The farming practice of ploughing and/or planting across a slope following its elevation contour lines, considered an active form of sustainable agriculture. These contour lines create a water break which reduces the formation of rills and gullies during times of heavy precipitation, allowing more time for the water to settle into the soil. In contour ploughing, the ruts made by the plough run perpendicular rather than parallel to the slopes. This method is also known for preventing tillage erosion, which causes reduced crop productivity, worsened water quality, lower effective reservoir water levels, flooding and habitat destruction. A similar practice is contour bunding, where stones are placed around the contours of slopes.