Stress-Adaptive Irrigation and Fertigation

Abstract

Embodiments of the present invention are directed to a subsurface irrigation system configured to operate in a plant-responsive mode and further configured to make specific adaptations in response to plant stress. Stress adaptations can include, for example, selectively increasing the source pressure of the irrigation fluid, heating or cooling the irrigation fluid, and / or injecting fertilizers and / or non-fertilizer amendments into the irrigation fluid.

Description

[0001] This application is a divisional application of the invention patent application entitled "Irrigation and fertilization capable of adapting to stress", with an international application date of July 16, 2020, an international application number of PCT / US2020 / 042282, and a national application number of 202080045370.0. Technical Field

[0002] The present invention relates generally to plant irrigation. More particularly, but not by way of limitation, embodiments of the present invention provide systems and methods for stress-adapted irrigation and fertigation. Background Art

[0003] Various systems and methods are known for plant irrigation and fertigation. Irrigation refers to the controlled delivery of water; fertigation generally means injecting fertilizer or other amendments into an irrigation system. As used herein, "irrigation" may include fertigation.

[0004] A variety of stress conditions are known to damage plants and reduce crop yields. Many irrigation systems and methods fail to adequately compensate for such stresses. Furthermore, known methods of altering irrigation schedules solely in response to perceived stress, such as by increasing the duration of irrigation in above-ground sprinkler systems, are generally not effective in subsurface drip irrigation (SDI) systems. Improved irrigation systems and methods that can adapt to stress are needed. Summary of the Invention

[0005] Embodiments of the present invention relate to a subsurface irrigation system configured to operate in a plant-responsive mode and further configured to adapt specifically to plant stress. Stress adaptations may include, for example, selectively increasing the source pressure of the irrigation fluid, heating or cooling the irrigation fluid, and / or injecting fertilizers and / or non-fertilizer amendments into the irrigation fluid. Alternative embodiments and their advantages are described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a flow chart of an irrigation method according to one embodiment of the present invention;

[0007] Figure 2 is an assembly diagram of a delivery pipe shown in cross section according to one embodiment of the present invention;

[0008] Figure 3A is an assembly diagram of a delivery pipe shown in cross section according to one embodiment of the present invention;

[0009] Figure 3B is an assembly diagram of a delivery pipe shown in cross section according to one embodiment of the present invention;

[0010] Figure 4Schematic diagram of an irrigation system according to an embodiment of the present invention;

[0011] Figure 5 Schematic diagram of an irrigation system according to an embodiment of the present invention;

[0012] Figure 6 Schematic diagram of an irrigation system according to an embodiment of the present invention;

[0013] Figure 7 is Figure 5 Schematic diagram of the shown liquid reservoir;

[0014] Figure 8 is Figure 6 Schematic diagram of the shown liquid reservoir;

[0015] Figure 9A and Figure 9B is a flowchart of a method of using the Figure 5 and Figure 6 shown system; and

[0016] Figure 10A and Figure 10B is a flowchart of a method of using the Figure 5 and Figure 6 shown system. Detailed Embodiments

[0017] Embodiments of the present invention will be described below with reference to the accompanying drawings. Such embodiments are illustrative and not restrictive. The drawings are not drawn to scale. For clarity, some of the features shown in the drawings may be exaggerated in size and others may be completely omitted.

[0018] The following sections begin with a review of some environmental factors that can be monitored to assess environmental stress. The following description begins with an overview of plant stress. Then, this document describes irrigation methods (refer to Figure 1 ), exemplary microirrigation tubing (refer to Figure 2 , 3A and 3B), exemplary irrigation systems (refer to Figures 4 - 8 ) and methods of using such systems (refer to Figure 9A , 9B , 10A and 10B). ]>

[0019] For ease of organization, section headings are used below. The description of any claimed feature is not necessarily limited to any section of this specification.

[0020] Plant stress

[0021] Plant stress factors are caused by non-ideal growing conditions that increase plant requirements. Abiotic stress factors (environmental stress factors) are naturally occurring inanimate factors such as intense sunlight, strong winds, extreme temperatures (hot or cold), drought, flooding, herbicides, pesticides, and poor soil conditions such as salinity, acidity, lack of nutrients (macro and micro), and heavy metals. Less well-known abiotic stress factors usually occur on a smaller scale. They include poor soil conditions such as rock content and pH levels, high radiation, compaction, and pollution. Any of these stress factors can have a negative impact on plant development and crop productivity. Abiotic stress is considered the most harmful factor affecting crop growth and productivity. Abiotic stress factors are most harmful when they occur together in combinations of abiotic stress factors such as drought, desert climate.

