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Biological properties of soil and biodiversity

properties of soil soil biodiversity ecology biodiversity of soil soil botany soil profile types of soil

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Biological properties of soil and biodiversity

  1. 1. Biological properties of soil and biodiversity By HAFSA ARSHAD BBOF17M006
  2. 2. SUBMITTEDTO:Dr.ABDULGHANI DEPARTMENT OF BOTANY UNIVERSITY OF SARGODHA 2
  3. 3. 3  What is soil  Soil profile  Types  Soil horizons  Properties  Soil moisture  Soil drainage  Stages of soil  How is soil formed  Composition  Importance OUTLINE
  4. 4. 4  Technically, soil is a mixture that contains minerals, organic matter, and living organisms.  But broadly speaking, soil can refer to any loose sediment.  Soil is usually referred to as the naturally occurring organic materials found on the earth’s surface.  It is mainly composed of mineral, nutrients, water, other inorganic particles and some residues of plants and animals. WHATISSOIL
  5. 5. 5  “Soil profile is defined as the vertical section of the soil from the ground surface downwards to where the soil meets the underlying rock.”  The soil is the topmost layer of the earth’s crust mainly composed of organic minerals and rock particles that support life.  A soil profile is a vertical cross-section of the soil, made of layers running parallel to the surface. These layers are known as soil horizons. SOILPROFILE
  6. 6. 6  There are many types of soil that are distributed around the world and these are generally classified into the following: » Clay Soil » Sandy soil » Loamy Soil » Silt Soil TYPESOFSOIL
  7. 7.  Clay is the smallest particles amongst the other two types of soil.  The particles in this soil are tightly packed together with each other with very little or no airspace.  This soil has very good water storage qualities and making hard for moisture and air to penetrate into it. CLAYSOIL 7
  8. 8.  It is very sticky to the touch when wet, but smooth when dried.  Clay is the densest and heaviest type of soil which do not drain well or provide space for plant roots to flourish. CLAYSOIL 8
  9. 9.  It consists of small particles of weathered rock.  Sandy soils are one of the poorest types of soil for growing plants because it has very low nutrients and poor in holding water, which makes it hard for the plant’s roots to absorb water. SANDYSOIL 9
  10. 10.  This type of soil is very good for the drainage system.  Sandy soil is usually formed by the breakdown or fragmentation of rocks like granite, limestone, and quartz. SANDYSOIL 10
  11. 11.  Silt is known to have much smaller particles compared to the sandy soil.  It is made up of rock and other mineral particles which are smaller than sand and larger than clay.  It is the smooth and quite fine quality of the soil that holds water better than sand. SILT 11
  12. 12.  Silt is easily transported by moving currents and it is mainly found near the river, lake, and other water bodies.  The silt soil is more fertile compared to the other three types of soil. Therefore it is also used in agricultural practices to improve soil fertility. SILT 12
  13. 13.  Loam is the fourth type of soil.  It is a combination of sand, silt, and clay such that the beneficial properties from each is included.  For instance, it has the ability to retain moisture and nutrients, hence, it is more suitable for farming LOAM 13
  14. 14. » This soil is also referred to as an agricultural soil as it includes an equilibrium of all types of soil materials being sandy, clay, and silt and it also happens to have hummus. » Apart from these, it also has higher calcium and pH levels because of its inorganic origins. LOAM 14
  15. 15. 15 Various properties of soil include:  Soil Texture  Organic matter  Soil Color  Structure  Consistence  Cation exchange capacity  pH PROPERTIESOFSOIL
  16. 16. SOILTEXTURE 16 Soil Separate Diameter (mm) Sand 2.0 - 0.05 Silt 0.05 - 0.002 Clay < 0.002  Refers to the proportions of sand, silt and clay sized particles that make up the mineral fraction of the soil.
