Soils/media Information Portfolio - Essay Example

Names Instructor’s name Course title Date Soil portfolio Introduction Soil development is affected by the climate and the biological factors that acted upon the parent material as conditioned by the topography that the soil is under and the time that has been allowed for development. This results in a soil profile with different layers distinctively noticeable by the difference in color, texture, and porosity. Soils suitable for agriculture are grouped in four major horizons or soil layers. The upper horizon (horizon A) mostly consists of organic matter and is common where vegetation has thrived. The second horizon (horizon B), is the mineral surface layer and is heavily under influence of biological and human activity. It has the highest percentage of organic matter and mineral which cause it to have a darker appearance compared to the other soil horizons. The third horizon (horizon C), is the horizon of accumulation of clay and other substances leached from the upper horizons. The horizon D is made of a weathered parent material or bedrock. The zone in some cases is found to be composed of accumulated material from deposits of wind or glaciers in early ages. These horizons however may be poorly defined in poorly developed soils (Indorante, Follmer, Hammer, and Koenig, 285) The suitability of the soils for use in agriculture depends on its physical attributes such as color, texture and porosity. This dependence comes about as they determine the water retention, and aeration property of the soil which consequently determines the amount of water available for plants and amount of air in the soil. The amount of space between soil particles allows for varying amount of water and air circulation within the soil. When the spaces are packed the soil is said to be saturated, when the water drains freely because of gravity the remaining amount of water is called the field capacity. The field capacity is held within the micro-pores of the soil by capillary action or surface tension between water and soil particles. The amount of water that is available to plant is the Water Holding Capacity (W.H.C.) of the soil or otherwise known as the Plant Available Water (P.A.W.) (Indorante, Follmer, Hammer, and Koenig, 285). Plants can utilize this amount of water until the permanent wilting point is reached; this is a point at which the water is held too tightly by the soil for plant to extract. Soil chemical properties are caused by the colloidal surface and its attraction due to the charged surfaces. The soil’s colloids are able to attract ions within the soil solution and depending on the ion charge size and concentration; it can be held to the colloid and exchanged with other ions within the soil solutions. The ability of soils to attract and exchange ions is called its Exchange Capacity (E.C.). Soils may be dominated by the negative charges and therefore attract more positive charges to the exchange sites. The overall exchange capacity will be a greater Cation Exchange Capacity (C.E.C.) compared to the anion exchange capacity (A.E.C.) (Rayment, and Higginson, 314.) Another dimension of soil chemistry is the soil pH, this refers to the acidity or alkalinity and is usually a measure of the hydrogen ions in the soil, the higher the Hydrogen ions the lower the soil pH and vice versa. The pH affect the exchange capacity by altering the surface of colloids, higher amounts of Hydrogen ions neutralizes the anions thereby resulting in reduced cation exchange capacity. Soil function is affected by the concentration of salt; however this fact is mostly applicable to soils in arid and semi arid areas which experiences high evaporation. This leads to accumulation of salts in the upper horizons of the soil structure. In heavily irrigated areas the salt concentration is higher in the lower horizons due to leaching. Saline soils contain high amount of calcium, magnesium, and potassium and sodium (Rayment, and Higginson, 314). Salinity affects structure, porosity and plant water relation and may lead to lessened yield of the soil. Podosols Distribution: This soil type is mainly found in the temperate and boreal regions. The biological development of the soil is done mainly by fungi as large animals such as earthworms are scarce in this soil type (Sylvia, Fuhrmann, and Zuberer, 18). It is mostly composed of aluminum or iron and has a lot of leaching of organic material from the upper horizon to horizon B with percolation of rain water. The soil that remains is strongly leached and bleached and therefore lacks the A horizon. As a result of the leaching, this soil is highly acidic, has high aluminum content and low chemical fertility. Properties: The podzols are ash grey in color and are found under a dark surface horizon which is rich in organic matter and above a brown eluviations horizon. Due to bleaching the zone of eluviations contains normally less clay but the illuviation horizon has higher clay content (Brady and Weil, 41). Mineralogy of podsols is variable but has predominance of quartz which shows that the parent material may have been intermediate or of basic composition. The composition of aluminum and iron depends with regions, higher iron content is found in podsolic soils of USA while Western Europe has higher aluminum (Gardiner and Miller, 231). The soil is chemically characterized by accretion of phosphates in the lower B horizon. This horizon is therefore acidic with pH varying between 3.5 to 4.5 and increases with depth to a maximum of 5.5 in the deeper horizons (Brady and Weil, 46). Usage: Due to its low fertility low pH and low moisture, podsols are unattractive for agricultural use. The problems to overcome in reclamation processes include high aluminum toxicity, phosphorus deficiency and depth of ploughing to improve soil aeration and moisture capacity. The soils require liming and fertilization to counter these problems and make it suitable for agriculture. Ferrosols Distribution: Ferrosols occur in coasts north of Queensland to Tasmania in areas with mean annual rainfall ranges of 500mm to 3000mm. This soil type has the same definition as dermosols but their horizon B has higher iron oxide content which causes a characteristic physical and chemical property that differs from the other soil types. Properties: Ferosols have a strongly developed polyhedral compound that have smooth and shinny surfaces. Other ferrosols have a very fine granular or fine structure in the horizon B. most ferosols are permeable and have good aeration despite the high clay content. The ferosols are dominated by kaolinite, hematite and varying amounts of goethite which is usually found in regions of high rainfall. Usage: The soil is of diverse use although extensive agriculture is not usually practiced due to the topographic constraints. A large area supports dairy farming but this was basaltic soils that supported rainforests and are now cleared for agricultural use. Other areas are used for plantation forestry, sugar cane farming particularly around the Bundaberg and Innisfail in Queensland. Horticultural crops are grown in areas such as Atherton Tableland in north Queensland. Kandosols Distribution: