Adaptive irrigation of vegetation

• US 20060108439A1
• Filed: 01/10/2006
• Published: 05/25/2006
• Est. Priority Date: 07/23/2003
• Status: Active Grant

• Current Assignee: C I T Controlled Irrigation Technologies Limited
• Original Assignee: C I T Controlled Irrigation Technologies Limited
• Inventors: Zur, Benjamin
• Granted Patent: US 7,261,245 B2
• Time in Patent Office: Days
• US Class Current: 239/63
• CPC Class Codes: A01G 25/167 Control by humidity of the soil itself or of devices simulating soil or of the atmosphere; Soil humidity sensors
• CPC Class Codes: Y10T 137/189 Soil moisture sensing

Abstract

Adaptive irrigation of vegetation is achieved with a probe implanted into the soil for detecting rootage wetness needs by measuring soil impedance with contacts distributed along the probe. When a dryness threshold indicating rootage needs is met at a depth Z_BEGIN previously entered into a control logic coupled to the probe, then irrigation is started. Irrigation is stopped when a wetness front is detected at depth Zend(i) automatically provided by the control logic. The depth of arrest of the drainage front Z_final(i) descending below the depth Z_end(i) is compared with a depth Z_FINAL, also previously entered into the control logic. The depth Z_end(i) is adapted at each irrigation cycle i for the drainage front to stop at the depth Z_FINAL. The probe may be used to determine the depth Z_BEGIN where resistance drops are detected first, by measuring resistance over time.

Claims

1. A method for adaptive irrigation of vegetation including:

a control logic for operating and managing successive cycles i of irrigation, with i=i [0, 1, 2, . . . , n], for a vegetation having a maximum activity root layer, or MARL, spanning a range of soil depth,

at least one probe for insertion into the soil, each at least one probe having a length and carrying a plurality of contacts longitudinally distributed in spaced-apart parallel alignment for deriving depth-related soil impedance data under command of the control logic, the at least one probe being coupled to the control logic via an electric circuit,

a controller running the control logic and coupled to command an irrigation valve operative for starting and for stopping irrigation fluid flow to the vegetation to be irrigated,

at least one I/O device coupled to the controller and to the control logic,

a depth Z_FINAL below which a drainage front of the irrigation fluid should not descend, unless if so desired by a user, and

a depth Z_end(i), at which the flow of irrigation fluid is stopped, and which is adaptively adjusted at each irrigation cycle to converge as a drainage front towards the depth Z_FINAL, the method comprising the steps of;

selecting an irrigation-begin depth Z_BEGIN within the range of the MARL, and entering Z_BEGIN as a preset parameter into the control logic,

operating the control logic to automatically provide a dryness threshold representative of a relative soil dryness condition associated with rootage-driven fluid uptake properties of the vegetation, and

opening the irrigation valve when the dryness threshold is detected at the depth Z_BEGIN,

whereby irrigation fluid flow is started in response to wetness uptake properties of the rootage of the vegetation.

2. The method according to claim 1, wherein:

the depth Z_BEGIN, and the depth Z_FINAL which is a control objective, are both entered into the control logic via the at least one I/O device to provide rootage-property related depth values necessary for operating and for managing successive adaptive cycles of irrigation.

3. The method according to claim 1, wherein:

soil-impedance derivation is adjusted to changing soil conditions by running an impedance reset operation at least once for each irrigation cycle.

4. The method according to claim 3, wherein:

an impedance reset operation is performed immediately prior to start of irrigation fluid flow.

5. The method according to claim 1, wherein:

deriving soil dryness conditions is achieved by measurement of soil impedance between a pair of adjacent contacts at depth Z_BEGIN, and

soil-impedance derivation is kept adjusted to changing soil conditions by running an impedance reset operation after stopping irrigation fluid flow, and after a sufficient time delay directly associated with fluid uptake properties of the roots.

6. The method according to claim 5, wherein:

the time delay ranges between 5 hours and 20 hours.

7. The method according to claim 5, wherein:

the time delay lapses after 10 hours.

8. The method according to claim 1, wherein:

the irrigation-begin depth Z_BEGIN is derived by help of the probe by taking at least one soil impedance measurement between each one of the adjacent contacts distributed along the probe, at least once after the irrigation fluid flow is stopped, Z_BEGIN being detected within the MARL as a pronounced higher impedance.

9. The method according to claim 1, wherein:

the depth Z_end(i) at which the flow of irrigation fluid is stopped at the first irrigation cycle i=0 is optionally entered into the control logic via the at least one I/O device, and

the depth Z_end(i) is entered as any depth along the length of the probe, whereby a drainage front that descends below the depth of the probe for at least one irrigation cycle is an option.

10. The method according to claim 1, wherein:

the probe is built as a spike assembled out of a collection of elements selected in combination from the group of modular elements consisting of hollow contact pieces, hollow spacers, cones, and covers, each element being configured to provide solid mechanical retention support and firm fastening in longitudinal coextensive succession with an adjacent element,

the spike has at least four contact pieces, three spacers, one cone, and one cover, assembled to form one unitary rigid probe, and

the hollow contact pieces and the hollow spacers provide a coextensive and unobstructed passage interior to the spike.

