Effect of Drying Cycles on Changes in Resistance of Soil Moisture Units
1958
Cannell, Glen H.
Several different types of electrical resistance units were tested for displacement of calibration curves using a wetting-drying regime. The experiment was carried out in a temperature-light controlled growth chamber, and was designed to simulate field conditions with respect to moisture treatments; (1) excessive-leaching, and (2) slight-leaching. A cover crop of oats was used as a means to reduce the moisture content to near the wilting percentage in each drying cycle. Growth of the crop was controlled by clipping which permitted drying periods with intervals of nearly 7 days. Changes in moisture content during the drying cycle were obtained by use of a solution balance. Block resistance readings were recorded at the time weights were taken. Statistical analyses were made at several soil suctions for the 1st, 6th, and 11th drying cycles. The differences between drying cycles were statistically significant. Analyses of variability were calculated and comparisons made between blocks of a given type and between different block types at various soil suctions. In general, variability between blocks of one type increased with soil suction. However, the increase was not always consistent between different types of blocks.
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