Agricultural field drainage re-use system and method

Abstract

The present application belongs to the field of farmland irrigation and drainage technology, and particularly relates to a farmland drainage recycling system and method, which comprises a rice-growing area, a dry farming area adjacent to the rice-growing area, a water collection channel arranged on the rice-growing area and the dry farming area for collecting drainage from the rice-growing area and the dry farming area, a water collection point in communication with the water collection channel for collecting and storing the drainage, an irrigation water channel arranged on the rice-growing area and the dry farming area, and a pump station for delivering water from the water collection point to the irrigation water channel, and a drainage ditch in communication with the water outlet of the pump station. The present application solves the problems of shortage of fresh water resources, untimely conventional irrigation, insufficient utilization of farmland drainage, and unreasonable irrigation mode. The present application can save fresh water resources, reduce the emission of nitrogen and phosphorus pollutants in farmland, and reduce the cost of water lifting, and is practical and suitable for popularization and application.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of farmland irrigation and drainage, and particularly relates to a farmland drainage recycling system and method. BACKGROUND

[0002] In arid irrigation areas where fresh water resources are scarce, water is uniformly allocated from rivers, lakes or reservoirs, and due to the limitation of factors such as channel rotation irrigation cycle, if irrigation is not timely during the peak period of crop water demand, it will lead to crop yield reduction.

[0003] At present, the main food crops in Ningxia and other regions are rice, corn and wheat, the main irrigation method is channel water diversion surface irrigation, and the main drainage method is open ditch drainage and underground pipe drainage. In the prior art, a pump station is usually arranged at the underground pipe drainage outlet for water pumping. The system directly collects and discharges the underground pipe drainage to the drainage ditch, and the farmland drainage is not fully utilized. When the drainage is recycled, another pump station needs to be arranged to pump water from the drainage ditch for irrigation, which increases the irrigation cost and energy consumption.

[0004] The farmland drainage of dry crops contains a higher concentration of salt than fresh water. Unreasonable irrigation mode may cause secondary salinization of farmland soil, strengthen the stress effect of soil salt on crop root water absorption, hinder the normal growth of plants and lead to crop yield reduction. Compared with the farmland drainage of dry crops, the drainage of paddy fields has larger drainage volume, longer drainage duration, lower salt content and higher nitrogen and phosphorus concentration. Therefore, the usability of paddy field drainage is higher than that of dry farmland drainage, and it can be used for farmland irrigation. SUMMARY

[0005] To solve the problems of the prior art, the present application provides a farmland drainage recycling system, which can solve the problems of fresh water resource shortage, conventional irrigation not in time, insufficient utilization of farmland drainage water and fertilizer resources, and secondary salinization of soil caused by unreasonable irrigation mode, leading to crop yield reduction.

[0006] To solve the problems of the prior art, the technical scheme provided by the present application is as follows:

[0007] A farmland drainage recycling system, comprising: a rice growing area, a dry crop growing area adjacent to the rice growing area, a water collection channel arranged on the rice growing area and the dry crop growing area for collecting drainage of the rice growing area and the dry crop growing area, a water collection point in communication with the water collection channel for collecting and storing the drainage, an irrigation water channel arranged on the rice growing area and the dry crop growing area, and a pump station for conveying water in the water collection point to the irrigation water channel, wherein the water outlet end of the pump station is in communication with the irrigation water channel and the drainage ditch.

[0008] As an optimization scheme of the present case, the water collecting channel comprises: a plurality of drainage pipes embedded in the farmland, a water collecting well communicated with the end of the drainage pipe, and a water collecting pipe in series communication with each water collecting well and leading the water in the water collecting well to the water collecting point.

[0009] As an optimization scheme of the present case, the irrigation water channel comprises a ditch channel arranged on at least one side of the rice planting area and the dry planting area for introducing conventional irrigation water, and a plurality of farmland channels in scattered arrangement on the rice planting area and the dry planting area, one of which is arranged at the abutting position of the rice planting area and the dry planting area, and the other end of which is communicated with the water outlet end of the pump station.

