Dry land agriculture water-saving equivalent calculation method

Abstract

The invention belongs to the technical field of dry land agricultural water saving, and provides a dry land agricultural water saving equivalent calculation method, which comprises the following steps: S1, calculating the average moisture productivity WPave of a research area under the same type of soil and traditional management conditions; s2, the actual crop yield Ya and the actual crop evapotranspiration Eta after the target water saving technology is adopted in the research area are obtained; s3, according to the average moisture productivity WPave and the actual crop yield Ya, calculating the theoretical evapotranspiration EThheo of the crop yield Ya; s4, the difference between the theoretical evapotranspiration EThheo and the actual crop evapotranspiration Eta is obtained, and the agricultural water saving equivalent Wsav of the arid region after the water saving technology is adopted is calculated through unit conversion. According to the dry land agriculture water saving equivalent calculation method provided by the invention, the technical defect that the physical water saving amount cannot be calculated in dry farming and rain farming is broken through for the first time, so that the water saving technology can be converted into a visual water saving equivalent with a physical index. The blank that the field lacks direct water volume indexes for a long time is filled.

Description

Technical Field

[0001] This invention belongs to the field of water-saving technology in dryland agriculture, and relates to a method for calculating the water-saving equivalent of dryland agriculture. Background Technology

[0002] Dryland agriculture refers to crop growth and yield production that relies entirely on natural rainfall without irrigation. To promote the development of dryland agriculture, increase crop output, and improve the efficiency of rainfall utilization, various water-saving technologies have been developed both domestically and internationally in areas such as breeding, cultivation, and water and fertilizer management. These technologies include the widespread use of drought-resistant agents, mulching, deep tillage, application of water-retaining agents, and water-saving and drought-resistant crop varieties.

[0003] Currently, the evaluation methods for the above-mentioned technical means mainly include: (1) Yield comparison method: The yield difference between the treatment area and the control area is measured by field trials, and the yield increase is used to measure the technical effect.

[0004] (2) Water use efficiency method: While obtaining the yield, the actual evapotranspiration ET is measured, and WUE = yield / ET is calculated. The quality of the technology is evaluated by the degree of efficiency improvement.

[0005] (3) Physiological and biochemical index method: measure the relative water content of leaves, SOD activity, MDA content, etc., to indirectly infer the drought resistance of crops.

[0006] The methods mentioned above all focus on increasing yield or improving efficiency. However, an increase in water efficiency (WUE) may stem from increased yield or decreased water consumption (ET). To further differentiate between "high-yield, high-consumption" and "water-saving, high-yield" technologies and to achieve accurate water resource management and planning in arid regions, as well as to evaluate and investigate the benefits, it is necessary to further evaluate the water-saving equivalent of various technologies. In irrigated agriculture, the calculation of water-saving equivalent is a clear concept and a direct method. Under the premise of ensuring the same yield, the water saving is directly quantified by comparing the reduction in irrigation water volume before and after the application of water-saving irrigation technology. This is clearly stated in GB / T50363-2018 "Technical Standard for Water-Saving Irrigation Engineering".

[0007] However, for dryland rainfed agriculture, there has long been a prevalent technical bias in the field: because there is no irrigation water input throughout the crop growth process, it is impossible to define and calculate a physically meaningful water-saving equivalent as in irrigated agriculture. This bias has led to research and practical work generally using the improvement of water use efficiency as the sole or ultimate indicator for evaluating the effectiveness of water-saving technologies. Water use efficiency is a ratio characterizing water conversion efficiency. While it can reflect the efficiency improvement of the system, it has inherent flaws: it is an efficiency indicator, not a water quantity indicator, and may mask the true water consumption situation. For example, a technology that achieves a small increase in WUE by simultaneously and significantly increasing yield and water consumption may not be considered water-saving from the perspective of total water consumption.