  17. 17.  Color is foremost property which can be seen with naked eye and is useful in interpretation of valuable insight into the soil environment, thus it can be very important in assessment and classification of soil.  Can be used to understand parent material of the soil, the soil drainage, amount of iron and organic matter in soil. SOILCOLOR 17
  18. 18. The most influential colors in a well drained soil are white, brown, red and black.  White indicate the pre-dominance of silica (quartz) or the presence of salts.  Red indicates the presence of iron oxides.  Brown and black indicates the level and type of organic matter.  A color triangle can be used to show the names and relationships between the influential colors. SOILCOLOR 18
  19. 19. Structure influences the movement of water and gas through soils.  Soil particles that are held together by chemical and physical forces are called “peds”.  The types of soil peds define soil structure.  Structure is classified by describing:  Distinctiveness – structure of peds.  Size – size of peds.  Shape – shape of peds. SOILSTRUCTURE 19
  20. 20.  Relates to soil strength, the resistance of the soil to breaking.  Influences soil aeration and water movement through the soil and how the soil will respond to surface traffic and root penetration.  By crushing a soil ped in your hand soil consistence can be determined. SOILCONSISTANCY 20
  21. 21. . 21 SOILCONSISTANCE Loose - Non-coherent Very Friable - Soil crushes under very gentle pressure, but keeps a form when pressed together. Friable - Soil crushes under very gentle to moderate pressure, but keeps a form when pressed together. Firm - Soil is hard to crush under moderate pressure Very Firm - Soil crushes under strong pressure, barely crushable. The classes of consistence for moist soil are:
  22. 22. A measure of the acidity or alkalinity of soil and is measured in pH units.  pH scale goes from 0 (acidic) to 14 (basic) with pH 7 as the neutral point.  Most soils have pH values between 4 and 8.  The solubility of minerals and nutrients in soil is highly dependent on the pH of that soil. pH 22
  23. 23. Drainage is defined by the length of time it takes water to be removed from the soil in relation to the supply. Drainage is affected by: • Soil-External Factors • Soil-Internal Factors SOILDRAINAGE 23
  24. 24. External Factors:  Position on the slope – soils in upper positions tend to be better drained than those in the lower slopes.  Aspect – Southern aspects are warmer than northern aspects, therefore southern aspects will have less soil water and better drainage.  Climate – Areas that receive high amounts of rainfall will have poorer drainage than those that receive low amounts.  Bedrock – The presence and type of bedrock can affect the rate and the flow direction of soil water. SOILDRAINAGE 24
  25. 25. Internal Factors:  Soil texture – Coarse to medium textured soils will tend to have better drainage.  Stoniness – Soils with gravels and cobbles have a improved drainage.  Consistence – Soils with loose and friable consistence will have better drainage than those with firm and very firm consistence. SOILDRAINAGE 25
  26. 26. 26  The soil is arranged in layers or horizons during its formation. These layers or horizons are known as the soil profile.  It is the vertical section of the soil that is exposed by a soil pit. The layers of soil can easily be identified by the soil colour and size of soil particles  Topsoil  Subsoil  Parent rock LAYERSOFSOIL
  27. 27. 27  The soil profile is composed of a series of horizons or layers of soil stacked one on top of the other.  These layers or horizons are represented by letters O, A, E, C, B and R. • O horizon • A horizon • E horizon • C horizon • B horizon • R horizon SOILHORIZONS
  28. 28.  The O horizon is the upper layer of the topsoil.  It is mainly composed of organic materials such as dried leaves, grasses, dead leaves, small rocks, twigs, surface organisms, fallen trees, and other decomposed organic matter.  It contains about 20 to 30% of organic matter.  This horizon of soil is often black brown or dark brown in colour and this is mainly because of the presence of organic content. O-HORIZON 28
