Soil erosion is a gradual process that occurs when the actions of water, wind, and other factors eat away and wear down the land, causing the soil to deteriorate or disappear completely. Soil deterioration and low quality of water due to erosion and run off has often become a severe problem around the world. Many times the problems become so severe that the land can no longer be cultivated and is abandoned. The key to minimizing soil erosion and saving the farm lands is the farmer himself. Ultimately, he is the one who must reduce the level at which erosion sediments are dislodged from his cropland. This program will discuss the erosion process, its effects on crops and the environment, and the Best Management Practices that can be implemented to limit or contain soil movement from the land.
Soil erosion can be divided into two very general categories:
Geological erosion: Geological erosion occurs where soil is in its natural environment surrounded by its natural vegetation. This has been taking place naturally for millions of years and has helped create balance in uncultivated soil that enables plant growth. A classical example of the results of geological erosion is the Grand Canyon.
and Accelerated erosion: Accelerated erosion can be caused by man’s activities, such as agriculture and construction, which alter the natural state of the environment.
Accelerated erosion is the type that will be covered in most depth. It includes such problems as
The action of wind on exposed sediments and friable rock formations causes erosion (abrasion) and entrainment of sediment and soil. Eolian action also forms and shapes sand dunes, yardangs (streamlined bedrock hills) and other landforms. Subsurface deposits and roots are commonly exposed by wind erosion. Wind can also reduce vegetation cover in wadis and depressions, scattering the remains of vegetation in interfluves. Stone pavements may result from the deflation (removal) of fine material from the surface leaving a residue of coarse particles. Blowouts (erosional troughs and depressions) in coastal dune complexes are important indicators of changes in wind erosion. The potential for deflation is generally increased by shoreline erosion or washovers, vegetation die-back due to soil nutrient deficiency or to animal activity, and by human actions such as recreation and construction.
SIGNIFICANCE: Changes in wind-shaped surface morphology and vegetation cover that accompany desertification, drought, and aridification are important gauges of environmental change in arid lands. Wind erosion also affects large areas of croplands in arid and semi-arid regions, removing topsoil, seeds and nutrients.
HUMAN OR NATURAL CAUSE: Eolian erosion is a natural phenomenon, but the surfaces it acts upon may be made susceptible to active wind shaping and transport by human actions, especially those, such as cultivation and over-grazing, that result in the reduction of cover vegetation.
ENVIRONMENT WHERE APPLICABLE: arid and semi-arid lands
TYPES OF MONITORING SITES: Dune fields, coastlines, desert surfaces
SPATIAL SCALE: patch to landscape / mesoscale to regional
METHOD OF MEASUREMENT: Field observations, aided by airphotos and field surveys. Changes in vegetation cover can be monitored using historical records, sequential maps, air photos, satellite images, and by ground survey techniques.
FREQUENCY OF MEASUREMENT: Every 5-20 years
LIMITATIONS OF DATA AND MONITORING: The effect of wind erosion on different rock types and landforms (with contrasted aerodynamic shapes) varies, so that it is not easy to assess the degree of erosion of a complex landscape.
APPLICATIONS TO PAST AND FUTURE: Differential erosion by wind in the past may be detected through study of buried soil horizons developed on ancient erosional surfaces, which formed during dry (wind erosion) to wet (soil formation) climatic cycles.
POSSIBLE THRESHOLDS: Sediment erosion and transport takes place within a specific range of wind speeds, depending on grain size, degree of cementation and compaction, moisture content, and vegetation cover.
Differential erosion by wind in the past may be detected through study of buried soil horizons developed on ancient erosional surfaces, which formed during dry (wind erosion) to wet (soil formation) climatic cycles.
Raindrops can be a major problem for farmers when they strike bare soil. With an impact of up to 30 mph, rain washes out seed and splashes soil into the air. If the fields are on a slope the soil is splashed downhill which causes deterioration of