1. NUTRIENT MANAGEMENT SOIL PHYSICAL PROPERTIES

2. Soil Physical Properties  Soil texture  Soil structure  Density  Porosity  Water relations  Infiltration rate  Permeability (hydraulic conductivity)

3. Soil Texture  Definition – Proportions of sand, silt, and clay  Particle sizes – Rock Fragments >2 mm – Sand2-0.05 mm – Silt0.05-0.002 mm – Clay<0.002 mm

4. Compared to sand, clay-sized soil particles are characterized by: A.greater proportion of primary minerals B.less capacity to retain water C.less capacity to hold nutrients in plant-available forms D.greater surface area

5. Importance of Soil Texture physical properites  Structure, density, and porosity  Water holding capacity  Movement of water into and through soil  Erodibility  Shrink-swell capacity chemical properties  Organic matter content  Ability to store nutrients  Acidity and lime requirement

6. Clay Particle Al 3+ Ca 2+ K+K+K+K+ K+K+K+K+ H+H+H+H+ H+H+H+H+ exchangeableavailable (in solution) Al 3+ Ca 2+ K+K+K+K+ K+K+K+K+ H+H+H+H+ H+H+H+H+ K+K+K+K+ K+K+K+K+ K+K+K+K+ K+K+K+K+ H+H+H+H+ H+H+H+H+ H+H+H+H+ H+H+H+H+ H+H+H+H+ H+H+H+H+ K+K+K+K+ K+K+K+K+ K+K+K+K+ K+K+K+K+ Soil Texture and Nutrient Retention

7. Textural Triangle

8. Very sandy soils usually have: A.high shrink-swell capacity and low water storage capacity B.low shrink-swell capacity and high water storage capacity C.slow infiltration rates and high shrink-swell capacity D.rapid infiltration rates and low water storage capacity

9. Soil Structure  Definition – Arrangement of primary soil particles into aggregates or peds  Importance – Water infiltration and movement through soil – Soil stability – Heat transfer – Aeration

10. Types of Soil Structure  Granular  Platy  Blocky – Subangular blocky – Angular blocky  Prismatic  Columnar  Structureless – Massive – Single grain

11. Which soil structure would you expect to find in the subsoil of a soil formed in a humid climate? A.granular B.platy C.blocky D.massive

12. Granular Structure

13. Blocky Structure

14. Prismatic Structure

15. Platy Structure

16. Structureless Condition

17. Composition of a “Typical” Soil 20-30% Air 20-30% Water 45% Mineral 5% Organic

18. Bulk Density  Definition – Mass per unit volume of total dry soil, including pore space  Importance – Water movement into and through soil – Root growth – Aeration – Calculations on an acre/hectare basis

19. Bulk Density  Varies with soil properties and management factors  Organic layers…<1 g/cm 3  Medium-textured surface soils with 50% pore space…~1.3 g/cm 3  Compacted layers…approach ~2.00 g/cm 3  Root growth restricted above ~1.6 g/cm 3

20. How does bulk density usually change with depth within a soil? A.fairly constant with depth B.decreases with depth C.increases with depth D.decreases into the subsoil, then increases in the parent material

21. Porosity  Definition – Volume of nonsolid space  Total Porosity = Example: 1 - bulk density particle density 1 - 1.3 g/cm 3 2.6 g/cm 3 = 0.50, or 50%

22. Porosity  Macropores – Ready movement of air and water, but drained at field capacity  Mesopores – Retain plant-available water after drainage  Micropores – Hold water so tightly that plants cannot get it

23. Well-developed structure in a fine-textured soil increases permeability because it increases: A.total porosity B.macroporosity C.particle density D.microporosity

24. Water Relations  Field Capacity – Amount of water remaining in the soil two or three days after its having been saturated and free drainage has ceased  Wilting Point – The soil moisture content at which plants wilt and fail to recover

25. Water Relations  Available Water – Soil water that can be readily adsorbed by plants – Soil water released between field capacity and wilting point

26. How much water will a silt loam soil contain at field capacity: A.less a sandy loam B.the same as a sandy loam C.more than a sandy loam D.it depends on the particle density

27. Water Relations  Clayey soils hold more total water than silty or sandy soils – Higher total porosity – Most pores are micropores, so much of water held so tightly that it is not available to plants  Sandy soils hold less water than clayey or silty soils – Lower total porosity

28. Water Relations  Silty soils hold more plant available water than clayey or sandy soils – More mesopores sandsilt loamclay unavailable available soil water content (volume %) 0 50 fineness of texture field capacity wilting point saturation total

