Abstract This invention relates to an electrical resistivity method for testing the moisture content of soil. The electrical resistivity of the soil is sensed by a novel soil moisture sensor having two electrodes in direct contact with the soil under test. This combination of sensor and associated soil become a variable resistive component of an electronic network; whose output is used to energize either a meter for quantitative measurements or a miniature lite bulb for qualitative monitoring. The soil moisture sensor features a floating/breathing electrode to compensate for the adverse effects of unpredictable variations in contact pressure between the sensor electrodes and associated soil. The electrical circuitry features: a means for depolarizing sensor electrodes, a means for assuring against electrical ground loops, a novel solid state circuit for translating soil moisture into the light intensity of a miniature lite bulb.
In a system for determining the moisture content of soil wherein a soil moisture sensor is an electrical resistive component and where said sensor has a pair of spaced external electrodes in direct contact with the soil, a springlike means for maintaining a constant pressure relationship between each said electrode and the associated soil; said springlike means being a coherent assembly comprising each of said electrode, rubberlike matter and non-electrical conducting tubing; each said electrode being a flexible electrical conducting strip mounted in an annular arrangement on said tube; said mounting being so effected that there is an acute angled opening between each said electrode and said tube into which opening is wedged said rubberlike matter and so constituting the said springlike means.
Claim 2
Dependent Claim
123 words
In a system for determining the moisture content of soil wherein a soil moisture sensor is an electrical resistive component and where said sensor has a pair of spaced external electrodes in direct contact with the soil, a springlike means for maintaining a constant pressure relationship between each said electrode and the associated soil; said springlike means being a coherent assembly comprising each of said electrode, rubberlike matter and non-electrical conducting tubing; each said electrode being a flexible electrical conducting strip mounted in an annular arrangement on said tube; said mounting being so effected that there is an acute angled opening between each said electrode and said tube into which opening is wedged said rubberlike matter and so constituting the said springlike means.
Claim 3
Dependent Claim
62 words
In a soil moisture sensing system employing electrical resistivity principles and having a plurality of soil moisture sensors, a means for preventing electrical ground loops between said sensors; said means being effected by electrically isolating each electrode pair of each sensor from any other sensor electrode pair of said system; said electrical isolation being effected by the use of double-pole, multi-throw switching.
Claim 4
Dependent Claim
62 words
In a soil moisture sensing system employing electrical resistivity principles and having a plurality of soil moisture sensors, a means for preventing electrical ground loops between said sensors; said means being effected by electrically isolating each electrode pair of each sensor from any other sensor electrode pair of said system; said electrical isolation being effected by the use of double-pole, multi-throw switching.