Crop growth water demand calculation method and irrigation system formulated according to same

Abstract

The invention discloses a crop growth water demand calculation method and an irrigation system formulated according to the same, and relates to the field of agricultural irrigation. The method comprises the following calculation steps: selecting reference ET0, selecting and confirming the length of a growth stage, selecting a crop coefficient, adjusting the value of Kc ini to reflect the soil wetting frequency, adjusting the values of Kc mid and Kc end to adapt to regional climate conditions, calculating ETc, determining the effective water consumption and calculating the water balance of a soil root system layer. According to the irrigation water distribution system disclosed by the invention, a water demand calculation result in actual agricultural production can be reasonably adjusted and optimized in combination with a local water resource condition and an irrigation system capability, and during fertilization or pesticide spraying, the amount can be more accurately calculated by utilizing the calculated water amount, so that the irrigation efficiency is improved. And meanwhile, selective operation can be carried out according to a fertilization mode required by crops.

Description

Technical Field

[0001] The invention mainly relates to the technical field of agricultural irrigation, in particular to a method for calculating water requirement for crop growth and an irrigation system formulated based on the method. Background Art

[0002] The method for calculating the water requirement for crop growth is: using meteorological data and crop coefficients to calculate the reference crop evapotranspiration ET 0 Compared with crop evapotranspiration ET under standard conditions c Accurately calculating the water demand during crop growth is of great significance for improving irrigation efficiency, saving water resources and ensuring crop yields. With the increasingly severe global climate change and water shortage problems, mastering scientific methods for calculating water demand is particularly critical.

[0003] The patent document with application number 202210146656.9 discloses an irrigation method, device, equipment and storage medium based on soil and crop roots. The present invention relates to the field of irrigation technology, and in particular to an irrigation method based on soil and crop roots, comprising the steps of: obtaining the transpiration and evaporation of crops in a target area, leaf area index, and rainfall in the target area; obtaining the water requirement of crops in the target area according to the transpiration and evaporation of crops in the target area, leaf area index, rainfall in the target area and a water requirement calculation algorithm; obtaining the salt leaching rate of crops in the target area, obtaining the irrigation amount of crops in the target area according to the water requirement of crops in the target area, the salt leaching rate and the irrigation amount calculation algorithm, and generating a water storage instruction based on the irrigation amount of crops in the target area, and sending it to an irrigation device; obtaining soil moisture content data corresponding to the root depth of the crop according to the root depth of the crop, and controlling the irrigation device to perform irrigation and drainage operations according to the soil moisture content data and a preset water requirement threshold for each growth period of the crop to improve irrigation and drainage efficiency.

[0004] Existing irrigation systems generally use flood irrigation or drip irrigation during the irrigation period. They cannot adjust the irrigation water volume and irrigation method in time according to the actual growth species, stage, weather changes and geological changes of the crops. This will cause a certain degree of waste of water resources and inaccurate use of drugs / fertilizers, and irrigation cannot be carried out according to actual needs. Summary of the invention

[0005] The present invention discloses a method for calculating the water requirement for crop growth and an irrigation system developed based on the method, aiming to solve the technical problems that the existing irrigation system cannot adjust the irrigation water volume in time according to the actual growth species, stage, weather changes and geological changes of the crops, which will cause waste of water resources to a certain extent, inaccurate dosage of medicines / fertilizers, and cannot irrigate according to the irrigation method required by the crop growth stage.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for calculating the water requirement for crop growth, characterized in that: the calculation steps include: referring to ET 0 Selection of the growth stage length, selection and confirmation of the crop coefficient, and adjustment of K c ini The value of K is adjusted to reflect the frequency of soil wetting and c mid and K c end The value of ET is adapted to the regional climate conditions, c Calculate effective water usage and calculate water balance in the soil root zone.

