Soil Science

1. Soil Science “Land, then, is not merely soil; it is a fountain of energy flowing through a circuit of soils, plants, and animals.” - Aldo Leopold, A Sand County Almanac, 1949

2. IGNEOUS ROCK SEDIMENTARY ROCK METAMORPHIC ROCK The Rock Cycle Erode & Weather SEDIMENT Cool & Harden Compaction & Cementation Melt Erode & Weather Heat & Pressure Erode & Weather MAGMA Melt Heat & Pressure Melt

3. What is SOIL???? • The relatively thin surface layer of the Earth’s crust consisting of mineral and organic matter. Soil is not DIRT!

4. Q: What’s the difference between soil and dirt? • Location, • location, location! • Dirt is found under your nail, • soil is found beneath your feet

5. The 5 Soil-Forming Factors Formed from parent material (bedrock) that’s slowly broken down through weathering processes. • climate (water, wind, temperature) • biology (macro- and microorganisms, plants) • relief(topography) • parent material(rocks/minerals) • time Which is the MOST important?? CLIMATE!!!

6. What is Soil? How would you describe soil? Texture Color • Texture

7. Why the color? http://www.cs.cmu.edu http://www.msstate.edu http://www.mii.org Hematite: red Goethite: yellowish brown Ferrihydrite:reddish brown http://www.beg.utexas.edu http://www.pitt.edu http://www.organicgardeninfo.com Calcite: off white Quartz:white Organic matter:black

8. Soil Color Variation • Did you know ?????? • There are more than 20,000 different soil types in the United States

9. Soil Composition • Mineral matter comes from parent material • Air & Water percents are interchangeable • Humus is organic matter! Water (~25%) Humus (~5%) Air (~25%) Mineral (~45%)

10. Soil Composition continued… • Mineral Matter • Provides nutrient minerals for plants • Provides pore space for water & air • Older soils are: • More weathered • Lower in certain essential nutrient minerals • Humus: black/dark brown organic material remaining after decomposition • Leaf litter, animal dung, & decaying organisms • Increases the soil’s water-holding capacity by acting like a sponge

11. Soil Composition continued… Porosity • POROSITY = amt of soil pore spaces • Pore spaces occupy ~50% of a soil’s volume • Filled with varying proportions of soil water and soil air • Soil Air contains the same gases as atmospheric air, but in different proportions. • More CO2 and less O2 (from organism respiration) • Some bacteria need nitrogen (why??) • The CO2 can accelerate weathering • CO2 + H2O  H2CO3 (carbonic acid)

12. Soil Composition continued… • As water infiltrates the soil, it can carry dissolved materials with it. • Leaching: Removal of dissolved materials from the soil by water percolating downward • Illuviation: Deposition of leached material in lower layers • Some substances completely leach out of the soil because they’re so soluble that they migrate right down to the groundwater.

13. Observe this SOIL PROFILE through soil O: Organic material (may be absent) A: Topsoil - Organic material & mineral grains E: Leached zone (may be absent) B: Subsoil – rich in clay, iron, aluminum C: Weathered bedrock Soil layers are horizons and assigned letters R: Bedrock (parent material)

14. Soil Color by Horizon Fun Fact: It takes 100 to 600 years to form an inch of topsoil. A horizon: organic coatings B horizon: Iron coatings C horizon: little coating http://nesoil.com

15. Soil Color – Variation by Geography Red soils: Southeast US

16. Soil Color – Variation by Geography Brown/black soils: Midwest

17. Soil Color – Variation by Geography White (gypsum) sands: New Mexico http://www.scienceclarified.com

18. Soil Organisms • Ex: bacteria, fungi, algae, microscopic worms, protozoa, plant roots, insects, earthworms, moles, snakes, groundhogs, etc. • Soil organisms provide several Ecosystem Services (important environmental functions). • maintaining soil fertility • preventing soil erosion • breaking down toxic materials • cleansing water • affecting atmospheric composition

19. Earthworms & Ants: • Cycle minerals • Aerate the soil • Decomposing corpses contribute organic matter • Assist plants in reproduction by burying seeds • Mycorrhizae • Symbiotic relationship between fungi and the roots of vascular plants • Fungus absorbs nutrients from the soil, and provides it for the plant. • Plant produces food (photosynthesis), and provides it for the fungus.

20. Dr. Greg Pillar, Queens College

21. Physical Soil Properties PHYSICAL properties: Texture (%sand, silt, clay) Porosity & Permeability Ionic Charge

22. Physical Property: Texture • Texture is determined by its % sand, silt, and clay. • Texture determines the type of soil, and the soil’s properties. Loam: ideal for agricultural soil

23. Soil Components Q: What did the shy pebble say to the big rock? A. Do you think I’ll ever be a little boulder? http://school.discoveryeducation.com

24. Fine Texture - Clay https://www.soils.org/lessons

25. Course Texture - Sand https://www.soils.org/lessons

26. Soil Texture The relative portions of sand, silt, and clay-sized particles Sand: 2.0 – 0.05 mm Silt: 0.05 – 0.002 mm Clay: < 0.002 mm

27. Soil Texture Diagram Practice What type of soil has: • 20% clay, 40% silt, 40% sand • 40% clay, 10% silt, 50% sand • 30% clay, 60% silt, 10% sand Find the % of each particle at: • A • B • C • (1) Loam • (2) Sandy clay • (3) Silty clay loam A • 60%clay, 20%silt, 20%sand • 30%clay, 40%silt, 30%sand • 10%clay, 30%silt, 60%sand B C

28. Why is Soil Texture Important?

29. Physical: Porosity & Permeabilityagain… Think it is important?? • Definition? • amt of soil pore spaces Porosity Permeability • Definition? • ability of water to percolate through • ____ porosity = ____ permeability

30. Physical: Ionic Charge • Soil minerals are often present as ions. • Minerals ions are either positively or negatively charged. • Clay particles have mostly negative charges on their outer surfaces. • Positively charged mineral ions are attracted to the soil particles and are held for plant use. • potassium K+ and magnesium Mg2+ • Negatively charged mineral ions are repelled by the soil particles and are washed away from roots. • nitrate NO3-

31. Physical Characteristics (review) • Why would 100% sand be undesirable for plants? • Why would 100% clay be undesirable for plants? • Answer SAND / SILT / CLAY for the following: • A soil with a lot of _____ would have good drainage, but poor nutrient-holding characteristics. • A soil with a lot of _____ would have poor drainage, but good nutrient-holding characteristics. • A soil with a lot of _____ would have low porosity. • A soil with a lot of _____ would have high permeability.

