Contour ploughing is a well-established agronomic measure that contributes to soil and water conservation  (see figure 1). The soil is ploughed along the contour instead of up- and downward (see figure). This decreases the velocity of runoff and thus soil erosion by concentrating water in the downward furrows  (see figure 2).
Contour ploughing on the other hand purposely builds a barrier against rainwater runoff which is collected in the furrows. Infiltration rates increase and more water is kept in place. Contour ploughing is especially important at the beginning of the rainy season when biological conservation effects are poor . The effectiveness of contour ploughing decreases with increase in slope gradient and length, rainfall intensity and erodibility of the soil .