Patent Description:
Various systems and methods for plant irrigation and fertigation are known. Irrigation refers to controlled delivery of water; fertigation generally means the injection of fertilizer or other amendment into an irrigation system. As used herein, irrigation may include fertigation.

Various stress conditions are known to damage plants and reduce crop yields. Many irrigation systems and methods fail to adequately compensate for such stresses. Moreover, known methods that merely alter an irrigation schedule in response to perceived stress, for example by increasing an irrigation duration in an above-ground sprinkler system, are not generally effective in sub-surface drip irrigation (SDI) systems. Improved stress-adaptive irrigation systems and methods are needed.

<CIT> proposes an irrigation system, <CIT> discloses a hybrid irrigation tubing, and <CIT> discusses a delivery tube for irrigation.

In one aspect of the present invention there is provided an irrigation system in accordance with claim <NUM>. Further aspects and preferred embodiments are set out in claim <NUM> et seq. Embodiments of the invention are directed to a sub-surface irrigation system configured to operate in a plant-responsive mode, and further configured to make certain adaptations in response to plant stress. Stress adaptations may include, for example, selectively increasing source pressure of irrigation fluid, heating or chilling the irrigation fluid, and/or injecting fertilizer and/or non-fertilizer amendments into the irrigation fluid.

Embodiments of the invention are described below with reference to the drawings. Such embodiments are meant to be illustrative and not restrictive. Certain features illustrated in the drawings may be exaggerated in size, and other features may be omitted altogether, for clarity.

The following sections begin with a review of some environmental factors that can be monitored in an effort to assess environmental stress. The description below begins with an overview of plant stress. This document then describes an irrigation method (with reference to <FIG>), exemplary microporous irrigation tubing (with reference to <FIG>), exemplary irrigation systems (with reference to <FIG>), and methods for using such systems (with reference to <FIG>, <FIG>, <FIG>, and <FIG>).

Section titles are used below for organizational convenience. The description of any claimed feature is not necessarily limited to any section of this specification.

Plant stressors result from non-ideal growth conditions that increase the demands on the plant. Abiotic stressors (environmental stressors) are naturally occurring, inanimate factors such as: intense sunlight, high winds, extreme temperatures (hot or cold), drought, flooding, herbicides, pesticides, and poor soil conditions, for example, salinity, acidity, lack of nutrients (macro and micro), and heavy metals. Lesser-known abiotic stressors generally occur on a smaller scale. They include: poor edaphic conditions like rock content and pH levels, high radiation, compaction, and contamination. Any of these stressors can negatively influence plant development and crop productivity. Abiotic stress is considered the most harmful factor concerning the growth and productivity of crops. Abiotic stressors are most harmful when they occur together, in combinations of abiotic stress factors, such as arid, desert climates.

Biotic stressors include living disturbances such as fungi, bacteria, insects, and weeds. Viruses also cause biotic stress to plants. Fungi cause more diseases in plants than any other biotic stress factor. Microorganisms can cause plant wilt, leaf spots, root rot, or seed damage. Insects can cause severe physical damage to plants. Insects can also spread viruses and bacteria from infected plants to healthy plants. Weeds inhibit the growth of desirable plants by competing for space and nutrients.

A plant's first line of defense against abiotic and biotic stress is in its roots. If the soil holding the plant provides sufficient water and nutrients in response to plant needs, and is otherwise healthy and biologically diverse, the plant will have a higher chance of surviving stressful conditions above ground. Embodiments of the invention monitor plant stressors and provide an appropriate intervention at the rhizosphere to minimize a variety of plant stressors.

<FIG> is a flow diagram of a method for irrigation. As shown therein, the process begins in step <NUM> by performing sub-surface irrigation via microporous tubing treated with a hydrophilic polymer in a root-responsive mode, the root-responsive mode characterized by a relatively low supply pressure (to the tubing) and a closed- end fluid path. Such an irrigation mode is extremely water-efficient, and is the preferred irrigation mode when plants are not under stress.

