in irrigation districts, it completes various tasks such as clarifying the threshold values ​​of paddy field moisture monitoring indicators at each growth stage of rice, collecting paddy field moisture information, compiling dynamic rotational irrigation groups, determining irrigation quotas, and implementing precise rotational irrigation. This provides a new method for the high-quality promotion of water-saving irrigation technologies for rice such as controlled irrigation, rainwater harvesting irrigation, shallow wet irrigation, and intermittent irrigation at the irrigation district scale. In particular, it provides a practical and feasible infrastructure for traditional irrigation districts to gradually realize automatic monitoring, intelligent water allocation, and precise irrigation water supply and service during the transformation to smart irrigation districts, thus completing this invention.

[0009] Specifically, the purpose of this invention is to provide a method for precise rotational irrigation of rice in smart irrigation districts, the method comprising the following steps:

[0010] Step 1: Formulate irrigation control technology standards for rice in irrigation areas and clarify the threshold values ​​for paddy field water monitoring indicators at each growth stage of rice.

[0011] Step 2: Establish irrigation control units in the irrigation district and collect paddy field moisture information;

[0012] Step 3: Create a dynamic water situation map of the irrigation area and compile a dynamic rotation irrigation team;

[0013] Step 4: Divide the irrigation area into soil permeability identification zones and determine the irrigation quota;

[0014] Step 5: Set up irrigation district water supply service areas and implement precision rotation irrigation.

[0015] In step 1, the irrigation control technology standards for rice in the irrigation area include the planned wetting layer depth, the upper limit of the field surface water layer depth, the lower limit of the soil moisture content, the lower limit of the soil crack width, the upper limit of the rainfall storage, and the upper limit of the irrigation quota for rice at each growth stage in the irrigation area.

[0016] In step 1, the paddy field moisture monitoring indicators for each growth stage of rice include the field surface water depth monitored by a water level probe, the soil moisture content monitored by a soil moisture meter, the soil crack width monitored by a ruler, the rainfall monitored by a self-recording rain gauge, and the irrigation quota calculated according to the formula.

[0017] In step 1, the rice growth period refers to the entire growth period of the rice field, including the greening stage, early tillering stage, mid-tillering stage, late tillering stage, jointing and booting stage, heading and flowering stage, milk stage, and yellowing stage.

[0018] In step 2, the irrigation district is divided into several independent control irrigation units according to the control range of the secondary irrigation canal.

[0019] In step 2, control points are set up within the control range of representative terminal irrigation canals in each control irrigation unit to monitor the paddy field moisture status at the control points, and the monitored paddy field moisture status information at the control points is fed back to the irrigation district water supply and water service center in real time.

[0020] In step 2, the paddy field moisture status of each controlled irrigation unit is collected.

[0021] The paddy field moisture status of the controlled irrigation unit refers to the most unfavorable value among the paddy field moisture status information at all control points within the controlled irrigation unit.

[0022] In step 3, based on the rice controlled irrigation technology standards established in step 1 and the paddy field moisture status of the controlled irrigation units obtained in step 2, a dynamic water situation map of the irrigation area reflecting the paddy field moisture status of each controlled irrigation unit is created.

[0023] Preferably, in the irrigation district water situation dynamic map, green represents that the paddy field moisture value of the controlled irrigation unit is above the soil saturation moisture content;

[0024] Yellow represents the paddy field moisture value of the controlled irrigation unit being between the soil saturation moisture content and the lower limit of soil moisture content control;

[0025] Red indicates that the paddy field moisture value of the controlled irrigation unit has reached the lower limit of soil moisture content control.

[0026] In step 3, before each precise irrigation cycle, the control irrigation units with the same color in the irrigation area water situation dynamic map are grouped into a dynamic irrigation cycle group. Subsequently, precise irrigation work is carried out on each dynamic irrigation cycle group in the order of red, yellow and green.

[0027] In step 4, the irrigation area is divided into several soil permeability identification zones, and the upper limit of the field surface water depth control in each soil permeability identification zone is further obtained.

[0028] In step 4, when the paddy field moisture content is greater than or equal to the soil saturation moisture content and less than the upper limit of the field surface water depth control, the paddy field irrigation quota under controlled irrigation conditions is obtained by the following formula (I):

[0029] m ij =0.667×(h) max，ij -h 0，ij ) (one)

[0030] When the paddy field moisture content is less than the soil saturation moisture content but greater than the lower limit of soil moisture content control, the paddy field irrigation quota under controlled irrigation conditions is obtained by formula (II) as follows:

[0031] m ij =0.667×[H j (θ s，ij -θ 0，ij )+h max，ij ] (two)

[0032] In particular, when the paddy field moisture value equals the lower limit of soil moisture content control, the paddy field irrigation quota under controlled irrigation conditions reaches its maximum value, i.e., the upper limit of the irrigation quota, which is obtained using the following formula (iii):

[0033] m max，ij =0.667×[H j (θ s，ij -θ min，j ×θ s，ij )+h max，ij ] (three)

[0034] Where, m ij This represents the irrigation quota for paddy fields within the i-th soil permeability identification zone during the j-th growth stage of rice, in m³. 3 / mu;

[0035] m max，ij This represents the upper limit of irrigation quota for paddy fields within the i-th soil permeability identification zone during the j-th growth stage of rice, in m³. 3 / mu;

[0036] 0.667 indicates that the unit of measurement for irrigation quotas has been converted from "mm" (water depth) to "m". 3 Conversion factor for " / mu";

[0037] h max，ij The upper limit of the surface water depth control for paddy fields in the i-th soil permeability identification zone during the j-th growth stage of rice is indicated in mm.