[0022] Biotic stress factors include biological interferences such as fungi, bacteria, insects, and weeds. Viruses can also cause biotic stress in plants. Fungi cause more diseases in plants than any other biotic stress factor. Microorganisms can cause plant wilting, leaf spots, root rot, or seed damage. Insects can cause severe physical damage to plants. Insects can also transmit viruses and bacteria from infected plants to healthy plants. Weeds inhibit the growth of desired plants by competing for space and nutrients.

[0023] A plant's first line of defense against abiotic and biotic stress is in its roots. If the soil in which the plant is grown provides sufficient water and nutrients in response to the plant's needs and is otherwise healthy and biodiverse, then the plant will be more likely to survive stress conditions above ground. Embodiments of the present invention monitor plant stress factors and provide appropriate interventions in the rhizosphere to minimize various plant stress factors.

[0024] Exemplary irrigation method

[0025] Figure 1 is a flowchart of an irrigation method according to an embodiment of the present invention. As shown therein, the process starts at step 105 with subsurface irrigation via microporous tubing treated with a hydrophilic polymer in a root-responsive mode, which is characterized by a relatively low supply pressure (to the tubing) and a closed-end type fluid path. This irrigation mode is very water-efficient and is the preferred irrigation mode when the plant is not under stress.

[0026] Then, the process determines plant stress conditions in step 110. Step 110 can be performed, for example, by comparing sensor data with predetermined thresholds, by visual inspection, and / or by performing plant tissue or soil analysis. For example, readings from an ambient temperature sensor and / or a ground temperature sensor can be compared with a predetermined threshold to determine the presence of elevated temperature conditions. Similarly, wind speed data from an anemometer can be compared with a predetermined threshold. Preferably, temperature and wind data are integrated over time to more accurately simulate the transpiration effect. As a further example of step 110, visual inspection (whether performed or assisted by a person, a local imaging sensor, or an elevated device) can reveal leaf discoloration, plant wilting, lodging (stem or root displacement), disease, pest infestation, the presence of weeds, or other evidence of the presence or emergence of plant stress factors. Data from a subsurface salinity sensor can be compared with the known salt tolerance level of a given plant type. For example, soil analysis can reveal a lack of beneficial microorganisms in the soil or the presence of harmful fungi.

[0027] In step 115, the process selects a treatment provided by the system based on the plant stress conditions, and the treatment provided by the system includes a relatively high supply pressure and a recirculation fluid path. For example, in the case of temperature-related stress, the selected treatment provided by the system can include cooling or heating the irrigation fluid, and can also include adding a surfactant to the irrigation fluid. For wind stress not accompanied by extreme temperatures, the process can select only a relatively high supply pressure and a recirculation path. When it is determined in step 110 that the plant stress condition is a soil condition and / or a mineral imbalance, the process can select an agrochemical additive to modify the irrigation fluid to correct soil defects or problems in step 115. Similarly, when it is determined that there are biological stress factors, the process can select, for example, from one or more bioconditioners, root / soil activators, organic additives, or pesticides.

[0028] The relatively high supply pressure (preferred in all treatment cases) and the surfactant (when added) will tend to increase the discharge rate of the irrigation fluid from the tubing to the roots. The recirculation path (also preferred in all treatment cases) will help to deliver the irrigation fluid more uniformly (in terms of temperature and modifier concentration) along the functional length of the underground tubing.

[0029] The process performs the treatment provided by the system (described above) in step 120 and determines when to terminate the treatment provided by the system in step 125. The treatment provided by the system is intended to be temporary. The determination in step 125 can be based on a predetermined duration (e.g., based on the treatment type), a calculated duration (e.g., based on the severity of the determined stress factor(s)), or evidence of stress reduction (e.g., improvement in the data, observations, or analysis relied upon in step 110).

