agriculture electronics for engineering students

unit 1 notes

1. 191OE2A AGICULTURE ELECTRONICS Handled by, Dr. R. Jenitha Assistant Processor, ECE Dept, P.S.R. Engineering College

2. aypy7hw Google Classroom Code 7/17/2024 191OE2A - Agriculture Electronics 2

3. SOIL TEXTURE Soil texture refers to the relative percentage of sand, silt and clay in a soil. The proportion of each size in a given soil (the texture) cannot be easily altered and it is considered as a basic property of a soil. The soil separates are defined in terms of diameter in millimeters of the particles. Soil particles less than 2 mm is called fine earth and are excluded from soil textural determinations. SOIL TEXTURE

4. Soil Textural Classes Sand: It includes all soils in which the sand separates make up at least 70% of the material by weight. Silt: It includes soils with at least 80% silt and 12% or less clay. Particle size intermediate between sand and clay. Clay: It includes soils with at least 35-40% clay separate. SOIL TEXTURE

5. The textural triangle SOIL TEXTURE

6. Methods of Textural determination 1. Feel Method : Texture is commonly determined by the sense of feel. Sand feels gritty and its particles can be easily seen Silt(when dry) feels like flour/ talcum powder ; and is slightly plastic when wet Clay feels very plastic and is very sticky when wet and hard under dry conditions 2. Laboratory method : Elutriation method – Water & Air Pipette method iii) Decantation/ beaker method iv) Test tube shaking method SOIL TEXTURE

7. SOIL TEXTURE Influence of Soil Texture Separates on Some Properties of Soils Property/ behavior Sand Silt Clay Water-holding capacity Low Medium to high High Aeration Good Medium Poor Drainage rate High Slow to medium Very slow Soil organic matter level Low Medium to high High to medium Decomposition of organic matter Rapid Medium Slow Warm-up in spring Rapid Moderate Slow Compactability Low Medium High Shrink/Swell Potential Very Low Low Moderate to very high Ability to store plant nutrients Poor Medium to High High

8. SOIL STRUCTURE The arrangement of primary particles (sand, silt, clay) and their aggregates into a certain definite pattern is called soil structure. Influence of soil structure on soil physical properties: Aeration/ Porosity Temperature Density Consistency Colour Etc. SOIL STRUCTURE

9. I. TYPES OF SOIL STRUCTURE 1. Platy: Peds are flattened one atop the other; 1–10 mm thick. Found in the A-horizon of forest soils and lake sedimentation. 2. Prismatic and Columnar: Prismlike peds are long in the vertical dimension; 10–100 mm wide. Prismatic peds have flat tops, columnar peds have rounded tops. Tend to form in the B-horizon in high sodium soil where clay has accumulated. SOIL STRUCTURE PLATY SOIL COLUMNAR SOIL PRISMATIC SOIL

10. 3 . Angular and subangular : Blocky peds are imperfect cubes, 5–50 mm, angular have sharp edges, subangular have rounded edges. Tend to form in the B-horizon where clay has accumulated and indicate poor water penetration. 4. Granular and Crumb: Spheroid peds of polyhedrons, 1–10 mm, often found in the A-horizon in the presence of organic material. Crumb peds are more porous and are considered ideal. SOIL STRUCTURE ANGULAR BLOCKY SOIL SUB ANGULAR SOIL GRANULAR SOIL

11. II. CLASSES OF SOIL STRUCTURE SOIL STRUCTURE PLATY & SPHERICAL BLOCKY PRISMLIKE 1. Very fine or very thin <1 mm <5 mm <10 mm 2. Fine or thin 1–2 mm 5–10 mm 10–20 mm 3. Medium 2–5 mm 10–20 mm 20-50 4. Coarse or thick 5–10 mm 20–50 mm 50–100 mm 5. Very coarse or very thick >10 mm >50 mm >100 mm

12. III. GRADES OF SOIL STRUCTURE Structureless : No aggregation or orderly arrangement. Soil is entirely cemented together in one great mass. Weak: Poorly formed; Non-durable. Weak cementation allows peds to fall apart. Moderate: Well formed; moderately durable. Indistinct in undisturbed soil but may break into aggregates. This is considered ideal. Strong: Well formed; durable. Peds are distinct before removed from the profile and do not break apart easily. SOIL STRUCTURE

