Method and device for monitoring of moisture in soil

A device for monitoring moisture content of soil, comprising:

• a timing capacitor having an electrical potential and comprising a plurality of conductive elements operable upon insertion into the soil to sense the hydration state capacitance of said soil;
• a capacitance-to-frequency converter electrically connected to said timing capacitor and comprising an oscillator circuit having a frequency dependent upon the value of said timing capacitor and independent electrical losses in said timing capacitor;
• means for supplying electrical power to said capacitance-to-frequency converter;
• means for measuring the frequency generated by said capacitance-to-frequency converter, said frequency bearing a known relationship to the dielectric constant and, hence, the moisture content of said soil;
• and
• means for electrically guarding said conductive elements from capacitance extraneous to said soil comprising means for surrounding said conductive elements with shields of electrical potential substantially equal to that of said timing capacitor.