FACTORS OF SOIL FORMATION - Midlands State University

More documents

Recommendations

Info

FIG. 1.—Virgin prairie soil, Missouri. This soil profile shows a diffusion-like distribution of organic matter with depth. (Courtesy of Soil Conservation Service.) The Soil Profile.—In order to gain a more concrete notion of the term "soil," the reader is directed to turn his attention to Figs. 1 and 2, which represent typical soils as found in the United <strong>State</strong>s and other parts of the world. The pedologist's concept of soil is not that of a mere mass of inorganic and organic material; rather it takes cognizance of a certain element of organization that persistently presents itself in every soil. Although soils vary widely in their properties, they possess one common feature: they are anisotropic. FIG. 2.—Podsol soil. This type of profile exhibits marked horizon differentiation. Organic matter is accumulated mainly on the surface. The white, bleached zone (A2 horizon) is nearly free of humus. It overlies a dark brown layer of accumulations (B horizon) which contains moderate amounts of organic matter. {From the late Prof. C. F. Shaw's collection of photographs.)
To a certain extent, many geological formations such as granite, loess, limestone, etc., are macroscopically isotropic, i.e., the physical and chemical properties are independent of direction. If we draw a line through a huge block of granite, we find a certain sequence of quartz, feldspar, and mica, and of the elements silicon, aluminum, oxygen, etc. The same type of distribution pattern will be observed along any other line, selected in any direction (Fig. 3). All soils are anisotropic. The spatial distribution of soil characteristics is not randomized but depends on direction. Along a line extending from the surface of the soil toward the center of the earth—arbitrarily denoted as Z-axis—the sequence of soil properties differs profoundly from that along lines parallel to the surface (Fig. 3). The soil has vectorial properties. In the language of the pedologist, the anisotropism of soils is usually expressed with the words: "The soil has a profile." Its features are easily put into graphic form by choosing the vertical axis (Z-axis) as abscissa and plotting the soil properties on the ordinate, as shown in Fig. 4. FIG. 3.—Illustrating an isotropic type of parent material and the anisotropic soil derived from it. The curves in Fig. 4 exhibit well-defined hills or valleys, or relative maxima and minima. Pedologists call them "horizons." FIG. 4.—Three soil property-depth functions with maxima and minima (podsol profile). The ordinate indicates the amount of colloidal material in the various horizons. In the field, those zones of abundances and deficiencies run approximately parallel to the surface of the land. Naturally, every soil property has its own vertical distribution pattern or specific "depth function." In practice, special emphasis is placed on substances that migrate easily within the soil, such as
Page 1 and 2: FACTORS OF SOIL FORMATION A System
Page 3 and 4: To MY WIFE
Page 5 and 6: PREFACE The College of Agriculture
Page 7: FACTORS OF SOIL FORMATION CHAPTER I
Page 11 and 12: FIG. 6.—Illustration of a soil in
Page 13 and 14: FIG. 8.—The larger system. (After
Page 15 and 16: However, it remained for Hilgard in
Page 17 and 18: These terms are identical with the
Page 19 and 20: thus avoid lengthy excursions into
Page 21 and 22: CHAPTER II METHODS OF PRESENTATION
Page 23 and 24: Colloid chemists favor size-distrib
Page 25 and 26: These ratios afford a means of dete
Page 27 and 28: FIG. 14.—Illustration of soil var
Page 29 and 30: Studies on Experimental Weathering.
Page 31 and 32: een very rapid, an average thicknes
Page 33 and 34: FIG. 18.—This graph shows in a sk
Page 35 and 36: thickness of the eluvial horizon in
Page 37 and 38: material contained from 9 to 10 per
Page 39 and 40: FIG. 25.—Schematic illustration o
Page 41 and 42: Tujunga sand —> Hanford fine sand
