The Pedosphere PDF

The Pedosphere Pedosphere is the living skin of the earth, which is the sum total of all the organisms, soils, water, and air. Soil is an essential component of Earth that has enabled life to exist on the planet and continues to support it.It forms pedoshere– the foundation of terrestrial life on t...

The Pedosphere Pedosphere is the living skin of the earth, which is the sum total of all the organisms, soils, water, and air. Soil is an essential component of Earth that has enabled life to exist on the planet and continues to support it.It forms pedoshere– the foundation of terrestrial life on this planet. The term is derived is derived from the Greek words pedon which means “soil” and sfaira which means “sphere”. The pedosphere is the living skin of Earth which is a result of the dynamic interaction among  The Components of Soil Soil is made from portions of the geosphere, atmosphere, hydrosphere, and biosphere.It is generally composed of 45% mineral (gravel, sand, silt, and clay), 25% air, 25% water, and 5% organic matter(humus roots, and dead decaying organisms). These components reflect the processes that formed the soil. Soil Formation Soil forms when rock weathers. Weathering, or breakdown of rocks, may result from physical or chemical changes. Soil formation maybe a slow or a rapid process, depending Five factors that affect soil formation: 1. Parent Material- The parent or source material is important in soil formation because its chemistry and type will determine the soil that will be formed.Soil formed on site through weathering of the underlying rock are called residual soils.However , most soils are transported from their source to another area by agents of erosion and transportation such as water,wind and ice. 2. Climate- temperature, rainfall, and moisture effects the pattern and intensity of soil forming process such as weathering, leaching, transportation, and distribution.Climate also affects the type of organisms, biological activity, and rates of chemical reactions.Thus, soils types vary depending on climate. 3. Topography-the gradient of slope affects water flow erosion. Soil that form in steep slopes tend to be thinner because of higher rates of erosion. Slope aspect, which is the direction of the slope face, affects temeperature and moisture as slopes facing the sun are warmer. 4. Biological factors- organisms such as plants, animals, microorganisms, and human affect soil formation. 5. Time- the formation of soil is a long and continuous process which may take hundreds to thousands of years depending on climate and environment.In modern climates, it takes 200 to 400 years to develop 1 cm soil.  Soil Texture Defined as the relative proportion of the particle sizes in the soil- ---sand, silt, and clay. Soil is a naturally composed of a mixture of these particles and the proportion of which affects other soil properties such as porosity and water retention. The smallest particle is clay, followed by silt and followed by The texture of soil depends on the percentage of clay, silt and the sand that it has The proportion of clay, silt, and sand are plotted in the soil texture triangle to determine its soil type based on particle size. The ideal soil for agriculture use loam. Loam provides good aeration and drainage properties of large particles with nutrient- Nicolas L.Galve is considered as the Dean of Filipino Soil Scientist’. He laid down the foundation for the different fields of soil science in the Philippines. He trained Filipino soil scientists at the University of the Philippines College of Agriculture UPCA for 42 years.He recognized internationally with his  Soil Profile Soil formation is a gradual process which involves the development of a succession of zones or soil horizons. The sequence of soil horizons from the surface down to the underlying bedrock is called soil profile. O Horizon At the top of the profile is the O horizon. The O horizon is primarily composed of organic matter. Fresh litter is found at the surface, while at depth all signs of vegetation structure has been destroyed by decomposition. The decomposed organic matter, or humus, enriches the soil with nutrients (nitrogen, potassium, etc.), aids soil structure (acts to bind particles), and enhances soil moisture retention. A Horizon Beneath the O horizon is the A horizon. The A horizon marks the beginning of the true mineral soil. In this horizon organic material mixes with inorganic products of weathering. The A horizon typically is dark colored horizon due to the presence organic matter. Eluviation, the removal of inorganic and organic substances from a horizon by leaching occurs in the A horizon. Eluviation is driven by the downward movement of soil water. E Horizon The E horizon generally is a light-colored horizon with eluviation being the dominant process. Leaching, or the removal of clay particles, organic matter, and/or oxides of iron and aluminum is active in this horizon. Under coniferous forests, the E horizon often has a high concentration of quartz giving the horizon an ashy-gray appearance. B Horizon Beneath the E horizon lies the B horizon. The B horizon is a zone of illuviation where downward moving, especially fine material, is accumulated. The accumulation of fine material leads to the creation of a dense layer in the soil. In some soils the B horizon is enriched with calcium carbonate in the form of nodules or as a layer. This occurs when the carbonate precipitates out of downward moving soil water or from capillary action. The diagram below illustrates the effect of climate on eluviation and illuviation. Eluviation is significant in humid climates where ample precipitation exists and a surplus in the water balance occurs. Illuvial layers are found low in the soil profile. Illuvial zones are found closer to the surface in semiarid and arid climates where precipitation is scarce. Capillary action brings cations like calcium and sodium dissolved in soil water upwards where they precipitate from the water.  Soil orders The most general level of classification is the soil order consisting of 12 types. Gelisols- Frozen soils found in the coldest region on Earth. Histosols- High organic content and wet. Spodosols- sandy and acidic soils found in moist climates than often support dense forest.  Oxisols- very weathered and common in tropical climates. Vertisols- claylike soils that shrink and swell. Aridisols- very dry soil in arid regions. Ultisols-weathered soils Mollisols- Deep fertile soil. Alfisols- Moderately weathered productive soils found in temperate and humid regions. Inceptisols- slightly developed, young soils found on steep slopes and mountain ranges. Entisols- Newly- formed soils found in steep rocky lands.  Soil and Soil Quality Soil is not dirt it is a resource.It is a main component of land resources, agriculture, and ecological sustainability.It also provides food and foundation for shelter.Soil is important in sustaining man’s existence and provides humans services.  Arable land for agriculture- arable comes from latin word arabilis which means able to plowed.Arable land are plowable lands which could be used to grow crops.An important component of arable lands is soil  Regulating water and filtering potential pollutants- In the water cycle, soil plays an important part in absorbing water and storing it as ground water.  Nutrient Cycle Carbon, nitrogen ,phosphorus, and other essential nutrients are stored, transformed, and cycled in the soil. Nitrogen in the atmosphere, for example, cannot be readily used by organisms.  Mineral Deposits Soils are mined for their mineral content wether it be iron, nickel or aluminum. These soil are called laterites. They are commonly formed in hot and wet tropical areas.Laterites are mostly rusty-red in colr because of their high iron oxide content.They develop through an intensive and extended chemical weathering of underlying parent rocks, resulting in a  How Human Activities Degrade Soil Quality Soil is a non renewable, finite resource which is generally not recoverable within a human life span.The food and Agriculture Organization of United States Nations define soil degradation as a change in the soil health status, resulting in a diminished capacity of the ecosystem  Soil Erosion- causes the loss of topsoil and nutrients in the soil.It is indeed the most visible effect of soil degradation.  Soil compaction Reduces the amount of air, water, and space