[0008] In a preferred embodiment, according to the Penman-Monteith formula, referring to ET 0 The calculation program uses the daily meteorological data of 207 towns and villages in 19 counties and cities in 5 prefectures and cities in the Hexi Corridor irrigation agricultural area in recent years to determine the corresponding reference evapotranspiration ET. 0 , establish the corresponding equation, and the following functions can be realized:

[0009] 1. Select the location, time range and meteorological name (select single or multiple options, average temperature, average relative humidity, average wind speed, effective accumulated temperature ET 0 ) Generate average data graphs with day, week, ten-day, month as the time length;

[0010] 2. The single data graphs of two locations can be compared and displayed in the form of upper and lower graphs, and the single data of multiple locations can be compared and displayed in one graph;

[0011] 3. Query the highest / lowest / average temperature, relative humidity, wind speed, ET within the selected time range according to the location 0 and effective accumulated temperature, and displayed in a graph;

[0012] 4. Ability to display the average annual / monthly / daily maximum / minimum / average temperature, relative humidity, wind speed, effective accumulated temperature and ET for many years 0 Data and Figures.

[0013] Reference evaporation volume ET 0 calculate:

[0014]

[0015] R n Net radiation on crop surface MJ / m 2 *day;

[0016] G Soil heat flux MJ / m 2 *day;

[0017] T Daily average temperature at 2 meters height0 C;

[0018] u 2 Wind speed at 2 meters height m / s;

[0019] e s Saturated water vapor pressure kPa;

[0020] e a Actual water vapor pressure kPa;

[0021] Δ Slope of water vapor pressure curve kPa / 0 C;

[0022] γ Hygrometer constant kPa / 0 C.

[0023] In a preferred embodiment, the steps of selecting and confirming the length of the growth stage and selecting the crop coefficient are as follows:

[0024] ① Divide the growth period of the crops into different growth stages, make typical diagrams of crop characteristics in each growth period, and describe the characteristics based on the four-stage definition according to the biological characteristics of different crops;

[0025] ② Crop coefficient (K c ini , K c mid , K c end ) selection.

[0026] The crop growth stage is divided into early growth period (L ini ), rapid growth period, mid-growth period (L mid ) and late growth period (L late ) four stages, giving reminders based on different crops to help users make accurate choices.

[0027] Divide the growth period of the crops into different growth stages and make typical crop characteristics of each growth period. Figure 1 One-to-one correspondence. Based on the biological characteristics of different crops, characteristic descriptions are carried out on the basis of the four-stage definitions to achieve an effect of easy distinction.

[0028] In a preferred embodiment, the adjustment K c ini The value of reflects the soil moisture frequency based on:

[0029]

[0030] Where: f w is the percentage of the soil surface wetted by irrigation or rainfall;

[0031] K C ini (Table, Figure) obtained from Table 12, Figure 29 or 30 of the Guide to Calculating Crop Water Requirements FAO-56;

[0032] The adjusted K c mid and K c end are valued to adapt to regional climate conditions based on:

[0033]

[0034] In the formula: K c mid(表) is the K obtained from Table 12 c mid ;

[0035] u 2 is the daily average wind speed at a height of 2 m above the grass surface during the mid - growth period, in m / s, for 1 m / s < u2 < 6 m / s (the wind speed in meteorological data is at a height of 10 m and needs to be converted to the wind speed value at 2 m through a formula.);

[0036] RH min is the average value of the daily minimum relative humidity during the mid - growth period, in %, for 20% < RH min < 80%;

[0037] h is the average plant height during the mid - growth period, in m, for 0.1 < h < 10.

[0038] In a preferred embodiment, the data processing module further includes: ET c calculation, which is divided into the single - crop coefficient method for calculating ET c and the dual - crop coefficient method for calculating ET c .

[0039] The single - crop coefficient method for calculating ET c formula:

[0040]

[0041] The dual - crop coefficient method for calculating ET c formula:

[0042]

[0043] Function: It can determine the K c value on any day during the growth period according to the numerical calculation method of K c and can visually present it in the "graph" by selecting a date or inputting the number of days.