  29. 29.  This layer is rich in organic material and is known as the humus layer.  This layer consists of both organic matter and other decomposed materials.  The topsoil is soft and porous to hold enough air and water.  In this layer, the seed germination takes place and new roots are produced which grows into a new plant.  This layer consists of microorganisms such as earthworms, fungi, bacteria, etc. A-HORIZON 29
  30. 30.  It is the subsurface horizon, present just below the topsoil and above the bedrock.  It is comparatively harder and compact than topsoil. It contains less humus, soluble minerals, and organic matter.  It is a site of deposition of certain minerals and metal salts such as iron oxide.  This layer holds enough water than the topsoil and is lighter brown due to the presence of clay soil.  The soil of horizon-A and horizon-B is often mixed while ploughing the fields. B-HORIZONORSUBSOIL 30
  31. 31.  This layer is devoid of any organic matter and is made up of broken bedrock.  This layer is also known as saprolite.  The geological material present in this zone is cemented. C-HORIZONORSAPROLITE 31
  32. 32.  It is a compacted and cemented layer.  Different types of rocks such as granite, basalt and limestone are found here R-HORIZONORSAPROLITE 32
  33. 33. 33  Apart from the rocks, minerals, and layers, soil profile also consists of a water content, which is referred to as soil moisture.  Water in the soil is referred to as soil moisture.  Water absorption in soil is determined by various factors. It plays a major role in soil formation.  Moisture content in the soil can be measured using a device known as Tensiometer. SOILMOISTURE
  34. 34. 34 The different types of water present in the soil include: Gravitational Water The water that reaches the water table of the soil due to the gravitational force is referred to as gravitational water. This is not available to the plants. Hygroscopic Water This water is also not available to the plants. It is a thin film of water tightly held by the soil particles. TYPESOFSOILMOISTURE
  35. 35. 35 Chemically Combined Water The chemical compounds present in the soil particles contain water. This is known as chemically combined water. This is also not available to the plants. Capillary Water This water is available to the plants for absorption. This water exists between soil particles in small capillaries. Atmospheric Humidity The hanging roots of the epiphytes absorb the moisture in the air due to the presence of hygroscopic hairs and spongy velamen tissues. TYPESOFSOILMOISTURE
  36. 36. 36 There are three stages of soil:  Solid soil,  Soil with air in the pores,  Soil with water in the pores. STAGESOFSOIL
  37. 37. 37 Essentially, soil is formed when rocks eventually weather away and break down into small particles. Solid rock can weather away one of the three ways into the soil, namely: » Mechanical Weathering » Chemical Weathering » Biological Weathering HOWISSOILFORMED
  38. 38. » This is commonly observed near the surface of the earth. » Also called physical weathering, as this process is influenced by physical forces such as wind, water and temperature. MECHANICALWEATHERING 38
  39. 39. » As the name suggests, chemical weathering occurs when rocks are broken down by chemical reactions. » Often, such types of weathering can change the chemical composition of soil. CHEMICALWEATHERING 39
  40. 40. » Though not an actual weathering process, living organisms weaken and subsequently disintegrate rocks, often by initiating mechanical or chemical weathering. » For instance, tree roots can grow into cracks in the rock, prying them apart and causing mechanical fractures. » Microorganisms can secrete chemicals that can increase the rock’s susceptibility to weathering. BIOLOGICALWEATHERING 40
  41. 41. 41 The soil is composed of:  5% organic matter  45% minerals  20-30% different gases  20-30% water. Therefore, soil is known as a heterogeneous body. COMPOSITIONOFSOIL
  42. 42. Organic substance is found in very small amounts in soil. Plants and animals are the main sources of organic matter. Depending upon the decomposition stage, the organic matter is of the following three types:  Completely decomposed organic matter  Partially decomposed organic matter  Undecomposed organic matter ORGANICMATTER 42
  43. 43.  Mineral is an important element of the soil.  These are solid components composed of atoms.  These occur naturally and have a fixed chemical composition.  Olivine and feldspar are the main minerals present in the soil. MINERAL 43