[0038] h 0，ij The depth of the surface water layer in the paddy field within the i-th soil permeability identification zone before irrigation during the j-th growth stage of rice is expressed in mm.

[0039] H represents the planned wetting layer depth in the paddy field during the j-th growth stage of rice, in mm;

[0040] θ s，ij This represents the average saturated water content (percentage of soil volume) of the planned moist layer soil in the paddy field within the i-th soil permeability identification zone during the j-th growth stage of rice, in %;

[0041] θ 0，ij The average value of the planned moist layer soil moisture content (percentage of soil volume) in the paddy field within the i-th soil permeability identification zone before irrigation during the j-th growth stage of rice, in %;

[0042] θ min，j The lower limit of planned wetting layer soil moisture content (percentage of soil volumetric moisture content) for rice at the j-th growth stage is expressed as %.

[0043] In step 5, each water supply service area in the irrigation district can serve one or more controlled irrigation units and is staffed with personnel responsible for the water supply service work of the controlled irrigation units under its jurisdiction.

[0044] In step 5, based on the dynamic rotation irrigation group compiled in step 3 and the irrigation quota obtained in step 4, the staff of the water supply and water service area coordinate the rotation irrigation work between each water supply and water service area and the control irrigation units within the water supply and water service area, and the irrigation volume sequentially meets the water demand of the control irrigation units within the red, yellow and green dynamic rotation irrigation groups.

[0045] Preferably, precise rotational irrigation is implemented between each controlled irrigation unit and within each controlled irrigation unit, following the principle of prioritizing drought-stricken areas over less drought-stricken areas and prioritizing upstream areas over downstream areas.

[0046] The beneficial effects of this invention include:

[0047] (1) According to the precise rotation irrigation method for rice control irrigation in smart irrigation districts provided by the present invention, the method can further integrate control irrigation units to establish a larger-scale water supply service area based on the water supply service level of smart irrigation districts, thereby further reducing the human, material and financial resources required for irrigation and realizing smart irrigation.

[0048] (2) According to the precise rotation irrigation method for rice control irrigation in smart irrigation districts provided by the present invention, in this method, the control irrigation technical standards, control irrigation units, water dynamic map, and soil permeability identification area of ​​the irrigation district can be obtained in one go and can be reused in subsequent rotation irrigation processes. Only the water dynamic map of the irrigation district and the growth stage of rice need to be updated in real time, which can greatly reduce the operating cost while ensuring efficient water-saving irrigation.

[0049] (3) According to the precise rotation irrigation method for rice controlled irrigation in smart irrigation districts provided by the present invention, this method provides a new and highly operable precise rotation irrigation method for promoting rice controlled irrigation technology at the irrigation district scale with high quality. It also provides a new method for promoting rice water-saving irrigation technologies such as rainwater storage irrigation, shallow wet irrigation, and intermittent irrigation at the irrigation district scale with high quality. In particular, it provides a practical and feasible infrastructure for traditional irrigation districts to gradually realize water supply and use services such as automatic monitoring, intelligent water allocation, and precise irrigation in the process of transforming into smart irrigation districts.

[0050] (4) According to the precise rotation irrigation method for rice control irrigation in smart irrigation districts provided by the present invention, the method has many advantages such as water saving, energy saving, labor saving, high yield, high quality, low consumption, disease resistance, lodging resistance, and reduction of greenhouse gas emissions. It can not only promote water saving at the irrigation district scale and maximize water saving benefits, but also has important significance for realizing the transformation of rice production to green, high-yield and high-efficiency. Attached Figure Description

[0051] Figure 1 This application presents a flowchart illustrating the precise rotational irrigation method for rice controlled irrigation in smart irrigation districts.

[0052] Figure 2 The following is a dynamic water situation diagram of the Changgang Irrigation District shown in the embodiment;

[0053] Figure 3 This example shows a map of soil permeability identification zones in the Changgang Irrigation District.

[0054] Figure 4 The diagram shows the water supply service area of ​​Changgang Irrigation District in the embodiment. Detailed Implementation

[0055] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more apparent.

[0056] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0057] This invention provides a method for precise rotational irrigation of rice in smart irrigation districts, the entire process of which is as follows: Figure 1 As shown, the method includes the following steps:

[0058] Step 1: Formulate irrigation control technology standards for rice in irrigation areas and clarify the threshold values ​​for paddy field water monitoring indicators at each growth stage of rice.

[0059] In step 1, referring to national or local rice controlled irrigation technical specifications and combining them with the actual situation of rice production in the irrigation area, especially rainfall, groundwater level, soil permeability, topography, etc., the standards such as the planned wetting layer depth and the upper limit of the field surface water layer depth are adjusted to allow the paddy field to establish a suitable water layer for a short period of time after rice transplanting, thereby formulating rice controlled irrigation technical standards suitable for the irrigation area; the rice controlled irrigation technical standards include the planned wetting layer depth, the upper limit of the field surface water layer depth, the lower limit of soil moisture content, the lower limit of soil crack width, the upper limit of rainfall storage, and the upper limit of irrigation quota control for each growth stage of rice.