[0044] The crop coefficient K c is based on the ratio of the crop evapotranspiration ET c and the reference evapotranspiration ET 0 and it reflects the comprehensive influence of four main characteristics that distinguish the actual crop from the reference crop grass.

[0045] The double crop coefficient method uses the time-averaged single crop coefficient K c The double crop coefficient method requires more numerical calculations, timely irrigation system, soil water balance calculation and soil surface moisture and daily ET c The best approach is to study the impact of water values, soil water profiles and diurnal variations in deep infiltration fluxes.

[0046] Calculate the total effective water volume TAW

[0047]

[0048] Where: TAW is the total available water in the root zone, mm;

[0049] θ fc Field water capacity m 3 m -3 ;

[0050] θ wp Wilting point water volume m 3 m -3 ;

[0051] Z r Varying root zone depth m;

[0052] Calculate the amount of effective water that can be absorbed RAW

[0053]

[0054] Where: RAW is the effective water volume that can be easily absorbed by the root layer, mm;

[0055] p is the ratio of the amount of water that can be consumed from the root zone before water stress (ETc reduction) occurs to the total available water in the soil, taking [0-1];

[0056] Calculation of water stress coefficient K s

[0057]

[0058] Where: K s The transpiration reduction factor, which depends on the available soil moisture, is dimensionless;

[0059] D r Water consumption in the root zone mm;

[0060] TAW total available water in the root zone mm;

[0061] p is the ratio of the effective water absorbed by the crop from the root layer to the total effective water TAW when there is no water stress;

[0062] Calculate the soil root zone water balance:

[0063]

[0064] Where: D r,i The amount of water consumed by the soil root layer at the end of the i-th day (mm);

[0065] D r,i-1 The water content of the soil root layer at the end of the i-1th day (mm);

[0066] P i Rainfall on day i, mm;

[0067] RO i Surface runoff on the i-th day, mm;

[0068] I i The net precipitation that infiltrates into the root zone on the i-th day (mm);

[0069] CR i The capillary rise of groundwater on the i-th day (mm);

[0070] ET c,i Crop evapotranspiration on day i, mm;

[0071] DP i Water loss from deep seepage in the root layer on day i (mm);

[0072]

[0073] Initial water consumption:

[0074] θ i-1 It is the average moisture content of the effective root layer. When there is heavy rainfall or irrigation, users can assume that the root layer is close to the field water holding capacity, that is, D r,i-1 ≈0.

[0075] Deep Leakage:

[0076]

[0077] Table 1: Maximum effective root depth range (Z r ) Soil water consumption ratio under no stress conditions (p)

[0078] In a preferred solution, the system also includes a medicine storage and dispensing depot and a water supply network. The medicine storage and dispensing depot accurately controls the water volume based on the data obtained by the crop growth water requirement calculation method and then distributes the water to the water supply network. The medicine storage and dispensing depot includes a water supply reserve depot and a medicine dispensing depot. The water supply reserve depot and the medicine dispensing depot are connected in parallel. The water supply network combines drip irrigation and sprinkler irrigation. By changing the water supply pressure and adding a pressure valve to the water supply pipeline, it can realize switching between sprinkler irrigation and drip irrigation.

[0079] The data processing module calculates the actual water demand based on crop growth conditions, local geology and weather changes to control the irrigation system, thereby achieving precise control over the water delivery volume.

[0080] The invention discloses a method for calculating the water requirement for crop growth and an irrigation system developed based on the method, which have the following beneficial effects.

[0081] First, through the crop transpiration calculation program and adjusting K c ini The value of K is adjusted to reflect the frequency of soil wetting and c mid and K c end The values ​​are adjusted to adapt to the climatic conditions of the Hexi Corridor irrigation agricultural area, and variable models and the actual impact of variables are established, so that suitable crops can be selected more accurately.

[0082] Second, in actual agricultural production, the water demand calculation results can be reasonably adjusted and optimized based on the water resources situation and irrigation system capacity in the Hexi Corridor irrigated agricultural area.