[0010] As an optimization scheme of the present case, the water collecting well is arranged on the side opposite to the ditch channel of the rice planting area and the dry planting area, the water collecting point is arranged between the rice planting area and the dry planting area, the water collecting point is arranged in one of the water collecting wells close to the abutting position of the rice planting area and the dry planting area in the rice planting area, and a plurality of the water collecting wells are arranged with a certain slope from the two sides of the water collecting point to the water collecting point.

[0011] As an optimization scheme of the present case, the gate is arranged on the ditch channel in the rice planting area, the water outlet end of the pump station is provided with a first water conveying pipeline communicated with the irrigation water channel and a second water conveying pipeline communicated with the drainage ditch, and the first water conveying pipeline and the second water conveying pipeline are both provided with a valve and a water meter.

[0012] As an optimization scheme of the present case, the pump station is a solar photovoltaic pump station.

[0013] As an optimization scheme of the present case, the solar photovoltaic pump station comprises: a solar cell panel, an inverter connected with the output end of the solar cell panel, an output end of the inverter connected with an input end of a storage battery, an output end of the storage battery connected with a water pump, and a water outlet end of the water pump connected with a water outlet pipe for leading water out.

[0014] As an optimization scheme of the present case, the solar photovoltaic pump station further comprises a float ball switch arranged on the water surface and connected with the storage battery for controlling the water level. The solar photovoltaic pump station further comprises a maintenance hole and a ladder arranged on the water collecting well for maintenance.

[0015] The present application also provides a farmland drainage recycling method, comprising the following steps:

[0016] The rice planting area and the dry planting area are arranged in abutment;

[0017] A water collecting channel for collecting the drainage of the rice planting area and the dry planting area is arranged, a water collecting point for collecting and storing the drainage is arranged, an irrigation water channel of the rice planting area and the dry planting area is arranged, a pump station for conveying the water in the water collecting point to the irrigation water channel is arranged, and a drainage ditch is arranged at the water outlet end of the pump station.

[0018] The irrigation mode mainly includes: only farmland drainage irrigation, mixed irrigation or rotation irrigation of conventional water and farmland drainage according to a certain proportion, and only conventional water irrigation.

[0019] As an optimization scheme of the present application, the step further comprises: adjusting the planting proportion of rice and dry crops according to the drainage amount of the paddy field and the water requirement of the dry crops, so that the paddy field drainage can fully meet the water requirement of the dry crop irrigation.

[0020] The present application has the following beneficial effects:

[0021] 1. The farmland drainage recycling system of the present application can save the amount of fresh water for irrigation, reduce the cost of water lifting, avoid crop yield reduction caused by delayed irrigation, realize efficient reuse of nitrogen, phosphorus and other nutrients in the drainage, improve the water and fertilizer utilization efficiency of farmland, and protect the water environment of farmland.

[0022] 2. The farmland drainage recycling system of the present application is arranged adjacent to the paddy field and the dry land, fully utilizes the availability of paddy field drainage, and can adjust and control the water flow and drainage direction of drainage irrigation, so that the drainage recycling can be realized, and when the salt content of the farmland drainage is high, the water collected at the water collection point can be directly discharged to the drainage ditch through the drainage pipeline by the pump station, so as to avoid the secondary salinization of soil and the resulting crop yield reduction.

[0023] 3. The farmland drainage recycling system of the present application uses a solar photovoltaic pump station, which does not need to set up another pump station to pump water from the drainage ditch for irrigation, thereby reducing the irrigation cost and energy consumption.

[0024] 4. The farmland drainage recycling system of the present application can be directly upgraded and modified on the basis of the existing and already built underground drainage system without damaging the existing underground drainage system, and has low construction cost.

[0025] 5. The farmland drainage recycling method of the present application considers the suitability of farmland drainage recycling, uses different irrigation modes according to the drainage rate and salinity of the paddy field, and jointly uses the farmland drainage and fresh water delivered to the irrigation farmland canal, so as to avoid the adverse effects on crops caused by the irrigation of farmland drainage with too little amount or too high salt content in some months. At the same time, the planting proportion of rice and dry crops is reasonably adjusted according to the drainage law of the paddy field and the water requirement characteristics of the dry crops, and the planting structure of crops is scientifically determined, so as to increase the regional water saving benefit. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram of the farmland drainage recycling system of the present application;

[0027] Figure 2 This is a detailed schematic diagram of the solar photovoltaic pump station of the present invention;

[0028] Figure 3 This is a schematic diagram illustrating the changes in mineralization during drainage through underground pipes in rice-growing areas according to the present invention.

