Transcript of Contour Plowing
Drawbacks to contour plowing have caused it to be less widely used than conventional tillage methods. Some farmers may not have been fully aware of erosion damage and prevention. Lack of access to equipment, funding, or training sometimes take their toll. One of the main limitations of contour plowing results from its contribution of pockets of untilled land. These untended spots eventually develop weeds, which require extra herbicides. Killing off the weeds sometimes destroys surrounding grasses, which in turn leaves another opportunity for rainwater runoff to arise. To combat this possibility, contour plowing is often applied in combination with other soil conservation techniques, such as terracing.
The Phoenicians first developed the practice of contour farming and spread it throughout the Mediterranean. However, the Romans preferred cultivation in straight furrows and this practice became standard in Europe. This was one of the main procedures promoted by the US Soil Conservation Service (the current Natural Resources Conservation Service) during the 1930s. The US Department of Agriculture established the Soil Conservation Service in 1935 during the Dust Bowl when it became apparent that soil erosion was a huge problem along with desertification. The practice is effective only on slopes with between 2% and 10% gradient and when rainfall does not exceed a certain amount within a certain period. On steeper slopes and areas with greater rainfall, a procedure known as strip cropping is used with contour farming to provide additional protection. I'ts simple definition is that it is a process of parallel ploughing to the contours of hill slopes to form a natural barrier for water to flow down the slope.
In Thomas Jefferson's time, contour plowing was called more simply "horizontal plowing." Jefferson had won a coveted medal from the major agricultural society in France for his design of the moldboard plow, but he began to notice drawbacks to the heavy use of that instrument. Instead of funneling water down, like shingles on the roof of a house, it caught the rain in little ridges of up turned earth. Jefferson commented on a noticeable improvement, specifying that the horizontal furrows retained surplus rainwater and allowed it to evaporate back into the soil.
The farming practice of plowing across a slope following its elevation contour lines. Contour plowing is where soil is plowed in curved bands that follows the shape of the land, or its contour. This method prevents the water from flowing directly down slopes. In other words, the method prevents gullying. The plowing is usually a curvy shape. Contour plowing was one of the earliest methods of conservation. The rows form slow water run offs during rainstorms to prevent soil erosion and allows the water to settle into the soil.
One of the earliest methods of conservation tillage came to be known as contour plowing, or "plowing on the contour." Tilling the soil along the gentle slopes of a piece of cropland, instead of up and down the gradient, prevents fertile topsoil from being carried downhill by flowing rainwater. This preventive measure is most important in areas which are prone to violent storms or heavy rains. Not only is the topsoil kept in place, minerals like salt or additives such as fertilizers, insecticides or weed control agents, as well as bacteria from animal waste are not swept away to pollute bodies of potable water.
Even after this successful experiment, later versions of the moldboard plow caused damage to the delicate top-soil of the great plains and prairies of the Midwest United States. The most dramatic evidence of soil erosion took the form of huge dust storms and crop failures during the Great Depression. Since then, contour plowing and other forms of conservation tillage have been re instituted.
Contour Plowing conserve the soil and protect it from erosion and weathering. Contour plowing helps prevent or minimize soil erosion from rain. Helps keep the soil from washing away when it rains, because the furrows are on the same level. It stops erosion by creating relatively small levees perpendicular to the natural flow of "runoff" rainwater.