Page 43 and 44: CHAPTER IV PARENT MATERIAL AS A SOI
Page 45 and 46: they would have to be considered as
Page 48 and 49: Physical and Chemical Rock Decay.
Page 50 and 51: FIG. 31.—Comparison of relative b
Page 52 and 53: environment should produce soils th
Page 54 and 55: TABLE 13.—RELATIVE PERCOLATION VE
Page 56 and 57: In certain parts of the world, espe
Page 58 and 59:
minds of all students of loessial s
Page 60 and 61:
that parent material is one of the
Page 62 and 63:
Jersey, out of 48 soil types, 24, o
Page 64 and 65:
Scherf claims that the climate of t
Page 66 and 67:
13. KAY, G. F., and APPEL, E. T.: T
Page 68 and 69:
FIG. 42.—Relationship between slo
Page 70 and 71:
Specific examples of the relationsh
Page 72 and 73:
FIG. 46.—Distribution of organic
Page 74 and 75:
suffered salinization. Some of the
Page 76 and 77:
from Marbut's standpoint; but, in t
Page 78 and 79:
FIG. 50.—Distribution of mean ann
Page 80 and 81:
main, they have not been very succe
Page 82 and 83:
modifications in environment due to
Page 84 and 85:
correlation exists between total so
Page 86 and 87:
FIG. 59.—Soil nitrogen-depth func
Page 88 and 89:
eliminates chance correlation. More
Page 90 and 91:
TABLE 25.—CHEMICAL EVIDENCE OF TH
Page 92 and 93:
(49), and thereby identify the soil
Page 94 and 95:
FIG. 65.—Relationship between CaO
Page 96 and 97:
published in the Soil Survey Report
Page 98 and 99:
(usually pH 7) is known as the base
Page 100 and 101:
In Table 30 are given corresponding
Page 102 and 103:
particularly in the more humid regi
Page 104 and 105:
The hydrogen ion concentration and
Page 106 and 107:
Soil Color.—In humid regions of t
Page 108 and 109:
Nitrogen and Organic Matter as a Fu
Page 110 and 111:
area by soil scientists of the U. S
Page 112 and 113:
TABLE 38.—DATA FOR THE PARENT MAT
Page 114 and 115:
Crowther correlates clay compositio
Page 116 and 117:
Podsols.—In vast areas of norther
Page 118 and 119:
FIG. 85.—Diagrammatic section of
Page 120 and 121:
FIG. 87.—Comparison of podsolizat
Page 122 and 123:
ft. above sea level, the total nitr
Page 124 and 125:
Generalized Soil-climate Functions.
Page 126 and 127:
d. Under conditions of constant moi
Page 128 and 129:
horizons. The decrease in the clay
Page 130 and 131:
directly from the melting ice. Thic
Page 132 and 133:
FIG. 97.—Climatic and vegetationa
Page 134 and 135:
soil processes occur mainly during
Page 136 and 137:
FIG. 98.—Chernozem soil near Khar
Page 138 and 139:
FIG. 99.—Marbut's classification
Page 140 and 141:
47. MARBUT, C. F.: A scheme for soi
Page 142 and 143:
CHAPTER VII ORGANISMS AS A SOIL-FOR
Page 144 and 145:
as a consequence of natural reinocu
Page 146 and 147:
intensive leaching supports acidoph
Page 148 and 149:
TABLE 51.—AREAS OF NATURAL VEGETA
Page 150 and 151:
TABLE 53.—DRY WEIGHTS OF LIVING U
Page 152 and 153:
TABLE 56.—RAINFALL AND PLANT PROD
Page 154 and 155:
the yields of corn: that is to say,
Page 156 and 157:
disappear and acid-tolerant species
Page 158 and 159:
TABLE 60.—COMPARISON OF PRAIRIE A
Page 160 and 161:
differences are found in the distri
Page 162 and 163:
Here also the leaves of the deciduo
Page 164 and 165:
indeterminate past. The land, after
Page 166 and 167:
chapters, we must be content with a
Page 168 and 169:
Duley (44) initiated the first scie
Page 170 and 171:
matter acts as a binding agent betw
Page 172 and 173:
areas in the San Joaquin Valley of
Page 174 and 175:
independent variables. These latter
Page 176 and 177:
Inherent Productive Capacity of Soi
Page 178 and 179:
FIG. 121.—Showing the relation be
Page 180 and 181:
FIG. 123.—Decline of soil nitroge
Page 182 and 183:
FIG. 124.—This graph depicts the
Page 184 and 185:
25. HOSKING, J. S.: The carbon-nitr
Page 186 and 187:
CHAPTER VIII CONCLUSIONS In this ch
Page 188 and 189:
the other correlates soils in terms
Page 190 and 191:
knowledge of the physical, chemical
show all

FACTORS OF SOIL FORMATION - Midlands State University

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?