13. FACTORS AFFECTING SOIL STRUCTURE Climate: Climate influences the degree of aggregation as well as on the type of soil structure. In arid regions there is very little aggregation. In semi arid regions, the degree of aggregation is greater. 2. Organic matter: Organic matter improves the structure of sandy soil & clay soil. In case of sandy soil, the sticky and slimy material produced by decomposing om cement the sand particles together to form aggregates. In case of clayey soil, it modifies the properties of clay by reducing its cohesiveness. This helps make clay more crumby. 3. Adsorbed cations : Aggregate formation is influenced by nature of cation adsorbed. Na⁺ --- Deflocculation --- Poor structure Ca²⁺ --- Flocculating --- Good structure SOIL STRUCTURE

14. 4 . Tillage: Intensive cultivation increased infiltration capacity and penetrability, but spolied soil structure. For obtaining good soil structure, tillage operation should be made at optimum moisture conditions. 5. Type of vegetation: Grasslands and forest soils have high stability of aggregates. 6. Animals: Among the soil fauna small animals like earthworms, moles and insects etc., that burrow in the soil are the chief agents that take part in the aggregation of finer particles. 7. Microbes: Algae, fungi, actinomycetes and fungi keep the soil particles together. 8. Fertilizers: Fertilizer like Sodium Nitrate destroys granulation by reducing the stability of aggregates. Few fertilizers for example, CAN help in development of good structures. 9. Wetting and drying: When a dry soil is wetted, the soil colloids swell on absorbing water. On drying, shrinkage produces strains in the soil mass gives rise to cracks, which break it up into clods and granules of various sizes. SOIL STRUCTURE

15. Role of soil structure in relation to plant growth Soil structure influences the amount and nature of porosity. Structure controls the amount of water and air present in the soil. It affects tillage practices. Structure controls runoff and erosion. Platy structure normally hinders free drainage whereas sphere like structure (granular and crumby) helps in drainage. Crumby and granular structure provides optimum infiltration, water holding capacity, aeration and drainage. It also provides good habitat for microorganisms and supply of nutrients.

16. Soil properties Soil texture Soil porosity Soil chemistry Soil color Soil permeability Consistence Particle density Bulk density Pore space Atterberg limits

17. WHAT IS SOIL? SOIL PROFILE : A vertical exposure of the horizon sequence of the soil is termed a soil profile. The layers that make up a soil profile are called horizons. The Horizons are identified by the letters A, E, B, C, O and R. Each zone has a different composition, and has different influences on what type of life that soil can support.

18. SOIL TEXTURE The Texture refers to the relative amount of sand, silt, and clay in the soil. The particles that make up soil are categorized into three groups by size – sand, silt, and clay. Sand are the largest particles and feel “gritty” Silt are medium sized and feel soft, silky or “floury” Clay are the smallest sized particles and feel “sticky” Soil containing equal amount of sand, slit and clay is called “Loam”. SAND SLIT CLAY

19. SOIL TEXTURE CONT. The proportions of different sized mineral particles in the soil or the relative amount of sand, silt, and clay present in the soil expressed as percentages. SOIL TEXTURAL CLASSES: Textural classification of soil means classification of soils on the basis of their texture into different groups or classes such as Sand, Sandy-loam and Silty loam. The broad and fundamental groups of soil textural classes are recognized as Sands, Silt and Clays. There are 12 textural class categories.

20. SOIL TEXTURE CONT. IMPORTANCE : Soil texture is one of the most important properties of a soil, and it greatly affects land use and management. It affects the amount of water and nutrients that a soil can hold and supply to plants. Soil physical properties such as structure, and movement of air and water through the soil are affected by texture.

21. SOIL STRUCTURE The arrangement of particles in the soil mass is called soil structure. Soil structure also be defined as aggregates into which soil breaks up. OR Simply, The way in which soil particles are grouped or bound together to form lumps or aggregates is known as soil structure. The primary soil particles such as sand, silt and clay usually occur grouped together in the form of aggregates. Natural aggregates are called peds whereas artificial aggregates are called clods.