[0029] Figure 4 This is a schematic diagram illustrating the changes in mineralization during drainage through underground pipes in dryland areas according to the present invention.

[0030] In the diagram: 1-Irrigation canal, 2-Drainage pipe, 3-Sluice gate, 4-Collection well, 5-Collection pipe, 6-Water meter, 7-Valve, 8-Pump station, 9-Water pipeline, 10-Collection point, 11-Well number, 12-Diversion canal, 13-Drainage ditch, R1-Rice growing area, R2-Dryland growing area, 81-Solar panel, 82-Inspection hole, 83-Outlet pipe, 84-Inverter, 85-Battery, 86-Ladder, 87-Wire, 88-Float switch, 89-Water pump, 90-Well bottom plate, →-Water flow direction. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0032] Example 1

[0033] like Figure 1 As shown, this embodiment proposes a farmland drainage reuse system.

[0034] The system includes a farm canal 1, a drainage culvert 2, a gate 3, a collection well 4, a collection pipe 5, a water meter 6, a valve 7, a pumping station 8, a water conveyance pipeline 9, a water collection point 10, a well number 11, a distribution canal 12, and a drainage ditch 13. The drainage culvert 2 is pre-buried in the corresponding location in the farmland. The drainage culvert 2 collects water to the collection well 4. Each collection well 4 is connected by a collection pipe 5 to collect water to the collection point 10. A pumping station 8 is set up at the collection point 10. The pumping station 8 transports the drainage from the paddy field to the farm canal through the water conveyance pipeline 9. The drainage water is then used in conjunction with conventional irrigation water for rotational or mixed irrigation of dryland crops.

[0035] In this embodiment, irrigation canals 1 are horizontally arranged in parallel within the farmland as irrigation channels. Drainage pipes 2, pre-buried in corresponding locations within the farmland, are typically arranged horizontally alongside the irrigation canals. They collect and discharge groundwater or excess soil moisture through small holes in the pipe walls or pipe connections. The ends of the drainage pipes 2 are connected to collection wells 4, which are located on one side of the farmland. These wells collect the drainage from the drainage pipes and temporarily store water. The drainage collected in the wells 4 is transported to a collection point 10 via a collection pipe 5, which is impermeable. The collection pipe 5 connects the various wells 4 in series, guiding the drainage to the collection point 10. The collection point 10 is connected to the outlet of the collection pipe 5 to collect and store the drainage. Multiple collection wells 4 are provided according to actual needs, numbered using well number 11. In this embodiment, these include 1#-11#. An arrow → is used to indicate the direction of water flow.

[0036] In this embodiment, the farmland includes a rice-growing area R1 and an adjacent dryland area R2. A water collection point 10 is located between the rice-growing area R1 and the dryland area R2. Water collection wells 4 are arranged on the same side of the rice-growing area and the dryland area. One of the water collection wells can be used as the water collection point. Water collection point 10 is a water collection well located in the rice-growing area R1 near the dryland area R2. Figure 1 The well shown is number 6. The wells in the rice paddy area R1 and the dryland area R2 are set up from both sides of the collection point 10 towards the collection point with a certain slope. Drainage from the rice paddies flows through the drainage pipe 2 to the corresponding wells 1#, 2#, 3#, 4#, 5#, and 6#. Well 1# flows into well 2# through the collection pipe 5, and so on, eventually flowing into well 6#. Drainage from the dryland flows through the drainage pipe 2 to the corresponding wells 11#, 10#, 9#, 8#, and 7#. Well 11# flows into well 10# through the collection pipe 5, and so on, eventually flowing into well 6#.

[0037] In this embodiment, pump station 8 is located at the water collection point 10, and its outlet end is connected to water conveyance pipe 9. Two water conveyance pipes 9 can be provided. One end of the first water conveyance pipe is connected to the outlet of the pump station 8, and the other end is connected to the irrigation canal 1, so as to transport the water collected and stored at the water collection point 10 to the irrigation canal 1 for irrigation. One end of the second water conveyance pipe is connected to the outlet of the pump station 8, and the other end is connected to the drainage ditch 13, so as to transport the water collected and stored at the water collection point 10 to the drainage ditch 13.