[0060] In this application: the rice growth period refers to the entire growth period of the rice field, including the greening stage, early tillering stage, mid-tillering stage, late tillering stage, jointing and booting stage, heading and flowering stage, milk stage, and yellowing stage. These growth periods are identified according to national or local standards. The planned wetting layer depth refers to the planned wetting depth of the soil layer in paddy fields where controlled irrigation technology is promoted, determined by referring to national or local rice controlled irrigation technical specifications and considering factors such as the groundwater level in the irrigation area. The upper limit of the surface water layer depth refers to the maximum allowable surface water layer depth in paddy fields where controlled irrigation technology is promoted. This maximum value is determined by referring to national or local rice controlled irrigation technical specifications and considering factors such as the groundwater level in the irrigation area. The soil moisture content control limit is determined by comprehensively considering factors such as soil permeability and topography in the irrigation area. The lower limit of soil moisture content control refers to the minimum allowable soil moisture content in the planned wetting layer of paddy fields where controlled irrigation technology is promoted. This minimum value is expressed as the percentage of soil moisture content to soil saturation moisture content and is determined with reference to national or local rice controlled irrigation technical specifications. The lower limit of soil crack width control refers to the width of soil cracks on the field surface when the planned wetting layer soil moisture content in paddy fields where controlled irrigation technology is promoted reaches the lower limit of soil moisture content control. This crack width is determined with reference to national or local rice controlled irrigation technical specifications. Using this indicator, the lower limit of soil moisture content control can be identified easily and quickly.

[0061] In this application, the upper limit of rainfall storage control refers to the maximum amount of rainfall that a paddy field using controlled irrigation technology can temporarily store after the soil is saturated. This maximum value is determined with reference to national or local rice controlled irrigation technical specifications. This invention emphasizes the efficient use of natural rainfall, but when rainfall causes the water layer depth on the field surface to exceed the upper limit of rainfall storage control, the water on the field surface should be drained back to the upper limit in a timely manner, and the continuous time at which the upper limit of rainfall storage is reached should not exceed 7 days.

[0062] In this application, the upper limit of irrigation quota control refers to the irrigation quota required to bring the paddy field moisture to the upper limit of the surface water depth control after the paddy field moisture reaches the lower limit of soil moisture content control when the paddy field promotes controlled irrigation technology. The upper limit of irrigation quota control refers to the maximum value of the paddy field irrigation quota in each soil permeability identification zone, which can be used as a reference for water allocation in the secondary and final stage rotational irrigation channels.

[0063] Under the current water supply and service level, paddy field moisture monitoring indicators can prioritize easily monitored indicators such as field surface water depth and soil crack width. In this application, the paddy field moisture monitoring indicators include field surface water depth monitored by water level probes, soil moisture content monitored by soil moisture meters, soil crack width monitored by rulers, rainfall monitored by self-recording rain gauges, and irrigation quotas calculated according to formulas.

[0064] Traditional methods for measuring the water depth in paddy fields using conventional instruments such as electronic water gauges and radar level gauges present several difficulties: First, radar level gauges measure water level, requiring the paddy field surface to be set as the water level reference. However, due to cultivation and irrigation, the elevation of the paddy field surface is difficult to maintain, affecting the water depth measurement results. Second, electronic water gauges typically have an accuracy of 5mm and 10mm, which is insufficient for controlled irrigation techniques in rice cultivation. Therefore, this invention employs a 0.1mm precision water level probe to monitor the water depth in paddy fields. During measurement, the probe tip is brought into contact with both the paddy field surface and the water surface, and readings are taken to obtain a 0.1mm precision water depth.

[0065] Step 2: Establish irrigation control units in the irrigation district and collect paddy field moisture information;

[0066] In step 2, the irrigation district is divided into several independent control irrigation units according to the control range of the secondary irrigation canal.

[0067] Preferably, in order to track the paddy field moisture status of each controlled irrigation unit in real time and to facilitate a rapid response to the water demand of each controlled irrigation unit, control points are set up within the control range of representative terminal irrigation canals in each controlled irrigation unit to monitor the paddy field moisture status at the control points and to feed back the monitored paddy field moisture status information at the control points to the irrigation district water supply and service center in real time.

[0068] Preferably, under the current water supply and service level, indicators such as soil crack width and surface water depth can be used to determine the paddy field moisture status at the control point.

[0069] Since a control irrigation unit typically has several terminal irrigation channels, even if control points are set up within the control range of a representative terminal irrigation channel, the paddy field moisture monitored at each control point is usually not the same due to the large spatial variability of soil moisture. Therefore, the paddy field moisture status of the control irrigation unit mentioned in step 2 refers to the most unfavorable value among the paddy field moisture status information at all control points within the control irrigation unit.

[0070] In this invention, the most unfavorable value of paddy field moisture status information at all control points within a certain irrigation control unit is divided into two cases: for the soil moisture content index, the most unfavorable value refers to the minimum soil moisture content at all control points; for the soil crack width index, the most unfavorable value refers to the maximum soil crack width at all control points.

[0071] Step 3: Create a dynamic water situation map of the irrigation area and compile a dynamic rotation irrigation team;

[0072] In step 3, based on the irrigation control technology standards for rice in the irrigation area established in step 1 and the paddy field moisture status of the controlled irrigation units obtained in step 2, a dynamic water situation map of the irrigation area reflecting the paddy field moisture status of each controlled irrigation unit is created as the basis for compiling dynamic rotation irrigation groups.

[0073] Preferably, in the irrigation district water situation dynamic map, green represents that the paddy field moisture value of the controlled irrigation unit is above the soil saturation moisture content;

[0074] Yellow represents the paddy field moisture value of the controlled irrigation unit being between the soil saturation moisture content and the lower limit of soil moisture content control;

[0075] Red indicates that the paddy field moisture value of the controlled irrigation unit has reached the lower limit of soil moisture content control.

[0076] Preferably, the irrigation area can generate a dynamic water situation map of the irrigation area at one time, and then automatically update it in real time based on the paddy field water information monitored at the control points.

