GB2225520A - Control of irrigation water supply - Google Patents

Control of irrigation water supply Download PDF

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Publication number
GB2225520A
GB2225520A GB8828195A GB8828195A GB2225520A GB 2225520 A GB2225520 A GB 2225520A GB 8828195 A GB8828195 A GB 8828195A GB 8828195 A GB8828195 A GB 8828195A GB 2225520 A GB2225520 A GB 2225520A
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United Kingdom
Prior art keywords
water
growth medium
plant growth
valve
humidity
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB8828195A
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GB8828195D0 (en
Inventor
Colin Draper
Original Assignee
Colin Draper
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Colin Draper filed Critical Colin Draper
Priority to GB8828195A priority Critical patent/GB2225520A/en
Publication of GB8828195D0 publication Critical patent/GB8828195D0/en
Publication of GB2225520A publication Critical patent/GB2225520A/en
Withdrawn legal-status Critical Current

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Classifications

    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01GHORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G25/00Watering gardens, fields, sports grounds or the like
    • A01G25/16Control of watering
    • A01G25/167Control by humidity of the soil itself or of devices simulating soil or of the atmosphere; Soil humidity sensors
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/121Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid for determining moisture content, e.g. humidity, of the fluid

Abstract

Apparatus for the control of irrigation water supply to one or more units of plant growth medium, such as trays or beds 15, 16 includes a sensor 17, 18 in each unit, including an element the conductivity of which varies with the humidity of its environment. Mains voltage is applied via a step-down transformer 20 and rectifier 19 across the sensors and the sensor output applied to two voltmeters 22, 23 and to a comparator 24 which triggers a switch 25 to operate a valve 12 when the outputs indicate that humidity has fallen below a predetermined threshold value in both units. Valve 12 allows the water held in a cistern 10 to be fed via sprinklers 13, 14 to the beds 15, 16. The cistern is refilled through a float-controlled valve 11 and provides a predetermined volume of irrigation water. <IMAGE>