[0008] Therefore, those skilled in the art, under the influence of habitual thinking, are generally satisfied with using water use efficiency to indirectly and qualitatively describe the water-saving effect. This prevalent technical bias seriously hinders the accurate assessment of the water-saving benefits of agriculture in arid areas, the horizontal comparison between different technologies, and the effective connection between water-saving achievements and policies such as water resource management and ecological compensation.

[0009] With the rapid development of dryland rainfed agriculture technology, there is an urgent need for a calculation method that can break through the above-mentioned technical biases and directly quantify water-saving equivalents, so as to fill the gap in existing technologies in this key area.

[0010] This invention proposes a method for calculating water-saving equivalents in dryland agriculture, breaking the technical prejudice that dryland rainfed agriculture cannot calculate physical water savings for the first time. It enables the transformation of water-saving technologies into an intuitive, physical indicator of water-saving equivalents, filling a long-standing gap in this field due to the lack of direct water quantity indicators.

[0011] The technical solution of this invention is implemented as follows: A method for calculating water-saving equivalents in dryland agriculture includes the following steps: S1. Calculate the average water productivity of the study area under the same soil type and traditional management conditions. WP ave ; S2. Obtain the actual crop yield after the target water-saving technology is applied in the study area. Y a and actual crop evapotranspiration AND a ; S3, Based on the average moisture productivity WP ave and the actual crop yield Y a Calculate crop yield Y a Theoretical evaporation AND TheoThe calculation formula used is as follows. AND Theo = Y a / WP ave ; S4. Based on theoretical evaporation rate AND Theo Compared with actual crop evapotranspiration AND a The water-saving equivalent of agriculture in arid areas after adopting this water-saving technology was calculated. W sav The calculation formula is: W sav = k × ( AND Theo - AND T ),in, k Unit conversion factor.

[0012] The traditional management conditions, namely fertilization, variety, seeding rate, sowing period, and pest and disease control, are all implemented according to the agricultural production management model commonly used in the local area, without adopting the target water-saving technology.

[0013] Preferably, when W sav The unit is m³ / mu. AND Theo and AND a When the unit is mm, k = 0.667.

[0014] Preferably, in step S1, the average water productivity of the study area under the same soil type and conventional management conditions is calculated. WP ave Specifically, it includes: Obtain the multi-year average crop yield of the study area Y ave and multi-year average crop evapotranspiration AND ave ; According to the formula WP ave = Y ave / AND ave Calculate the average water productivity of the region. WP ave .

[0015] Preferred average annual crop yield Y ave and multi-year average crop evapotranspiration ANDave The data are derived from long-term field observation data of ≥5 years using the water balance method, lysimeter method, or eddy covariance method.

[0016] Preferably, the method for obtaining the multi-year average crop yield of the study area is... Y ave and multi-year average crop evapotranspiration AND ave Specifically, it includes: Obtain crop yield data for the study area over many years under the same soil type and traditional management conditions, and calculate the multi-year average crop yield. Y ave The calculation formula is: ; Obtain multi-year crop evapotranspiration data for the study area under the same soil type and traditional management conditions, and calculate the multi-year average crop evapotranspiration. AND ave The calculation formula is: ; In the formula: Y ave and Y i They are respectively the multi-year average crop yield and the first i The obtained crop yield, kg / hm 2 ; N The total number of crop yields was obtained through literature review and research. N ≥5; AND ave and AND i These are the multi-year average crop evapotranspiration and the first i The obtained crop evapotranspiration, mm; M The total number of crop evapotranspiration data obtained from literature review. M ≥5.

[0017] Preferably, in step S2, the actual crop evapotranspiration after the target water-saving technology is applied in the study area is obtained using the water balance method, lysimeter method, or eddy covariance method. AND a .

[0018] Preferably, in step S2, the actual crop evapotranspiration after the target water-saving technology is applied in the study area is obtained. AND a The water balance method is adopted, specifically as follows: AND a = Δ W + P ; where Δ WThis refers to the amount of water consumed by the soil during the crop's growing season. P This refers to the amount of rainfall during the crop's growing season.

