| A | B |
|---|
| prime farmland | best combinations of physical and chemical characteristics for producing food, fiber, seed ... |
| lithosphere | the rigid outer layer of the earth's crust |
| nitrogen fixing bacteria | change atmospheric nitrogen to a form plants can use |
| lightning | can also "fix" atmospheric nitrogen |
| atmospheric nitrogen | N2 (diatomic nitrogen) cannot be used by plants |
| erosion | process by which soil is transported from one place to another by wind, running water, gravity, glaciers and waves |
| three types of erosion by surface water runoff | sheet, rill, and gully |
| sheet erosion | gradual eroding away of a very thin, uniform layer (sheet) of soil (difficult to see) |
| rill erosion | tiny channels (very small to a few inches in depth); occurs on gentle slopes |
| gully erosion | occurs as rills become larger, forming deeper and wider channels; develops on steeper slopes with little or no vegetation |
| stream bank erosion | along stream banks with little or no vegetation after heavy rainfall |
| wind erosion | occurs in areas of high winds and low rainfall; cover crops reduce wind erosion |
| land slippage | refers to blocks of water-saturated soils moving down slopes in response to gravity (ex., bluff overhanging a river) |
| sediment | #1 pollutant of NC's waterways |
| soil as a natural resource | is not renewable over the short term |
| rainfall, runoff, slope, soil erodibility and vegetative cover | affect the rate of erosion |
| Death Valley, CA | almost no annual rainfall |
| Washington State | 140 inches annual rainfall |
| soil erodibility factor | relative index of the susceptibility of bare, cultivated soil to particle detachment and removal and transport by rainfall |
| massive or platy structure | slow rate of infiltration; more water runoff; thus more potential for erosion |
| silt and sandy soils | weaker bonding; thus more erodibility |
| soil loss tolerance | an estimated maximum annual soil erosion that will permit crop productivity |
| Heavily vegetated soils | seldom erode at a high rate |
| 10 percent slope of the land | drops 10 feet in depth over a distance of 100 ft |
| BMP | Best Management Practices |
| Crop rotation, conservation tillage, contour farming, cover crop | BMPs |