[0030] As indicated by conditional step 135, if the treatment provided by the system includes fluid modification, the process proceeds to step 140; otherwise the process returns directly to step 105. Flushing step 140 preferably includes supplying irrigation fluid at a relatively high supply pressure and using a recirculation fluid path, but without adding modifiers. An exception is when the treatment provided by the system includes modification with a surfactant, in which case flushing step 140 preferably includes modification with a thickener to counteract the effect of the surfactant on fluid discharge.

[0031] Example of a micro - irrigation pipeline

[0032] Figure 2 、 3A Figures 3A and 3B are each an assembly view of a delivery tube shown in cross-section according to alternative embodiments of the present invention. As Figure 2 shown, the microporous membrane 205 is welded to the liner 210 along the region 215 to form an irrigation tube having an inner cavity 220. Figure 3A and 3B The embodiments shown in provide irrigation tubes without a liner 210. Instead, in these examples, the microporous membrane 305 wraps around itself to form an irrigation delivery tube having an inner cavity 320. Figure 3A The embodiment in includes a butt-welded seam portion 310 with beads 315; Figure 3B The embodiment in includes a finned seam portion 325.

[0033] The microporous membranes 205, 305 can be made of, for example, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET, a / k / a polyester), or other suitable materials. As an example, the microporous membranes 205, 305 can be DuPont Tyvek TM or other non-woven or spunbonded fabrics. Preferably, the microporous membranes 205, 305 are treated (either completely or selectively) with a hydrophilic polymer to enhance responsiveness to root exudates.

[0034] For Figure 2 the tubing embodiments in, the liner 210 is preferably a material that is less expensive than the microporous membrane 205. The liner 210 also preferably has fewer pores (i.e., is effectively poreless) compared to the microporous membrane 205. For thermal compatibility, in the case where the microporous membrane 205 is PE, the liner 210 is preferably also made of PE; in the case where the microporous membrane 205 is PP, the liner 210 is preferably PP; and in the case where the microporous membrane 205 is PET, the liner 210 can be PET. For any given length of tubing, the surface areas of the microporous membrane 205 and the liner 210 do not need to be equal.

[0035] Other micro-irrigation line configurations and welding types are feasible and can also be used in combination with one or more stress-adaptable systems and methods disclosed herein. Additionally, some features or embodiments may equally apply to both surface and subsurface applications of micro-irrigation lines.

[0036] Exemplary system

[0037] An exemplary system for performing the above method and its variants are described below with reference to Figures 4 to 8 as follows.

[0038] Figure 4 FIG. is a schematic diagram of an irrigation and fertigation system according to an embodiment of the present invention. For example, Figure 4 the illustrated embodiment may be applicable to large-scale commercial agricultural operations. As shown therein, a supply system 405 supplies a main line 485 that is coupled to a plurality of subsurface micro-irrigation delivery tubes 493. Multiple plants 495 have roots 497 within the effective range of the delivery tubes 493. The delivery tubes 493 may be constructed, for example, as described above with reference to Figure 2 , 3A or 3B.

[0039] The supply system 405 includes a reservoir (RES) 410 that is coupled to receive fluid from a well pump (W) 415, a municipal water connection (CW) 420, and a recirculation pump (RE) 425. Each of these inputs to the reservoir 410 may be coupled via a valve (not shown). In the illustrated embodiment, the reservoir 410 includes a heater (HT) 430. Valves 440, 445 are coupled to the output of the reservoir 410. A inline cooler (CH) 435 is coupled to the output of valve 445.

[0040] Appropriate recirculation pumps 425 are manufactured according to application requirements by, for example, Blue Torrent Pool Products, Floject, Flotec, and other suppliers. The heater 430 may be, for example, a glass-encapsulated electric heating element, but other geothermal or other heating methods may also be applied depending on design choices. The inline cooler 435 may be or include, for example, Heatwave, GBB (Great Big Bopper by AquaCal), or other water source heat pumps.

[0041] In the supply system 405, the output of the reservoir 410 is further coupled to a filter (F) 450 and is also coupled to tanks (T) 455, 460, 465, and 470 and a pressure regulator 480. Any of the tanks 455, 460, 465, 470 may include a pump (not shown).

