Soil Science Commons^™

Vertical Mesoscale Water Vapor Flux In An Irrigated Valley, Esmaiel Malek

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To obtain the profiles of dry bulb and wet bulb temperature, specific humidity, q, and air density, ρ, to a height of 200 meters above the ground, a precise lightweight thermocouple psychrometer was designed. To lift the thermocouple psychrometer and the attached wires in obtaining the ρq profiles, a rigid polyethylene balloon augmented with 5.5-feet outdoor or 100-g meteorological balloons were used. Using the height dependent eddy exchange coefficient and a one-dimensional time-dependent profile model, the nighttime variations of ρq as a function of height were predicted and compared with observed values. It was found that the general shape of …

Evaluation Of The Filter Paper Method For Estimating Soil Water Potential, Samir Al-Khafaf

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The filter paper method for measuring soil water potential was evaluated. The method was calibrated using salt solutions (-1.4 bars to -22.4 bars), sample chamber psychrometer (-1 to -50 bars), pressure plate (-0.1 to -15 bars) and soil column at equilibrium (0 to -0.2 bars). It was found that the absolute temperature had little effect on the predicted soil water potential, but a temperature variation had a large effect. It was found that the temperature fluctuation must be small. The predicted water potential was influenced by the type of contact of the soil with the filter paper. It is suggested …

Model For Predicting Simultaneous Distribution Of Salt And Water In Soils, Satish C. Gupta

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Knowledge of water and salt movement in soils is necessary for development of a management scheme for controlling the quality of irrigation return flow. A computer model was developed to predict the distribution of water and salts in the root zone under varying initial and boundary conditions. The model consists of water flow and salt flow sub-models. The water flow sub-model considers the numerical approximation of the general water flow equation with modification for water loss by evapotranspiration (and thus root extraction). The salt flow sub-model considers the mass flow of salts, chemical exchange, precipitation or dissolution of CaCO_{3 …}

Relationship Of The Soil Water Content And Microclimate To The Plant Growth Water Use Relationship Of Several Plants, Philip Dean Sandberg

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Studies involving field plots, lysimeters, and garbage can lysimeters showed that an intermediate soil water level produced the most growth for a given amount of water use by oats, corn, and barley. For crested wheatgrass the lowest water level produced the most growth per water used. Field plots which were covered with sheet metal between the rows produced more plant growth per water used than the uncovered plots for the crops used in this study. One year's data were obtained on the effect of positioning the garbage can lysimeters. One half of the cans were placed on the soil surface …

Calcium Carbonate Dissolution And Precipitation In Water: Factors Affecting The Carbonate Saturometer Method, Lyle M. Dabb

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The carbonate saturometer method developed by Weyl (1961) was studied in respect to the effect of several variables on the solubility of carbonates. The solubility of three solid carbonate materials was measured in four different salt solutions, at four ionic strengths, and at two different temperatures. The solids studied included: calcite, dolomite, and a calcareous soil.

It was found that the three solid carbonate materials varied in solubility from a low in the soil carbonates to a high in dolomite.

Increasing the ionic strength of the solution increased the solubility of most of the solid carbonate materials.

By decreasing the …

Salinity And Water Potential Sensor For Evaluation Of Soil Water Quality, Melvin Dee Campbell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The objective of this study was to evaluate response times of a salinity sensor and a soil psychrometer. Influences of pressure, temperature and molar concentration changes were to be measured.

Salinity sensor response times ranged from 50 to 130 minutes during solution adsorption while desorption response times were perhaps ten times as long. Temperature affected both response times and equilibrium values, but pressure did not affect either.

Soil psychrometer response times ranged from from 40 to 80 minutes for either adsorption or desorption of solution. However, other factors probably related to indirectness of measurement made the soil psychrometer fail to …

The Influence Of Thermo-Gradients Upon Water Movement And Retention In Unsaturated Soils, Jose V. Salazar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Temperature differences of about 5, 10, and 15 V, were applied to uniformly packed and insulated horizontal column of Millville silt loam soil using mean temperatures near 13, 14, 15, 16, 17, 18, 19, 20 and 23.5 C. The temperature distribution along the soil column was determined using copper constantan thermocouples. Soil samples were taken to determine volumetric moisture content, and soil water potential, using the vapor pressure psychometer technique. The thermodynamic flow equation of Taylor and Cary, (1964) was used to calculate the hydro-thermal transfer coefficient (ß) as given by:

-ß = d(μ_w)_T / dlnT

where …

Simultaneous Movement Of Water And Herbicides In Unsaturated Soils, Ming-Shyong Yang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Since weed killers were developed in the early part of the decade beginning in 1940, herbicides have been increasing in use until they are now widely used to control weeds. The application of herbicides has thus become a regular agricultural and ecological practice.

