Soil More thanjustDirt!
Atmosphere Biosphere Pedosphere Hydrosphere Lithosphere • Weathering • Uptake by plants • Evapotranspiration • Precipitation • Decomposition • Nutrient cycling • Infiltration • Groundwater flow • Leaching
Soil Composition • http://www.youtube.com/watch?v=nL7CpNQnquM
Soil formation • Three stages: • Mechnical and chemical weathering • Introduction of living organisms • Decomposition and the formation of an organic component
Soil horizons Organic material / leaf litter Mixed mineral-organic Eluvial or leached Illuvial or deposited Weathered rock from which the soil forms Parent material (bedrock)
Type of particle Clay Silt Sand Gravel Diameter (mm) <0.002 0.02-0.05 0.05-2.0 >2.0 Ideal soiltype
What is soil degradation? • Loss of soil • Processes that take away the soil (soil erosion) • When do you think this would occur? • Loss of soil fertility • Processes that make the soil less suitable for use. • When do you think this might occur?
Case Studies • Read the case studies about soil degradation. • Write down what is happening to the soil and the causes.