[0042] The pressure regulator 480 is preferably configured to output a fluid stream at a relatively low pressure (e.g., for settings in the range of 0.5 PSI to 5.0 PSI) from the supply system 405 to the manifold 485 for compatibility with the microporous delivery tube 493. An exemplary regulator 480 is a Model 3865 diaphragm regulator manufactured by Ziggity Systems, Inc. The required pressure setting of such an adjustable pressure regulator can vary depending on the characteristics of the delivery tube 493. In alternative embodiments, other pressure settings and / or other regulators 480 may be used.

[0043] In operation, the reservoir 410 is selectively supplied by the well pump 415, the municipal water connection 420, and / or the recirculation pump 425. The fluid in the reservoir 410 is selectively heated by the heater 430; the in-line cooler 435 is used to selectively cool the fluid at the output of the reservoir 410 by the operation of valves 440, 445. In some operating modes, the fluid in the supply system 405 is not heated or cooled. Depending on the fluid modifier and the recirculation state, the flow through the filter 450 can also be selective (e.g., by an additional valve, not shown). Generally, each tank 455, 460, 465, and 470 can contain a unique type of fluid modifier. For example, tank 455 can contain fertilizer, tank 460 can contain surfactant, tank 465 can contain thickener, and tank 470 can contain microparticles for suspended matter. The contents (or a portion) of each tank �55, 460, 465, and 470 can be selectively added to the irrigation fluid in the supply system 405, either individually or in any combination, by the operation of the respective valves 475. The regulator 480 controls the supply pressure of the irrigation fluid to the manifold 485 and the delivery tube 493. During selective recirculation (i.e., depending on the state of the recirculation pump 425), the irrigation fluid returns to the supply system 405 via the recirculation path 490.

[0044] The supply system 405 can operate in alternative modes. For example, in a conventional low-pressure device response mode, the heater 430 and the cooler 435 can be off, the valve 440 can be open, the valves 445 and 475 can be closed, the regulator 480 can be adjusted to a relatively low pressure (e.g., 1.5 psi), and the recirculation pump 425 can be off. In a treatment mode, the heater 430 or the cooler 435 can be on, one or more valves 475 can be open, the regulator 480 can be set at a relatively high pressure (e.g., 5.0 psi), and the recirculation pump 425 can be on.

[0045] Figure 4Variations of the system shown and described above are also possible. For example, some embodiments do not require the well pump 415, the municipal water connection 420, or the recirculation pump 425. In alternative embodiments, the heater 430 may be arranged in series outside the reservoir 410. The heater 430 may be combined with the cooler 435, for example, in a heat pump unit. The number and order placement of the filters 450 and the tanks 455, 460, 465, and 470 may vary. In an automatic or semi-automatic embodiment, the supply system 405 may include a controller; the controller may receive signals from one or more environmental sensors, and the controller may output control signals to the recirculation pump 425, the heater 430, the inline cooler 435, the valves 440, 445, 475, and / or the pressure regulator 480.

[0046] Figure 5 is a schematic view of an irrigation system according to an embodiment of the present invention. As shown therein, the supply system 500 supplies a main pipe 505 that is coupled to a plurality of underground micro-irrigation delivery pipes 493. Multiple plants 495 have roots 497 within the range of action of the delivery pipes 493. The delivery pipes 493 may be constructed, for example, with reference to Figure 2 , 3A or 3B as described above. Each delivery pipe is fluidly coupled to the bottom 506. The sensor 508 may be or include, for example, an underground temperature sensor and / or a salinity sensor. <{

[0047] The supply system 500 is configured such that a pressurized water source (W / S) 501 may be serially coupled to a transducer 502, a first pressure regulator 503 (which is set for a relatively low pressure output, e.g., 1.0 psi), a transducer 504, and the main pipe 505. For some applications, the RDI model APR-Z053 type may be suitable for the first pressure regulator 503.