[0083] Third, when applying fertilizers or spraying pesticides, the amount of water can be calculated to use more accurately. At the same time, selective operations can be carried out according to the fertilization method required by the crops (foliar fertilization - sprinkler irrigation, root fertilization - drip irrigation). BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 This is a flow chart of a method for calculating water requirement for crop growth proposed by the present invention.

[0085] Figure 2 The present invention provides a method for calculating the water requirement for crop growth and an irrigation system flow chart formulated based on the method.

[0086] Figure 3 To generate reference crop evapotranspiration (ET) based on actual experiments in the irrigated agricultural area of ​​the Hexi Corridor 0 ) bar chart.

[0087] Figure 4 Guidelines for calculating crop water requirements FAO-56 Taking pulse crops in arid areas as an example K c Graph.

[0088] Figure 5FAO-56 crop coefficient curves for crop water requirement calculation guide.

[0089] In the attached figure: 100, medicine storage and dispensing warehouse; 101, water supply reserve warehouse; 102, medicine distribution warehouse; 200, water supply pipeline network. DETAILED DESCRIPTION

[0090] The technical solutions in the examples of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0091] The present invention discloses a method for calculating the water requirement for crop growth and an irrigation system developed based on the method. The method is mainly used in the existing irrigation system, which cannot timely adjust the irrigation water volume according to the actual growth species, stage, weather changes and geological changes of the crops, which will cause water resources to a certain extent and cannot irrigate according to the irrigation method required by the crop growth stage.

[0092] Reference Figure 1 and Figure 3 , a method for calculating the water requirement for crop growth, the steps of which include: referring to ET 0 Selection of the growth stage length, selection and confirmation of the crop coefficient, and adjustment of K c ini The value of K is adjusted to reflect the frequency of soil wetting and c mid and K c end The value of ET is adapted to the regional climate conditions, c Calculate effective water usage and calculate water balance in the soil root zone.

[0093] In this scheme, according to the Penman-Monteith formula, refer to ET 0 The calculation program uses the daily meteorological data of 207 towns and villages in 19 counties and cities in 5 prefectures and cities in the Hexi Corridor irrigation agricultural area (no shade, little precipitation, high surface temperature, and sufficient sunshine) in recent years to determine the corresponding reference ET 0 in accordance with:

[0094]

[0095] R n Net radiation on crop surface MJ / m 2 *day,

[0096] G Soil heat flux MJ / m 2 *day,

[0097] T Daily average temperature at 2 meters height 0 C,

[0098] u 2Wind speed at 2 meters height m / s,

[0099] e s Saturated water vapor pressure kPa,

[0100] e a Actual water vapor pressure kPa,

[0101] Δ Slope of water vapor pressure curve kPa / 0 C,

[0102] γ Hygrometer constant kPa / 0 C.

[0103] The following functions can be realized:

[0104] 1. Select the location, time range and meteorological name (single or multiple selections of average temperature, average relative humidity, average wind speed, effective accumulated temperature, ET 0 ) Generate average data graphs with day, week, ten-day, month as the time length;

[0105] 2. Ability to compare and display the single data graphs of two locations in the form of top and bottom;

[0106] 3. Ability to compare and display single data of multiple locations in one graph;

[0107] 4. Query the highest / lowest / average temperature, relative humidity, wind speed, ET within the selected time range according to the location 0 and effective accumulated temperature, and displayed in a graph;

[0108] 5. Able to display the average annual, monthly or daily maximum (maximum) / minimum (minimum) / average temperature, relative humidity, wind speed, effective accumulated temperature and ET for many years 0 Data and graphs (such as Figure 3 ).

[0109] Among them, refer to Figure 1 and 3 In a preferred embodiment, the steps of selecting and confirming the length of the growth stage and selecting the crop coefficient are as follows:

[0110] Divide the growth period of the crops into different growth stages, make typical diagrams of crop characteristics in each growth period, and describe the characteristics based on the four-stage definition according to the biological characteristics of different crops;

[0111] Crop coefficient (K c ini , K c mid , K c end ) selection.

