Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Plants, Soils, and Climate

Department name when degree awarded

Soil Science

Committee Chair(s)

Raymond W. Miller


Raymond W. Miller


The study of soil erodibility has become of paramount interest in the last few decades. The effects of soil erosion are serious and extensive and affect nearly all people.

In general, man can do little or nothing about the geologic erosion or natural erosion in which the processes of rock weathering and soil erosion gradually wear down the earth's surface. However, human disturbance of the natural conditions of the land surface often creates accelerated erosion. Fertility of eroded soil is usually reduced measurably and crop yields are lowered considerably as erosion removes seed soil nutrients and cover crops. Loss of fine soil fractions such as silt, clay and organic matter and the loss of various nutrients is tremendous. Such losses are difficult to replenish even in several generations.

In irrigation and drainage engineering the study of soil erosion is essential because the life of reservoirs and distribution systems is shortened by silting. In addition, the erosion factor is an important item to be considered in devising the appropriate irrigation method for an area. The effectiveness of methods for both surface and subsurface drainage depends upon the knowledge of the erosiveness of the soils in question. Erosion control measures on the farm and the development of general agricultural machinery also involve knowledge of the erosive characteristics of the soil.

In watershed management, also, soil erosion is a primary problem. It affects the quality and quantity of water as well as the time of peak flow and duration of flow. In addition to this, good watersheds control floods and exhibit valuable range land.

As a result of these many factors, the study of soil erosion has secured an important place in the various fields of science which depend directly on water, livestock, crops and timber production.

There is general agreement that soil detachment is one of the important influences on erosion of soil. Raindrops are one of the most disruptive agents and artificial rainfall has frequently been used in the study of soil detachment. Very often the erosiveness of soils on equal slopes and with similar climate and cover will be directly related to the detachability of the soil. Attempts to find a simpler measure than rainfall to determine the detachability of soil brought about the use of two measures, aggregate stability and the dispersion ratio. The relationship of these latter methods to soil detachment by rainfall has been both good and poor in various studies.

Consequently, these three methods -- rainfall, dispersion ratio and stability of aggregates -- are used here in an initial study of the detachability of selected Utah soils. An attempt is made to estimate the detachability of these soils and to observe the relation, if there is one, between soil detachment, aggregate stability and dispersion ratio.



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