1. Introduction to Soils Compliments of: Elizabeth Sulzman OSU Soil Science James Cassidy OSU Soil Science Teresa Matteson Benton SWCD Heath Keirstead Benton SWCD

2. Soil is … Absolutely crucial for life on Earth! www.pikeconservati on.org/SoilEcosyste m.htm

3. 5 functions of soil Soil anchors and provides nutrients for plants. Some animals live in soil; it is a habitat. Soil recycles waste through decomposition. Soil cleans and stores water. Soil has engineering uses.

4. The five factors of soil formation Climate Organisms Topography/relief Parent Material Time Soil = f(cl,o,r,p,t) Passive Factors Active Factors

5. Missoula Floods delivered parent material to Willamette Valley

6. Landscape positions

7. Soil O horizon: organic matter, plant and animal litter A horizon: topmost mineral horizon, darker than B horizon B horizon: mineral horizon: zone of accumulation C horizon: weathering soil; little organic matter or life R horizon: unweathered parent material; rock Soil O horizon: organic matter, plant and animal litter A horizon: topmost mineral horizon, darker than B horizon B horizon: mineral horizon: zone of accumulation C horizon: weathering soil; little organic matter or life R horizon: unweathered parent material; rock Soil O horizon: organic matter, plant and animal litter A horizon: topmost mineral horizon, darker than B horizon B horizon: mineral horizon: zone of accumulation C horizon: weathering soil; little organic matter or life R horizon: unweathered parent material; rock Soil O horizon: organic matter, plant and animal litter A horizon: topmost mineral horizon, darker than B horizon B horizon: mineral horizon: zone of accumulation C horizon: weathering soil; little organic matter or life R horizon: unweathered parent material; rock Soil O horizon: organic matter, plant and animal litter A horizon: topmost mineral horizon, darker than B horizon B horizon: mineral horizon: zone of accumulation C horizon: weathering soil; little organic matter or life R horizon: unweathered parent material; rock Soil O horizon: organic matter, plant and animal litter A horizon: topmost mineral horizon, darker than B horizon B horizon: mineral horizon: zone of accumulation C horizon: weathering soil; little organic matter or life R horizon: unweathered parent material; rock Soil O horizon: organic matter, plant and animal litter A horizon: topmost mineral horizon, darker than B horizon B horizon: mineral horizon: zone of accumulation C horizon: weathering soil; little organic matter or life R horizon: unweathered parent material; rock Soil O horizon: organic matter, plant and animal litter A horizon: topmost mineral horizon, darker than B horizon B horizon: mineral horizon: zone of accumulation C horizon: weathering soil; little organic matter or life R horizon: unweathered parent material; rock

8. Minerals Organic matter Water Air Soil has four components

9. The four components of soil:

10. Mineral component Makes up less than 50% of a “soil” Varies in chemical composition Contains particles of several size ranges (small to really really small) Depends on the underlying geology/bedrock

11. Organic matter Small constituent by weight, but huge influence on soil properties Made up of partially decomposed plant & animal residues + organic compounds synthesized by soil microbes O ni

12. Functions of Organic Matter 1. Stabilizes soil structure, making soil easily managed 2. Increases the amount of water a soil can hold (and availability of the water) 3. Major source of plant nutrients 4. Main food/energy for soil organisms

13. Soil Water Held to varying degrees depending on amount of water and texture of soil Not all soil water is available to plants

15. Soil Air 1. High spatial variability 2. High temporal variability 3. High moisture content (Rh  100%) 4. High CO 2 content 5. Low O 2 content

16. Soil Physical Properties Color Texture Structure Aggregate stability

17. Soil Color Moisture Mineralogy (calcite, hematite, manganese) Coatings on particles: O.M. darkens underlying colors Fe and Al oxides (red & yellow)

18. Texture – Proportions of sand, silt, and clay Determines water holding capacity, water availability, nutrient supply capacity… Loam is a soil texture with optimal sand, silt and clay contents for growing plants. Clay is a soil particle size and a soil texture.