[0112] In this scheme, the crop growth stage is divided into early growth stage (L ini), rapid growth period, mid-growth period (L mid ) and late growth period (L late ) Four stages:

[0113] Early growth period: from the day of sowing until the ground coverage reaches 10%;

[0114] Rapid growth period: The crop growth stage starts from about 10% ground coverage to the ground being effectively fully covered. For many crops, effective coverage is completed at the beginning of flowering;

[0115] Mid-growth period: from when all the plants are effectively covered until they begin to mature;

[0116] Late growth phase: lasts from the beginning of maturity to harvest or complete senescence.

[0117] Maturity: Reminders are given based on different crops to help users make accurate choices. For example, the method for determining the maturity of peppers is as follows: the maturity of pepper varieties is divided into very late maturing, late maturing, medium maturing, early maturing, and very early maturing types, mainly based on the first flowering node. The first flowering node is below 8 nodes for very early maturing varieties; the first flowering node is between 8 and 12 nodes for early maturing varieties; the first flowering node is between 12 and 16 nodes for medium maturing varieties; the first flowering node is between 16 and 20 nodes for late maturing varieties; and the first flowering node is above 20 nodes for very late maturing varieties.

[0118] Divide the growth period of the crops into different growth stages and make typical crop characteristics of each growth period. Figure 1 One-to-one correspondence. Based on the biological characteristics of different crops, characteristic descriptions are carried out on the basis of the four-stage definitions to achieve an effect of easy distinction.

[0119]

[0120] Table 2 Measured data on the length of crop growth and development stages in the irrigated agricultural area of ​​the Hexi Corridor obtained from the experiment (days)

[0121] Further, see Figure 1 , 4 and 5. In a preferred embodiment, adjusting K c ini The value of reflects the soil moisture frequency based on:

[0122]

[0123] Table 3: K for different crops in FAO-56 Guide for Calculating Crop Water Requirements c ini , K c mid and K c end Typical value

[0124]

[0125] Where: fw is the percentage of the soil surface wetted by irrigation or rainfall 0 to 100%;

[0126] K c ini（表，图） Obtained from Table 12, Figure 29 or 30 of the Guidelines for Calculating Crop Water Requirements FAO-56.

[0127]

[0128] Table 4: The water requirement of the crop shown in FAO-56: The water requirement of the topsoil moistened by rainfall or irrigation w The general value of

[0129] If coated, K c ini The value is generally 0.10.

[0130] Adjust K c mid and K c end The value of is based on regional climate conditions:

[0131]

[0132] Where: K c mid(表) K obtained from Table 12 of the Guidelines for Calculating Crop Water Requirements FAO-56 c mid；

[0133] u 2 The daily average wind speed at 2m above the grass surface during the growth period is m / s, for 1m / s 2 < 6m / s (The wind speed in the meteorological data is at a height of 10m and must be converted to the wind speed value at a height of 2m through a formula);

[0134] RH min Average value of daily minimum relative humidity during the mid-growth period, for 20% < RH min <80%;

[0135] h Average plant height in mid-growth period m, for 0.1 m <h<10m。

[0136]

[0137] Table 5: Guidelines for calculating crop water requirements and RH for the general climate classification given in FAO-56 mean Comparative RH min Typical value

[0138]

[0139] This formula is only used for the When the value exceeds 0.45, (表) ​<0.45 (i.e. = (表) ) The value is not corrected.

[0140] When the crop is allowed to wilt and dry in the field (using <0.45 as a sign), u 2 and RH min right The impact is small, no need to correct, if the film is applied, and The values ​​are reduced by 10-30%.

[0141] Stipple K c The general procedure of the curve is to draw K points in weeks, ten days or months. c curve, connecting the four growth stages with straight line segments; the initial stage and mid-growth stage Draw horizontal lines; use diagonal lines to connect crops during their rapid growth stages and , connect with slash in the late growth period and .

[0142] Furthermore, the ET c Calculation, which is divided into single crop coefficient method to calculate ET c ET calculation by double crop coefficient method c .

