Effects of Cassava Cultivation on Soil Quality Indicators in the Humid Forest Zone of Cameroon

Abstract

A study was conducted at Ongot in the humid forest zone (HFZ) of Cameroon to determine the extent to which selected soil quality indicators are affected by cassava cultivation along a chronosequence of 5, 10 and 20 years. Soil samples were collected from cassava farms along this chronosequence and from a nearby forest as reference. The samples were analyzed for soil organic matter (SOM), organic carbon (OC), total nitrogen (TN) and pH. SOM, OC and TN decreased significantly (P<0.05) following years of cassava cultivation. Thus after 20 years of cultivation, SOM and OC contents reduced by 50% compared to the reference (SOM=35.08 g kg-1, OC=20.39 g kg-1). TN decreased from 2.19 g kg-1 in the reference to 1.24 g kg-1 in farms where cassava has been cultivated for 20 years. Soil pH ranged from 5.4 to 5.6 but did not differ (P<0.05) irrespective of years of cassava cultivation. Generally, significant differences in soil quality indicators were not observed between the forest soil and soils from five-year old cassava farms. This could imply that management strategies to improve soil quality in the HFZ of Cameroon are warranted mainly after four years of cassava cultivation.