[0077] Traditional canal rotation irrigation systems generally employ two methods: centralized grouping and interspersed grouping. Centralized grouping groups several adjacent canals of the same level together, while interspersed grouping groups canals of the same level according to odd or even numbers. After centralized or interspersed grouping, the superior canals supply water in rotation according to the grouping. These two traditional canal rotation irrigation grouping methods have played an important role in calculating canal design flow rates during the irrigation district planning and design phase, as well as in the practical application of canal water distribution in irrigation districts. However, in irrigation districts where controlled irrigation technology for rice has been widely adopted, the secondary and final-level rotation irrigation canals of controlled irrigation units that have reached the lower control limit may not necessarily appear adjacent to each other, nor may they necessarily meet the requirement of odd or even numbering. Neither centralized nor interspersed grouping rotation irrigation methods can adequately address the dynamic water demand of each controlled irrigation unit.

[0078] This invention uses a dynamic irrigation rotation group based on the dynamic water situation map of the irrigation area to quickly and accurately respond to the dynamic water demand of the controlled irrigation unit. Specifically, before each rotation, controlled irrigation units with the same color in the dynamic water situation map of the irrigation area are grouped into the same dynamic rotation group. Subsequently, precise rotation irrigation work is carried out on each dynamic rotation group in the order of red, yellow and green in the dynamic water situation map of the irrigation area.

[0079] Step 4: Divide the irrigation area into soil permeability identification zones and determine the irrigation quota;

[0080] Because soil permeability varies among different paddy fields, paddy fields with higher soil permeability will reach the lower control limit earlier when irrigated with the same water quota during a single irrigation. Therefore, the irrigation quota should be adjusted appropriately according to the soil permeability of the paddy field.

[0081] Based on this, in step 4, taking into account factors such as soil permeability and topography in the irrigation area, and following principles such as facilitating irrigation water allocation and water supply services, the irrigation area is divided into several soil permeability identification zones, and the upper limit of the field surface water depth control for each soil permeability identification zone is further determined. After dividing the soil permeability identification zones, a soil permeability identification zone map of the irrigation area can be generated at once, making it easy to look up the upper limit of the field surface water depth control for each identification zone.

[0082] In step 4, when the paddy field moisture content is greater than or equal to the soil saturation moisture content and less than the upper limit of the field surface water depth control, the paddy field irrigation quota under controlled irrigation conditions is obtained by the following formula (I):

[0083] m ij =0.667×(h) max，ij -h 0，ij ) (one)

[0084] When the paddy field moisture content is less than the soil saturation moisture content but greater than the lower limit of soil moisture content control, the paddy field irrigation quota under controlled irrigation conditions is obtained by formula (II) as follows:

[0085] m ij =0.667×[H j (θ s，ij -θ 0，ij )+h max，ij ] (two)

[0086] In particular, when the paddy field moisture value equals the lower limit of soil moisture content control, the paddy field irrigation quota under controlled irrigation conditions reaches its maximum value, i.e., the upper limit of the irrigation quota, which is obtained using the following formula (iii):

[0087] m max，ij =0.667×[H j (θ s，ij -θ min，j ×θ s，ij )+h max，ij ] (three)

[0088] Where, m ij This represents the irrigation quota for paddy fields within the i-th soil permeability identification zone during the j-th growth stage of rice, in m³. 3 / mu;

[0089] mmax，ij This represents the upper limit of irrigation quota for paddy fields within the i-th soil permeability identification zone during the j-th growth stage of rice, in m³. 3 / mu;

[0090] 0.667 indicates that the unit of measurement for irrigation quotas has been converted from "mm" (water depth) to "m". 3 Conversion factor for " / mu";

[0091] h max，ij The upper limit of the surface water depth control for paddy fields in the i-th soil permeability identification zone during the j-th growth stage of rice is indicated in mm.

[0092] h 0，ij The depth of the surface water layer in the paddy field within the i-th soil permeability identification zone before irrigation during the j-th growth stage of rice is expressed in mm.

[0093] H represents the planned wetting layer depth in the paddy field during the j-th growth stage of rice, in mm;

[0094] θ s，ij This represents the average saturated water content (percentage of soil volume) of the planned moist layer soil in the paddy field within the i-th soil permeability identification zone during the j-th growth stage of rice, in %;

[0095] θ 0，ij The average value of the planned moist layer soil moisture content (percentage of soil volume) in the paddy field within the i-th soil permeability identification zone before irrigation during the j-th growth stage of rice, in %;

[0096] θ min，j The lower limit of planned wetting layer soil moisture content (percentage of soil volumetric moisture content) for rice at the j-th growth stage is expressed as %.

[0097] Preferably, when the paddy field moisture content is greater than or equal to the soil saturation moisture content, h 0，ij Take the actual measured value of the water layer depth on the paddy field surface before irrigation; when the paddy field moisture value is less than the soil saturation moisture content but greater than the lower limit of soil moisture content control, θ 0，ij The average value of the measured soil moisture content in the planned moist layer of the paddy field before irrigation is taken.

[0098] Preferably, the following operations need to be performed before performing step 4:

[0099] Sub-step 1 involves using soil testing and other methods to obtain the planned wetting layer depth H of the paddy field at each growth stage of rice, and the average soil saturated water content θ of the planned wetting layer of the paddy field at each growth stage of rice within each soil permeability identification zone. s，ij ;

[0100] Sub-step 2 involves identifying the soil permeability identification zone i where the paddy field is located, determining the current growth stage j of the rice, and thus determining the upper limit h of the current paddy field surface water depth control. max，ij and soil moisture content control lower limit θ min，j ;

[0101] Sub-step 3: Obtain the actual value of the water layer depth on the paddy field surface before irrigation or the measured value of the soil moisture content of the planned wetting layer of the paddy field.

[0102] Step 5: Set up irrigation district water supply service areas and implement precision rotation irrigation.