32. Chemical Property: Acidity • Most soil pH is 4-8. Plants are happiest at 6-7.  • Plants are affected by soil pH. (1) The solubility of certain nutrient minerals varies with differences in pH • Low pH = Al & Mn are more soluble, and can be absorbed in toxic amounts. • High pH = some salts are less soluble, and are less available to the plants. (2) Soil pH affects the leaching of nutrient minerals. • Acidic soil = positively charged ions are less soluble and are unavailable for plants.

33. Soil Conditioners (Lime) • CaCO3 or MgCO3 • Soil amendment / conditioner… not a fertilizer! • Important functions: • Corrects soil acidity • Adds important plant nutrients— Ca & Mg • Reduces solubility & toxicity of certain elements in the soil • Al, Mn, Fe • This toxicity could reduce plant growth under acid conditions. • Promotes availability of major plant nutrients. • Zn, Cu, P • Increases bacterial activity & mutualistic relationships. http://www.wvu.edu/~Agexten/hortcult/turf/liming.htm

34. Soil Conditioners (Compost) • Decayed organic matter • Replaces some nutrients • Improves soil structure • The soil becomes more porous, increasing air circulation and the ability of the soil to absorb and hold moisture. • Makes the soil more spongy! http://www.wvu.edu/~Agexten/hortcult/turf/liming.htm

35. Why is Soil Important? Fun Fact: There are more living organisms in a cubic foot of soil then all of China! Fun Fact: There are more living organisms in a cubic foot of soil then all of China! Fun Fact: 1 teaspoon of good soil contains more than 1 million bacteria! Soil supports life http://www.Istockphoto.comL. Clarke and Corbis, 2008 Dr. Greg Pillar, Queens College

36. Soil stores important nutrients Phosphorus (P) Nitrogen (N) Potassium (K) Calcium (Ca) Magnesium (Mg) Dr. Greg Pillar, Queens College http://www.lesco.com/

37. Soil Holds Water Dr. Greg Pillar, Queens College

38. Soil provides support for buildings Dr. Greg Pillar, Queens College http://www.pbase.com

39. Soil filters, buffers, detoxifies…. Soil Dr. Greg Pillar, Queens College http://extension.missouri.edu

40. Inputs/Outputs Are these Soil Inputs or Soil Outputs? Mass Movements (landslides, etc) Precipitation Parent Material Leaching Infiltration Uptake by Plants Organic Matter Energy O I I O I O I I

41. Transfers/Transformations Recall: Transfers simply MOVE things… they reorganize the soil! Transformations CHANGE things… they alter the soil’s makeup in some way. Are these Soil Transfers or Transformations? Decomposition Erosion Deposition Weathering Nutrient Cycling transformation transfer transfer transformation transformation

42. Soil PollutionPart II

43. Soil Pollution = any physical or chemical change in soil that adversely affects the health of plants and other organisms living in and on it. Many soil pollutants… ARE MOBILE! move into groundwater, surface water, or air ARE PERSISTENT! seep into tiny cracks called micropores and adhere to the soil particles COME FROM FERTILIZERS / PESTICIDES! CAN ACCUMULATE! Sustainable Agriculture practices can help… …more on this later…

44. Salinization of Irrigated Soil Irrigation water soaks through the soil area where the plant roots grow, adding to the existing water. The additional irrigation water causes the underground water-table to rise, bringing salt to the surface. When the irrigated area dries & the underground water table recedes, salt is left on the surface soil. Each time the area is irrigated this salinity process is repeated. ALL IRRIGATION WATER CONTAINS SOME DISSOLVED SALTS.

45. Salinization of Irrigated Soil This is in Australia – occurred not from irrigation, but from lack of water-loving plants. Extra water flows through the soil, mixing w/ salt underground, and bringing it to the surface. Irrigation salinization is basically the same concept, and the ground would look just like this.

46. Effects of Salinized Soil on Plants Normally, the water concentration inside plant cells is lower than that in the soil resulting in a net movement of water into the root cell. When soil contains a high amount of salt, its relative water concentration can be lower than the water concentration inside cells. This causes water to move out of the roots into the soil, even when the soil is wet.

47. Soil Remediation Until recently, the only way to remove soil contaminants was to… Why is this a bad thing to do?? Impractical, kills all beneficial organisms, creates waste, expensive… DIG IT UP & INCINERATE IT!

48. Soil Remediation Techniques Dilution Add lots of water; leach out pollutants Vapor extraction Inject air into soil to remove volatile organic compounds Bioremediation Use microorganisms to degrade organic contaminants (oil, sludge) Phytoremediation Use plants to absorb contaminants such as salts or heavy metals.

49. DILUTION: Pump & Treat / Soil Washing Water Extraction well GROUND LEVEL Pollutant low sorption potential = not attracted to soil easily washed away Pollutant high sorption potential = not easily washed

50. … But what’s the problem here? GROUND LEVEL How can this problem be fixed??? Source Identification and Removal !!!!