[0038] A water meter 6 and a valve 7 are installed on the first water supply pipeline and the second water supply pipeline, respectively; the water meter 6 is used to measure the water flow rate; the valve 7 is used to control the drainage direction, regulate the water flow rate and prevent backflow; the water flow direction is controlled by opening and closing the valve.

[0039] The pump station 8 is provided with pipes respectively leading to the farmland ditch 1 and the drainage ditch, and the flow direction and flow rate of the drainage are controlled by the valve 7 and the water meter 6. The water outlet of the pump station 8 is delivered to the farmland ditch 1 through the water delivery pipe 9 for irrigation of dry crops, or delivered to the drainage ditch through the drainage pipe.

[0040] A side of the rice planting area R1 and the dry crop planting area R2 is provided with a bucket ditch 12, which can be arranged on the other side opposite to the side where the water collecting well 10 is located. The bucket ditch is communicated with the farmland ditch and used for introducing conventional irrigation water or drainage recycling water to irrigate the farmland. A gate 3 is arranged on the bucket ditch of the rice planting area at the joint of the rice planting area R1 and the dry crop planting area R2. The gate 3 is used for controlling the opening and closing of the water outlet of the bucket ditch, and can be used to intercept water flow, control water level, adjust flow rate, etc. When the conventional irrigation water is used to irrigate the farmland, the gate 3 is opened to make the irrigation water flow into each farmland ditch. When the drainage of the rice field is needed to irrigate the farmland, the gate 3 on the bucket ditch 12 is closed or a certain flow rate is set, and then the valve 7 and the water meter 6 on the first water delivery pipe are opened. The drainage in the water collecting well 4 is pumped by the pump station 8 and flows into the farmland ditch 1 through the water delivery pipe 9. When the water flow in the farmland ditch 1 reaches a certain water level, it flows into the bucket ditch 12 and then flows into each farmland ditch through the bucket ditch 12, so as to realize the irrigation of the dry crop farmland by the drainage of the rice field. Thus, by opening and closing or controlling the gate 3, the conventional irrigation water is combined with the drainage recycling water of the rice field to realize the rotation irrigation or mixed irrigation of the dry crops.

[0041] It should be noted that, generally, the drainage amount of the dry land is smaller than that of the rice field, and the drainage in the irrigation and drainage unit is mainly the drainage of the rice field. If the salt content of the farmland drainage is high, the water outlet of the pump station can be directly discharged to the drainage ditch through the second water delivery pipe by controlling the valve 7.

[0042] As shown in FIG. 1, in the embodiment, the pump station 8 is a solar photovoltaic pump station, which does not need to be additionally provided with electric wires, transformers and other equipment, and can save energy and improve the underground pipe drainage capacity. Figure 2 The solar photovoltaic pump station is provided with a solar panel 81, an inspection hole 82, a water outlet pipe 83, an inverter 84, a storage battery 85, a ladder 86, an electric wire 87, a floating ball switch 88, a water pump 89 and a well bottom plate 90.

[0043] The inspection hole 82 and the ladder 86 are used for maintenance by the staff.

[0044] The solar panel 81 is arranged above the water collecting well and used for receiving solar radiation to convert light energy into direct current.

[0045] The inverter 84 is connected with the output end of the solar panel 81 and used for converting the direct current into alternating current.

[0046] The output end of the inverter 84 is connected with the storage battery 85, which is used for storing the alternating current and supplying power for the water pump 89.

[0047] The float switch 88 is arranged on the water surface and is connected with the battery 85 for controlling the water level. The float switch 88 controls the operation of the water pump 89 to maintain the liquid level. When the water level reaches the set height, the solar photovoltaic pumping station stops pumping water. In the embodiment, the set water level is 2.5 meters below the ground surface. The water level can be selected according to the actual situation.

[0048] The water outlet of the water pump 89 is connected with the water outlet pipe 83. The water outlet pipe 83 is connected with the first water conveying pipe and the second water conveying pipe to guide the water pumped by the pumping station to the dry farmland for irrigation or to the drainage ditch 13.

[0049] In the embodiment, the water pump 89 is a centrifugal or axial flow water pump. In a system with small power, if the lift is required to be high and the flow is required to be small, a positive displacement water pump is preferably selected.