19. % clay % silt % sand

20. “Big”  smaller  really small Sand  silt  clay Relative Size Comparison of Soil Particles (fine earth fraction)

21. Sand Clay Fine clay has ~10,000 times as much surface area as the same weight of medium grain sand!

22. Coarse textured soils larger pores Fine textured soils greater total pore space Sand Clay

23. Clay particle mostly negative charged surface - + - + - + - + Ca ++ - - - - - - - - - - - - - - + - K+K+ NH 4 + Ca ++ - - Fe++

24. Influence of Texture SandSiltClay Water-holding capacity Aeration Drainage Nutrient retention LowMediumHigh GoodPoor Medium SlowVery slowHigh LowMedium

25. Types of Soil Structure

26. Why Are Aggregates Important? Increase porosity Increase water infiltration, drainage, decrease runoff Increase water holding capacity http://www.youtube.com/watch?v=9_ItEhCrLoQ

27. Effect of OM on aggregate stability

29. Compaction Pore spaces are where plants get air, water, and nutrients. Soil compaction decreases valuable pore space between soil particles. Adapted from Sulzman and Frey, 2003

30. Less Greater Compaction

31. Take home message Clay soils have a higher water-holding capacity than sandy soils Water in coarse textured soils is easier for plants to remove than in fine textured soils Much of the water in high-clay soils is unavailable to plants, while most water in sandy soils is available

32. A cup of soil contains... Bacteria Fungi Protozoa Nematodes Arthropods Earthworms 200 billion 100,000 meters 20 million 100,000 50,000 <1 The immobile ones all primarily found in the rhizosphere, the zone of soil closest to plant roots

33. Bacteria

34. Nematodes Protozoa

35. Mites Springtails

36. Other invertebrates

37. Worms Voles! Ant Colony!

38. Aggregates held together by: –Fungal hyphae –Bacterial “glues” –Organic matter sand silt hyphae clay bacteria

39. Amoebae Ciliate Flagellate Nematode feed on bacteria and fungi release plant nutrients – protozoa KEY for N Nematode Microfauna

40. Collembola (springtails) Fungus feeding mite feed on fungi, protozoa, nematodes, mites important in regulating populations of everything smaller Nematode feeding mite Mesofauna

41. Photo by Suzanne Paisley shred plant material feed on bacteria and fungi associated with organic matter Macrofauna

42. Earthworms Important component of soil fauna (not in acid soils, not in very dry soils) Pass as much as 30 tons/ha of soil through their bodies each year Casts (poop) are higher in N, P, K, Ca, Mg, pH, and CEC than soil Promote good soil structure and aeration

43. Earthworm casts vs. soil CharacteristicEarthworm castsSoils % silt & clay22.2 Structural stability65 CEC (cmol c /kg)3.5 38.8 849 13.8

44. Nitrogen Fixation (bacteria) Take N 2 from atmosphere, convert to soil NH 4 + Nodules formed on roots Examples include: –Rhizobia on legumes –Frankia on alder via organic matter N  N NH 4 +

45. SOIL ORGANIC MATTER Living Organisms: BIOMASS Dead tissues and wastes: DETRITUS Non-living, non-tissue: HUMUS SOM: What it is

46. Sand Clay Large surface area means more charge so greater ability to hold water and nutrients

47. Set up a soil column to see how soil purifies water. Hands-on FUN!!!

48. Back to why we might care… …plants = food

49. Erosion: A process that transforms soil into sediment –Natural (soils form over time in most settings) –Human-induced (e.g., over-grazing, forest harvest) Tied with damage to plant communities Wind vs. water (usually 2/3 by water)

50. Downward spiral of land degradation

51. Three steps of water erosion Most erosion is initiated by the impact of raindrops, NOT by the flow of running water

52. Wind erosion 40% of soil transported by erosion in USA In six of the Great Plains states, wind erosion exceeds water erosion Fine particles can even be transported to other continents

55. Current problems World population is increasing rapidly Only 10% of the world’s land area is suitable for growing crops Most of the most arable land is already in production Soil quality is degrading world-wide

56. The real voyage of discovery consists not in seeking new landscapes but in having new eyes. ~Marcel Proust