Earth's creatures, such as worms and rodents and roots tunnel through it, mixing the minerals below with the organic matter above. This process gives soil its density and structure/texture. Ideal soil contains a high proportion of organic material and loose, porous consistency to allow for drainage, aeration and a high nutrient load.
The earth's surface is always in flux. Soil is continuously shifting from soil formation to soil degradation. Undisturbed land has a slightly higher rate of formation then degradation. Human activity, mainly agriculture, increases degradation without enhancing any formation. There is a large consensus that conservation is needed.
Wind erosion is the most obvious form of soil degradation. In dry climates, wind will erode unprotected fine soils. Water erosion is a greater concern in humid climates and on steep slopes. In both cases, erosion increases with the loss of vegetative cover. Cover slows the wind and decreases the water run impact. Additionally, it stabilizes soil with root systems. So every time a field is plowed increases the rate of erosion, specifically if a grass field is removed to plant crops.
Conservation.
Soil erosion first became a concern in the early 20's as a result of scientific research into the causes of flooding. The research showed that levee construction was an insufficient method of control to stop flooding. The first steps were made to provide for reforestation and soil conservation. The Clarke-McNary Act of 1924, the Mississippi Flood Control Act of 1928, and the McSweeney-McNary Act of 1928 were all directed towards reforestation and soil conservation. In 1935, Congress created the Soil Conservation Service under an act declaring a policy of permanent provision for control and prevention of soil erosion, and for control of floods. Legislation and public knowledge helped renew and carry a surge of public conservation activity that occurred during the Great Depression of the 1930s.
