Abstract: A soil tester is disclosed, and comprises a housing and a sampling apparatus. The housing includes an interior sampling chamber configured to receive a sample container. The sampling apparatus comprises a photodetector and a light source. The photodetector is mounted along a portion of the interior sampling chamber and has a variable resistance determined by a property of incident light. The light source is mounted to the interior sampling chamber in a transmissive orientation relative to the photodetector so that a beam of light can be transmitted from the light source to the photodetector through the interior sampling chamber. A display on the housing is responsive to the photodetector.

Abstract: The tools and methods disclosed herein can convert an analog signal from the soil sensor probes into a digital format that can be read by a low cost digital microcontroller which acts on the digital data with formulae and tables so that the displayed information is the same or nearly the same as the readings in the same soil from the analog meters. To provide accurate readings, the described tools can apply either of a fixed or floating calibration method to set a reference of the measured soil pH and moisture measure. The floating calibration method also permits adjustment of the measure reference to correct calibration imprecision induced by fluctuation in the battery voltage.

Abstract: A soil tester is disclosed, and comprises a housing and a sampling apparatus. The housing includes an interior sampling chamber configured to receive a sample container. The sampling apparatus comprises a photodetector and a light source. The photodetector is mounted along a portion of the interior sampling chamber and has a variable resistance determined by a property of incident light. The light source is mounted to the interior sampling chamber in a transmissive orientation relative to the photodetector so that a beam of light can be transmitted from the light source to the photodetector through the interior sampling chamber. A display on the housing is responsive to the photodetector.

Abstract: The tools and methods disclosed herein can convert an analog signal from the soil sensor probes into a digital format that can be read by a low cost digital microcontroller which acts on the digital data with formulae and tables so that the displayed information is the same or nearly the same as the readings in the same soil from the analog meters. To provide accurate readings, the described tools can apply either of a fixed or floating calibration method to set a reference of the measured soil pH and moisture measure. The floating calibration method also permits adjustment of the measure reference to correct calibration imprecision induced by fluctuation in the battery voltage.