[0048] The transfer device 502 is also connected to a plurality of injection valves 517 and bypass valves 518. Each injection valve 517 is connected in series to the input end of a corresponding in-line injection device 511. The in-line injection device 511 is preferably configured to accurately add soluble fertilizers or other amendments. The output end of the in-line injection device 511 is connected to the output end of the bypass valve 518 and the first input end of the reservoir 510. The first output end of the reservoir 510 is connected in series to a pump 512 and a cooler / heater 513. In an alternative embodiment, the cooler / heater 513 can be a cooler or a heater instead of a combined cooler / heater. The output end of the cooler / heater 513 is connected to the second input end of the reservoir 510. The second output end of the reservoir 510 is connected in series to a recirculation pump 519, a second pressure regulator 514 (set for a relatively high pressure output, such as 5.0 psi), and a transfer device 504. For some applications, the RDI model APR-M758 type can be applicable to the second pressure regulator 503. The bottom 506 is connected in series to a recirculation valve 509 and the third input end leading to the reservoir 510.

[0049] The controller 516 is an optional component depending on the design selection. If included, the controller 516 can be configured to receive data from the sensor 508 and can control the operation of any one or more of the components shown as part of the supply system 500 (except for directly controlling the pressurized water source 501). The recirculation pump 520 is also an optional component based on application requirements. For example, if the reservoir 510 is set at a much higher height than the bottom 506, the recirculation pump 520 may be required.

[0050] In the normal (and most water-saving) mode, the supply system 500 can supply unamended irrigation fluid to the main pipe 505 at a relatively low pressure, and the termination point is at the recirculation valve 509.

[0051] In the case of system-provided treatment in response to plant stress, the supply system 500 can be configured to supply irrigation fluid to the main pipe 505 at a relatively high pressure, with or without amendments from one or more in-line injection devices 511, and with or without heating or cooling generated by the cooler / heater 513. The operation during the system-provided treatment preferably includes a recirculation path via the open recirculation valve 509 and with the assistance of the recirculation pump 519 (and the recirculation pump 520, if applicable).

[0052] Figure 6 is a schematic diagram of an irrigation system according to an embodiment of the present invention. Except for the slight differences between the supply system 600 and the supply system 500, Figure 6 the irrigation system shown in Figure 5The irrigation system shown. In particular, the supply system 600 removes the pump 512, replaces the reservoir 510 with a reservoir 610, and connects the cooler / heater in series. The supply system 600 requires that the selected in-line injection device 511 can provide sufficient flow rate for the selected cooler / heater 513. In this prompted case, the supply system 600 can provide the same "conventional" and "system-provided processing" modes as described above with reference to the supply system 500. As explained above, in an alternative embodiment, the cooler / heater 513 can be a cooler or a heater, rather than a combined cooler / heater.

[0053] Figure 7 is Figure 5 A schematic diagram of the reservoir 510 shown. The reservoir 510 includes a heat-insulating wall 705, three input ports 710, 715, 720, two output ports 725, 730, and a drain port 735. The fluid 740 is maintained below a predetermined filling line 745 with the help of a float switch (not shown), for example. Referring to Figure 5 : The input port 710 can come from the output ports of the in-line injection device 511 and the bypass valve 518; the input port 715 can come from the cooler / heater 513; and the input port 720 can be connected to the recirculation valve 509. The output port 725 can be connected to the pump 512, and the output port 730 can be connected to the recirculation pump 519.

[0054] Figure 8 is Figure 6 A schematic diagram of the reservoir 610 shown. Compared with the reservoir 510, the reservoir 610 removes the input port 710 and the output port 725.

[0055] Figure 9A and Figure 9B is according to an embodiment of the present invention using Figure 5 and Figure 6Flowchart of a method of the system shown. Step 905 is to supply fluid from a pressurized water source 501 to an underground micro-irrigation pipeline 493 at a relatively low set pressure via a first pressure regulator 503. The pipeline 493 is treated with a hydrophilic polymer, and the fluid path through the pipeline terminates at a closed recirculation valve 509. Step 910 is to determine plant stress conditions and select at least one amendment based on the plant stress conditions. Step 915 is to transfer the fluid from the pressurized water source 501 to at least one injection device 511 instead of the first pressure regulator 503. Each of the at least one injection device 511 is associated with a corresponding one of the at least one amendment. Step 920 is to use the at least one injection device 511 to inject the at least one amendment respectively, combining the outputs of the at least one injection device to produce a modified irrigation fluid. Step 925 is to output the modified irrigation fluid into the pipeline 493 at a relatively high set pressure via a second pressure regulator 514, and this relatively high set pressure is higher than the relatively low set pressure. Step 930 is to open the recirculation valve 509 and start at least one recirculation pump 519, 520. The fluid path through the pipeline is converted into a recirculation path by this opening and starting. The recirculation path is fluidly connected to the second pressure regulator 514, the pipeline 493, the recirculation valve 509, and the at least one recirculation pump 519, 520. Step 935 is to terminate the injection, terminate the output of the modified irrigation fluid, and connect the pressurized water source 501 to the recirculation path using a bypass valve 518. Step 940 is to wait for a predetermined period of time after terminating the injection and terminating the output of the modified irrigation fluid. Step 945 is to close the bypass valve 518, close the recirculation valve 509, deactivate the at least one recirculation pump 519, 520, and transfer the fluid from the pressurized water source 501 to the pipeline 493 at a relatively low set pressure via the first pressure regulator 503.