This type of soil is found in low rainfall regions (200mm to 4000mm mean annual rainfall) and is evenly distributed in Australia (Gardiner and Miller, 243). The parent material is mainly acidic igneous and sedimentary rocks that weather faster due to the high organic activity encouraged by the climatic conditions. The natural vegetation under which the soil is found is eucalyptus woodlands and open forests. Usage: Kandosols are suitable for agricultural use particularly sugar cane farming in the coasts of queensland and pasture for dairy cattle in monsoonal Australia. The drier areas are utilized for sheep and cattle grazing. However their nutritional content is low in nitrogenous compounds and the soil also has limitation to root development Properties: Kandosols are soils with weak soil structure and high clay content in the horizon B and they also lack texture contrasts within the soil profile Kandosols have moderate water availability and are very well drained and aerated. The soil also is subjected to crusting and fast hard setting which make it workability difficult. Dermosols Distribution: This soil type has a distinctive strong structure of horizon B and lacks a contrasting texture between subsequent horizons A and B. the soils has less free iron percentage and are not calcareous. The two major groups of dermosols are the red and brown dermosol. The red dermosol are found in eastern part of Australia and around the coasts of Tasmania. The areas with higher rainfall have less eutrophic and calcareous forms of dermosols. Probable parent rock of dermosols is intermediate igneous and metamorphic rock derived from alluvium. Usage: Dermosols are used for farming of wheat in New South Wales and also for pasture in the lower terraces of north east Victoria. Acidic dermosols in the north of Queensland are commonly used for plantation agriculture especially large scale farming of sugar cane. Properties: The dermosols have a water capacity of more than 100mm and this increase with soil depth and maximizes out at 200mm in deeper soils. The soils have a very well developed soil structure which consequently results in very good soil drainage and unrestricted soil aeration and root development. The soil nutritional value varies with cultivation as uncultivated land has more organic matter compared to cultivated land. Tenosols. Distribution: Tenosols are found in regions of Western Australia and to a lesser extent in the eastern parts of Australia. The soils are found under mean annual rainfall range of 200mm to 2000mm and a wide latitudinal range from tropical to temperate. Usage: The usage is for expansive grazing as its high levels of acidity make it unfavorable for crop farming. In some areas however the soil is improved to support cereals where rainfall is adequate. The vegetation is diverse and varies on the amount of precipitation, from grassland in the arid areas to forest in the high rainfall eastern occurrences Properties: These are soils that lack a distinctive degree of development of the horizons. They are weakly developed in consideration of the color, texture or structure of the soil profile. The qualities of tenosols are high water availability with good drainage and aeration, low fertility and high acidity which hinder agricultural use (Brady and Weil, 52). The soil has a contrastingly good workability. Chromosols Distribution: Chromosol are found in the eastern region of Australia but are not so common in the south west Australia. The climate under which they are found is of an average precipitation of 300 to 1200mm. the parent materials vary from Aeolian sediment to the igneous rocks. The natural vegetation of the soil is eucalypt woodland and sclerophyll forests. Usage: Chromosols are used for wheat farming in the south of new south wale, north of Victoria, while in the south of Australia they are used for oil seed growing. In the tropics chromosols are used for cattle grazing or pastures or dairy cattle. Properties: The chromosols have high levels of clay in their horizon B but still have good drainage. The soil has varying water availability but the amount of soil water is usually adequate for plan growth. The drainage is impediment with well drained horizon B and adequate aeration despite occurrences of saturation in the horizon A. the nutritional value is characterized by low concentrations of phosphorus and nitrogen but the soil generally has a good response to improvements by addition of fertilizer. The improvements also enhance the workability which is generally poor, characterized by hard setting and degraded surfaces. Vertosols Distribution: Vertosols are commonly found in Tasmania, New South Wales and Queensland. The climate in these areas has a mean annual rainfall of 500 mm to 1000mm with dominant summers and winters. The parent material is basic igneous rock while the vegetation is dominantly grassland or eucalypt woodland. Nutition and usage: Vertosols are used for oilseed crops or dry land cereals. In other areas and under irrigation the soil may be used for growing cotton or otherwise used for native pasture where rainfall is inadequate. Properties: This is mainly clay soil with characteristic ability to shrink and expand resulting in deep cracks. The soil has varying colors but mainly is brown, black or grey. The soil has moderate water availability and an imperfect aeration. The soil has limited root development ability as panning limits the growth of roots. Nutritional value has characteristic low nitrogen levels which decline further under cropping. The soils workability is improved by self mulching; however the plough panning reduces the workability. Conclusion The characteristic of soils depends on the parent material, age and organic activity which aid in the weathering process. For soils to be considered good for agricultural use there should be an orchestration of suitable texture, color and porosity which result from the soil forming process. These three soil characteristic will determine the amount of water available to plants and also the aeration of the soil. Poorly aerated soils either due to compaction or saturation with water has poor agricultural potential and therefore has less use in agriculture unless improved. The various soil types are widely distributed over Australia and the interplay between the soil characteristics and the vegetation supported is evident with the distribution of soils and coinciding vegetation. Works cited Brady Norman and Weil, Ray., The Nature and Properties of Soils, 13th edition. Upper Saddle River, New Jersey. Prentice Hall. 2002. Gardiner Derek, and Miller Richard. Soils in Our Environment, 10th edition. Upper Saddle River, New Jersey. Pearson education, Inc,2004. Indorante, Samuel , Follmer, Leon and Hammer David. and Koenig, P.G. “Particle-Size Analysis by a modified Pipette procedure.” Soil Sci. Soc. AM.J., (1990) 285 Rayment, George and Higginson, Frank, Australian Laboratory Handbook of Soil and Water Chemical Methods: Melbourne. Inkata Press, (1992) Sylvia, DeMello, Fuhrmann, Jacob., Hartel, Peter, Zuberer, David. Principles and applications of soil microbiology. Upper Saddle River, New Jersey. Prentice Hall. 1998. Read More

