A FIELD-TEST OF AN ELECTRICAL-CAPACITANCE METHOD FOR MEASURING SOIL-WATER CONTENT

Several studies have compared gravimetric sampling to the neutron-atte nuation method of soil-water measurement. However, less is known of th e relationship between these two methods and a more recently developed technique based on electrical capacitance. Our field experiment allow ed us to: (1) determine the accuracy of the neutron-moderation and ele ctrical-capacitance methods by comparison to gravimetric sampling; (2) establish a relationship between the three methods; and (3) determine the field effectiveness, applicability, and ease of operation of the methods. The principal hypotheses are that we can establish the relati onship between the three methods using simple regression, and that the three methods give statistically equivalent measures of soil-water co ntent and thus can be used interchangeably. An alternative hypothesis is that no valid relationship exists between the three methods, with e ach giving a statistically different measure of soil-water content. We found that the electrical-capacitance method provides a viable altern ative to the neutron-attenuation method of soil-water measurement in t he field.