Contour ploughing

Contour plowing or contour farming or Contour bunding is the farming practice of plowing and/or planting across a slope following its elevation contour lines. These contour lines create a water break which reduces the formation of rills and gullies during times of heavy water run-off; which is a major cause of soil erosion. The water break also allows more time for the water to settle into the soil. In contour plowing, the ruts made by the plow run perpendicular rather than parallel to slopes, generally resulting in furrows that curve around the land and are level. This method is also known for preventing tillage erosion.Tillage erosion is the soil movement and erosion by tilling a given plot of land. A similar practice is contour bunding where stones are placed around the contours of slopes.

Soil erosion prevention practices such as this can drastically decrease negative affects associated with soil erosion such as reduced crop productivity, worsened water quality, lower effective reservoir water levels, flooding, and habitat destruction. Contour farming is considered an active form of sustainable agriculture.

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 recent years, contour farming systems are considered as field and farm practices to build climate-smart agriculture as they improve water-use efficiency and conservation.

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.

...
Wikipedia