Description

Control of Irrigation Water Supply This invention relates to the control of the supply of irrigation water to a plant growth medium.
Plants in greenhouses, under frames, or in conservatories or other protected environments usually have to be watered artificially as they are not exposed to natural rainfall. Generally speaking small beds, pots and'Growth Bags' are watered by hand, while commercial greenhouses garden centres and the like may be watered by sprinklers or d drip feeds or merely by hosepipes. Usually such watering is done either at the whim of the gardener, when judged to be necessary, or when remembered! On a larger scale watering may be under the control of a time switch which turns the flow on for a predetermined period after a preset interval, according to a rigid timetable.
Both approaches can lead to under-watering, which causes stunted growth, low crop or flower yields* and a dessicated plant which may include dead or dying shoots and leaves or complete death of the plant; or to overwatering which 'dawns' the plant, impeding the flow of air to the roots, causing death and decay of roots and lower and encouraging fungi and parasites. This also may cause the death of the whole plant and is at least detrimental.
The ideal is for the rate of water supply to balance the depletion of water from the soil which depends upon drainage through the soil, evaporation from the top of the soil, and the take up of water by the plant which is in turn determined by the stage of development of the plant.
growth and fruit formation increase demands as water is taken into the tissues, and the rate of transpiration, which like evaporation from the soil varies from hour to hour and day to,day with the local atmospheric temperature and humidity.
An object of this invention is to provide apparatus for the controlled supply of irrigation water to growing plants which supplies water only when objectively required and does so automatically.
The invention accordingly provides means for controlling the supply of irrigation water to a plant growth medium comprising detector means for sensing the humidity of the medium and water supply means for supplying a predetermined volume of water to the medium when the humidity of the medium falls below a threshold value.
The detector means may include electrical terminals or a sensor element buried in the plant growth medium and connected to a source of electric current,and electrical measuring means to measure the electrical conductivity of the element as a measure of the moisture content of the medium, and the water supply means may have a valve operable by a device triggered by the measuring means on reaching the threshold value.
The predetermined quantity of water may be assessed as the flow in a given time through a valve, or stored in a cistern for release by opening of the valve, the cistern then refilling through a float-operated valve which closes when the cistern is full again. The water may be supplied to the plant growth medium by means of sprinklers, perforated tubes, drip feed devices etc.
The plant growth medium may be soil, or an artificially blended mixture of peat, humus, nutrients and other material, including potting mixtures and so-called 'Grow Bags'. The water may if desired contain nutrients, hormones etc. in suspension or solution.
The detector means are implanted in the growing medium and may incorporate an element the conductivity of which varies with the moisture content of its environment. An input may be applied may be applied across the element in the form conveniently of A/C current at 50Hz, stepped down to 15 volts from mains and rectified. The voltage is mortified by changes in the conductivity of the element, and these can be measured to give a measure of the humidity of the plant growth medium. A voltmeter means may be used to trigger a valve operating switch when the measured humidity of one ormore units of plant growth medium has reached a threshold value.
The units of plant growth medium may be beds, or parts of beds in commercial greenhouses, or any unit down to individual pots or growing bags.
A preferred embodiment of apparatus according to the invention will now be described by way of example, with reference to the accompanying drawing which is a diagram illustrating the apparatus according to the invention.
As shown diagramatically, irrigation water is stored in a cistern or reservoir 10, to which it is admitted by a float controlled valve 11. Outflow of water from the reservoir 10 is controlled by a valve 12 to flow to sprinkler branches 13, 14 which are disposed over plant growing troughs 15, 16.
The troughs each contain a plant growth medium with fruiting or flowering plants for example growing therein. The plant growth medium is optimised for the species of plant being grown, and may be a blend of suitable materials e.g. natural soil, sand, humus, organic and inorganic fertilisers etc. as required.
A humidity sensor 17 is buried in the medium in trough 15, and another humidity sensor 18 in trough 16. The input side of each sensor is connected via a rectifier 19 and step-down transformer 20 to a mains electrical supply 21.
The output side of each sensor is connected to a respective voltmeter 22, 23 and a comparator 24, which is arranged to trigger a switch 25 in the power circuit of a solenoid which operates valve 12.
In use, the conductivity of the sensors 17, 18 reduces as the moisture content of the medium in the respective troughs reduces due to take up and transpiration by the plants, and evaporation from the medium, until a minimum is reached. When both sensors reach the preset minimum conductivity, the comparator 24 triggers the switch 25 (e.g. by de-energising a holding coil which holds the switch open) thereby completing the circuit to the solenoid of valve 12 to operate the valve. The valve 12 is opened and water fed to the sprinkler branches 13, 14. A predetermined quantity of water may be supplied by latching the valve open for a preset period by a timer switch (not shown), or valve 12 may remain open until the reservoir is emptied, the capacity of the reservoir being the predetermined quantity.
After closure of the valve 12, the reservoir 10 refills through the float controlled valve 11.
In the described embodiment, the valve 12 will only release water when both the troughs 15 and 16 are sensed as being dry, that is the conductivity of both sensors 17, 18 has fallen below the threshold value, as determined by the comparator 24. However it is possible within the scope of the invention to allow flow to each trough or bed individually or to 'gang' a larger number of troughs or beds, for example all those in a commercial greenhouse. The troughs comprise units of plantgrowth medium, and alternative units may be beds or parts of beds, individual pots, or growth bags.
Nutrients fertilisers and/or hormones may be added to the water supply as deemed appropriate.
The apparatus of the invention is applicable to any scale of cultivation, and while sprinklers are described for watering the units, other means such as drip feeds may be used.
The electrical components may be varied as required, and may be as simple as indicated, or be complex enough to justify control by a pre-programmed micro-processer. -J

Claims (10)

  1. Claims 1. Irrigation supply apparatus, comprising detector means for sensing the humidity of a plant growth medium, and water supply means for supplying a predetermined volume of water to the plant growth medium when the humidity of the medium falls below a threshold value.
  2. 2. Apparatus according to Claim 1 including means for comparing an output from the detector means with a preset value, to determine when the output indicates-that the humidity of the medium has fallen below said threshold value.
  3. 3. Apparatus according to Claim 1 or 2 wherein the detector means includes a sensor element buried in the plant growth medium and connected to a source of electric current, and electrical measuring means to measure the output of the sensor element as a measure of the moisture content of the plant growth medium.
  4. 4. Apparatus according to Claim 2 wherein the water - supply means has a valve operable by a device which is triggered by the measuring means on the output of the sensor element falling below the preset value.
  5. 5. Apparatus according to Claim 4 wherein the water is supplied in a predetermined quantity stored in a cistern for release by opening of said valve, refilling of the cistern being through a float-operated valve which closes when the refilling is complete.
  6. 6. Apparatus according to Claim 4 or 5 wherein the water is supplied to the growth medium by means of sprinkler
  7. 7. Apparatus according to Claim 4 or 5 wherein the water is supplied to the growth medium by means of perforated tubes.
  8. 8. Apparatus according to Claim 4 or 5 wherein the water is supplied by means of a drip feed device.
  9. 9. Apparatus according to Claim 1 or 2 wherein the detector means are implanted in the growing medium and each incorporate an element the conductivity of which varies with the moisture content of its environment, an input being applied across the element in the form of a/c-current at 50Hz.
    stepped down to 15 volts from mains and rectified, voltmeter means and a comparator being used to trigger a valve operating switch when the measured conductivity of the elements in one or more units of plant growth medium indicate that the humidity thereof has reached a threshold value, to allow the predetermined volume of water to be fed to the unit or units of plant growth medium.
  10. 10. Irrigation water supply apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.
GB8828195A 1988-12-02 1988-12-02 Control of irrigation water supply Withdrawn GB2225520A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8828195A GB2225520A (en) 1988-12-02 1988-12-02 Control of irrigation water supply

