Introduction to the Soils of PA

1. Introduction to the Soils of PA Troy Area High School Mr. Schanbacher

2. Essential Questions • UEQ: What is soil? • How are soils formed? • What is parent material? • What are soil horizons? • How do I measure soil texture? • What are active fractions? • What are soil aggregates? • Why is soil water important? • What is mottling and how is it related to soil drainage class? • Why is soil pH an important property for soil formation? • How are soils classified? • How do I utilize a soil survey? • What is a capability class and subclass? • What is a limiting factor? • How do I measure slope?

3. What is Soil? • Soil is a naturally occurring mixture of mineral and organic ingredients with a definite form, structure, and composition. The exact composition of soil changes from one location to another. The following is the average composition by volume of the major soil ingredients: • 45% Minerals (clay, silt, sand, gravel, stones). • 25% Water (the amount varies depending upon precipitation and the water holding capacity of the soil). • 25% Air (an essential ingredient for living organisms). • 5% Organic matter or humus (both living and dead organisms).

4. How are soils formed? • The five soil-forming factors are: • Parent material • Climate • Time • Living organisms • Landscape position • Relief

5. What is Parent Material • The material the soil develops from • Bedrock • Limestone Soils: Great for agriculture • Sandstone: Coarse and dry out quickly • Shale: Fine Textured, Acidic and Low in Nutrients • With fertilizers they can be farmed • Support mixed forests • Much has been lost to mining • Residual Soils: • Transported Parent Material • Glaciated: Glacial Till (fragipans=bad for drainage) • Aelian(loess): wind • Colluvial: Gravity (Footslopes)(also have fragipans) • Alluvial: Sediment carried by flowing water (great for agriculture…bad for buildings

9. Climate and Time • Plant and Animal Life • Rainfall: more life…quicker chemical reactions • Temperature: Warmer and More Moisture=faster soil development Think rain forest vs. tundra This process takes centuries…

10. Living Organisms • Vegetative Matter • Roots (Living and Dead) • Deeper the better…Why? • Water Movement: • Litter • Provide food for and are broken down by fungi, bacteria, insects, earthworms, and burrowing animals. • Change organic material into usable nutrients for plants • Microbes and humus (broken down organic matter) act as a glue for soil

11. Landscape Position • Water and Wind move soil • Steepness, Length, and Shape of slope influences the rate at which water moves into or over soil. • Erosion: the movement of soil (unprotected soils)

12. Assignment: • Use the Soil Survey of Bradford and Sullivan Counties to complete the following assignment: • Explain how each of the five soil forming factors have influenced soil formation in Bradford County? You should write at least 3 sentences for each factor. (25 Points)

13. What are Soil Horizons?

14. Soil Horizons Continued.. • O Horizon - The top, organic layer of soil, made up mostly of leaf litter and humus (decomposed organic matter). • A Horizon - The layer called topsoil; it is found below the O horizon and above the E horizon. Seeds germinate and plant roots grow in this dark-colored layer. It is made up of humus (decomposed organic matter) mixed with mineral particles. • E Horizon - This eluviation (leaching) layer is light in color; this layer is beneath the A Horizon and above the B Horizon. It is made up mostly of sand and silt, having lost most of its minerals and clay as water drips through the soil (in the process of eluviation). • B Horizon - Also called the subsoil - this layer is beneath the E Horizon and above the C Horizon. It contains clay and mineral deposits (like iron, aluminum oxides, and calcium carbonate) that it receives from layers above it when mineralized water drips from the soil above. • C Horizon - Also called regolith: the layer beneath the B Horizon and above the R Horizon. It consists of slightly broken-up bedrock. Plant roots do not penetrate into this layer; very little organic material is found in this layer. • R Horizon - The unweathered rock (bedrock) layer that is beneath all the other layers.

15. How do I measure soil texture? • Soil texture: the percent sand, silt and clay in a soil sample • Clay= <0.002mm • Silt= 0.002mm-0.05mm • Sand= 0.05mm-2mm

16. Just another way to look at particle sizes…

17. Amount of sand, silt and clay in a soil. • Nutrient holding capacity • Water holding capacity • Drainage • Tilth Soil Texture Classification

18. How do I measure soil texture? • Feel Test • Ribbon Test • Soil Sieve • Chemical Test.

19. Sand • Large pore spaces in soil • Drains rapidly • Remains soft and light so roots penetrate and spread easily • Too much sand will not hold water or nutrients for plants • Has high bearing strength so it makes a stable foundation for buildings

20. Silt • Optimal amount of water retention and air circulation for agriculture. • Silt is easily carried by the wind…loess soils are silty soils

21. Clay • Extremely good water holding capacity. • Coats larger soil particles and binds them together to create soil aggregates. • High percentage of clay is said to be heavy soils b/c it creates drag on the plow and plant roots • Compaction smashes soil aggregates and closes channels for air and water. • The soil becomes impermeable, slippery, muddy when wet, hard and cracked when dry and plants will not grow! • Clay soils do not make good foundations b/c clay changes in volume and crack as moisture content changes

22. Blocky Granular Prismatic Platy Columnar Single Grained Massive Mineral Organic Air Water Soil Structure • Arrangement of sand, silt and clay in a soil • Compaction • Tilth • Root growth • Water movement

24. Active Fractions • Clay and Organic matter increase the Cation Exchange Capacity (CEC) of soil. • Clay and Organic Matter carry a negative charge (-) and electrically attract positively charged(+) ions that are floating in soil water. • These ions such as Ca, K, and Mg are then available for plants • Increases fertility • Reduces fertilizer (nutrient) losses • Cleans effluents from septic tanks

25. Cation Exchange Capacity

26. Soil Water • All about the texture of the soil • Drainage conditions are indicated by soil color • Depth to Mottling (patches of gray and orange discolorations caused by soil that is saturated for part of the year) • Often dependent on landscape position • The further down the hill the poorer the drainage • Building on poorly drained soil will lead to wet basements and septic issues • Plants will have shallow root sytems

27. >40”=Well Drained • 20-40”= Moderately Well Drained • 10-20”=Somewhat Poorly Drained • <10”=Very Poorly Drained

29. Twelve Soil Orders • Gelisols - soils with permafrost within 2 m of the surface • Histosols- organic soils • Spodosols- acid forest soils with a subsurface accumulation of metal-humus complexes • Andisols- soils formed in volcanic ash • Oxisols- intensely weathered soils of tropical and subtropical environments • Vertisols- clayey soils with high shrink/swell capacity • Aridisols- CaCO3-containing soils of arid environments with subsurface horizon development • Ultisols- strongly leached soils with a subsurface zone of clay accumulation and <35% base saturation • Mollisols- grassland soils with high base status • Alfisols- moderately leached soils with a subsurface zone of clay accumulation and >35% base saturation • Inceptisols- soils with weakly developed subsurface horizons • Entisols- soils with little or no morphological development

30. Soil Color

31. Why is soil pH important? • Soil pH of 6.5 is optimal for most crops • PA Soils tend to be acidic because of acid rain • Our need for lime! • Further West=Less Rain