[0103] Since the control range of canals at the same level is usually not the same, the area of ​​controlled irrigation units often varies greatly. Under the current level of water supply and service, in order to reduce the input of manpower, material resources, and financial resources, controlled irrigation units can be appropriately integrated to set up water supply and service areas. Each water supply and service area can serve one or more controlled irrigation units and be staffed with personnel responsible for the water supply and service work of the controlled irrigation units under its jurisdiction. Under the guidance of the precise rotation irrigation method for rice controlled irrigation in smart irrigation districts provided in this application, controlled irrigation units can be further integrated to establish larger-scale water supply and service areas, further reducing the input of manpower, material resources, and financial resources, and realizing smart irrigation.

[0104] Preferably, in step 5, based on the dynamic rotation irrigation group compiled in step 3 and the irrigation quota obtained in step 4, the staff of the water supply and water service area coordinate the precise rotation irrigation work between each water supply and water service area and within each control irrigation unit, so that the irrigation volume sequentially meets the water demand of the control irrigation units in the red, yellow and green dynamic rotation irrigation groups.

[0105] Preferably, precise rotational irrigation is implemented between each controlled irrigation unit and within each controlled irrigation unit, following the principle of prioritizing drought-stricken areas over less drought-stricken areas and prioritizing upstream areas over downstream areas.

[0106] In a preferred embodiment, the irrigation control technology standards, irrigation control units, and soil permeability identification zones for rice in irrigation districts in this application can be formulated once based on the actual conditions of the irrigation district, and then adjusted and implemented according to the actual conditions of the irrigation district.

[0107] Preferably, the irrigation area water situation dynamic map in step 3 of this application can be generated at once and then automatically updated in real time based on the paddy field water information monitored at the control points of each irrigation unit.

[0108] The precise rotation irrigation method for controlled irrigation of rice in smart irrigation districts provided in this application offers a new and highly operable method for the high-quality promotion of controlled irrigation technology for rice at the irrigation district scale. It also provides a new method for the high-quality promotion of water-saving irrigation technologies for rice such as rainwater harvesting irrigation, shallow wet irrigation, and intermittent irrigation at the irrigation district scale. In particular, it provides a practical and feasible infrastructure for traditional irrigation districts to gradually realize automatic monitoring, intelligent water allocation, and precise irrigation services during the transformation to smart irrigation districts.

[0109] Generally, preferably, the precise rotational irrigation method for controlled irrigation of rice in smart irrigation districts can be implemented according to the flowchart drawn in this invention (see...). Figure 1 ) Implementation.

[0110] Example

[0111] Changgang Irrigation District, located in Lanxi County, Heilongjiang Province, is a pumping irrigation district that uses the Hulan River as its water source. It has a three-tiered fixed canal system, including one main canal, 14 branch canals, and 129 distribution canals. The main canal serves as a continuous irrigation channel, while the branch and distribution canals are used for rotational irrigation. In 2021, Changgang Irrigation District conducted eight rotational irrigation cycles, all using a precision rotational irrigation method for rice controlled irrigation, designed for smart irrigation districts. The specific implementation process for the water supply service from June 16th to 18th, 2021, included the following steps:

[0112] Step 1: Formulate irrigation control technology standards for rice in the irrigation area, and clarify the threshold values ​​for paddy field moisture monitoring indicators at each growth stage of rice. Specifically, referencing the Ministry of Water Resources of China's "Irrigation Experiment Specifications" (SL 13-2015), identify the following stages of the entire rice growth period in the Changgang irrigation area: greening stage, early tillering stage, mid-tillering stage, late tillering stage, jointing and booting stage, heading and flowering stage, milk stage, and yellowing stage. Referring to the Heilongjiang Provincial Local Standard "Technical Specifications for Water-Saving Controlled Irrigation of Rice in Cold Regions" (DB 23 / T 1500-2013), and considering the actual rice production conditions in the irrigation area, formulate irrigation control technology standards for the entire growth period of rice in the Changgang irrigation area (see Table 1). Among these standards, three criteria—lower limit for soil moisture content control, lower limit for soil crack width control, and upper limit for rainfall storage control—are consistent with the "Technical Specifications for Water-Saving Controlled Irrigation of Rice in Cold Regions" (DB 23 / T 1500-2013). The standards are consistent with those of 1500-2013; the two standards of planned wetting layer depth and field surface water layer depth control upper limit have been adjusted according to the actual situation of rice production in the irrigation area; in particular, an upper limit indicator for irrigation quota control has been added.

[0113] Specifically, according to the "Technical Specification for Water-Saving Controlled Irrigation of Rice in Cold Regions" (DB 23 / T 1500-2013), the planned wetting layer depth for paddy fields in the Changgang Irrigation District is 400 mm during the milk-ripe and yellow-ripe stages. However, when rice in the Changgang Irrigation District is in the milk-ripe and yellow-ripe stages, irrigation is rarely carried out due to the arrival of the rainy season. In particular, the groundwater level is high during the yellow-ripe stage, and even in dry weather, "running water" irrigation can meet the water needs of the paddy fields. Therefore, the planned wetting layer depth for the milk-ripe and yellow-ripe stages is adjusted to 200 mm.

[0114] Regarding the 20mm upper limit for the field surface water depth control during the greening stage and the 30mm upper limit for the field surface water depth control during the early tillering, mid-tillering, jointing and booting, and heading and flowering stages recommended in the "Technical Specification for Water-Saving Control Irrigation of Rice in Cold Regions" (DB 23 / T 1500-2013), this invention has adjusted the upper limit for the field surface water depth control in each soil permeability identification zone of the Changgang Irrigation District (see step 4 for the method of dividing the soil permeability identification zone) (see Table 1). Among them, the upper limit for the field surface water depth control in the riverside identification zone is 40mm, the upper limit for the field surface water depth control in the upstream identification zone is 35mm, the upper limit for the field surface water depth control in the midstream identification zone is 30mm, and the upper limit for the field surface water depth control in the downstream identification zone is 20mm.