29. Infiltration Rate  Definition – Rate at which water enters the soil  Depends on properties of surface horizon – Texture – Structure – Organic matter content  Slope gradient affects amount of water infiltrating but not the infiltration rate – More runoff on steeper slopes

30. Permeability (Hydraulic Conductivity)  Definition – Rate of water movement through the soil profile after the water has infiltrated  The permeability (hydraulic conductivity) of a soil profile in usually based on the permeability (hydraulic conductivity) of the least permeable horizon

31. Saturated hydraulic conductivity would be slowest for soil horizons dominated by: A.strongly aggregated silty clay B.poorly aggregated silty clay C.poorly aggregated loamy sand D.strongly aggregated loamy sand

32. Texture, Structure, and Permeability

33. Infiltration and Percolation

34. NUTRIENT MANAGEMENT SOIL MORPHOLOGY AND MAPPING

35. Soil Morphology

36. Soil Morphological Properties  Soil texture  Soil structure  Soil color – Redoximorphic features  Soil horizons

37. Soil Color Observed soil color is controlled by:  the natural color of the soil minerals  the presence of soil organic matter or humus  coatings of iron oxides and hydroxides on ped surfaces Color may be acquired during soil development or inherited from the soil parent material

38. Soil Color  Dark, brown to black  organic matter  Yellow, orange, red  iron oxides  Gray  silicate minerals (quartz, clay)  White  carbonates and other salts  Black, purple  manganese oxides  Green, blue  reduced iron minerals

39. Uniform gray colors in the subsoil commonly indicate: A.High organic matter content B.High clay content C.Well drained soil conditions D.Prolonged saturated soil conditions

40. What does color tell us? Soil color may be used to make inferences about:  soil drainage  soil productivity  soil weathering  soil salinity/sodicity  soil moisture content

41. Redoximorphic Features  Matrix color—the color that occupies the greatest volume of a given soil layer  Mottles—spots or blotches of different color or shades of color interspersed with the dominant (matrix) color but not associated with the compositional properties of the soil  Redoximorphic features—mottles associated with wetness properties of the soil

42. Redoximorphic Features

43. Master Soil Horizons  O – Organic  A – Darkened mineral  E – Lighter colored; material moved out  B – Brighter color; material moved in  C – Little change from deposition  R – Hard rock

44. Major Horizons in WV Soils  O  A or Ap – plowed  E  Bh, Bs, Bhs – accumulation of organic matter and Fe and Al oxides  Bt – clay accumulation

45. Major Horizons in WV Soils  Bw –weakly developed  Bg – gleyed or gray  Bx – fragipan  Cr – soft bedrock  R – hard bedrock

46. Major Horizons A A Bt Bx BA

47. Btg A A Major Horizons

48. Ap Bw R R

49. 0 ft 1 ft 2 ft 3 ft A A E Bt C C Major Horizons

50. 0 ft 1 ft 2 ft 3 ft O O E Bs C C Bhs BC Major Horizons

51. Which of the following soil horizon sequences represents the most poorly drained soil? A.A-E-EB-Bt-BC-C B.Ap-Bw-R C.A1-A2-Bg-Cg D.O-A-Bw-C

52. Soil Mapping

53. Soil Survey Maps  Map of inferred soil properties based on field observations of related environmental variables – topography, drainage, vegetation Purpose  Delineate uniform management areas

55. Map Unit  Definition – A collection of areas defined and named the same in terms of their soil components – Each individual area on the map is called a delineation

56. Map Unit Names  Consist of taxonomic name plus phases  Phases are groupings created to serve specific purposes in individual surveys – Commonly include only part of the range of features exhibited by the taxonomic unit  Example – Monongahela silt loam, 3 to 8 percent slopes, severely eroded (MnB3)

57. Kinds of Map Units  Consociation  Complex  Association  Undifferentiated Group

58. Consociation  Delineation dominated by one soil taxon and similar soils  May have some dissimilar soils (described in mapping unit description)  Examples – Wheeling silt loam, 0 to 3% slopes – Dekalb channery loam, 12 to 25% slopes

59. Complex  Two or more dissimilar soils occurring in regularly repeating patterns on the landscape  Soils cannot be separated and mapped separately at the scale of mapping  Dominant soil named first, and word ‘complex’ used  Hyphen between soil names  Examples – Dekalb-Hazleton complex, 3 to 15% slopes, very stony – Gilpin-Upshur-Rock outcrop complex, 35 to 70% slopes