The process then determines a plant stress condition in step <NUM>. Step <NUM> may be performed for instance, by comparing sensor data to predetermined threshold, by visual inspection, and/or by performing plant tissue or soil analysis. For example, readings from ambient temperature and/or ground temperature sensors can be compared to predetermined threshold values to determine that an elevated temperature condition exists. Likewise, wind speed data from an anemometer can be compared to predetermined thresholds. Temperature and wind data are preferably integrated over time to model transpiration effects more precisely. As a further example of step <NUM>, visual inspection, whether performed or aided by humans, local imaging sensors, or overhead assets, can reveal leaf discoloration, plant wilting, lodging (displacement of stems or roots), disease, pest infestation, the presence of weeds, or other evidence of present or emerging plant stressors. Data from subsurface salinity sensors can be compared to a known salt tolerance level for a given plant type. Soil analysis can reveal, for instance, a lack of beneficial microbes in the oil, or the presence of harmful fungi.

In step <NUM>, the process selects a system-delivered treatment based on the plant stress condition, the system-delivered treatment including a relatively high supply pressure and a recirculating fluid path. In the case of temperature-related stress, for example, the selected system-delivered treatment may include chilling or heating the irrigation fluid, and may also include adding a surfactant to the irrigation fluid. For wind stress not accompanied by temperature extremes, the process may select the relatively high supply pressure and the recirculating path alone. When the plant stress condition was determined in step <NUM> to be a soil condition and/or a mineral imbalance the process may select an agrochemical additive to amend the irrigation fluid to correct the soil deficit or problem in step <NUM>. Likewise, where biotic stressors are determined to be present, the process may select, for instance, from one or more biological amendments, root/soil activators, organic additive, or pesticides.

The relatively high supply pressure (preferred in all treatment cases), and surfactant (when added), will tend to increase the emission rate of irrigation fluid from the tubing to the root sone. The recirculation path (also preferred in all treatment cases) will facilitate a more homogeneous delivery (in terms of temperature and amendment concentration) of the irrigation fluid along the functional length of the subsurface tubing.

The process performs the (above-described) system-delivered treatment in step <NUM>, and determines when to terminate the system-delivered treatment in step <NUM>. System-delivered treatment is intended to be temporary. The determination in step <NUM> could be based on a predetermined duration (for example, based on treatment type), on a calculated duration (for instance, based on a severity of determined stressor(s)), or based on evidence of reduced stress (e.g., improvements in data, observations, or analysis relied upon in step <NUM>).

As indicated by conditional step <NUM>, if the system-delivered treatment included a fluid amendment, then the process advances to step <NUM>; otherwise the process returns directly to step <NUM>. Clearing step <NUM> preferably includes supplying the irrigation fluid at the relatively high supply pressure, and using the recirculation fluid path, but without addition of amendments. One exception is that where the system-delivered treatment included amendment with a surfactant, clearing step <NUM> preferably includes amendment with a thickening agent to counteract the effects of the surfactant on fluid emission.

<FIG> are each an assembly view of a delivery tube, illustrated in cross-section. As shown in <FIG>, a microporous membrane <NUM> is welded along regions <NUM> to a backer <NUM> to form an irrigation tube having a lumen <NUM>. The embodiments illustrated in <FIG> each provide an irrigation tube without a backer <NUM>. Instead, in these examples, a microporous membrane <NUM> is wrapped upon itself to form an irrigation delivery tube having a lumen <NUM>. The embodiment in <FIG> includes a flat seam weld <NUM> with a bead <NUM>; the embodiment in <FIG> includes a fin weld <NUM>.

The microporous membrane <NUM>, <NUM>, may be, for instance, manufactured from polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET, a/k/a polyester) or other suitable material. As an example, the microporous membrane <NUM>, <NUM>, may be DuPont Tyvek™ or other non-woven or spun-bonded fabric. Preferably, the microporous membrane <NUM>, <NUM>, is treated (entirely or selectively) with a hydrophilic polymer to enhance responsiveness to root exudate.

For the tubing embodiment in <FIG>, the backer <NUM> is preferably a less expensive material than the microporous membrane <NUM>. The backer <NUM> is also preferably much less porous (i.e., effectively non-porous) compared to the microporous membrane <NUM>. For thermal compatibility, where the microporous membrane <NUM> is PE, the backer <NUM> is preferably also manufactured from PE; where the microporous membrane <NUM> is PP, the backer <NUM> is preferably PP; and where the microporous membrane is <NUM> is PET, the backer <NUM> may be PET. The surface area of the microporous membrane <NUM> and the surface area of the backer <NUM> need not be equal for any given length of tubing.