[0019] Preferably, the amount of water consumed by the soil during the crop's growth period Δ W Calculated using the following formula: In the formula: Δ W The amount of water consumed by the soil during the crop's growing season, in mm; Z i For the first i The thickness of the soil layer, in mm; γ i For the first i Bulk density of the soil layer, g / cm³ 3 ; and The measurements were taken at crop sowing and harvesting times, respectively. i Average weight moisture content of the soil layer, g / g; N The number of soil layers; i For the first i Layer of soil.

[0020] Preferably, measuring the average weight moisture content of the i-th soil layer specifically includes: taking soil samples at at least 3 representative sampling points at a sampling depth of 2 m, and taking samples in multiple layers according to soil conditions; then obtaining the soil moisture content of each soil layer by weighing; and using the data from all sampling points, calculating the average soil moisture content of each layer in the study area; preferably, the calculation formula is: In the formula: For the first i Average weight moisture content of the soil layer, g / g; In the first j Point measurement i The weight moisture content of the soil layer, in g / g; N The number of soil layers when measuring soil moisture content.

[0021] Preferably, the water-saving technology includes one or more combinations of drought-resistant agents, plastic film mulching, deep tillage, water-retaining agents, or drought-resistant varieties.

[0022] Preferably, the water-saving equivalent is calculated in S4. W savThen, the water-saving ratio was further calculated. R The calculation formula is: R =( AND Theo - AND a ) / AND a .

[0023] The beneficial effects of the present invention using the above technical solution are as follows: 1. The method for calculating water-saving equivalents in dryland agriculture provided by this invention breaks the technical prejudice that dryland rainfed agriculture cannot calculate physical water savings for the first time, enabling the transformation of water-saving technology into an intuitive, physical indicator of water-saving equivalents. This fills the long-standing gap in this field where direct water quantity indicators are lacking.

[0024] 2. This invention overcomes the drawbacks of traditional methods that rely on multiple indicators such as yield, WUE, and soil moisture content for decentralized and qualitative evaluation, and provides a unified and universal indicator for the horizontal comparison and selection of different water-saving technologies.

[0025] 3. Traditional water efficiency metrics may mask the true water consumption. The method of this invention can accurately identify and quantify water-saving types that are difficult to reveal using traditional methods. For example, for technologies that improve water efficiency through significant increases in production and small increases in water consumption, this invention can calculate the substantial water savings achieved due to efficiency improvements, preventing their water-saving contribution from being underestimated. Furthermore, for technologies that primarily save water by reducing evapotranspiration, this invention can provide the specific amount of water saved, not just the reduction in ET (efficiency threshold), resulting in a more direct and profound evaluation.

[0026] 4. This invention is based on the principle of water balance. The required yield, soil moisture, and precipitation data can all be obtained through conventional field observations and surveys. The calculation process is clear, standardized, and highly operable. It does not rely on expensive and complex specialized equipment and is suitable for different scales, from field trials to regional assessments. It is easy to promote and apply on a large scale in technology dissemination, project evaluation, and scientific research in vast dryland farming areas. Attached Figure Description