22. SOIL STRUCTURE CONT. Clods are formed due to disturbance of the field by ploughing or digging. The words fragmentation and concretions are often used in connection with the structure of soil. Fragment is a broken peds whereas when salts dissolved in percolating water precipitate, it results in the formation of concretions. The soil conditions and characteristics such as water movement, heat transfer, aeration, bulk density and porosity will be much more influenced by structure.

23. SOIL STRUCTURE CONT. IMPORTANCE : Soil structure is one of the most important soil’s physical factors controlling or modulating the flow and retention of water, solutes, gases, and biota in agricultural and natural ecosystems. Soil structure is very important in soil productivity and is a limiting factor of crop yield. Soil structure controls many processes in soils. It regulates water retention and infiltration, gaseous exchanges, soil organic matter and nutrient dynamics, root penetration, and susceptibility to erosion.

24. SOIL COLOR Soil color is one property that can be used to describe horizonation and soil morphology. The change in soil color with depth is directly related to a variety of processes that are occurring in the soil The colour of soils is due to the colour of their constituents. For example: Black coloured soils are rich in organic matter and therefore fertile. Red coloured soils are rich in ferric oxide Yellow color is due to hydrated iron oxides and hydroxide. The colour of a soil is inherited from its parent rock material. As for example, red soil developed from red sand stone and sand developed from quartz.

25. SOIL COLOR CONT. Soil color is described by the parameters called Hue, Value and Chroma. Hue represents the dominant wave length or color of the light. Value, refers to the lightness of the color. Chroma, relative purity or strength of the color. The colour of the soil in terms of the above parameters could be quickly determined by comparison of the sample with a standard set of colour chips mounted in a note-book called MUNSELL SOIL COLOUR CHARTS ( Munsell Soil Colour Charts, 1973).

26. SOIL COLOR IMPORTANCE : Color is an important characteristic used in the identification of soil conditions that affect the value of land for agricultural uses. Soil color gives an indication of the various processes going-on in the soil as well as the type of minerals in the soil. The colour of a soil is an indication of the nature of an individual soil. The soil color does not effect the behavior of the soils, but provides insights into environmental conditions, formation processes, and other Influences on the soil. Soil color is also used to for classification of soils.

27. SOIL DENSITY The Soil Density is defined as the property of soil, suggesting how closely the soil grains will be arranged within the volume of soil. There can be spaces between particles, containing air and water. Soil density is expressed in two well accepted concepts which are, Particle density Bulk density

28. SOIL DENSITY CONT. PARTICLE DENSITY : (Also termed as true density) The weight per unit volume of the solid portion of soil is called Particle density. It refers to only the solids excluding the voids. In the metric system, particle density can be expressed in terms of mega grams per cubic meter (Mg/m3). Generally particle density of normal soils is 2.65 grams per cubic centimeter. The particle density is higher if large amount of heavy minerals such as magnetite; limonite and hematite are present in the soil. With increase in organic matter of the soil the particle density decreases.

29. SOIL DENSITY CONT. BULK DENSITY: (Also called as apparent density) Bulk density is considered as the total mass of the soil (includes water present) divided by soil volume. OR The oven dry weight of a unit volume of soil inclusive of pore spaces is called Bulk density. The bulk density of sandy soil is about 1.6 g / cm3, whereas that of organic matter is about 0.5. The bulk density of a soil is always smaller than its particle density. Bulk density normally decreases, as mineral soils become finer in texture.

30. SOIL DENSITY CONT. IMPORTANCE: Soil density is important from the point of view of plant growth especially root penetration. A shallow plant root and poor plant growth resulting from compacted and high bulk density soils will influence crop yield and reduce vegetative cover available to protect soil from erosion. Bulk density reflects the soil’s ability to function for structural support, water and nutrient and microbial life movement, and soil aeration.

31. SOIL POROSITY Porosity refers to how many pores, or holes, a soil has. The porosity of a soil is expressed as a percentage of the total volume of the soil material. The space between particles is called pore space which determines the amount of water that a given volume of soil can hold. Pore spaces between the aggregates of soil particles are macro pores Pore spaces between the individual particles of the aggregates are micro pores. Mainly, pore spaces facilitate the availability and movement of air or water within the soil environment.