Other microporous irrigation tubing configurations and weld types are possible, and could also be used in combination with one or more stress-adaptative systems and methods disclosed herein. Moreover, some features or embodiments may be equally applicable to surface and sub-surface applications of microporous irrigation tubing.

Exemplary systems for performing the above method, and variants thereof, are described below with reference to <FIG>.

<FIG> is a schematic diagram of an irrigation and fertilization system. The embodiment illustrated in <FIG> might be applicable, for instance, to a large commercial farming operation. As shown therein, a supply system <NUM> feeds a header pipe <NUM> that is coupled to multiple sub-surface microporous irrigation delivery tubes <NUM>. Multiple plants <NUM> have roots <NUM> within a functional distance of delivery tubes <NUM>. The delivery tubes <NUM> could be constructed, for example, as described above with reference to <FIG>.

The supply system <NUM> includes a reservoir (RES) <NUM> coupled to receive fluid from well pump (W) <NUM>, city water connection (CW) <NUM>, and recirculation pump (RE) <NUM>. Each of these reservoir <NUM> inputs could be coupled via a valve (not shown). In the illustrated embodiment, the reservoir <NUM> includes a heater (HT) <NUM>. Valves <NUM>, <NUM> are coupled to outputs of the reservoir <NUM>. An in-line chiller (CH) <NUM> is coupled to an output of valve <NUM>.

Suitable recirculation pumps <NUM> are manufactured, for instance, by Blue Torrent Pool Products, Floject, Flotec, and other suppliers, according to application requirements. The heater <NUM> could be, for example, a glass-encased electric heating element, although geo-thermal or other heating modalities could also be applied according to design choice. The in-line chiller <NUM> could be or include, for instance, a TropiCool®, Heatwave, GBB (Great Big Bopper by AquaCal), or other water-source heat pump.

In the supply system <NUM>, the reservoir <NUM> output is further coupled to filters (F) <NUM>, and also coupled to tanks (T) <NUM>, <NUM>, <NUM>, and <NUM> and to pressure regulator <NUM>. Any of the tanks <NUM>, <NUM>, <NUM>, <NUM> could include a pump (not shown).

The pressure regulator <NUM> is preferably configured to output a relatively low-pressure fluid flow from the supply system <NUM> to the header pipe <NUM>, for instance for a setting within the range of <NUM>,<NUM> - <NUM>,<NUM> bar (<NUM> - <NUM> PSI), for compatibility with the microporous delivery tubes <NUM>. An exemplary regulator <NUM> is the Model <NUM> diaphragm regulator manufactured by Ziggity Systems, Inc. The desired pressure setting for such an adjustable pressure regulator may vary accordingly to properties of the delivery tubes <NUM>. In alternative embodiments, other pressure settings and/or other regulators <NUM> could be used.

In operation, the reservoir <NUM> is selectively supplied by well pump <NUM>, city water connection <NUM>, and/or recirculation pump <NUM>. Fluid is selectively heated in the reservoir <NUM> via heater <NUM>; fluid is selectively cooled at an output of the reservoir <NUM> using in-line chiller <NUM> via operation of valves <NUM>, <NUM>. In some modes of operation, fluid in supply system <NUM> is not heated or chilled. Flow through filters <NUM> may also be selective (for instance via additional valves, not shown) according to fluid amendment and recirculation status. Generally, each tank <NUM>, <NUM>, <NUM>, and <NUM> could contain a unique type of fluid amendment. For example, tank <NUM> could contain a fertilizer, tank <NUM> could contain a surfactant, tank <NUM> could contain a thickening agent, and tank <NUM> could contain particulate for a suspended load. Contents (or a portion) of each tank <NUM>, <NUM>, <NUM> and <NUM> can be selectively added to irrigation fluid in the supply system <NUM>, alone or in any combination, via operation of a corresponding valve <NUM>. Regulator <NUM> controls a supply pressure of irrigation fluid to header pipe <NUM> and delivery tubes <NUM>. During selective recirculation (i.e., according to status of the recirculation pump <NUM>), irrigation fluid is returned to the supply system <NUM> via recirculation path <NUM>.