[0027] Figure 1 The meteorological conditions during the wheat growing season in the experimental area of ​​Example 1 of this invention in 2024-2025. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] The method for calculating water-saving equivalents in dryland agriculture provided by this invention breaks the technical prejudice that "physical water savings cannot be calculated in dryland rainfed agriculture." It enables the transformation of water-saving technologies into an intuitive, physical indicator of water-saving equivalents, providing a unified and universal index for the comparative optimization of different water-saving technologies. The water-saving technologies may include one or more combinations of drought-resistant agents, mulch film covering, deep tillage, water-retaining agents, or drought-resistant varieties. The specific calculation method includes the following steps: S1. Calculate the average water productivity of the study area under the same soil type and traditional management conditions. WP ave Specifically, the steps include the following: S101. Through literature review and field surveys, collect and organize crop yields and crop evapotranspiration data for ≥5 years under similar soil types and traditional management conditions in the study area. AND The data are derived from long-term field observation data using the water balance method, lysimeter method, or eddy covariance method. The multi-year data should include at least 5 years of data to eliminate the extreme effects of individual bumper or lean years, so as to ensure the stability of the benchmark while reflecting recent production levels. S102. Using the data from literature reviews and local surveys obtained in S101, calculate the multi-year average crop yield. Y ave and multi-year average crop evapotranspiration AND ave The calculations are performed using formula (1) and formula (2) respectively. (Formula 1) (Formula 2) In the above formula: Y ave and Y i They are respectively the multi-year average crop yield and the first i The obtained crop yield, kg / hm 2 ; N The total number of crop yields was obtained through literature review and research. N ≥5; AND ave and AND i These are the multi-year average crop evapotranspiration and the first i The obtained crop evapotranspiration, mm; M The total number of crop evapotranspiration data obtained from literature review. M ≥5; S103, based on Yave and AND ave Calculate the average water productivity of the region. WP ave The calculation is performed using formula (3); WP ave = Y ave / AND ave (Formula 3) In the formula: WP ave Average water productivity of crops, kg / hm 2 / mm; Y ave The multi-year average crop yield calculated using formula (1) is expressed in kg / hm². 2 ; AND ave The multi-year average crop evapotranspiration calculated using formula (2) is in mm; S2. Obtain the actual crop yield after the target water-saving technology is applied in the study area. Y a and actual crop evapotranspiration AND a Specifically, it includes the following steps: S201. Obtain the actual crop yield after the target water-saving technology is applied in the study area. Y a : Depending on the size of the study area, samples were taken from at least five representative sites. The yield at each site was then calculated, and the average yield was taken as the actual crop yield after adopting the target water-saving technology. Y a The calculation formula is formula (4); wherein, the representative sample points should follow the principle of random sampling and cover different micro-topography (such as on the slope, in the middle of the slope, and at the bottom of the slope) in the study area, and the number of sample points is determined according to the area of ​​the study area and the soil variation coefficient; (Formula 4) In the formula: Y a and Y a,i These represent the actual crop yield after adopting the target water-saving technology and the... i Crop yield obtained from each sample point, kg / hm 2 ; N The number of sampling points is greater than or equal to 5; S202. Obtain the actual crop evapotranspiration after the target water-saving technology is adopted in the study area. AND a : Soil moisture content was obtained by weighing soil samples, and crop evapotranspiration was calculated by the horizontal equilibrium method. Specifically, soil samples were taken at least three representative sampling points at the time of crop sowing and harvest, with a sampling depth of 2m, depending on the size of the study area. At the same time, multiple layers of samples were taken according to the soil conditions. The soil moisture content of each soil layer was obtained by weighing. The average soil moisture content of each layer in the study area was calculated using all the data from the sampling points and calculated using formula (5). (Formula 5) In the formula: For the first i Average weight moisture content of the soil layer, g / g; In the first j Point measurement i The weight moisture content of the soil layer, in g / g; N The number of soil layers when measuring soil moisture content; Based on the average soil moisture content of each layer, the amount of water consumed in the soil during the entire growth period of the crop, ΔW, is calculated using formula (6). (Formula 6) In the formula: Δ W The amount of water consumed by the soil during the crop's growing season, in mm; Z i For the first i The thickness of the soil layer, in mm; γ i For the first i Bulk density of the soil layer, g / cm³ 3 ; and The measurements were taken at crop sowing and harvesting times, respectively. i Average weight moisture content of the soil layer, g / g; N The number of soil layers; i For the first i Layer of soil; Using the soil water consumption ΔW calculated by formula (6) and the observed precipitation P, the actual evapotranspiration during the crop growth period is calculated. AND a The calculation formula is formula (7); AND a = Δ W + P (Formula 7) In the formula: AND a The actual crop evapotranspiration after adopting the target water-saving technology is expressed in mm. Δ W The amount of water consumed by the soil during the crop growth period, calculated using formula (6), is in mm; P Rainfall during the crop growing season, in mm; S3, Based on the average moisture productivity WP ave and the actual crop yield Y a Calculate crop yield under traditional management conditions Y a Theoretical evaporation AND Theo The calculation formula used is as follows. AND Theo = Y a / WP ave ; In the formula: AND Theo Crop production under traditional management conditions Y a Theoretical evaporation required for production, in mm; Y a The actual crop yield after adopting the target water-saving technology is expressed in kg / hm². 2 ; WP ave The average water productivity of the study area; S4. Based on theoretical evaporation rate AND Theo Compared with actual crop evapotranspiration AND a The water-saving equivalent of agriculture in arid areas after adopting this water-saving technology was calculated. W sav The calculation formula is: W sav = k × ( AND Theo - AND a ),in, k For unit conversion factors; when W savThe unit is m³ / mu. AND Theo and AND a When the unit is mm, k = 0.667; In the formula: W sav To determine the water-saving equivalent of agriculture in arid areas after adopting the target water-saving technology, m 3 / mu; AND Theo The theoretical evaporation rate calculated in step S3 AND Theo mm; AND a The actual crop evapotranspiration after adopting the target water-saving technology is expressed in mm. Unit conversion factor k =0.667, which means the water depth unit (mm) is converted to the water volume per acre (cubic meters, m³). 3 A water depth of 1 mm evenly distributed over 1 mu (approximately 0.16 acres) is equivalent to 667 m. 2 The water volume is calculated as 1 mm × 667 m. 2 =0.667 m 3 / mu, therefore, the water depth in mm is converted to water volume in m³. 3 The unit conversion factor k = 0.667.