32. SOIL POROSITY CONT. POROSITY IN SANDY AND CLAY SOILS: Sandy soils have a higher percentage of macro pores.  Typically, moisture content in sandy soils is relatively low when compared to clay soils. Whereas, Clay soils contain a higher percentage micro pores when compared to sandy soils. Clay soils are more susceptible to water logging which can adversely affect root respiration and microbial activity.

33. SOIL POROSITY CONT. IMPORTANCE : Porosity is one of the major important property of the soil as it facilitates the storage of water availability of air within the soil. Porosity also affects the structure and consistency of the soil. It helps the plant roots to grow further move easily within the soil environment. Porosity is a main indicator of soil structural quality. Therefore, its characterization is essential for assessing the impact of adding organic matter to a soil system.

34. SOIL CONSISTENCE Soil consistence is defined as a term to designate the manifestation of physical forces of cohesion and adhesion acting within the various level of moisture content. It is the physical condition of the soil at various moisture content as evidenced by the behavior of that soil toward mechanical stresses or manipulation. The manifestation as stated in the definition includes as follows: Behavior of the soil towards gravity, pressure, thrust and pull. Tendency of the soil mass to adhere to foreign bodies. Tactile quality of soil on rubbing between the fingers.

35. SOIL CONSISTENCE CONT. SOIL TILLAGE: Tillage is the physical manipulation of soil with tools and implements to result in good tilth for better germination of seeds and subsequent growth of crops. Tillage helps to replace natural vegetation with useful crop and to improve the physical condition of soil, control of weeds, insect-pests and diseases and also bring the nutrient available to plant. The cultivation is not possible without tillage operation.

36. SOIL CONSISTENCE CONT. SOIL COMPACTION : Soil compaction is the process of increasing dry bulk density of soil, reducing the pore space by expulsion of air through applied pressure on a soil body. Under very high pressure, the soil particles may themselves be compressed but only slightly. Compaction due to the machines used for tillage of land, harvesting and threshing of crops has adverse effects on the growth of plants due to reduced aeration and increased bulk density of the soil. Compaction of the soil may also be due to grazing of animals, human activities in the field and intense rainfall as well as irrigation.

37. SOIL CONSISTENCE CONT. IMPORTANCE : Soil consistence provides a means of describing the degree and kind of cohesion and adhesion between the soil particles as related to the resistance of the soil to deform or rupture. Consistence is an important characteristic of the soil as affects the nature of force between particles of the soil. It is important for Tillage or traffic consideration.

38. SOIL TEMPERATURE Soil micro-organisms show maximum growth and activity at optimum soil temperature range. All crops practically slow down their growth below the temperature of about 9°C and above the temperature of about 50°C. The biological processes for nutrient transformations and nutrient availability are controlled by soil temperature and soil moisture.

39. SOIL TEMPERATURE CONT. Sources of Soil Temperature are: SOLAR RADIATION : The main source of heat is the sun. The temperature of the soil is primarily dependent upon the amount of radiant energy received from the sun. The sun rays reach the earth after they pass through the atmosphere and warms the surface of the soil on which they fall. A part of soil temperature is lost to the air by radiation.

40. SOIL TEMPERATURE CONT. CONDUCTION : The heat is absorbed from solar radiation by surface soil and is conducted down the depth of the soil. The interior of the earth is very hot, the conduction of this heat to the soil is very slow. BIOLOGICAL AND CHEMICAL REACTION : In a soil, various biological and chemical reaction occurs. As a result, some amount of heat is liberated in the soil due to biological and chemical reaction.

41. SOIL TEMPERATURE CONT. IMPORTANCE : Soil temperature is important to growers, especially for spring planting. Many seeds need a certain minimum temperature for germination. Soil temperature has a profound influence on seed germination, root and shoot growth, and nutrient uptake and crop growth. Seeds do not germinate below or above a certain range of temperature but micro-organism functioning in the soil is very active while a certain range of temperature, which is about 27° to 32°C.