Simultaneous Flow Of Heat And Water In Plant Tissue, Gaylon Sanford Campbell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Although biological phenomena may be partially described in a general way without the use of mathematics and physics, the experimental results may be more meaningful if they are analyzed on the basis of physical and mathematical laws. The complexity of biological systems has made the application to them of mathematics and physics rather difficult, and only recently has much progress been made. Although it has yet been possible to describe only a few simple biological systems by actual equations, a great deal of qualitative information may be obtained by applying physics and mathematics. Russell (1960, p. 439) said

In principle …

The Influence Of Soil Moisture Regimes And Atmospheric Environments On Transpiration And The Energy Status Of Water In Plants, Sampatrao A. Gavande

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Plant responses to different soil moisture regimes have been extensively studied. Because of interactions between the soil, plant and climatic factors, few convincing generalizations concerning the influence of soil water on the transpiration of water by plants have been established. Generally single factors or at most the interaction of two have been studied at any one time. Useful theories describing the conditions of water retention in plant tissues and movement of water through plants have been proposed. Equally useful theories have been suggested for describing the retention and transmission of water in soil. The integration of these theories and their …

The Interaction Of Water And Salt Flow In Unsaturated Soils, Mahmoud Hassan Abd-El Aziz

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The movements of salt and water, particularly in fairly dry soils or compacted shales, are important processes in both agronomic studies and hydraulics of deep ground water which is important in the location of oil.

Salt Effect On Water Requirements Of Plants, Abdel-Wahhab M. H. Sallam

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Water requirement was defined by Briggs and Shantz in 1911 as the ratio of the weight of water absorbed by a plant during its growth to the weight of dry matter produced. Ballard (1933) and Williams (1935) defined water requirement as the ratio of the amount of water transpired to the amount of dry matter produced. Ballard (1933) and Williams (1935) defined water requirement as the ratio of the amount of water transpired to the amount of dry matter formed during the whole or any part of the life cycle of the plant. Miller (1938) and Kramer (1959) postulated that …

Pressure Dependence Of Soil Water Matric Potential, Bozorg Bahrani

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The partial specific Gibbs¹ free energy or the chemical potential has been shown to be the most desirable thermodynamic function for describing soil-water systems. The absolute value of the chemical potential of soil water cannot be determined. If pure water at standard temperature and pressure is taken as the reference, the difference between the chemical potential of soil water and that of the reference can be measured and is called "soil water potential," which has the dimension of energy per unit mass.

The barometric pressure at the sea level has been accepted as the standard reference pressure. Thus, any …

The Influence Of Temperature On The Impedance To Water Flow Through Plants, Royal Duane Jensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This era has been termed the atomic or space age. The greatest concern of most people seems to be centered around survival from the destruction and suffering that might be caused by atomic and nuclear weapons. However, along with this, the world is confronted with perhaps a greater disaster--a potential calamity seldom realized by most people, yet a problem which grows more serious in the world each year--a tragedy which would probably be worse than destruction from nuclear weapons. This encroaching catastrophe is starvation.

Even today the majority of the people in the world do not have enough food. Each …

An Application Of A Thermodynamic Flow Equation To Water Movement In Unsaturated Soil, Brennan Derry Soane

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The movement of water in soil presents many interesting problems to the research worker. It is also a subject which finds wide and important application in agriculture and several branches of engineering.

The object of this work was to examine the usefulness of a new equation of flow of water in unsaturated soil. If valid, this new approach may be able to eliminate some of the gaps in our present knowledge of the subject.

All soil lying above the capillary fringe of a water table is in the unsaturated state with respect to water. This means that in any macroscopic …

The Freezing Point Of Water In Puddled And Unpuddled Soils At Different Soil Moisture Tension Values, Robert B. Campbell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A technique that will adequately describe the physical condition of water in the soil has long been desired by scientists. The method should include the effect of soluble materials on the osmotic pressure of the soil solution, and also the effect of surface force action between the soil and soil water.

Parker (8) demonstrated that the freezing point was reduced in the presence of finely divided material. This suggested the possibility of using the cryoscopic procedure to measure the physical condition of water soil. More recently, the introduction of Thermistors for accurate temperature measurement have made it desirable to investigate …

A Study Of The Equilibria Between Bentonite And The Various Replacing Agents In Alcoholic And Water Solutions, Joel E. Fletcher

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Investigators in soils have long recognized the importance of the colloidal fraction of soil, and also the almost inseparable problem of replaceable bases. It is generally accepted that the replaceable base fraction of a colloid controls to a large degree the physical properties exhibited by it. Volumes of work have been written on the problem of controlling the reactions of this fraction and on studies of the properties exhibited by it when it is saturated with various cations. Each worker has proceeded in his own individual way or followed the example set by some previous worker with specific modifications.

Bulletin No. 115 - The Movement Of Water In Irrigated Soils, J. A. Widtsoe, W. W. Mclaughlin

UAES Bulletins

This bulletin embodies a part of the data secured in the irrigation investigations of this Station. It aims to contribute something to our knowledge of the movement of water in irrigated soils . The science of irrigation can not well be built until the laws involved in the mutual relationships of waters, soils and crops are understood with fair accuracy. Much has been done by numerous investigators, during the last fifty years, to give a clearer comprehension of the movement of soil moisture; but the field experiments have dealt largely with saturated soils, and the laboratory experiments have seldom taken …