[0056] Thus, in an embodiment of the present invention, before returning to the relatively low pressure and the closed-end root response mode, by supplying only unmodified fluid in the recirculation path at a relatively high pressure for a predetermined period of time, the amendment introduced during the treatment provided by the system is removed from the underground irrigation pipeline.

[0057] Figure 10A and 10B is used according to an embodiment of the present invention Figure 5 [[ID=?]]and Figure 6Flowchart of the method of the system shown. Step 1005 is to supply fluid from a pressurized water source 501 to a subsurface micro-irrigation line 493 at a relatively low set pressure via a first pressure regulator 503, the line 493 being treated with a hydrophilic polymer, and the fluid path through the line terminates at a closed recirculation valve 509. Step 1010 is to determine plant stress conditions and select at least one amendment based on the plant stress conditions, the at least one amendment including a surfactant. Step 1015 is to divert the fluid from the pressurized water source 501 to at least one injection device 511 instead of the first pressure regulator 503, each of the at least one injection devices 511 being associated with a corresponding one of the at least one amendment. Step 1020 is to use the at least one injection device 511 to inject the at least one amendment respectively, combining the outputs of the at least one injection device to produce a modified irrigation fluid. Step 1025 is to output the modified irrigation fluid to the line 493 at a relatively high set pressure via a second pressure regulator 514, the relatively high set pressure being higher than the relatively low set pressure. Step 1030 is to open the recirculation valve 509 and start at least one recirculation pump 519, 520, and the fluid path through the line is converted to a recirculation path by this opening and starting, the recirculation path being fluidly coupled to the second pressure regulator 514, the line 493, the recirculation valve 509, and the at least one recirculation pump 519, 520. Step 1035 is to terminate the injection of the at least one amendment and newly inject at least one thickener using the at least one injection device 511, combining the outputs of the at least one injection device to produce a thickened irrigation fluid. Step 1040 is to output the thickened irrigation fluid to the line 493 at a relatively high set pressure via the second pressure regulator 514. Step 1045 is to wait for a predetermined period of time after terminating the injection and output of the modified irrigation fluid. Step 1050 is to close the bypass valve 518, close the recirculation valve 509, deactivate the at least one recirculation pump 519, 520, and divert the fluid from the pressurized water source 501 to the line 493 at a relatively low set pressure via the first pressure regulator 503.

[0058] Thus, in an embodiment of the present invention, before returning to a relatively low pressure and a closed-end root response mode, by supplying water with a thickener in the recirculation path at a relatively high pressure for a predetermined period of time, the effect of the surfactant introduced during the treatment provided by the system is at least partially offset from the subsurface irrigation line.

[0059] Conclusion

[0060] Those skilled in the art can readily recognize that numerous changes and substitutions can be made in the present invention, its applications, and its construction to achieve substantially the same results as those achieved by the embodiments described herein. For example, the features described in the present application with reference to different embodiments can be combined in a manner not explicitly described. Accordingly, it is not intended to limit the present invention to the exemplary forms disclosed. Many variations, modifications, and alternative constructions fall within the scope and spirit of the disclosed invention.

