Relationship Between Soil Characteristics and FertilityImplications in Two Typical Dystrandept Soils of the CameroonWestern Highland

Abstract

The study was undertaken to evaluate the relationships and fertility implications between Organic Carbon (OC), total nitrogen (N), exchangeable potassium (K) and available phosphorus (P) concentrations and sand, silt and clay contents in two dystrandept profiles in the Western Highland of Cameroon. The study was done in the field and completed by a battery of laboratory analyses. The results showed that the two weathering profiles developed on basalt and trachyte were 4 m thick. Among the different soil fractions, sand contents were the lowest, while silt and clay contents were high. There was no significant correlation between sand and the others soil fractions. A negative significant correlation between silt and clay fractions on contrary was noted. Total OC amounts were very high in the humiferous horizon. There was no significant relationship between OC and clay fractions, indicating that these two soil colloids responsible for the studied soil fertility acted independently. The presence of kaolinite as the unique clay mineral characterized by low surface area and Cation Exchange Capacity (CEC) compared to organic matter, implies that OC was the main source of soil fertility. There was a significant positive correlation between N and OC (r = 0.99, p<0.0001), N and sand fraction (r = 0.93, p<0.02) and between N and K (r = 0.98, p<0.04). Also, there was a significant negative correlation between C:N and K + . Globally, amounts of K were below the critical levels. Available P exhibited a significant positive correlation with OC (r = 0.87, p<0.05) and total N (r = 0.89, p<0.05). Relationships existed among soil physicochemical properties, which positively or negatively interfered with nutrient availability.