The supply system <NUM> may be operated in alternative modes. For instance, in a normal low-pressure plant-responsive mode, the heater <NUM> and chiller <NUM> may be inactive, valve <NUM> may be open, valves <NUM> and <NUM> may be closed, the regulator <NUM> may be adjusted for a relatively low pressure (for instance <NUM> bar (<NUM> PSI)), and the recirculation pump <NUM> could be turned off. In a treatment mode, the heater <NUM> or chiller <NUM> may be on, one or more valves <NUM> may be open, the regulator <NUM> may be set at a relatively high pressure (for instance <NUM>,<NUM> bar (<NUM> PSI)), and the recirculation pump <NUM> may be on.

Variations to the system illustrated in <FIG> and described above are possible. For instance, some embodiments do not require well pump <NUM>, city water connection <NUM>, or recirculation pump <NUM>. In alternative embodiments, heater <NUM> could be placed in-line, external to the reservoir <NUM>. The heater <NUM> could be combined with the chiller <NUM>, for instance in a heat pump unit. The number and sequential placement of filters <NUM> and tanks <NUM>, <NUM>, <NUM>, and <NUM> could vary. In an automated or semi-automated embodiment, the supply system <NUM> could include a controller; the controller could receive signals from one or more environmental sensors, and the controller could output control signals to the recirculation pump <NUM>, heater <NUM>, in-line chiller <NUM>, valves <NUM>, <NUM>, <NUM>, and/or pressure regulator <NUM>.

<FIG> is a schematic diagram of an irrigation system. As shown therein, a supply system <NUM> feeds a header pipe <NUM> that is coupled to multiple sub-surface microporous irrigation delivery tubes <NUM>. Multiple plants <NUM> have roots <NUM> within a functional distance of delivery tubes <NUM>. The delivery tubes <NUM> could be constructed, for example, as described above with reference to <FIG>. Each of the delivery tubes is fluidically coupled to the footer <NUM>. Sensors <NUM> could be or include, for example, in-ground temperature and/or salinity sensors.

Supply system <NUM> is configured so that a pressurized water source (W/S) <NUM> can be serially coupled to a diverter <NUM>, a first pressure regulator <NUM> (which is set for a relatively low pressure output, for instance <NUM>,<NUM> bar (<NUM> PSI)), a diverter <NUM>, and the header pipe <NUM>. For some applications, RDI model APR-Z053 may be suitable for the first pressure regulator <NUM>.

Diverter <NUM> is also coupled to multiple injector valves <NUM> and bypass valve <NUM>. Each of the injector valves <NUM> is serially coupled to an input of a corresponding inline injector <NUM>. Inline injectors <NUM> are preferably configured for accurate addition of soluble fertilizer or other amendments. Outputs of the inline injectors <NUM> are coupled to an output of the bypass valve <NUM> and to a first input of a reservoir <NUM>. A first output of the reservoir <NUM> is serially coupled to a pump <NUM> and chiller/heater <NUM>. In alternative embodiments, the chiller/heater <NUM> could be a chiller, or a heater, instead of a combined chiller/heater. An output of the chiller/heater <NUM> is coupled to a second input of the reservoir <NUM>. A second output of the reservoir <NUM> is serially coupled to a recirculation pump <NUM>, a second pressure regulator <NUM> (which is set for a relatively high pressure output, for instance <NUM>,<NUM> bar (<NUM> PSI)) and the diverter <NUM>. For some applications, RDI model APR-M758 may be suitable for the second pressure regulator <NUM>. The footer <NUM> is serially coupled to the recirculation valve <NUM> and a third input to the reservoir <NUM>.

Controller <NUM> is an optional component, according to design choice. If included, controller <NUM> could be configured to receive data from the sensors <NUM>, and could control the operation of any one or more components illustrated as part of supply system <NUM> (with the exception of directly controlling the pressurized water source <NUM>). Recirculation pump <NUM> is also an optional component, based on application needs. Recirculation pump <NUM> may be required, for instance, if the reservoir <NUM> is disposed at a much higher elevation than the footer <NUM>.