42. Atterberg Limits The Atterberg Limits are: the shrinkage limit, plastic limit, and liquid limit. In addition, there is the commonly referred to ‘Plasticity Index’: The Shrinkage Limit (SL) is the water content where further loss of moisture will not result in any more volume reduction. The Plastic Limit (PL) is minimum water content at which a soil is considered to behave in a ‘plastic’ manner, i.e. is capable of being moulded . The Liquid Limit (LL) is the maximum water content a silt or clay can have before becoming a liquid, i.e. turning into mud. The Plasticity Index (PI) is the range of moisture contents where the silt or clay remains plastic (PI = LL – PL).

43. Soil Formation Soil formation or pedogenesis, is the combined effect of human impact on environment, physical, chemical and biological processes working on soil parent material. Climate regulates soil formation. Soils are more developed in areas with higher rainfall and more warmth. The rate of chemical weathering increases by 2-3 times when the temperature increases by 10 degree Celsius.

44. Soil Formation Addition Loss Translocation Transformation

45. Addition Water from rainfall. O2 & CO2 from the atmosphere. OM from decomposition of plants & animals residues. Eroded materials from sediments Nutrients or ions from rain water, atmosphere, etc. Energy from sunlight

46. Losses Water through evapotranspiration. Nitrogen by denitrification & volatilization. O2 & CO2 through oxidation of OM. Soil by erosion Water & nutrients by leaching. Energy by radiation.

47. Translocation (from one location to another) Salts that are dissolved in water. Nutrients that cycle in plants. Soil by animals, e.g.. Earthworms

48. Eluviation It is the mobilization and translocation of certain constituent’s viz. Clay, Fe2O3, Al2O3, SiO2, humus, CaCO3, other salts etc. from one point of soil body to another. It is the process of removal of constituents in suspension or solution by the percolating water from the upper to lower layers. The horizon formed by the process of eluviation is termed as eluvial horizon (A2 or E horizon).

49. Fundamental soil forming process Humification is the process of decomposition of organic matter and synthesis of new organic substances. It is the process of transformation of raw organic matter into formation of surface humus layer, called Ao- horizon. The percolating water passing through this layer dissolves certain organic acids and affects the development of the lower A-horizon and the B- horizon. 1. humification

50. Fundamental soil forming process Eluviation is the process of removal of constituents by percolation from upper layers to lower layers. This layer of loss is called eluvial and designated as the A-horizon. The eluviated producers move down and become deposited in the lower horizon which is termed as the illuvial or B-horizon. The eluviation produces textural differences. The process of illuviation leads to the textural contrast between A2 and B1 horizon. 2.&3. Eluviation and illuaviation

51. 4. Horizonation The development of all the horizons in soil is termed as horizonation . In the favorable conditions it take about 250 years but in adverse conditions take even 1000 years.

52. Soil moisture

53. Soil ph

54. Nutrient availability in relation to soil pH

55. Mcq on soil formation Which of the following is NOT a factor of soil formation? A) Climate B) Parent material C) Topography D) Pollution What is the primary role of parent material in soil formation? Determining soil color B) Providing mineral content C) Influencing soil pH D) All of the above

56. Mcq on soil formation Which soil horizon is typically known as the topsoil? A) O horizon B) A horizon C) B horizon D) C horizon Which process involves the breakdown of rocks into smaller particles to form soil? A) Erosion B) Leaching C) Weathering D) Sedimentation

57. Mcq on soil formation Humus is an important component of soil because it: A) Increases water retention B) Provides essential nutrients C) Improves soil structure D) All of the above

58. Mcq on soil Soil Moisture What term is used to describe the amount of water soil can hold against gravity? A) Field capacity B) Wilting point C) Saturation D) Permeability At which point do plants start to wilt because they cannot extract water from the soil? A) Field capacity B) Wilting point C) Saturation point D) Hygroscopic point

59. Mcq on soil Soil Moisture Which type of soil typically has the highest water-holding capacity? A) Sandy soil B) Silty soil C) Clay soil D) Loamy soil What does the term "percolation" refer to in soil science? A) The movement of air through soil B) The downward movement of water through soil C) The absorption of water by plants D) The evaporation of water from the soil surface