| A | B |
|---|
| humus | well-decomposed organic matter which is dark brown, porous, spongy with earthy smell |
| older soils | have deep A and B horizons; less fertile due to leaching |
| younger soils | more fertile; thin A and B horizons |
| soil additions | anything added to the soil from outside sources (plants, rainfall, animals...); usually increase plant nutrients |
| soil losses | occur from leaching and erosion by wind and water |
| soil translocations | mocwmwnr of organic and inorganic matter within a soil profile |
| soil transformations | mineral weathering and organic matter decomposition |
| agronomy | the application of scientific principles to farming field crops |
| pedons | soil profile |
| soil horizon | soil layer |
| soil profile | a vertical cross section of all the layers of the soil at a particular location |
| Horizon O | surface litter; fallen leaves, partially decomposed organic matter |
| Horizon A | Topsoil (darker colored than lower horizons) |
| Horizon E | Zone of Leaching - characterized by light color or bleached appearance |
| Horizon B | Subsoil (Zone of Accumulation) |
| Horizon C | Zone of least weathering |
| Horizon R | bedrock |