In a normal (and most water-efficient) mode, unamended irrigation fluid can be supplied by the supply system <NUM> to the header pipe <NUM> at a relatively low pressure and with a termination point at the recirculation valve <NUM>.

In the case of system-delivered treatment in response to plant stress, the supply system <NUM> can be configured to supply irrigation fluid to the header pipe <NUM> at a relatively high pressure, with or without amendment from one or more inline injectors <NUM>, and with or without heating or cooling enabled by the chiller/heater <NUM>. Operation during system-delivered treatment preferably includes a recirculation path through an open recirculation valve <NUM>, and with the aid of recirculation pump <NUM> (and recirculation pump <NUM>, if applicable).

<FIG> is a schematic diagram of an irrigation system. The irrigation system illustrated in <FIG> is substantially similar to the irrigation system illustrated in <FIG> except for minor differences between supply system <NUM> and the supply system <NUM>. In particular, supply system <NUM> deletes the pump <NUM>, replaces reservoir <NUM> with reservoir <NUM>, and couples the chiller/heater inline. Supply system <NUM> requires that selected inline injectors <NUM> can provide sufficient flow for the selected chiller/heater <NUM>. With that caveat, the supply system <NUM> can supply the same "normal" and "system-delivered treatment" modes described above with reference to supply system <NUM>. As noted above, in alternative embodiments, the chiller/heater <NUM> could be a chiller, or a heater, instead of a combined chiller/heater.

<FIG> is a schematic diagram for the reservoir <NUM> illustrated in <FIG>. Reservoir <NUM> includes thermally-insulated walls <NUM>, three inputs <NUM>, <NUM>, <NUM>, two outputs <NUM>, <NUM>, and a drain <NUM>. Fluid <NUM> is maintained below a predetermined fill line <NUM>, for instance with aid of a float switch (not shown). With reference to <FIG>: input <NUM> may be from outputs of the inline injectors <NUM> and bypass valve <NUM>; input <NUM> may be from the chiller/heater <NUM>; and input <NUM> may be coupled to the recirculation valve <NUM>. Output <NUM> may be to the pump <NUM>, and output <NUM> may be to the recirculation pump <NUM>.

<FIG> is a schematic diagram for the reservoir <NUM> illustrated in <FIG>. Compared to reservoir <NUM>, reservoir <NUM> deletes input <NUM> and output <NUM>.

<FIG> and <FIG> are a flow diagram of a method for using the system illustrated in <FIG>, or <FIG>. Step <NUM> is supplying fluid from a pressurized water source <NUM> to subsurface microporous irrigation tubing <NUM> via a first pressure regulator <NUM> at a relatively low set pressure, the tubing <NUM> being treated with a hydrophilic polymer, a fluidic path through the tubing being terminated at a closed recirculation valve <NUM>. Step <NUM> is determining a plant stress condition and selecting at least one amendment based on the plant stress condition. Step <NUM> is diverting the fluid from the pressurized water source <NUM> to at least one injector <NUM> instead of the first pressure regulator <NUM>, each of the at least one injectors <NUM> being associated with a corresponding one of the at least one amendments. Step <NUM> is injecting each of the at least one amendments using the at least one injectors <NUM>, outputs of the at least one injectors being combined to produce an amended irrigation fluid. Step <NUM> is outputting the amended irrigation fluid to the tubing <NUM> via a second pressure regulator <NUM> at a relatively high set pressure, the relatively high set pressure being higher than the relatively low set pressure. Step <NUM> is opening the recirculation valve <NUM>, and activating at least one recirculation pump <NUM>, <NUM>, the fluidic path through the tubing being converted by the opening and the activating to a recirculation path fluidically coupling the second pressure regulator <NUM>, the tubing <NUM>, the recirculation valve <NUM>, and the at least one recirculation pump <NUM>, <NUM>. Step <NUM> is terminating the injecting, terminating the outputting of the amended irrigation fluid, and coupling the pressurized water source <NUM> to the recirculation path using a bypass valve <NUM>. Step <NUM> is waiting for a predetermined time after terminating the injecting and terminating the outputting of the amended irrigation fluid. Step <NUM> is closing the bypass valve <NUM>, closing the recirculation valve <NUM>, deactivating the at least one recirculation pump <NUM>, <NUM>, diverting the fluid from the pressurized water source <NUM> to the tubing <NUM> via the first pressure regulator <NUM> at the relatively low set pressure.