[0030] Furthermore, the water-saving equivalent was calculated. W sav Then, the water-saving ratio was further calculated. R The calculation formula is: R =( AND Theo - AND a ) / AND a .

[0031] Example 1 Southern Shanxi is a typical dryland rainfed farming area in my country, with winter wheat as the typical crop. However, the rainfall during the winter wheat growing season cannot meet the water consumption requirement of 300-400 mm for evapotranspiration, making water a crucial factor limiting wheat growth and yield. Spraying drought-resistant agents is a typical agronomic water-saving technique. By spraying drought-resistant agents onto the winter wheat canopy, leaf growth can be significantly improved, enhancing leaf drought resistance, thereby promoting growth and increasing yield. This example was conducted in Weijiazhuang Village, Guojiazhuang Town, Wenxi County, Shanxi Province. Wenxi County is located in Yuncheng City in southern Shanxi and is a typical dryland farming area with predominantly loess soil. From March to May 2025, the drought-resistant agent seaweed polysaccharide was sprayed once each during the jointing, tillering, and grain-filling stages of winter wheat in Weijiazhuang Village, Guojiazhuang Town, Wenxi County, Shanxi Province. The application rate was 50 ml / mu each time. The yield of winter wheat was measured at the end of May when the wheat was harvested. The seaweed polysaccharide was purchased from Qingdao Haida Biotechnology Group Co., Ltd. Simultaneously, daily precipitation during the winter wheat growing season was obtained using the local national meteorological station, and the total precipitation was calculated. Soil moisture at a depth of 0-2 m was measured at five points before winter wheat sowing and after harvest, specifically on October 20, 2024, and May 25, 2025, respectively. By collecting agricultural statistical data from Wenxi County and reviewing research conducted in Wenxi County and southern Shanxi Province, as well as published academic papers, the local winter wheat yield and evapotranspiration over many years were obtained. Based on this data, the agricultural water-saving equivalent after spraying drought-resistant agents was calculated.

[0032] 1. Basic Information of the Experiment Experiment title: Evaluation of the water-saving equivalent of drought-resistant agents in dryland winter wheat in southern Shanxi.