  44. 44.  The air-filled pores of the soil contain the gaseous components.  Nitrogen and oxygen present in the pores is generally the atmospheric air fixed by the microorganisms.  However, the composition of carbon dioxide is higher due to the gas produced by microorganisms present in the soil. GASEOUSCOMPOUNDS 44
  45. 45.  The soil dissolves the minerals and nutrients in water and transports it to different parts of plants.  Water is essential for the growth and development of the plant. WATER 45
  46. 46. 46 » Soil is an important element essential for the survival of living organisms. The importance of soil is mentioned below:  The fertile soil helps in the growth and development of the plants.  The plants thus produced are healthy and provide food, clothing, furniture, and medicines.  Provides habitat for organisms IMPORTANCEOFSOIL
  47. 47. 47 » The topsoil supports certain life activities such as reproduction, hatching, nesting, breeding, etc. of a few organisms. » The organic matter present in the soil increases the fertility of the soil which is responsible for the growth of the plants. » It also contains certain minerals and elements that are necessary for the plants to carry out their cellular activities. IMPORTANCEOFSOIL
  48. 48. 48  It supports many life forms including bacteria, fungi, algae, etc.  These microbes, in turn, maintain environmental balance by retaining the moisture and decaying the dead organisms. » Useful mineral medicines such as calcium, iron, and other substances such as petroleum jelly for cosmetics are extracted from the soil. IMPORTANCEOFSOIL
  49. 49. 49  The soil absorbs the rainwater.  This water is evaporated and released into the air during sunny days, making the atmosphere cooler  Providing a growth medium for the plants  Acts a modifier of the earth’s atmosphere  One of the most crucial components of the biosphere IMPORTANCEOFSOIL
  50. 50. 50  Which soil is called as the gardener’s best friend? Loam or Loamy soil is called as the gardener’s best friend.  Which crop can be grown in Loamy soil? Loamy soil is suitable and best soil for growing crops such as Cotton, oil seeds, sugarcane, wheat, pulses, jute, and other Vegetables.  Which soil is preferable to grow coconut and melon? Sandy soil is the preferable soil to grow coconut and melon. SOMEQUESTIONSABOUTSOIL
  51. 51. 51  What are the basic components of Soil? Air, water, minerals and other organic matter are the basic components of soil.  What are the horizons of soil? The soil profiles are composed of a series of horizons or layers of soil, which are stacked one above the other. The 4 horizons of soil are: • The O-Horizon. • The A-Horizon. • The B-Horizon. • The C-Horizon. SOMEQUESTIONSABOUTSOIL
  52. 52. SOIL BIODIVERSITY My subtitle
  53. 53. 53  Soil biodiversity is generally defined as the variability of living organisms in soil and the ecological complexes of which they are part  This includes diversity within species, between species and of ecosystems  Soil biodiversity refers to the relationship of soil to biodiversity and to aspects of the soil that can be managed in relation to biodiversity.  Soil biodiversity relates to some catchment management considerations. SOILBIODIVERSITY
  54. 54. 54 The diversity of organisms living within soils is critical to all earth ecosystems because soil organisms are  essential for the cycling of ecosystem nutrients  necessary for plant growth and plant nutrition.  improve the entry of water into soil and its storage in the soil WHYISSOILBIODIVERSITYIMPORTANT
  55. 55. 55  The highest amount of the soil ecological capital is in the form of microbial biomass (bacteria and fungi).  The absolute and the relative amount of these organisms give a good indication of the activity and stability of the ecosystem.  Both can be determined in one measurement, e.g. by automised spectroscopy. HOWISSOILBIODIVERSITYMEASURED
  56. 56. 56  The activity of soil biodiversity can be stimulated by improving soil living conditions, such as aeration, temperature, moisture, and nutrient quantity and quality.  In this regard, reduced soil tillage and minimized compaction - and refraining chemical use - are of particular note HOWISSOILBIODIVERSITYIMPROVED
  57. 57. Thank You HAFSA ARSHAD hafsaranjha.botanist@gmail.com

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