[0050] Embodiment 2

[0051] The embodiment provides a farmland drainage recycling method. Main steps include:

[0052] 1. The rice farmland and the dry farmland are arranged adjacently.

[0053] 2. A water collecting channel for collecting the drainage of the rice farmland and the dry farmland is arranged. A water collecting point for collecting and storing the drainage is arranged. An irrigation water channel of the rice farmland and the dry farmland is arranged. A pumping station for conveying the water in the water collecting point to the irrigation water channel is arranged. A drainage ditch is arranged at the water outlet of the pumping station. Specifically, the farmland drainage recycling system is the farmland drainage recycling system as described in the embodiment 1.

[0054] 3. Different irrigation modes are used according to the drainage rate and the drainage salinity of the rice field. The irrigation modes mainly include: farmland drainage irrigation, mixed irrigation or rotation irrigation of the conventional water and the farmland drainage according to a certain proportion, and conventional water irrigation.

[0055] 4. The planting proportion of the rice and the dry farmland is adjusted according to the drainage amount of the rice field and the water demand characteristics of the dry farmland, so that the drainage of the rice field can completely meet the water demand of the dry farmland irrigation.

[0056] Specifically, when the drainage rate of the rice field is greater than the water demand of the crops, and the drainage salinity meets the salinity requirement of the irrigation water quality of the dry farmland, the farmland drainage irrigation can be used. The gate 3 on the check dam 12 is closed or a certain flow is set. Then the valve 7 and the water meter 6 on the first water conveying pipe are opened. The drainage in the water collecting well 4 is pumped by the pumping station 8 and flows into the farmland ditch 1 through the water conveying pipe 9. When the water flow in the farmland ditch 1 reaches a certain water level, the water flow is collected into the check dam 12 and then into each farmland ditch, so as to realize the farmland drainage irrigation of the dry farmland.

[0057] When the drainage rate of the rice field is large but the drainage salinity is high (according to the provisions in the national standard GB5084-2021, that is, the total salt content of farmland drainage in non-saline-alkali soil area is greater than 1g / L, and the total salt content of farmland drainage in saline-alkali soil area is greater than 2g / L) cannot meet the salt requirement of irrigation water quality in dry farming area, conventional water and farmland drainage can be mixed irrigation or rotation irrigation according to a certain proportion. When mixed irrigation, the gate 3 on the solar pump station 8 and the canal 12 is opened at the same time, the flow rate is controlled through the valve 7, water meter 6 and gate 3 on the first water conveying pipeline, the valve 7 uses check valve to prevent water backflow, and the mixed irrigation ratio is calculated according to formula (1). When rotation irrigation, the solar pump station 8 is first opened for farmland drainage irrigation, and when the irrigation water reaches a certain amount, the solar pump station 8 is closed and the gate 3 on the canal 12 is opened for fresh water irrigation, and the rotation irrigation ratio is calculated according to formula (1) or according to the experience of salt and fresh water rotation irrigation.

[0058] V1 / V2=(C-C2) / (C1-C) (1)

[0059] V1 is the farmland drainage irrigation amount, m 3 ; V2 is the conventional water irrigation amount, m 3 ; C1 is the total salt content of farmland drainage, g / L; C2 is the total salt content of conventional water, g / L; C is the total salt content threshold of irrigation water, g / L, 1g / L in non-saline-alkali soil area, and 2g / L in saline-alkali soil area.

[0060] When the rice field drainage amount is small or there is no drainage in part of the months, the dry crop needs to be irrigated, and the conventional water irrigation can be carried out by opening the gate 3 on the canal 12.

[0061] If the drainage amount of the dry land is large and the salt content is high, the outlet of the pump station 8 can control the drainage through the valve 7 to be directly discharged to the drainage ditch 13 through the drainage pipeline.

[0062] In order to ensure the maximum utilization of farmland drainage resources and ensure that the rice field drainage can completely meet the water demand of dry crop irrigation as much as possible, the planting proportion of rice and dry crop can be adjusted to match the drainage amount of the rice field area with the water demand of the dry crop irrigation area, which can be calculated according to the following formula (2).

