Soil Study

Physical Properties of Soil The soil properties that we can see or feel and are relatively more permanent than chemical properties are called physical properties of soil. Such properties are difficult to change. Soil physical properties include texture, structure, particle and bulk density, porosity, air and water content, consistency, colour and temperature. Soil Texture and its Significance                                                                    It refers to relative proportions of the three primary soil separates (sand, silt and clay). Texture is important because it determines the ease of tilling the soil, the amount of aeration, water intake rates and water storage in the soil. It also influences soil fertility. For instance, a fine textured clayey soil is difficult to till, has poor aerati...

Soil Water The availability of water in soil is essential for plant growth. It is also essential to microorganisms that grow in soil and decompose organic matter. It is important in the weathering process which involves the breakdown of rocks and minerals to form soil and release plant nutrients. Water is the solvent that together with the dissolved nutrients make up the solution from which plants absorb nutrients mainly through the roots. Soil water can provide control over both soil air and soil temperature. Water is generally held in the soil by micro pores. The force of gravity causes water to move downward through the soil particularly in the larger pores. Soil Water Potential                                                 The di...

Ion Exchange It is interchange of ions between colloids and soil solution and/or between the solid phases if these are in a close contact. If the process is between cations; it is called cation exchange and for anions it is termed as anion exchange. These are reversible reactions. Cations are positively charged ions. Soil colloids have negative charges on their surfaces. Cations are adsorbed at these negatively charged sites. The adsorbed cations can be exchanged by other cations present in soil solution. This change of one positive ion by another is called cation exchange. For example, when an NH 4 + containing fertilizer is added to a soil, many of the numerous NH 4 + ions replace the other cations that are already adsorbed to the exchange sites. Cations exchange takes place on the surface of clay and humus colloids as well as on the surface of plant roots. The cations mostly present on the cation exchange sites of the soil colloids are Ca + , Mg + , H + , Na + , K + and Al ...

Climate It is the average weather conditions at a particular place over period of time as determined by temperature, precipitation, wind velocity and other morphological factors. Climate is the dominant factor of soil formation because of the effects of temperature, rainfall and wind. These sub factors affects the rate of chemical, physical and biological processes that are responsible of soil development. The biochemical changes are sensitive to temperature. These changes are favoured by temperature range of 20-30 o C. Temperature also influences the organic matter content of the soil. Decomposition of organic matter is more at higher temperature. Moisture is another important actor in soil formation. Rainfall is the major source of moisture. In areas receiving low rainfall, there is shallow accumulation of carbonates in the soil, in humid areas, acid soils are developed under conditions of intense weathering and leaching. Erosion caused by water may remove upper fertile port...

Topography It is the difference in elevation or slope between the uplands and lowlands of a valley or it is the earth’s surface contour. Topography of a land can hasten or delay the work of climatic forces. In smooth and flat surface excess water is moved less rapidly than in areas of steep slopes. Soils having steep slopes encourage natural erosion of the soil surface which reduces the possibilities of the development of a deep soil. On the other hand, if water remains available for part or all of the year on gentle slopes there will be more vegetation and organic matter accumulation resulting in the development of a deep soil profile. Topography also determines the type and amount of vegetation. Higher plants and more vegetation are present on north facing slopes but scarce and small shrubs are present on the south facing slopes.

Bioremediation It is a process that uses microorganism, plants or microbial or plant enzymes to detoxify contaminates in the soil and other environment. A number of bioremediation strategies can restore soil environment quality. For a given contaminant, one or more of the following strategies may be needed to ensure successful bioremediation. Passive bioremediation is a natural bioremediation of contaminated sites by indigenous microorganism. In this kind of bioremediation rate of degradation may be too slow for some situation. Bio stimulation is the addition of nutrients such as nitrogen and phosphorus to stimulate indigenous microorganisms in soil. Bioventing is a process in which gaseous stimulants such as oxygen and methane are added in the soil to stimulate microbial activity. Bioaugmentation  is a process in which inoculation of a contaminated site with microorganism to facilitate biodegradation. Composting is the use of microorganism in constructed piles of soil windr...

Composting It is controlled biological process which converts organic constituents usually wastes into humus like material suitable for use as a soil amendment or organic fertilizer Composting Process It consists of a period of rapid decomposition and self-heating followed by a cooler, slower decay of remaining organic substrates. All the three major groups of soil microorganisms, bacteria actinomycetes and fungi are involved in this process. Regulating the kinds of organic substrates and controlling the physical and chemical attributes of the decomposition environment in the compost pile facilitate the process. Manipulating moisture content, pH, nutrients concentrations and oxygen can bring about increased decomposition rates and changes the characteristics of the compost. Today, enhancement in the modern engineering has resulted in the growing use of composting for municipal and industrial waste treatment and nutrient recovery. The same microbial process is used by the both ...