Assessment of the level of soil degradation in three watersheds affected by intensive farming practices in Benin

Soil degradation is a serious problem for people living in watersheds of Benin.This degradation is mainly due to poor farming practices and because of this poor management annual maize production reduced critically.This study was aimed to estimate the state of physical and chemical soil degradation of three watersheds of southern Benin.One reference site representing sacred forest was also chosen for comparing the results of watershed.Soil cores were also collected from these selected sites.Physical and chemical parameters were determined from the collected soil samples.Results of study revealed that the watershed soil is more compact and lower in nutrients than the soil of reference sites.The bulk soil density was significantly higher in Govié and Lokogba watersheds compared to their reference site.As a result of intensive farming and water erosion, root biomass of the soil has significantly decreased from 86 to 82% in Govié, 69 to 67% in Lokogba and 75 to 70% in Linsinlin.The total soil nitrogen of watershed declined significantly, from 33 to 24% in Govié, 32 to 30% in Lokogba and 38 to 25% in Linsinlin.Available soil phosphorus decreased from 10.93 ppm to 7.11 ppm in the Lokogba watershed.The soil phosphorus of Linsinlin watershed was reported highest from 5.5 ppm to 8.00 ppm compared to the reference site.The soil organic matter of watershed declined from 38 to 37% in Govié and 68 to 66% in Lokogba.Lokogba watershed is the most degraded one compared to three watersheds studied.