FIELD STUDY OF RESPONSE OF THE ELECTRICAL RESISTANCE OF 2− AND 4-ELECTRODE PLASTER OF PARIS BLOCKS TO VARIATIONS IN SOIL MOISTURE

Abstract

This paper is a further report upon the studies made by 2 of the authors on the relation of the resistance of plaster of Paris blocks containing 2 and 4 electrodes. Previous work were laboratory studies. This reports field trials with sugar beets and Sudan grass on soils confined to the Yolo series. The results indicate that the blocks have approx. the same resistances at the permanent wilting %. This should make them useful as indicators for the need of irrigation. A resistance of the blocks of about 10.000 ohms is a warning that the moisture content, with soil in contact with the blocks, is almost depleted.