Pollution and Siltation of Rivers in the Western Highlands of Cameroon: a Consequence of Farmland Erosion by Runoff

In the western highlands agro-ecological zone of Cameroon, rivers are constantly silted and polluted with waste from cultivated plots. This study investigated on the characterization and quantification of sediment from plots cultivated in the watershed Méloh; among these sediment we highlighted soil, plant residues, chemical packages and plastic casing used for irrigation. In a natural rocky bottom wells, we performed for a period of three years the collection, differentiation and measurement of trapped sediment in the cultivated part of river that runs through the watershed. The total cultivated area is about 7.5 ha; slopes are operated between 14% and 17%. During the years 2012 and 2013 where farmers practiced both flatbed and ridging along the steepest slope, two methods of land preparation that do not contribute positively to water conservation, we collected an average of 10.429 t.ha-1. During the 2013 crop year, with the participation of curious farmers we experimented tied ridging in a potato; this technique was adopted on 75% of plots in 2014 and we collected 3.586 t.ha-1, a decrease of 65.61% compared to the average of previous years. This study showed that traditional agricultural practices are a cause of siltation and pollution of the Méloh river, thus almost all rivers in the study area by what the topography is similar and agriculture the main activity. Tied ridging significantly reduced siltation of rivers; it is thus an effective technique to fight against water pollution in mountain agriculture.