[0143] Calculation of ET using the single crop coefficient method c in accordance with:

[0144]

[0145] in:

[0146] Where: i is the number of days in the growing period1…length of the growing cycle;

[0147] K ci Crop coefficient on day i;

[0148] L stage The number of days in the growing season studied;

[0149] Total length of all preceding growth days;

[0150] Function: Can be based on K c The numerical calculation method is used to determine the K value of any day in the growing period. c The values ​​can be visualized in the "Graph" by selecting the date or entering the number of days.

[0151] Crop coefficient K c Based on crop evapotranspiration ET c and reference evapotranspiration ET 0 The ratio reflects the combined effect of four main characteristics that distinguish actual crops from reference crop grasses.

[0152] These characteristics are: Crop height: Crop height affects the aerodynamic drag term r in the FAO Penman-Montalth equation. a and water vapor migrate from crops to the atmosphere in a turbulent manner.

[0153] Crop-soil surface reflectivity (reflectance): It is affected by ground cover and soil moisture. Crop-soil surface reflectivity affects net radiation R n , R n It is the main source of energy exchanged during the evaporation process.

[0154] Canopy resistance: The resistance of crops to water vapor migration, which is affected by leaf area, number of stomata, leaf age, conditions and degree of stomatal control. Canopy resistance affects surface resistance r s .

[0155] Soil evaporation, especially evaporation from bare soil; the degree of moisture on the soil surface and the degree of vegetation coverage affect the surface resistance r s As the soil becomes wet, the water vapor mobility of the soil becomes high, especially when the ground is not completely covered. The canopy surface resistance and the soil surface resistance combine to form the total surface resistance r s The surface drag term in the Penman-Montalth equation represents the resistance to the flow of water vapor from between plant leaves and beneath the soil surface.

[0156] Figure 5 All K c The value can be obtained directly from the curve. The mid-ten-day value is the K value for a period of 10 days. c Average value; only the second tenth day of June K c The value changes suddenly, requiring some calculations; K in the first five days of the second decade of June c =0.15, by the end of the 10th day of the second decade, K c The value changes from 0.15 to 0.36; therefore, K c The value is: 5 / 10(0.15)+5 / 10(0.15+0.36) / 2=0.20.

[0157] Calculation of ET by the double crop coefficient method c in accordance with:

[0158]

[0159] The double crop coefficient method uses the time-averaged single crop coefficient K c The double crop coefficient method requires more numerical calculations, timely irrigation system, soil water balance calculation and soil surface moisture and daily ET c The best approach is to study the impact of water values, soil water profiles and diurnal variations in deep infiltration fluxes.

[0160] Further, the steps to determine effective water consumption are as follows:

[0161] (1) Calculate the total effective water volume TAW:

[0162]

[0163] Where: TAW is the total available water in the root zone (mm);

[0164] θ fc Field water capacity m 3 m -3 ;

[0165] θ wp Wilting point water volume m 3 m -3 ;

[0166] Z r Varying root zone depth m;

[0167] (2) Calculate the amount of effective water that can be easily absorbed RAW:

[0168]

[0169] Where: RAW is the effective water volume that can be easily absorbed by the root layer, mm;

[0170] P is the ratio of the amount of water that can be consumed from the root layer before water stress occurs to the total available water in the soil, ranging from [0-1];

[0171] (3) Calculation of water stress coefficient K s :

[0172]

[0173] Where: K s The transpiration reduction factor, which depends on the available soil moisture, is dimensionless;

[0174] D r Water consumption in the root zone mm;

[0175] TAW is the total available water in the root zone, mm;

[0176] P is the ratio of the effective water absorbed by the crop from the root zone to the total effective water TAW when there is no water stress.

