Hard red duplex soils (HRDS) cannot sustain economically productive vineyards without careful management. An experiment was conducted at Rosbercon Vineyard, Picola from 1995 to 1998 in a vineyard block of Chardonnay on Ramsey rootstock planted in 1972. The hypotheses tested were: a) transient waterlogging decreases root growth and grapevine performance, and b) hardening of soil decreases root growth and grapevine performance. (For complete summary open document)

Thesis (M.S.)--Ohio University, March, 1997. / Title from PDF t.p.

Dissertation submitted in compliance with the requirements for Master's Degree in Technology: Electrical Engineering (Light Current), Durban Institute of Technology, 2002. / Modern society as a whole seems destined to have an ever-increasing demand for power for both industrial and domestic use, as continued population growth means that cities, suburbs and industrial areas become larger and denser. At the same time the trend toward increased productivity in all segments of industry is influencing the development and techniques employed at locating faults in power cables and networks to ensure only limited downtime and reduced direct and indirect costs associated with the location of faults / M

The Speedy Delivery (SD) waveform does not undergo dispersion in transmission lines. The waveform was first introduced by Dr. Robert Flake in US Patent 6,441,695 B1 issued on August 27, 2002. Use of the SD waveform allows for high precision time domain measurements on transmission lines. High precision time domain reflectometry (TDR) and time domain transmission (TDT) measurements are described. An example measurement is presented. The design of the experimental apparatus is detailed. Voltage bias adjustments are made during measurements to increase the repeatability. Voltage bias adjustments are examined in detail. Efforts to produce short terminated measurements with high precision are included. A technique for performing TDR measurements with highly attenuated signals is presented with results. / text

No description available.

Effective management of saline soils requires rapid, reliable methods of monitoring both soil water content (theta) and salt concentration, the latter measured in terms of electrical conductivity (sigma). This thesis examines estimation of theta, and bulk soil sigma (sigmaa) and soil water sigma (sigmaw), using time domain reflectometry (TDR). Calibration experiments were conducted in soil columns and in a vineyard that were irrigated with saline water. Within a theta range of 0.025--0.490 m3/m3, the correlation between TDR theta (thetaTDR) and gravimetrically determined theta (theta g) was high (r2 = 0.979 in soil columns, r2 = 0.836 in the field). The error of estimate of thetaTDR was 0.020 m3/m3 or less. Field thetaTDR estimates were sensitive to high salinity (sigmaw > 10 dS/m). Using a dual pathway parallel conductance (DPPC) model, sigma a was derived from sigmaw of saturated paste extracts and theta g. The correlation of TDR sigmaa to DPPC sigmaa was good in the laboratory (r2 = 0.915), and moderate in the field (r2 = 0.791), indicating a functional relationship between sigmaw and theta and TDR sigmaa. Models, to estimate sigmaw, were built by regression between paste extract sigma w and TDR sigmaa and thetaTDR. In a sigma w range of 3.0--23.4 dS/m in the columns, error of estimate of sigma w was small at 1.50 dS/m (+/-12.4% relative error range). In a sigma w range of 2.2--25.2 dS/m in the field, error of estimate of sigma w was 3.37 dS/m (+/-37% relative error range), which was significantly higher than the acceptable error range of +/-10%. ANOVA tests indicated that both TDR sigmaa and sigmaw·theta changed significantly with respect to the same sources of variance. Error in field estimates of sigmaw was associated with effects of salinity on thetaTDR and variability of soil conditions, particularly with respect to depth and time of sampling.

Time domain reflectometry (TDR) is becoming a widely used method to determine volumetric soil water content ($ theta$) and bulk soil electrical conductivity (EC$ sb{ rm a}$). It has been found that the $ theta$ and EC$ sb{ rm a}$ values obtained by this method, on certain soils, require calibration. The purpose of this study was to monitor the effects of soil texture (most particularly the clay type and clay content) on $ theta$ and EC$ sb{ rm a}$ estimated by TDR. / Water content was measured, gravimetrically and by TDR, on packed columns of nine soil mixtures, composed of three clay types (Hydrite, Bentonite, and Ste. Rosalie clay) and coarse sand at three levels (8, 16, and 30% by weight) of these clay materials. Three replicates of each mixture (a total of 27 columns) were made to statistically establish the effect of the clay type and the clay content on $ theta$ and EC$ sb{ rm a}$ readings by TDR. It was found that the TDR overestimated $ theta$ for the Hydrite and Ste. Rosalie (Natural) materials but accurately predicted for the Bentonite materials, compared to gravimetric determinations. / Bulk soil electrical conductivity was simultaneously measured by two independent techniques, TDR and 4-probe, on the same soils. It was found that the clay types and clay contents have almost equal effects on the EC$ sb{ rm a}$ as measured by TDR and 4-probe techniques. It was found that the estimated EC$ sb{ rm a}$ values obtained by TDR and 4-probe methods for the fine-textured Bentonite materials were lower than those for the Hydrite and Ste. Rosalie materials at equal $ theta$ and EC$ sb{ rm W}$ (electrical conductivity of soil water).

Zugl.: Karlsruhe, Univ., Diss., 2008 / Hergestellt on demand

Thesis (M. Sc. Agr.)--University of Sydney, 1999. / Title from title screen (viewed Apr. 21, 2008). Submitted in fulfilment of the requirements for the degree of Master of Science in Agriculture to the Dept. of Agricultural Chemistry & Soil Science, Faculty of Agriculture. Includes bibliography. Also available in print form.

Universität Karlsruhe (TH), Diss., 2008.