Assessment of Soil Quality in the Farming Systems of Southwestern Nigeria.

Tropical soils are easily prone to degradation and lack resilience to recover after being degraded. With the current demographic pressure on land resources for farming, the extent of degraded land has increased over the past decade. Evaluation of potential soil measurements that can indicate directional changes in soil quality are needed, for understanding and managing soils in tropical ecosystems. A soil quality protocol for tropical soils was developed at the Institute of Agricultural Research and Training, Ibadan, Nigeria. During the development of the protocol, several physical, chemical and biological soil measurements were assessed under different management systems. Results show that soil quality varied with management systems. Alternative methods of land clearing, tillage and cropping systems were more beneficial for soil quality, while conventional farming methods based on plowing and harrowing led to soil degradation. Soil measurements that were sensitive to management include the soil organic matter, aggregate stability, microbial biomass, biologically active carbon, mineralizeable nitrogen, infiltration rate and pH. Based on the soil quality measurements, traditional practices such as slash and burn for land clearing, minimum tillage (hoeing and animal traction), mixed cropping and agroforestry methods minimized soil quality degradation. This study also shows that plow and harrow based tillage system currently being practiced for arable crop production, is unsustainable in tropical ecosystems.