The disc harrow plays, next to the disc plough, an important role in motorized tillage. To investigate how specialists perceive the relation between the use of disc harrows and soil degradation, questions were asked on this subject specifically.

Most respondents identified a direct relationship between the use of disc harrows and an increase of chances that erosion takes place. Motorization of tillage generally results in intensified soil disturbance at a greater depth in comparison with hand labour and animal traction. Secondly, there is the inappropriate use, misuse and maladjustment of the implement that add to the harmfulness. The use of disc harrows on soils that are too light and fragile, and tillage in direction of the slope are particularly harmful practices. The Gambia reports gravely soils becoming more gravely on the surface under the use of disc harrows. In general, the use of disc harrows on light fragile soils is dissuaded.

The drawbacks mentioned in the last paragraph are however not exclusively reserved for the disc harrow; they apply to most forms of motorized tillage. This also explains that other respondents find the disc harrow to be less harmful; it depends on what it is compared with. In comparison with the disc plough or powered implements such as rotary cultivators and powered rotating harrows the disc harrow is less harmful. In general the belief is that implements that pulverise the soil too much cause erosion in light, fragile soils, but may be suitable for other soils. The disc harrow is believed to be an appropriate implement for both primary and secondary tillage on soils that are stable enough, such as soils with high loam or clay content, and rice plains.

The question of whether the disc harrow is the appropriate implement in some circumstances in West Africa or merely the best implement available remains unanswered. It is clear however that the choice of implement has great consequences for soil and water conservation aspects.