[0177] Furthermore, the calculation of soil root layer water balance is based on:

[0178]

[0179] Where: D r,i The amount of water consumed by the soil root layer at the end of the i-th day (mm);

[0180] D r,i-1 The water content of the soil root layer at the end of the i-1th day (mm);

[0181] P i Rainfall on day i, mm;

[0182] RO i Surface runoff on day 1 (mm);

[0183] I i The net precipitation that infiltrates into the root zone on the i-th day (mm);

[0184] CR i The capillary rise of groundwater on the i-th day (mm);

[0185] T c,i Crop evapotranspiration on day i, mm;

[0186] DP i Water loss from deep seepage in the root layer on day i (mm);

[0187]

[0188] Initial water consumption:

[0189] θ i-1 It is the average moisture content of the effective root layer. When there is heavy rainfall or irrigation, it can be assumed that the root layer is close to the field water holding capacity, that is, D r,i-1 ≈0.

[0190] Deep Leakage:

[0191] Including: Reference crop evapotranspiration (ET 0 ) is usually calculated using the Penman-Monteith equation; the crop coefficient (K c ) is determined based on factors such as crop type, growth stage, and soil conditions.

[0192] Further, see Figure 1 and 2In a preferred embodiment, the system also includes a storage and dispensing warehouse 100 and a water supply network 200. The storage and dispensing warehouse 100 accurately controls the water volume based on the data obtained by the crop growth water requirement calculation method and then distributes it to the water supply network 200. The storage and dispensing warehouse 100 includes a water supply reserve warehouse 101 and a drug dispensing warehouse 102. The water supply reserve warehouse 101 and the drug dispensing warehouse 102 are connected in parallel. The water supply network 200 combines drip irrigation and sprinkler irrigation in water supply mode. By changing the water supply pressure and adding a pressure valve to the water supply pipeline, it can realize switching between sprinkler irrigation and drip irrigation.

[0193] In actual agricultural production, the water demand calculation results of this solution can be reasonably adjusted and optimized in combination with local water resources conditions and irrigation system capacity. At the same time, the connection to drug or water-soluble fertilizer distribution can more accurately control the distribution of drugs and fertilizers and avoid uneven application of drugs or fertilizers.

[0194] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The substitution may be a substitution of some method steps or a complete technical solution. Any equivalent substitution or change according to the technical solution of the invention and its inventive concept shall be included in the protection scope of the invention.

Claims

1. A method for calculating the water requirement for crop growth, characterized in that: The calculation steps include: reference ET0 selection, growth stage length selection and confirmation, crop coefficient selection, K adjustment c ini The value of K is adjusted to reflect the frequency of soil wetting and c mid and K c end The value of ET is adapted to the regional climate conditions, c Calculate and determine effective water use and calculate soil root zone water balance.

2. A method for calculating crop growth water requirement according to claim 1, characterized in that: The method for selecting the reference ET0 is as follows: According to the Penman-Monteith formula, referring to the ET0 calculation program, using the recent daily meteorological data of 207 towns and villages in 5 prefectures, cities and counties, 19 counties and districts in the Hexi Corridor irrigation agricultural area, the corresponding reference evapotranspiration ET0 is determined: Where: ET0 refers to the evaporation rate mm / day; R n Net radiation on crop surface MJ / m 2 *day; G Soil heat flux MJ / m 2 *day; T Daily average temperature at 2 meters height 0 C; u22m wind speed m / s; e s Saturated water vapor pressure kPa; e a Actual water vapor pressure kPa; e s -e a Saturated water vapor pressure difference kPa; Δ Slope of water vapor pressure curve kPa / 0 C; γ Hygrometer constant kPa / 0 C.

3. A method for calculating crop growth water requirement according to claim 1, characterized in that: The steps for selecting and confirming the length of the growth stage and selecting the crop coefficient are as follows: ① Divide the growth period of the crops into different growth stages, make typical diagrams of crop characteristics in each growth period, and describe the characteristics based on the four-stage definition according to the biological characteristics of different crops; ② Crop coefficient K c ini , K c mid , K c end choice.

4. A method for calculating crop growth water requirement according to claim 1, characterized in that: The adjustment K c ini The value of reflects the frequency of soil moisture based on: Where: f w is the percentage of the soil surface wetted by irrigation or rainfall; K c ini（表，图） Obtained from Table 12, Figure 29 or 30 of the Guidelines for Calculating Crop Water Requirements FAO-56.