22. A computer readable memory storing instructions that, when executed by a microprocessor cause the microprocessor to perform each of the method steps of claim 1.

23. A computer readable memory storing instructions that, when executed by a microprocessor cause the microprocessor to perform each of the method steps of claim 2.

24. A computer readable memory storing instructions that, when executed by a microprocessor cause the microprocessor to perform each of the method steps of claim 3.

25. A computer readable memory storing instructions that, when executed by a microprocessor cause the microprocessor to perform each of the method steps of claim 4.

26. A computer readable memory storing instructions that, when executed by a microprocessor cause the microprocessor to perform each of the method steps of claim 5.

11. A system for irrigation of vegetation configured to intimately associate supply of irrigation fluid in response to vegetation-rootage related properties and needs, by adaptively adjusting successive irrigation cycles i, with i=i [0, 1, 2, . . . , n], to converge toward a drainage fluid front arrest depth, comprising:

a control logic for operating and managing irrigation for a vegetation having a maximum activity root layer, or MARL, spanning a range of soil depth,

at least one probe for insertion into the soil, each at least one probe having a length and carrying a plurality of contacts longitudinally distributed in spaced-apart parallel alignment for deriving depth-related soil impedance data from the soil under command of the control logic, the at least one probe being coupled to the control logic via an electric circuit,

a controller running the control logic, and coupled to command an irrigation valve operative for starting and for stopping irrigation fluid flow to the vegetation to be irrigated,

at least one I/O device coupled to the controller and to the control logic,

a depth Z_FINAL below which a drainage front of the irrigation fluid should not descend, except if so desired by a user, and

a depth Z_end(i), at which the flow of irrigation fluid is stopped, and which is adaptively adjusted at each irrigation cycles to converge towards the depth Z_FINAL,

characterized by;

an irrigation-begin depth Z_BEGIN selected within the range of the MARL, and entered as a preset parameter into the control logic,

a dryness threshold automatically provided by the control logic, and representative of a relative soil dryness condition associated with rootage-driven wetness uptake properties, and

the irrigation valve being opened when the dryness threshold is detected at the depth Z_BEGIN,

whereby irrigation fluid flow is started in response to wetness uptake properties and needs of the roots of the vegetation.

12. The system according to claim 11, wherein:

the depth Z_BEGIN, and the depth Z_FINAL which is a control objective, are both entered into the control logic via the at least one I/O device, as two vegetation-related rootage property values necessary for operating and managing successive cycles of adaptive irrigation.

13. The system according to claim 11, wherein:

soil-impedance derivation is adjusted to changing soil conditions by running an impedance reset operation at least once for each irrigation cycle.

14. The system according to claim 13, wherein:

an impedance reset operation is performed just before starting irrigation fluid flow.

15. The system according to claim 11, wherein:

soil dryness conditions are derived by measurement of soil impedance between a pair of adjacent contacts at depth Z_BEGIN, and

soil-impedance derivation is adjusted relatively to changing soil conditions by running an impedance reset operation after stopping irrigation fluid flow, and after a lapse of a delay sufficient for and directly associated with fluid absorption properties of the roots of the vegetation.

16. The system according to claim 15, wherein:

the time delay ranges between 5 hours and 20 hours.

17. The system according to claim 15, wherein:

the time delay lapses after 10 hours.

18. The system according to claim 11, wherein:

the irrigation-begin depth Z_BEGIN is obtained via the probe by sampling at least one impedance measurement for each one of the successive pairs of contacts distributed along the probe, at least once after the irrigation fluid flow is stopped, the depth Z_BEGIN being distinguished within the range of the MARL as a distinctive higher impedance.

19. The system according to claim 11, wherein:

the depth Z_end(i) at which the flow of irrigation fluid is stopped at the first irrigation cycle i=0 is optionally entered into the control logic via the at least one I/O device as any depth along the length of the probe,

whereby a drainage front that descends below the depth of the probe for at least one irrigation cycle is an option.

20. The system according to claim 11, wherein:

the probe is built as a spike assembled out of a collection of elements selected in combination from the group of modular elements consisting of hollow contact pieces, hollow spacers, cones, and covers, each element being configured to provide solid mechanical retention support and firm fastening in longitudinal coextensive succession with an adjacent element,

the spike has at least four contact pieces, three spacers, one cone, and one cover, assembled to form one unitary rigid probe, and

the plurality of hollow contact pieces and of hollow spacers provide a coextensive and unobstructed passage interior to the spike.

21. The system according to claim 11, wherein:

the depth Z_BEGIN and a depth Z_FINAL are entered into the control logic via the at least one I/O device, as two rootage-property related depth values necessary for operation of adaptive irrigation, and

the depth Z_end(i) is adaptively adjusted by the control logic, at each irrigation cycle, for the irrigation fluid flow to stop at the depth Z_FINAL.