05033397 is referenced by 86 patents and cites 6 patents.

A real time soil chemical sensor and precision agricultural chemical delivery system includes a plurality of ground-engaging tools in association with individual soil sensors which measure soil chemical levels. The system includes the addition of a solvent which rapidly saturates the soil/tool interface to form a conductive solution of chemicals leached from the soil. A multivalent electrode, positioned within a multivalent frame of the ground-engaging tool, applies a voltage or impresses a current between the electrode and the tool frame. A real-time soil chemical sensor and controller senses the electrochemical reaction resulting from the application of the voltage or current to the leachate, measures it by resistivity methods, and compares it against pre-set resistivity levels for substances leached by the solvent. Still greater precision is obtained by calibrating for the secondary current impressed through solvent-less soil. The appropriate concentration is then found and the servo-controlled delivery system applies the appropriate amount of fertilizer or agricultural chemicals substantially in the location from which the soil measurement was taken.

Title
Soil chemical sensor and precision agricultural chemical delivery system and method
Application Number
7/562210
Publication Number
5033397
Application Date
July 31, 1990
Publication Date
July 23, 1991
Inventor
John W Colburn Jr
Houston
TX, US
Agent
D Arlon Groves
Assignee
Aguila Corporation
TX, US
IPC
A01C 23/00
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