5. A method for calculating crop growth water requirement according to claim 1, characterized in that: The adjustment K c mid and K c end The value of is based on regional climate conditions: Where: K c mid(表) K obtained from Table 12 of the Guidelines for Calculating Crop Water Requirements FAO-56 cmid ; u2 Daily average wind speed at 2m above the grass surface during the mid-growth period m / s 1m / s <u2< 6m / s; RH min Average daily minimum relative humidity during the mid-growth period (%) for 20% < RH min <80%; h Average plant height in mid-growth period m for 0.1m <h<10m。 6. A method for calculating crop growth water requirement according to claim 1, characterized in that: The ET c Calculation, which is divided into single crop coefficient method to calculate ET c , Double crop coefficient method to calculate ET c .

7. A method for calculating water requirement for crop growth according to claim 6, characterized in that: The single crop coefficient method calculates ET c in accordance with: Where: K c The crop coefficient is dimensionless; The double crop coefficient method is used to calculate ETc based on: Where: K cb The basic crop coefficient is dimensionless; K e The soil evaporation coefficient is dimensionless; ET0 refers to the evaporation rate in mm / day.

8. A method for calculating water requirement for crop growth according to claim 1, characterized in that: The steps to determine effective water consumption are as follows: (1) Calculate the total effective water volume TAW: Where: TAW is the total available water in the root zone (mm); θ fc Field water capacity m 3 m -3 ; θ wp Wilting point water volume m 3 m -3 ; Z r Varying root zone depth m; (2) Calculate the amount of effective water that can be easily absorbed RAW: Where: RAW is the effective water volume that can be easily absorbed by the root layer, mm; p is the ratio of the amount of water that can be consumed from the root zone before water stress occurs to the total available water in the soil; (3) Calculation of water stress coefficient K s : Where: K s The transpiration reduction factor, which depends on the available soil moisture, is dimensionless; D r Water consumption in the root zone mm; TAW is the total available water in the root zone, mm; RAW: effective water volume that can be easily absorbed by the root layer (mm); p is the ratio of the effective water absorbed by the crop from the root zone to the total effective water TAW when not suffering from water stress. It is dimensionless.

9. A method for calculating crop growth water requirement according to claim 1, characterized in that: The calculation of soil root layer water balance is based on: Where: D r,i The amount of water consumed by the soil root layer at the end of the i-th day (mm); D r,i-1 The water content of the soil root layer at the end of the i-1th day (mm); P i Rainfall on day i, mm; RO i Surface runoff on the i-th day, mm; I i The net precipitation that infiltrates into the root zone on the i-th day (mm); CR i The capillary rise of groundwater on the i-th day (mm); ET c,i Crop evapotranspiration on day i, mm; DP i Water loss from deep seepage in the root layer on day i (mm); Initial water consumption: Where: θ i-1 It is the average moisture content of the effective root layer. When there is heavy rainfall or irrigation, it can be assumed that the root layer is close to the field water holding capacity, that is, D r,i-1 ≈0.

10. An irrigation system developed based on the method for calculating the water requirement for crop growth, characterized in that: According to the crop growth water requirement calculation method described in any one of claims 1 to 9, the system also includes a storage and dispensing warehouse (100) and a water delivery network (200). The storage and dispensing warehouse (100) accurately controls the water volume based on the data obtained by the crop growth water requirement calculation method and then distributes it to the water delivery network (200). The storage and dispensing warehouse (100) includes a water supply reserve warehouse (101) and a drug distribution warehouse (102). The water supply reserve warehouse (101) and the drug distribution warehouse (102) are connected in parallel. The water delivery mode of the water delivery network (200) combines drip irrigation and sprinkler irrigation. By changing the water delivery pressure and adding a pressure valve to the water delivery pipeline, it can realize the switching between sprinkler irrigation and drip irrigation.

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