[0033] Experimental year and season: The experiment was conducted during the 2024-2025 dryland winter wheat experimental season, specifically from October 20, 2024 to May 25, 2025.

[0034] 2. Test Site and Regional Background Specific geographical location: Wenxi County Wenyan Agricultural Machinery Professional Cooperative, Weijiazhuang Village, Guojiazhuang Town, Wenxi County, Shanxi Province, 111°08'50''E, 35°19'09''N.

[0035] Regional climate type: This region belongs to the temperate continental monsoon climate, with a frost-free period of 185 days per year, abundant sunshine, an average annual sunshine duration of 2179 hours, an average annual temperature of 13.70 ℃, and an average annual precipitation of 439.80 mm, of which more than 60% is concentrated in July to September. The winter wheat growing season, from October to June of the following year, is arid and has little rainfall.

[0036] Topography: The experimental site is a typical loess hilly and gully area with an elevation of 515 m and flat terrain.

[0037] 3. Basic physical and chemical properties of soil According to the Chinese soil classification, the soil type is brown soil.

[0038] Soil texture: The 0-200 cm soil layer is silty loam.

[0039] Plot shape: rectangular, 215m long and 20m wide, flat terrain, the previous crop was last winter wheat.

[0040] 4. Meteorological data Data source: Field automatic weather stations.

[0041] Data period: Covering the entire crop growth period.

[0042] Specific meteorological elements: Daily precipitation P: Unit: mm.

[0043] Average, highest, and lowest temperatures: Unit: °C.

[0044] Relative humidity: Unit: %.

[0045] Wind speed: Unit: m / s.

[0046] Total solar radiation per day: Unit: MJ / m².

[0047] like Figure 1 This refers to the meteorological conditions during the wheat growing season in the experimental area in 2024-2025.

[0048] 5. Test Crops and Management Crop type and variety: Winter wheat, variety 'Shannong 25'.

[0049] Sowing density: 112.5 kg / ha.

[0050] Sowing and harvesting dates: Sowing date is October 26, 2024, and harvesting date is May 20, 2025. Growing period is 207 days.

[0051] Fertilization Management: A single fertilization was applied, coinciding with sowing, on October 26, 2024. The fertilizer used was Green Energy Compound Fertilizer, purchased from Middle East Fertilizer Co., Ltd., with a specific fertilization plan of N 108 kg·hm². -2 P2O5 120 kg·hm -2 K2O 42 kg·hm -2 .

[0052] Pest and disease control: Focus on pest and disease control during the sowing and greening-jointing stages. During sowing, use seed coating and seed dressing to control underground pests and seedling diseases, reducing seed rot and seedling damage. During the greening-jointing stage, use foliar aerial spraying to control spider mites and sheath blight, specifically using abamectin + thifluzamide. In case of continuous rainy weather, for pests and diseases induced by high humidity, use foliar sprays of tebuconazole or cyazofamid to prevent Fusarium head blight; and after rain when leaves are dry, use foliar sprays of imidacloprid to control aphids.

[0053] 6. Experimental Treatment Design Water-saving treatment: Drought-resistant agents are sprayed during the critical growth period of wheat. The agent's main component is seaweed polysaccharide.

[0054] Specific implementation parameters: During the wheat's tillering, jointing, and grain-filling stages, namely April 1, April 25, and May 12, agricultural spraying drones will be used for foliar spraying. The application rate of the formulation is 50 ml / mu each time, diluted to 2L / mu. The spraying location is the functional leaves of the wheat canopy. During the jointing and grain-filling stages, the upper leaves of the winter wheat canopy will be sprayed.

[0055] Experimental design replication: Each treatment was set up with 3 replicates, each replicate plot area was 20×10 m, with a 5 m protection zone in the middle. The plots were arranged in a completely randomized block design to eliminate random errors. The data results are the average of the replicates.

