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Some Tests of a Four‐Electrode Probe for Soil Moisture Measurement
Author(s) -
Kirkham Don,
Taylor G. S.
Publication year - 1950
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1950.036159950014000c0010x
Subject(s) - citation , library science , service (business) , computer science , business , marketing
Two years ago at the Cincinnati meetings of the Society, a wetness survey chart used in a soil moisture study was shown (6). The chart presented surface moisture conditions for a 160-acre farm. Four degrees of wetness were represented: wet, very wet, oozy, surface water. The degrees of wetness were not quantitative; they were determined merely by visual inspection and the feel of the soil. It was recognized that an instrument which could give rapid quantitative measurements of soil moisture was needed. Some type of probe was visualized. The present paper gives the theory and describes some tests of a rapid-reading soil moisture probe. Actually the probe in question does not measure soil moisture, but measures the specific electrical conductivity of the soil. However,* since the electrical conductivity of the soil is related to its moisture content, the instrument upon calibration should give a measure of soil moisture. The nylon soil moisture element of Bouyoucos (1) and the fibre glass element of Coleman (2) both utilize the fact that the electrical conductivity of a moisture element is a function of moisture content. The element in our case is the soil itself. An advantage of the probe is that, unlike most soil moisture measuring devices, no waiting time is required for the sensing element to come to equilibrium. The four-electrode method described here is not to be confused with a four-electrode method described by McCorkle (8) and by Edlefsen and Anderson (4).