[0115] Table 1 Technical Standards for Controlled Irrigation of Rice Fields Throughout the Changgang Irrigation District

[0116]

[0117] In 2021, the paddy field moisture monitoring indicators adopted by Changgang Irrigation District included soil crack width, surface water depth, and soil moisture content.

[0118] Step 2: Establish irrigation control units in the irrigation district and collect paddy field moisture information;

[0119] The Changgang irrigation district was divided into 14 independent control irrigation units based on the control range of the secondary and final-level irrigation channels (branch canals). Control points were set up within the control range of the representative secondary and final-level irrigation channels (splitter canals) of each control irrigation unit to monitor the paddy field moisture status. A total of 45 control points were set up, as detailed in Table 2.

[0120] Staff at the Changgang Irrigation District Water Supply and Service Area regularly monitor rice growth stages, soil crack widths, field surface water depths, and soil moisture content at 45 control points, and promptly report the monitored information to the Changgang Irrigation District Water Supply and Service Center.

[0121] The paddy field moisture status of each controlled irrigation unit is evaluated using the worst-case values ​​of paddy field moisture status information at all control points within the controlled irrigation unit.

[0122] Table 2. Statistics on the Layout of Paddy Field Moisture Monitoring and Control Points in Changgang Irrigation District

[0123]

[0124] Step 3: Create a dynamic water situation map of the irrigation area and compile a dynamic rotation irrigation team;

[0125] Based on the spatial distribution of each irrigation control unit, the Changgang Irrigation District Water Supply and Use Service Center has created a dynamic water situation map of the Changgang Irrigation District, such as... Figure 2 As shown in the figure, and based on the technical standards for controlled irrigation of paddy fields throughout the entire growth period of rice in Changgang Irrigation District established in step 1 and the paddy field moisture information collected at the control points in step 2, the paddy field moisture status of 14 controlled irrigation units was determined, and the dynamic map of water conditions in the irrigation district was updated in real time.

[0126] In the dynamic water situation map of Changgang Irrigation District, green represents the paddy field moisture value of the controlled irrigation unit being above the soil saturation moisture content; yellow represents the paddy field moisture value of the controlled irrigation unit being between the soil saturation moisture content and the lower limit of soil moisture content control; and red represents the paddy field moisture value of the controlled irrigation unit having reached the lower limit of soil moisture content control.

[0127] Depend on Figure 2 As shown in the dynamic water situation map of Changgang Irrigation District, during this water supply service, the red control irrigation units are the branches of branch canals 1, 6, 9, 10, and 11. The branches corresponding to these control irrigation units are organized into the first irrigation group for this rotation. Similarly, the branches of branch canals 4, 5, 8, and 13 corresponding to the yellow control irrigation units are organized into the second irrigation group, and the branches of branch canals 2, 3, 7, 12, and 14 corresponding to the green control irrigation units are organized into the third irrigation group.

[0128] Step 4: Divide the irrigation area into soil permeability identification zones and determine the irrigation quota;

[0129] Taking into account factors such as soil permeability and topography in the irrigation area, and following the principles of facilitating irrigation water allocation and water supply services, the Changgang Irrigation District was divided into four soil permeability identification zones: along the river, upstream, middle, and downstream. A soil permeability identification zone map of the Changgang Irrigation District was created (see...). Figure 3 The upper limit of the water depth control in the paddy field surface of each identification area was obtained, as detailed in Table 3.

[0130] Table 3 Upper Limit of Water Layer Depth Control in Paddy Fields in Changgang Irrigation District

[0131]

[0132] In step 4,

[0133] When the paddy field moisture content is greater than or equal to the soil saturation moisture content and less than the upper limit of the field surface water depth control, the paddy field irrigation quota under controlled irrigation conditions is obtained by the following formula (I):

[0134] m ij =0.667×(h) mix，ij -h 0，ij ) (one)

[0135] When the paddy field moisture content is less than the soil saturation moisture content but greater than the lower limit of soil moisture content control, the paddy field irrigation quota under controlled irrigation conditions is obtained by formula (II) as follows:

[0136] m ij =0.667×[H j (θ s，ij -θ 0，ij )+h max，ij ] (two)

[0137] When the paddy field moisture content equals the lower limit of soil moisture control, the paddy field irrigation quota under controlled irrigation conditions reaches its maximum value, i.e., the upper limit of the irrigation quota, which is obtained using the following formula (iii):

[0138] m max，ij =0.667×[H j (θ s，ij -θ min，j ×θ s，ij )+h max，ij ] (three)

[0139] Where, m ij This represents the irrigation quota for paddy fields within the i-th soil permeability identification zone during the j-th growth stage of rice, in m³. 3 / mu;

[0140] m max，ij This represents the upper limit of irrigation quota for paddy fields within the i-th soil permeability identification zone during the j-th growth stage of rice, in m³. 3 / mu;

[0141] 0.667 indicates that the unit of measurement for irrigation quotas has been converted from "mm" (water depth) to "m". 3 Conversion factor for " / mu";

[0142] h max，ij The upper limit of the surface water depth control for paddy fields in the i-th soil permeability identification zone during the j-th growth stage of rice is indicated in mm.

[0143] h 0，ij The depth of the surface water layer in the paddy field within the i-th soil permeability identification zone before irrigation during the j-th growth stage of rice is expressed in mm.

