Tuesday, 8 November 2005
6

Averaging Water Content and Electrical Conductivity of a Layered Soil Using Time Domain Reflectmetry.

Hiroyuki Ochiai and Kosuke Noborio. Meiji University, School of Agriculture, 1-1-1 Higashimita Tama, Kawasaki, Japan

It is necessary to know the movement of solute in soil to understand the reaction of nitrate in underground. Using time domain reflectmetry (TDR) is popular to measure water content (q) and bulk electrical conductivity (ECb) in the field because it is not destructive. Vertically-installed TDR probes have been used for this purpose. However, it is still uncertain if TDR works as a perfect integrator or not when TDR probes are perpendicularly inserted into several soil layers, which have different water and/or salt contents, along the rod's length. The goal of this research is to reveal that vertically-installed TDR probes accurately average q and/or ECb of the layered soil. Three acrylic columns (78mm in diameter and 25mm high) were used for making different water contents and concentrations of solution in three layers. A horizontally-installed TDR probe in each column measured q and ECb in the column. A vertical TDR probe was inserted from the soil surface through the three columns to measure average q and ECb. Sodium chloride solution was used for making different concentrations of solution. By comparing q and ECb measured with horizontally- and vertically-installed TDR probes, the performance of the vertically-installed TDR probe was investigated.

Handout (.pps format, 630.0 kb)

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