The pH affect the exchange capacity by altering the surface of colloids, higher amounts of Hydrogen ions neutralizes the anions thereby resulting in reduced cation exchange capacity. Soil function is affected by the concentration of salt; however this fact is mostly applicable to soils in arid and semi arid areas which experiences high evaporation. This leads to accumulation of salts in the upper horizons of the soil structure. In heavily irrigated areas the salt concentration is higher in the lower horizons due to leaching.

Saline soils contain high amount of calcium, magnesium, and potassium and sodium (Rayment, and Higginson, 314). Salinity affects structure, porosity and plant water relation and may lead to lessened yield of the soil. Podosols Distribution: This soil type is mainly found in the temperate and boreal regions. The biological development of the soil is done mainly by fungi as large animals such as earthworms are scarce in this soil type (Sylvia, Fuhrmann, and Zuberer, 18). It is mostly composed of aluminum or iron and has a lot of leaching of organic material from the upper horizon to horizon B with percolation of rain water.

The soil that remains is strongly leached and bleached and therefore lacks the A horizon. As a result of the leaching, this soil is highly acidic, has high aluminum content and low chemical fertility. Properties: The podzols are ash grey in color and are found under a dark surface horizon which is rich in organic matter and above a brown eluviations horizon. Due to bleaching the zone of eluviations contains normally less clay but the illuviation horizon has higher clay content (Brady and Weil, 41).

Mineralogy of podsols is variable but has predominance of quartz which shows that the parent material may have been intermediate or of basic composition. The composition of aluminum and iron depends with regions, higher iron content is found in podsolic soils of USA while Western Europe has higher aluminum (Gardiner and Miller, 231). The soil is chemically characterized by accretion of phosphates in the lower B horizon. This horizon is therefore acidic with pH varying between 3.5 to 4.5 and increases with depth to a maximum of 5.

5 in the deeper horizons (Brady and Weil, 46). Usage: Due to its low fertility low pH and low moisture, podsols are unattractive for agricultural use. The problems to overcome in reclamation processes include high aluminum toxicity, phosphorus deficiency and depth of ploughing to improve soil aeration and moisture capacity. The soils require liming and fertilization to counter these problems and make it suitable for agriculture. Ferrosols Distribution: Ferrosols occur in coasts north of Queensland to Tasmania in areas with mean annual rainfall ranges of 500mm to 3000mm.

This soil type has the same definition as dermosols but their horizon B has higher iron oxide content which causes a characteristic physical and chemical property that differs from the other soil types. Properties: Ferosols have a strongly developed polyhedral compound that have smooth and shinny surfaces. Other ferrosols have a very fine granular or fine structure in the horizon B. most ferosols are permeable and have good aeration despite the high clay content. The ferosols are dominated by kaolinite, hematite and varying amounts of goethite which is usually found in regions of high rainfall.

Usage: The soil is of diverse use although extensive agriculture is not usually practiced due to the topographic constraints. A large area supports dairy farming but this was basaltic soils that supported rainforests and are now cleared for agricultural use. Other areas are used for plantation forestry, sugar cane farming particularly around the Bundaberg and Innisfail in Queensland. Horticultural crops are grown in areas such as Atherton Tableland in north Queensland. Kandosols Distribution: This type of soil is found in low rainfall regions (200mm to 4000mm mean annual rainfall) and is evenly distributed in Australia (Gardiner and Miller, 243).

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