[0063] A1 / A2=I / D (2)

[0064] Wherein, A1 is the rice planting area, hm 2 ; A2 is the dry crop planting area, hm 2 ; I is the water demand of dry crop, m 3 ; D is the rice field drainage amount, m 3 .

[0065] Example 3

[0066] This embodiment is a specific description of example 1 and example 2:

[0067] This embodiment takes a typical irrigation and drainage unit in Pingluo County, Ningxia as an example, selects 2# and 4# observation wells as typical wells for analyzing the mineralization of R1 subsurface pipe drainage in rice-growing areas, and selects 8# and 10# observation wells as typical wells for analyzing the mineralization of R2 subsurface pipe drainage in dryland areas. According to the measured results of the mineralization of farmland drainage in the region in 2019 and 2020 (see Figure 3 and Figure 4 ), the mineralization of farmland drainage in the rice-growing area is between 0.5 and 1.6 g / L from mid-May to mid-August, which is lower than the mineralization of farmland drainage in the dryland area, and meets the salt requirements of irrigation water. From May to September, the farmland drainage in the rice-growing area is suitable for irrigation in the dryland area.

[0068] In this embodiment, except for May to September, the salinity of drainage is high in the remaining months, which cannot meet the salt requirements of irrigation water in the dryland area. In April, the drainage rate of the rice field subsurface pipe is still large, and the drainage rate of the rice field subsurface pipe is still large. Figure 3 The mineralization of rice field drainage in April is 2.25 g / L, and fresh water and farmland drainage can be mixed for irrigation in a certain proportion. The mineralization of the Yellow River water in Ningxia area is 0.505 g / L, and according to formula (1), the irrigation proportion of farmland drainage and Yellow River water is about 6:1. In the remaining months, due to the small amount of rice field drainage, when the dry crop needs to be irrigated, fresh water can be irrigated by opening the gate 3 on the main canal.

[0069] In this embodiment, according to the measured results of the drainage flow of rice field subsurface pipe and the irrigation water requirement of dry crop in the region in 2019 and 2020 (see Table 1), the drainage rate of rice field is 1.77-3.59 mm / d from May to September, and the irrigation water requirement of dry crop is 1.29-4.49 mm / d. If the water loss is not considered, the suitable planting area ratio of rice and dry crop is 0.3-1.5. In order to ensure that the rice field drainage can completely meet the water demand of dry crop irrigation from May to August, it is recommended that the planting ratio of rice and dry crop be 3:2.

[0070] Table 1

[0071]

[0072] The above specific embodiments and examples are specific support for the technical idea of the present application, and cannot limit the protection scope of the present application. Any equivalent changes or equivalent modifications made according to the technical idea of the present application on the basis of the technical solution are still within the protection scope of the technical solution.