[0144] H represents the planned wetting layer depth in the paddy field during the j-th growth stage of rice, in mm;

[0145] θs，ij This represents the average saturated water content (percentage of soil volume) of the planned moist layer soil in the paddy field within the i-th soil permeability identification zone during the j-th growth stage of rice, in %;

[0146] θ 0，ij The average value of the planned moist layer soil moisture content (percentage of soil volume) in the paddy field within the i-th soil permeability identification zone before irrigation during the j-th growth stage of rice, in %;

[0147] θ min，j The lower limit of planned wetting layer soil moisture content (percentage of soil volumetric moisture content) for rice at the j-th growth stage is expressed as %.

[0148] Soil property testing results indicate that the saturated water content of the soil layer (0–400 mm) in the Changgang irrigation area ranges from 47.0% to 52.8%. Figure 3 The distribution of soil permeability identification zones in the irrigation area, the upper limit of the field surface water layer depth control determined in step 1, the planned wetting layer depth and soil moisture content control lower limit and the planned wetting layer soil moisture content in Table 1, and the irrigation quota for paddy fields can be obtained using formula (II). When the planned wetting layer soil moisture content before irrigation reaches the soil moisture content control lower limit, the upper limit of the irrigation quota control for the entire growth period of paddy fields in Changgang Irrigation Area obtained using formula (III) is shown in Table 4.

[0149] Table 4 Upper Limit of Irrigation Quota Control for Rice Fields Throughout the Entire Growth Period in Changgang Irrigation District (m²) 3 / mu)

[0150] Riverside Identification Area 41 37 37 28 43 48 35 28 Upstream identification area 37 33 33 27 38 43 33 27 Midstream identification zone 33 30 30 27 35 40 33 27 Downstream identification area 26 23 23 25 27 32 32 25

[0151] Step 5: Set up irrigation district water supply service areas and implement precision rotation irrigation;

[0152] The control areas of the various branch canals in the Changgang Irrigation District vary considerably. By integrating 14 irrigation control units and establishing 6 water supply service areas, a water supply service area map of the Changgang Irrigation District was created, as shown below. Figure 4 As shown in Table 5, each water supply service area is staffed with one person to provide water supply services for all controlled irrigation units within the service area.

[0153] Table 5 Water Supply Service Areas of Changgang Irrigation District

[0154] First Water Supply Service Area Branch canal 1, branch canal 3, branch canal 5 (west side) Second water supply service area Branch canal 5 (east side), branch canal 7, branch canal 9 Third Water Supply Service Area 2 branch canals Fourth Water Supply Service Area 4-branch canal, 6-branch canal, 8-branch canal Fifth Water Supply Service Area 13 branch canals Sixth Water Supply Service Area Branch canals numbered 10, 11, 12, and 14.

[0155] Depend on Figure 2 and Figure 4As can be seen, during this water supply service, the red controlled irrigation units are distributed in the first water supply service area (1 branch canal), the second water supply service area (9 branch canals), the fourth water supply service area (6 branch canals), and the sixth water supply service area (10 and 11 branch canals). Based on the rotation irrigation groups established in step 3, the staff of the water supply service areas will coordinate the rotation irrigation work among the first, second, fourth, and sixth water supply service areas, as well as among all controlled irrigation units within each service area. According to the irrigation quota for paddy fields determined in step 4, the water supply will be implemented in rotation irrigation according to the order of the 1st (red), 2nd (yellow), and 3rd (green) rotation irrigation groups. Within each rotation irrigation group, between each controlled irrigation unit (each branch canal) and within each controlled irrigation unit (between canals), precise rotation irrigation will be implemented following the principles of prioritizing areas with severe drought and those with milder drought, and prioritizing upstream areas over downstream areas.

[0156] In 2021, the controlled irrigation precision rotation method for rice was adopted, with a total of 8 irrigations and a water consumption of 7.96 million cubic meters. 3 The electricity consumption was 425,800 kWh, irrigating 14,994 mu of paddy fields. Six people were involved in irrigation services in the water supply service area, with an average water consumption of 531 cubic meters per mu of paddy field. 3 The average electricity consumption per mu is 28.40 kWh, and the average yield per mu is 542 kg.

[0157] Comparative example:

[0158] Data from the Changgang Irrigation District in 2018, whose annual precipitation is close to that of 2021, was compared with the above-mentioned examples, as follows:

[0159] In 2018, controlled irrigation technology for rice was promoted, with a total of 10 irrigations and a water consumption of 9.38 million cubic meters. 3 The electricity consumption was 51.48 kWh, the irrigated paddy field area was 14,992 mu, and a total of 9 people participated in the irrigation service work in the water supply service area. The average water consumption per mu of paddy field was 626 cubic meters. 3 The average electricity consumption per mu is 34.34 kWh, and the average yield per mu is 496 kg.

[0160] The results of the above comparison show that the precise rotation irrigation method for rice controlled irrigation in smart irrigation districts provided in this application saves 18% more water, 21% more energy, and increases yield by 9% on the basis of rice controlled irrigation, while also reducing the workload of irrigation services.

[0161] The present invention has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present invention based on these embodiments, all of which fall within the scope of protection of the present invention.