Claims

1. An irrigation system, comprising: A pressurized water source; An underground microporous irrigation pipeline, the irrigation system being configured to selectively connect the pressurized water source to the main pipeline of the underground microporous irrigation pipeline via a first path, a second path or a third path; The first path includes a first pressure regulator disposed between the pressurized water source and the underground microporous irrigation pipeline, the first pressure regulator being configured to output a relatively low fluid pressure to the main pipeline; The second path includes at least one injection device and a second pressure regulator disposed between the pressurized water source and the underground microporous irrigation pipeline. Each of the at least one injection devices is configured to inject a modifier into the second path. The output end of the at least one injection device is connected to the input end of the second pressure regulator. The second pressure regulator is configured to output a relatively high fluid pressure to the main pipeline, and the relatively high fluid pressure is higher than the relatively low fluid pressure; The third path includes a bypass valve that connects the pressurized water source to the input end of the second pressure regulator and bypasses the at least one injection device; a recirculation valve that is connected to the bottom of the underground microporous irrigation pipeline and the input end of the second pressure regulator; and A recirculation pump that is connected between the recirculation valve and the second pressure regulator.

2. The irrigation system according to claim 1, further comprising a reservoir disposed in the second path and connected between the output end of the at least one injection device and the input end of the second pressure regulator.

3. A method of using the irrigation system according to claim 1, comprising the following steps: a) Supplying fluid from the pressurized water source to the underground microporous irrigation pipeline at the relatively low fluid pressure via the first pressure regulator. The fluid path through the underground microporous irrigation pipeline terminates at the recirculation valve; b) Determining plant stress conditions and selecting at least one modifier based on the plant stress conditions; c) Transferring fluid from the pressurized water source to at least one injection device instead of the first pressure regulator. Each of the at least one injection devices is associated with a corresponding one of the at least one modifiers; d) Using the at least one injection device to respectively inject the at least one modifier and combining the outputs of the at least one injection device to produce a modified irrigation fluid; e) Outputting the modified irrigation fluid to the underground microporous irrigation pipeline at the relatively high fluid pressure via the second pressure regulator; and f) Opening the recirculation valve and starting the recirculation pump. The fluid path through the underground microporous irrigation pipeline is converted into a recirculation path by this opening and starting. The recirculation path fluidly connects the second pressure regulator, the underground microporous irrigation pipeline, the recirculation valve and the recirculation pump.

4. The method according to claim 3, further comprising the following steps: g) Terminate the injection, terminate the output of the modified irrigation fluid, and connect the pressurized water source to the recirculation path using the bypass valve; h) Wait for a predetermined period of time after terminating the injection and the output of the modified irrigation fluid; and i) Close the bypass valve, close the recirculation valve, deactivate the recirculation pump, and transfer fluid from the pressurized water source to the subsurface microporous irrigation line at the relatively low fluid pressure via the first pressure regulator.

5. A method of using the irrigation system of claim 1, comprising the steps of: a) Supply fluid from the pressurized water source to the subsurface microporous irrigation line at the relatively low fluid pressure via the first pressure regulator, and the fluid path through the subsurface microporous irrigation line terminates at the recirculation valve; b) Determine plant stress conditions and select at least one amendment based on the plant stress conditions, the at least one amendment including a surfactant; c) Transfer fluid from the pressurized water source to at least one injection device instead of the first pressure regulator, each of the at least one injection devices being associated with a corresponding one of the at least one amendments; d) Inject the at least one amendment using the at least one injection device respectively, and combine the outputs of the at least one injection devices to produce a modified irrigation fluid; e) Output the modified irrigation fluid to the subsurface microporous irrigation line at the relatively high fluid pressure via the second pressure regulator; and f) Open the recirculation valve and start the recirculation pump, and the fluid path through the subsurface microporous irrigation line is converted into a recirculation path by the opening and starting, and the recirculation path fluidly connects the second pressure regulator, the subsurface microporous irrigation line, the recirculation valve, and the recirculation pump.

6. The method of claim 5, further comprising the steps of: g) Newly inject at least one thickener using the at least one injection device, and combine the outputs of the at least one injection devices to produce a thickened irrigation fluid; h) Output the thickened irrigation fluid to the subsurface microporous irrigation line at the relatively high fluid pressure via the second pressure regulator; i) Wait for a predetermined period of time after terminating the injection and the output of the modified irrigation fluid; and j) Close the bypass valve, close the recirculation valve, deactivate the recirculation pump, and transfer fluid from the pressurized water source to the subsurface microporous irrigation line at the relatively low fluid pressure via the first pressure regulator.

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