Claims

1. A method for reusing farmland drainage, characterized in that, The system utilizes a farmland drainage reuse system, which includes: a rice-growing area (R1), a dryland area (R2) adjacent to the rice-growing area (R1), a water collection channel arranged on the rice-growing area (R1) and the dryland area (R2) for collecting drainage from the rice-growing area (R1) and the dryland area (R2), a water collection point (10) connected to the water collection channel for collecting and storing drainage, an irrigation channel arranged on the rice-growing area (R1) and the dryland area (R2), and a pumping station (8) for transporting water from the water collection point (10) to the irrigation channel. The outlet of the pumping station (8) is also connected to a drainage ditch (13). The water collection system includes: multiple drainage pipes (2) pre-buried in the farmland, a water collection well (4) connected to the end of the drainage pipe (2), and a water collection pipe (5) that connects each water collection well in series and diverts the water in the water collection well (4) to the water collection point (10). The irrigation waterway includes a canal (12) set on at least one side of the rice-growing area (R1) and the dry-growing area (R2) for introducing conventional irrigation water, and multiple farm canals (1) with one end connected to the canal (12) and distributed on the rice-growing area (R1) and the dry-growing area (R2). One of the multiple farm canals (1) is located at the junction of the rice-growing area (R1) and the dry-growing area (R2), and the other end of the farm canal (1) is connected to the outlet of the pumping station (8). The water collection well (4) is located on the side opposite to the canal (12) on the rice-growing area (R1) and the dry-growing area (R2). The water collection point (10) is located between the rice-growing area (R1) and the dry-growing area (R2). The water collection point (10) is located in one of the water collection wells (4) in the rice-growing area (R1) near the junction of the rice-growing area (R1) and the dry-growing area (R2). A gate (3) is installed on the irrigation canal (12) located in the rice-growing area (R1). The pump station (8) is equipped with a first water conveyance pipe connected to the irrigation waterway and a second water conveyance pipe connected to the drainage ditch (13). Valves (7) and water meters (6) are installed on both the first water conveyance pipe and the second water conveyance pipe. The steps of the farmland drainage reuse method include: The rice-growing areas and dryland-growing areas are arranged adjacent to each other; Arrange water collection channels for collecting drainage from the rice-growing and dry-growing areas; arrange water collection points for collecting and storing drainage; arrange irrigation waterways for the rice-growing and dry-growing areas; set up pump stations to transport water from the water collection points to the irrigation waterways, and arrange drainage ditches at the outlet of the pump stations. Different irrigation modes are used for irrigation based on the drainage rate and salinity of the paddy field. Irrigation modes include: irrigation with only farmland drainage, mixed irrigation or rotational irrigation of conventional water and farmland drainage in proportion, and irrigation with only conventional water. When the drainage rate of the paddy field underground pipe is greater than the water demand of the crop, and the salinity of the drainage meets the salinity requirements of irrigation water in dryland areas, farmland drainage irrigation is used. First, the gate (3) on the distribution canal (12) is closed or a predetermined flow rate is set. Then, the valve (7) and water meter (6) on the first water conveyance pipeline are opened. The drainage in the collection well (4) is pumped by the pump station (8) and flows into the agricultural canal (1) through the water conveyance pipeline (9). After the water flow in the agricultural canal (1) reaches the preset water level, it flows into the distribution canal (12) and then into each agricultural canal (1) through the distribution canal (12). When the drainage rate of the paddy field underground pipe is high but the salinity of the drainage is high, which cannot meet the salinity requirements of irrigation water in dryland areas, conventional water and farmland drainage are mixed or rotated for irrigation in proportion. During mixed irrigation, the gates (3) on the pump station (8) and the canal (12) are opened simultaneously, and the flow rate is controlled by the valve (7), water meter (6) and gate (3) on the first water conveyance pipeline. The valve (7) is a check valve to prevent backflow of water. During rotational irrigation, the pump station (8) is opened first for farmland drainage irrigation. When the preset water volume is reached, the pump station (8) is closed and then the gate (3) on the canal (12) is opened for conventional water irrigation. The formulas for calculating the mixed irrigation ratio and the rotational irrigation ratio are as follows: V1 / V2=(C-C2) / (C1-C) In the formula, V1 represents the amount of farmland drainage for irrigation, in meters. 3 V2 represents the conventional irrigation water volume, in meters. 3 C1 represents the total salinity of farmland drainage, in g / L; C2 represents the total salinity of conventional water, in g / L; C represents the threshold for total salinity of irrigation water. When the paddy field has little or no drainage, regular irrigation is carried out by opening the gate (3) on the irrigation canal (12) when the dry crops need irrigation.

2. The method for reusing farmland drainage according to claim 1, characterized in that, The steps also include: adjusting the planting ratio of rice and dryland crops according to the drainage of paddy fields and the water requirements of dryland crops, so that the drainage of paddy fields can fully meet the water requirements for irrigation of dryland crops.

3. The method for reusing farmland drainage according to claim 1, characterized in that, Multiple water collection wells (4) are set up from both sides of the water collection point (10) toward the water collection point (10) with a certain slope.

4. The method for reusing farmland drainage according to claim 1 or 3, characterized in that, The pump station (8) is a solar photovoltaic pump station.

5. The method for reusing farmland drainage according to claim 4, characterized in that, The solar photovoltaic pump station includes: a solar panel (81), an inverter (84) connected to the output end of the solar panel (81), the output end of the inverter (84) connected to the input end of the storage battery (85), the output end of the storage battery (85) connected to the water pump (89), and the water outlet end of the water pump (89) connected to the water outlet pipe (83) to draw water out.

6. The method for reusing farmland drainage according to claim 4, characterized in that, The solar photovoltaic pump station also includes a float switch (88) connected to the battery (85) on the water surface for controlling the water level.

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