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8828195A GB2225520A (en) 1988-12-02 1988-12-02 Control of irrigation water supply

Publications (2)

Publication Number Publication Date
GB8828195D0 GB8828195D0 (en) 1989-01-05
GB2225520A true GB2225520A (en) 1990-06-06

Family

ID=10647868

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8828195A Withdrawn GB2225520A (en) 1988-12-02 1988-12-02 Control of irrigation water supply

Country Status (1)

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GB (1) GB2225520A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105409724A (en) * 2015-12-31 2016-03-23 江苏汇智知识产权服务有限公司 Intelligent drip irrigation system
WO2017124525A1 (en) * 2016-01-24 2017-07-27 罗剑锋 Method for automatically watering flowers according to soil humidity threshold, and sprinkler

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3553481A (en) * 1968-07-24 1971-01-05 Harold W Hasenbeck Automatic soil watering system
GB1320053A (en) * 1970-04-28 1973-06-13 Caltogirone N Apparatus for moistening a mass of soil
US3777976A (en) * 1973-03-29 1973-12-11 S Milovancevic Electronically controlled watering
GB2017868A (en) * 1977-09-02 1979-10-10 Beckmann G Irrigation valve device
US4197866A (en) * 1977-09-19 1980-04-15 Neal Jerry D Soil moisture sampler and controller
US4216789A (en) * 1977-01-17 1980-08-12 Hasenbeck Harold W Conduction type soil matric potential sensor
US4256133A (en) * 1977-08-22 1981-03-17 Coward Noel D Watering valve device
US4657039A (en) * 1984-08-30 1987-04-14 Ranya L. Alexander Moisture sensor
US4693419A (en) * 1981-11-02 1987-09-15 Water Sentry, Inc. Automatic control apparatus and method for sprinkling water over a predetermined area
US4718446A (en) * 1986-04-15 1988-01-12 Simpson Bobby R Time and moisture-responsive sprinkler control system

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3553481A (en) * 1968-07-24 1971-01-05 Harold W Hasenbeck Automatic soil watering system
GB1320053A (en) * 1970-04-28 1973-06-13 Caltogirone N Apparatus for moistening a mass of soil
US3777976A (en) * 1973-03-29 1973-12-11 S Milovancevic Electronically controlled watering
US4216789A (en) * 1977-01-17 1980-08-12 Hasenbeck Harold W Conduction type soil matric potential sensor
US4256133A (en) * 1977-08-22 1981-03-17 Coward Noel D Watering valve device
GB2017868A (en) * 1977-09-02 1979-10-10 Beckmann G Irrigation valve device
US4197866A (en) * 1977-09-19 1980-04-15 Neal Jerry D Soil moisture sampler and controller
US4693419A (en) * 1981-11-02 1987-09-15 Water Sentry, Inc. Automatic control apparatus and method for sprinkling water over a predetermined area
US4657039A (en) * 1984-08-30 1987-04-14 Ranya L. Alexander Moisture sensor
US4718446A (en) * 1986-04-15 1988-01-12 Simpson Bobby R Time and moisture-responsive sprinkler control system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105409724A (en) * 2015-12-31 2016-03-23 江苏汇智知识产权服务有限公司 Intelligent drip irrigation system
WO2017124525A1 (en) * 2016-01-24 2017-07-27 罗剑锋 Method for automatically watering flowers according to soil humidity threshold, and sprinkler

Also Published As

Publication number Publication date
GB8828195D0 (en) 1989-01-05

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