©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF...

©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458

THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil

Chapter 1 The Soils Around Us

Earth, unique for soil and water. (NASA)



Figure 1.1

(a) (b)

(c) (d)



Figure 1.2



Essential Elements

C.B. HOPKiNS CaFe, Co.

Closed Monday Morning and Night

See You Zoon, the Mg.



Figure 1.4



Figure 1.5



Figure 1.7



Figure 1.8



Figure 1.9



Soil Horizons• A soil horizon is a layer of soil, revealed in a soil profile, lying

approximately parallel to the earth's surface, and possessing relatively homogeneous physical, chemical, and biological properties.

• O Horizons– Organic horizon at the soil surface, usually unconsolidated organic material

(leaf litter, roots, leaves, etc.), not saturated with water.

– Oi Horizon• Fibric material - Recognizable plant and animal parts

– Oe Horizon• Hemic materials - Finely fragmented residues intermediately decomposed

– Oa Horizon• Sapric materials - Highly decomposed, smooth, and amorphous residues



Soil Horizons

• A Horizons– Mineral horizon formed at or near the surface where humified

organic matter is associated with mineral materials. Usually darker in color because of the organic matter.

• E Horizons– mineral horizon just below the soil surface that has lost its silicate

clay, organic matter, aluminum, or iron by downward movement, leaving a concentration of resistant sand and silt particles. "E" stands for "eluvial horizon," a soil layer formed by the removal of constituents such as clay or iron. Eluviation describes the process whereby constituents of soil are removed in suspension.



Soil Horizons• B Horizons

– A subsurface mineral horizon resulting from (1) the change in situ of soil material, i.e., the obliteration of the original rock structure, or (2) the washing in of material from overlying horizons, i.e., the accumulation of silicate clay, organic matter, aluminum, or iron. Illuviation describes the process of accumulation of materials from overlying horizons.

• C Horizons – Unconsolidated or weakly consolidated mineral horizon that

retains evidence of rock structure, but lacks diagnostic properties of the overlying A, E, and B horizons. This horizon is little affected by pedogenic (i.e. soil forming) processes. Examples include beach sand, windblown silt (or loess), alluvium deposited by rivers, and glacial till deposited by glacial ice.

• R Horizons– continuous (consolidated) hard or very hard bedrock.



Figure 2.33



Figure 2.35



Figure 2.36



Figure 2.37



Figure 1.10

(a) (b)



Figure 1.11



Figure 1.12



Figure 1.13

(a)

(b)



Figure 1.14



Figure 1.15



Figure 1.16



Figure 1.17



Figure 1.20

(a) (b)



Figure 1.21



Figure 1.22



Figure 1.23



Nutrient Uptake

• Root Interception

• Diffusion

• Mass Flow



Figure 1.26



Root Micrograph



Figure 1.24



Agricultural Production

• Population is growing• Cropland is destroyed by urban sprawl• New forest must be cleared for new croplands• Still the amount of cropland per person is

decreasing• Knowledge of soils help to increase yield per

acre



Figure 1.27



Historical Development

• Earliest People to Study Soils– Aristotle (384-322 B.C.)– Theophrastes (372-287 B.C.)

• Considered the properties of soil in relation plant nutrition

• Considered the properties of soil in relation plant nutrition.




• Roman writers who discussed differences among soils in relation to plant growth.– Cato the Elder (234-149 B.C.)

– Varro (116-27 B.C.)

– Virgil (70-19 B.C.)

– Columella (about A.D. 45)

– Pliny the Elder (A.D. 23-79)




• Lomonosov (1711-1765) – Russian that wrote about soil as an evolutionary process.

• Justus von Liebig – In 1840 published Chemistry in its Application to Agriculture and

Physiology in which he states plants assimilate mineral nutrients from the soil.

• German scientists including Ramann and Fallou – In the mid 1800s developed agroecology that viewed soil as

weathered, somewhat leached surficial rock.




• Dokuchaev (1846-1903) – In 1883 developed many of the early applications of soil science.

His dynamic research and teaching fueled extended studies of soil genesis in Russia.

• Glinka (1867-1916) and Neustruyev (1874-1928) – Continued the work of Dokuchaev, stating that soil is a weathered

crust that exhibits specific properties correlated with climatic zones.

• Williams (1863-1939)– Another Russian soil scientist, emphasized the concept that soil

genesis was a biological process.




• Hilgard (1833-1916)– One of the first U.S. soil scientists, wrote about the relationships

between soils and climate.

• Marbut (1863-1935) – Did much of the significant early work in soils in the United States

emphasizing the soil profile.

• Smith (1907-1981) – Was the chief architect of Soil Taxonomy, which advanced and

refined soil genesis in support of soil classification and soil survey.

©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF...

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