Claims

1. A method for precise rotational irrigation of rice under controlled irrigation in smart irrigation districts, characterized in that, The method includes the following steps: Step 1: Formulate irrigation control technology standards for rice in irrigation districts and clarify the threshold values ​​for paddy field water monitoring indicators at each growth stage of rice. In Step 1, the irrigation control technology standards for rice in irrigation districts include the planned wetting layer depth, the upper limit of the field surface water layer depth control, the lower limit of soil moisture content control, the lower limit of soil crack width control, the upper limit of rainfall storage control, and the upper limit of irrigation quota control at each growth stage of rice. Step 2: Establish irrigation control units in the irrigation district and collect paddy field moisture information; In step 2, the irrigation district is divided into several independent control irrigation units according to the control range of the secondary and final irrigation channels; In step 2, control points are set up within the control range of representative terminal irrigation canals in each control irrigation unit to monitor the paddy field moisture status at the control points and to feed back the monitored paddy field moisture status information at the control points to the irrigation district water supply and service center in real time. In step 2, the paddy field moisture status of each controlled irrigation unit is collected; The paddy field moisture status of the controlled irrigation unit refers to the most unfavorable value among the paddy field moisture status information at all control points within the controlled irrigation unit. Step 3: Create a dynamic water situation map of the irrigation area and compile a dynamic rotation irrigation team; In step 3, based on the rice controlled irrigation technology standards established in step 1 and the paddy field moisture status of the controlled irrigation units obtained in step 2, a dynamic water situation map of the irrigation district reflecting the paddy field moisture status of each controlled irrigation unit is created. In the irrigation district water situation dynamic map, green represents that the paddy field water value of the controlled irrigation unit is above the soil saturation water content; Yellow represents the paddy field moisture value of the controlled irrigation unit being between the soil saturation moisture content and the lower limit of soil moisture content control; Red indicates that the paddy field moisture value of the controlled irrigation unit has reached the lower limit of soil moisture content control; In step 3, before each rotation irrigation, the control irrigation units with the same color in the dynamic water situation map of the irrigation area are grouped into a dynamic rotation irrigation group. Subsequently, the precise rotation irrigation work is carried out on each dynamic rotation irrigation group in the order of red, yellow and green. Step 4: Divide the irrigation area into soil permeability identification zones and determine the irrigation quota; In step 4, taking into account the soil permeability and topographical factors of the irrigation area, and following the principles of facilitating irrigation water allocation and water supply services, the irrigation area is divided into several soil permeability identification zones, and the upper limit of the field surface water layer depth control in each soil permeability identification zone is further obtained. Step 5: Set up irrigation district water supply service areas and implement precision rotation irrigation.

2. The method for precise rotational irrigation of rice in smart irrigation districts according to claim 1, characterized in that, In step 1, the rice growth stages refer to the following stages throughout the entire growth period of the rice paddy: the greening stage, the early tillering stage, the mid-tillering stage, the late tillering stage, the jointing and booting stage, the heading and flowering stage, the milk stage, and the yellowing stage.

3. The method for precise rotational irrigation of rice in smart irrigation districts according to claim 1, characterized in that, In step 1, the paddy field moisture monitoring indicators for each growth stage of rice include the field surface water depth monitored by a water level probe, the soil moisture content monitored by a soil moisture meter, the soil crack width monitored by a ruler, the rainfall monitored by a self-recording rain gauge, and the calculated irrigation quota.

4. The method for precise rotational irrigation of rice in smart irrigation districts according to claim 1, characterized in that, In step 4, when the paddy field moisture content is greater than or equal to the soil saturation moisture content and less than the upper limit of the field surface water depth control, the paddy field irrigation quota under controlled irrigation conditions is obtained by the following formula (I): (one) When the paddy field moisture content is less than the soil saturation moisture content but greater than the lower limit of soil moisture content control, the paddy field irrigation quota under controlled irrigation conditions is obtained by formula (II) as follows: (two) When the paddy field moisture content equals the lower limit of soil moisture control, the paddy field irrigation quota under controlled irrigation conditions reaches its maximum value, i.e., the upper limit of the irrigation quota, which is obtained using the following formula (iii): (three) in, Indicates the first Paddy fields within the soil permeability identification zone during the rice growing season Irrigation quota during the reproductive period, unit: m 3 / mu; Indicates the first i Paddy fields within the soil permeability identification zone during the rice growing season j Upper limit of irrigation quota during the reproductive period, unit: m 3 / mu; 0.667 indicates that the irrigation quota unit has been converted from "mm" (water depth) to "m". 3 Conversion factor for " / mu"; Indicates the first i Paddy fields within the soil permeability identification zone during the rice growing season j Upper limit of surface water depth control during the growing season, unit: mm; Indicates the first i Paddy fields within the soil permeability identification zone during the rice growing season j The depth of the water layer on the field surface before irrigation during the growing season, in mm; Indicates the rice j Planned wetting depth of paddy fields during the growing season, unit: mm; Indicates the first i Paddy fields within the soil permeability identification zone during the rice growing season j Average saturated moisture content of the planned wetting layer soil during the growing season, unit: % Indicates the first i Paddy fields within the soil permeability identification zone during the rice growing season j Average soil moisture content of the planned wetting layer before irrigation during the growing season, in % %. Indicates the rice j Lower limit of planned moisture content control in the moist layer of paddy fields during the growing season, unit:%.

5. The method for precise rotational irrigation of rice in smart irrigation districts according to claim 1, characterized in that, In step 5, each water supply service area in the irrigation district can serve one or more controlled irrigation units and is staffed with personnel responsible for the water supply service work of the controlled irrigation units under its jurisdiction.

6. The method for precise rotational irrigation of rice in smart irrigation districts according to claim 5, characterized in that, In step 5, based on the dynamic rotation irrigation group compiled in step 3 and the irrigation quota obtained in step 4, the staff of the water supply and water service area coordinate the precise rotation irrigation work between each water supply and water service area and within each control irrigation unit of the water supply and water service area, so that the irrigation volume sequentially meets the water demand of the control irrigation units within the red, yellow and green dynamic rotation irrigation groups. Precision rotation irrigation is implemented between and within each controlled irrigation unit, following the principle of prioritizing areas with severe drought and those with mild drought, and prioritizing upstream areas over downstream areas.

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