[0056] 7. Measurement Indicators and Methods Actual crop evapotranspiration AND a The calculation is performed using the water balance method. AND a = Δ W + P - D - R, in, R This is surface runoff, which can be ignored due to low rainfall and relatively dry soil during the wheat growing season. D This refers to deep seepage. During the growing season, rainfall is generally less than 30 mm, therefore there is no deep seepage. The remaining parameters were measured as follows: Precipitation P Measurements and records were made using a combination of rain gauge observation and automatic detection by tipping bucket rain gauges.

[0057] Δ W Soil moisture content was measured at a depth of 2 m before sowing and after harvest, and the water storage capacity of the soil layer was calculated. Sampling time: before sowing and after harvest; Sampling depth: 0-20, 20-50, 50-100, 100-200 cm; Sampling method: Use a soil drill to take 5 points in an S-shape for each plot, and mix them together; Test method: The soil moisture content was determined by drying at 105℃ to constant weight. Calculation method: By combining moisture content with bulk density, the soil water storage capacity of each layer and the entire profile is calculated, Δ. W = Pre-sowing water storage - Post-harvest water storage

[0058] Actual crop yield Y a : Yield measurement method: When mature, collect all plants from a fixed area in the middle of each plot, such as 10 m².

[0059] Processing steps: threshing, winnowing, sun-drying, and then adjusting to a standard moisture content of 13%.

[0060] Weighing and conversion: Weigh and convert the yield to yield per mu (kg / mu).

[0061] The specific results of data collection and analysis are as follows: 1. Data collection: The agricultural extension station of Wenxi County Agricultural Bureau collected data on winter wheat yield and evapotranspiration over five years under the same soil type and traditional management conditions in arid areas (see Table 1). Data on soil moisture content (0-2m), winter wheat yield, and precipitation during the growing season were collected after the application of drought-resistant agents at the time of winter wheat sowing and harvest (see Table 2).

[0062] Table 1 Table 2 2. Calculate the multi-year average crop yield Y ave and multi-year average crop evapotranspiration AND ave : The average crop yield and average crop evapotranspiration over many years were calculated using formulas (1) and (2), and the obtained data were 3224 kg / hm². 2 And 314 mm.

[0063] 3. Calculate the average water productivity of crops. WP ave : Calculated using formula (3), for (kg / hm 2 / mm), to obtain the average water productivity of wheat. WP ave It is 10.27 kg / hm 2 / mm.

[0064] 4. Obtain winter wheat yield after spraying drought-resistant agents: Five wheat yields were obtained from five representative sampling sites in the study area, and the average yield was calculated to be 3806 kg / hm². 2 , as the wheat yield after spraying drought-resistant agents; Obtain soil moisture content after spraying drought-resistant agents and calculate winter wheat evapotranspiration: Three representative sampling points were selected in wheat fields sprayed with drought-resistant agents. The soil moisture content of four soil layers (0-20 cm, 20-50 cm, 50-100 cm, and 100-200 cm) was measured. The average weight moisture content of the four soil layers at sowing and harvest was calculated using formula (5). The soil water consumption Δ during the winter wheat growing season was calculated using formula (6). W It was 190.9 mm. This is combined with the precipitation during the growing season. P The evapotranspiration of winter wheat after applying drought-resistant agents was calculated to be 340.9 mm using formula (7), with a soil moisture content of 150 mm. The calculation results of soil water consumption and evapotranspiration are shown in Table 2.

[0065] 5. Calculate the winter wheat yield: 3806 kg / hm² 2 Required theoretical evaporation: Based on the average winter wheat water productivity of the study area WP ave =10.27 kg / hm 2 / mm and winter wheat yield after spraying drought-resistant agents Y a =3806 kg / hm 2 The yield of winter wheat was calculated to be 3806 kg / hm using formula (8). 2 Required theoretical evaporation AND Theo It is 371 mm.

