Name a common soil conservation technique.

Contour farming is a common soil conservation technique that involves plowing and planting across the slope of the land, following its natural contours. This method helps reduce soil erosion by slowing down water runoff and allowing more water to permeate the soil. The ridges formed by the furrows create barriers that catch water and sediment, which facilitates better moisture retention and protects the soil structure, leading to improved agricultural productivity and sustainability.

Overgrazing, polyculture, and deforestation do not serve as effective soil conservation methods. Overgrazing can lead to soil degradation and erosion as vegetation is depleted. While polyculture involves growing multiple crop species to increase biodiversity and resilience, it does not specifically refer to techniques aimed at soil conservation. Deforestation results in loss of vegetation and exposes soil to erosion and degradation, further negating any conservation efforts. Thus, contour farming stands out as a beneficial practice for conserving soil health and preventing erosion.