Accordingly, amendments introduced during system-delivered treatments are cleared from subsurface irrigation tubing by supplying only unamended fluid at relatively high pressure in the recirculation path for a predetermined time before returning to the relatively low-pressure and closed-ended root-responsive mode.

<FIG> and <FIG> are a flow diagram of a method for using the system illustrated in <FIG>, or <FIG>. Step <NUM> is supplying fluid from a pressurized water source <NUM> to subsurface microporous irrigation tubing <NUM> via a first pressure regulator <NUM> at a relatively low set pressure, the tubing <NUM> being treated with a hydrophilic polymer, a fluidic path through the tubing being terminated at a closed recirculation valve <NUM>. Step <NUM> is determining a plant stress condition and selecting at least one amendment based on the plant stress condition, the at least one amendment including a surfactant. Step <NUM> is diverting the fluid from the pressurized water source <NUM> to at least one injector <NUM> instead of the first pressure regulator <NUM>, each of the at least one injectors <NUM> being associated with a corresponding one of the at least one amendments. Step <NUM> is injecting each of the at least one amendments using the at least one injectors <NUM>, outputs of the at least one injectors being combined to produce an amended irrigation fluid. Step <NUM> is outputting the amended irrigation fluid to the tubing <NUM> via a second pressure regulator <NUM> at a relatively high set pressure, the relatively high set pressure being higher than the relatively low set pressure. Step <NUM> is opening the recirculation valve <NUM>, and activating at least one recirculation pump <NUM>, <NUM>, the fluidic path through the tubing being converted by the opening and the activating to a recirculation path fluidically coupling the second pressure regulator <NUM>, the tubing <NUM>, the recirculation valve <NUM>, and the at least one recirculation pump <NUM>, <NUM>. Step <NUM> is terminating the injecting of the at least one amendment, and newly injecting at least one thickening agent using the at least one injectors <NUM>, outputs of the at least one injectors being combined to produce a thickened irrigation fluid. Step <NUM> is outputting the thickened irrigation fluid to the tubing <NUM> via the second pressure regulator <NUM> at the relatively high set pressure. Step <NUM> is waiting for a predetermined time after terminating the injecting and terminating the outputting of the amended irrigation fluid. Step <NUM> is closing the bypass valve <NUM>, closing the recirculation valve <NUM>, deactivating the at least one recirculation pump <NUM>, <NUM>, diverting the fluid from the pressurized water source <NUM> to the tubing <NUM> via the first pressure regulator <NUM> at the relatively low set pressure.

Accordingly, the effects of surfactants introduced during system-delivered treatments are at least partially countered in subsurface irrigation tubing by supplying water with a thickening agent at relatively high pressure in the recirculation path for a predetermined time before returning to the relatively low-pressure and closed-ended root-responsive mode.

Claim 1:
An irrigation system comprising:
a pressurized water source (<NUM>);
subsurface microporous irrigation tubing (<NUM>), the irrigation system configured to selectively couple the pressurized water source to a header (<NUM>) of the subsurface microporous irrigation tubing via a first path, a second path, or a third path;
the first path including a first pressure regulator (<NUM>) disposed between the pressurized water source and the subsurface microporous irrigation tubing, the first pressure regulator being configured to output a relatively low fluid pressure to the header;
the second path including at least one injector (<NUM>) and a second pressure regulator (<NUM>) disposed between the pressurized water source and the subsurface microporous irrigation tubing, each of the at least one injectors configured to inject an amendment into the second path, outputs of the at least one injectors coupled to an input of the second pressure regulator, the second pressure regulator being configured to output a relatively high fluid pressure to the header, the relatively high fluid pressure being higher than the relatively low fluid pressure;
the third path including a bypass valve (<NUM>) coupling the pressurized water source to the input of the second pressure regulator and bypassing the at least one injector;
a recirculation valve (<NUM>) coupled to a footer (<NUM>) of the subsurface microporous irrigation tubing and the input of the second pressure regulator; and
a recirculation pump (<NUM>) coupled between the recirculation valve and the second pressure regulator.