[0066] 6. Calculate the water-saving equivalent after spraying the drought-resistant agent: Based on wheat production Y a =3806 kg / hm 2 Theoretical evaporation AND Theo =371 mm and average crop evapotranspiration after application of drought-resistant agents AND a =340.9 mm, calculate the agricultural water-saving equivalent after spraying drought-resistant agent using formula (9). W sav It is 20.1 m 3 / mu.

[0067] 7. Calculate the water-saving ratio R The calculation formula is:R = ( AND Theo - AND a ) / AND a =8.8%.

[0068] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for calculating water saving equivalent in dry land agriculture, characterized by, comprising the steps of: S1, calculate average water productivity of the study area under the same type of soil and traditional management conditions WP ave ; S2, obtaining actual crop yield after the target water-saving technology is adopted in the study area Y a and actual crop evapotranspiration ET a ; S3. The average water productivity is calculated according to the formula WP ave and the actual crop yield Y a , the theoretical evapotranspiration is calculated according to the formula Y a ET Theo wherein the calculation formula is ET Theo = Y a / WP ave ;​ S4, according to the theoretical evapotranspiration ET Theo with the actual crop evapotranspiration ET a , the calculation shows that the water-saving equivalent of the arid region agriculture after using the water-saving technology W sav , the calculation formula is: W sav = k × ( ET Theo - ET a ), wherein, k is the unit conversion coefficient.

2. The method of claim 1, wherein, The calculated study area in S1 is the average water productivity under the same type of soil and traditional management conditions WP ave and specifically comprises: obtaining multi-year average crop yield for the study area Y ave and multi-year average crop evapotranspiration ET ave ; According to the formula WP ave = Y ave / ET av , the average water productivity of the area is calculated WP ave .

3. The method of claim 1, wherein, said acquiring a multi-year average crop yield for the study area Y ave and a multi-year average crop evapotranspiration ET ave and specifically comprises: Obtaining the crop yield data of the research area in the same type of soil and traditional management conditions for many years, and calculating the average crop yield for many years Y ave , the calculation formula is ; Obtaining the crop evapotranspiration data of the research area under the same type of soil and traditional management conditions for many years, and calculating the average crop evapotranspiration for many years ET ave , and the calculation formula is ; wherein: Y ave and Y i is the multi-year average crop yield and the crop yield obtained in the i 2 th year, kg / hm​ N The total number of crop yields obtained from literature review and research, N ≥ 5; ET ave and ET i is the multi-year average crop evapotranspiration and the crop evapotranspiration obtained in the first i month, respectively, mm; M The total number of crop evapotranspiration obtained from the literature, M ≥ 5.

4. The method of claim 1, wherein, The actual crop evapotranspiration after the target water-saving technology is adopted in the research area is obtained by using water balance method, lysimeter method or eddy correlation method in S2 ET a .

5. The method of claim 1, wherein, The actual crop evapotranspiration after the target water-saving technology is adopted in the research area in S2 ET a The water balance method is adopted, specifically: ET a = Δ W + P ; wherein, Δ W is the water consumption of the soil in the crop growth period, P is the precipitation in the crop growth period.

6. The method of claim 1, wherein, the amount of water consumed by the soil during the growth period of the crop, Δ W This is calculated by the following formula: wherein: Delta W Water consumed by the soil during the growing period of the crop, mm; Z i For the first i Thickness of the layer of soil, mm; gamma i For the first i Bulk density of the soil layer, g / cm 3 ; and Day 0 and Day 100, respectively, are the days of planting and harvesting of the crop i Average gravimetric soil water content, g / g, of the layer N the number of soil fractions; i For the first i layer of soil.

7. The method of claim 1, wherein, The water-saving technology includes one or more combinations of drought-resistant formulations, mulching, deep tillage, water-retaining agents, or drought-resistant crop varieties.

8. The method of claim 1, wherein, The water saving equivalent is calculated at S4 W sav The water saving ratio is further calculated R The calculation formula is: R = ( ET Theo - ET a ) / ET a .

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