Study Guide for Exam
Study Guide for Exam PSS 3303
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This 7 page Study Guide was uploaded by Payton Gilmore on Monday October 3, 2016. The Study Guide belongs to PSS 3303 at Mississippi State University taught by Dr. Jac J. Varco in Fall 2016. Since its upload, it has received 40 views. For similar materials see Soils in plant and soil sciences at Mississippi State University.
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Date Created: 10/03/16
Study Guide 1. What are the effects of drainage on soil color? 2. Explain the difference between dispersion and flocculation of soil particles. 3. Define macropores and micropores relative to drainage? 4. What are the effects of soil texture on bulk density? 5. What are the effects of pore size distribution? 6. Field capacity occurs at a soil water potential of ________. 7. A soil with a bulk density of 1.42 g/cmand holds 26% volumetric water (Pv) at field capacity would have a macropore space of approximately _________. 8. Hydraulic conductivity (K) of soils depends greatly on ____________. 9. For three soils, all at a water potential of 0.3 bars, this texture would have the greatest volumetric water content. ____ A. sandy loam B. silt loam C. clay loam 10. All capillary water in soil is considered to be plant available. A. true B. false 11. Available water occurs within the soil water tension ranges of ______ to _______. 12. As soil with a bulk density of 1.27 g/cm^3 and holds 32% volumetric water (Pv) at field capacity would have macropore space of approximately _______. 13. For three soils, all at a water potential of 0.3 bars, this texture would have the lowest volumetric water content. ____ A. Silt loam B. Sandy loam C. Clay loam 14. Capillary water occurs in _____________. A. Micropores only B. Macropores only C. Both 15. This soil color would indicate poor drainage and the presence of reduced iron____________. 16. Excessive quantities of this cation in soil causes the greatest dispersion. ________. 17. The diameter of micropores is considered to be less than ______mm. 18. Which of the following pore size distribution (ration of macro to mircropores) might indicate a coarse or sandy soil texture? A. 65/35 B. 50/50 C. 35/65 19. In their native well aggregated state, this soil textural class generally has the lowest total pore space. ___________________. 2 20. _________________ _____________ The attraction between hydrogen of one molecule and the negative portion of another molecule, usually oxygen. 21. Define Adhesion. 22. Define Cohesion 23. ______________ ______ Moisture condition of a soil when all or nearly all of the pores are filled with water, also maximum retentive capacity. 24. ______________ __________ Soil in which large, aeration pores (macropores) are empty of water. 25. ________ Pressure or suction (tension) of approximately 760 mm Mercury (Hg) or a column of water 1023 cm in height. Approximately equal to one atmosphere (14.67 lb/in^2) 26. Define Gravitational water 27. ____________ water Soil water held in small (capillary) pores and as a film around soil particles. Moves in response to tension differences. 28. _________________ water Soil water held as a thin film on the surface of soil particles. Moves only by evaporation and condensation, i.e., in vapor state. 3 29. ____________ _______________ The amount of water held in soil when the gravitational water has drained out. Water is at approximately 0.1 to 0.33 bar SWP. 30. Define Wilting point 31. _______________ ____________ ______________ ______________(AWHC) The amount of water that a soil can hold that is available to growing plants, usually between 0.1 or 0.33 bars to 15 bars SWP. 32. Define Gravitational potential 33. __________ potential Attractive force between soil solids and soil water. Always negative (tension) and responsible for soil water adsorption and capillarity. 34. ____________ potential Soil water potential due to presence of solutes in water. A negative pressure or suction. 35. Water molecules are attracted to each other and to molecules of other substances by ____________________ bonding. Use I for increase and D for decrease, to indicate the direction of change in free energy of the water molecules in each process below: 36. Liquid water to water vapor (Evaporation) _____ 37. Water vapor to liquid (Condensation) ________ 4 38. Adsorption by soils or ions _____ 39. Increases temperature _____ 40. Movement from wet to dry soil _______ List the approximate range in pressure potential for each of the following forms of soil water. (Be sure to include units) Form of water Tension range 41. Field capacity ______________________ 42. Plant available water ______________________ 43. Capillary water ______________________ Use S to indicate saturated soil conditions and U for unsaturated soil conditions in regards to the following characteristics: 44. _____ Driving force is gravity 45. _____ Driving force is capillarity 46. _____ Large and small pores filled with water 47. _____ Water only in small pores 48. _____ Soil poorly aerated 49. _____ Soil aerated 50._____ Water movement through large pores 5 51. _____ Water movement through small pores 52. _____ Water movement mainly downward through soil 53. _____ Water movement may be in all directions 54. _____ Water movement slow 55. _____ Water movement rapid 56. _____ Water molecules have lower energy 57. _____ Water has only negative potential or tension (matric and osmotic) 58. _____ Water has positive potential (gravity) 59. If a soil is saturated with water, what would be the approximate percent by volume of water held (water content as a percentage of total soil volume)? _____________________________________________________________________ 60. If a soil is saturated with water and has a bulk density of 1.5 g/cm and a particle density of 2.65 g/cm^3, what is the percentage by weight of water held by the soil? _____________________________________________________________________ 6 7
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