60. Association  Two or more dissimilar soils occurring in regularly repeating patterns on the landscape  Soils can be mapped separately at the scale of mapping, but not separated because of economics or land use or lack of need  Dominant soil named first and word ‘association’ added  Hyphen used between soil names  Example – Berks-Pineville association, very steep, very stony

61. Undifferentiated Group  Two or more soils not consistently associated geographically, so do not always occur together in the same delineation  Some common feature such as slope, stoniness, or flooding determines use and management  The word ‘and’ is used between soil names, and the word ‘soils’ used  Example – Gilpin and Lily soils, 3 to 15 % slopes

62. Inclusions  Similar soils – Like the named soil(s) in most properties – Differences do not significantly affect interpretations  Dissimilar soils – Properties differ from named soil(s) – Differences significantly affect interpretations – Nonlimiting l Has no adverse affect on interpretations; maybe higher potential use – Limiting l Lower potential use  Described in map unit descriptions

63. Mapping Unit Composition ~50% Named series and phase ~25%Similar phase of same series ~15% Other similar series ~10% Contrasting series

64. The purpose of a soil survey map is to delineate: A.similar ecological areas B.uniform management areas C.homogeneous taxonomic units D.uniform soil areas

65. Soil Use and Management Interpretations SlightModerate Severe

66.  Limitation ratings – Based on hazards, risks, or obstructions presented by properties or characteristics of undisturbed soil – slight, moderate, severe  Suitability ratings – Based on the characteristics of the soils that influence the ease of using or adapting a soil for a specific use – good, fair, poor, unsuited  Land capability classification – Grouping of soil map units that have similar limitations and potentials

67. Limitation Ratings  Slight – None or minor problems for the specified use – Satisfactory performance with little or no modification  Moderate – Does not require exceptional risk or cost for the specified use – Soil has certain undesirable properties or features – Some modification of the soil, special designs, or maintenance required  Severe, Very Severe – Requires unacceptable risk to use the soil if not appreciably modified – Special design, a significant increase in construction cost, or an appreciably higher maintenance cost required

68. Suitability Ratings  Good – Soils have properties favorable for the specified use – Satisfactory performance and low maintenance cost can be expected  Fair – Soils have one or more properties that make the soil less suitable than those rated good  Poor, Very Poor – Soils have one or more properties that are unfavorable for the specified use – Overcoming the unfavorable properties requires special design, extra maintenance or cost, or field alteration  Unsuited – Soil is unacceptable for the specific use unless extreme measures are employed

69. Land Capability Classification  Grouping of soil map units that have similar limitations and potentials  Capability classes and subclasses included in all soil survey reports  Classes – Designated by Roman numerals I through VIII – Numerals indicate progressively greater limitations and narrower choices for practical use – Indicates severity of problem to overcome for agriculture

70. Land Capability Classification  Class I – Suitable for all uses – Cultivation requires only ordinary farm practices  Class II – Suitable for all uses, but simple conservation practices are need when cultivated  Class III – Suitable for all uses, but intensive conservation practices are needed if cultivated  Class IV – Suitable for all uses, but cultivation should be limited

71. Land Capability Classification  Class V – Suitable for pasture, woodland, or wildlife  Class VI – Suitable for extensive pasture, woodland, or wildlife – Generally not suited for cultivation unless protected  Class VII – Suited for woodland and wildlife use – Usually not suited for pasture unless protected  Class VIII – Suitable in some cases for wildlife production or recreation, not suitable for the economic production of cultivated crops, pasture, or woodland

72. Land Capability Classification  Subclasses – Indicate problems that need to be overcome – e = erosion and runoff – w = excess water – s = soil root zone limitations – c = climatic limitations  Examples: IVe, VIIs, Vw

73. Considerations  Rarely suitable for site-specific evaluations without onsite inspection of a given location  Provide information on the likelihood that an area is suitable for a particular land use  Presented in terms of limitations imposed by one or a few soil properties – Based on the property that poses the most serious limitation

74. Considerations  Economic value of land are not a part of soil interpretations – Location relative to roads, markets, and other services  Only applicable if site characteristics are similar to what they were when the soil mapping was completed

75. Interpretive Soil Properties  Interpretations are provided for specific soil uses  Based on a set of interpretative soil properties – Site generalities l e.g., slope gradient, surface stoniness – Measurements on individual horizons l e.g., particle size distribution, saturated hydraulic conductivity – Temporal repetitive characteristics of the whole soil l e.g., depth to water table, flooding – Potential for catastrophic events l e.g., down-slope movement

76. Examples