Soil Analysis Lab AP Biology November 2013

Properties of Soil Soil Texture –Determined by 3 soil components (listed largest to smallest) Sand Silt Clay –Loam Soil composed of 40:40:20 (Sand:Silt:Clay)

Soil Structure Defined by the way individual particles of sand, silt, and clay are assembled  forming “aggregates” Aggregation of soil particles can occur in different patterns, resulting in different soil structures. Circulation of water in soil varies greatly according to structure.

Color Can be an indicator of: –Humus content (dark brown or black) –Parent material –Soil drainage Ex. Well drained soils are usually brown or red. Poorly drained soils are often gray (b/c reduction of iron.) Munsell Color Chart

pH Closely related to soil’s ability to supply nutrients for plant growth Usually the most desirable pH range for mineral soils is 6.0 to 7.0 and for organic soils 5.0 to 5.5.

Water Content Plants need both water and air in soil

Nutrients Macronutrients –Nitrogen –Phosphorus –Potassium Micronutrients –elements essential for plant growth, but needed in only very small (micro) quantities –Calcium –Magnesium –Sulfur

Wetland (Marsh) Soil Characteristics Anoxic hydric soil High levels of clay pH varies –Organic soil has low pH –Mineral soil have pH of 7-8 Sources of water –Groundwater –Precipitation Usually has dark upper layer with underlying gray zone Reducing environment because of low O 2 capacityHigh capacity for positive metal ions (because of reduction reactions) such as Ca 2+, Mn 2+, K +, and Fe + Limiting factors for plant growth include N, P and K

Prairie Soil Characteristics Increased organic matter Generally has a high sand component Increased nitrites and nitrates and calcium Increased sulfates Increased phosphorous Neutral to high pH

Deciduous Forest Soil Characteristics Lowest pH of the three ecosystems Low fertility this time of year because of decreased/incomplete decomposition Soil is most similar to loam