ABSTRACT
This chapter aims to conceptualize the yield reduction and soil fertility degradation processes and how these interact and to evaluate the potential impact on yield. Intensification of smallholder agriculture is a must under high population densities but also desirable in less populated areas in order to protect natural ecosystems. After conversion of natural fallows to agricultural land, it has been observed that in the absence of the use of external nutrients, crop yields decline over time as do soil fertility conditions, often expressed as soil organic carbon (SOC) content. Sustainable Intensification (SI) requires increases in productivity and maintenance/restoration of ecosystem services. The chapter focuses on field-based ecosystem services that are regulated by soil conditions. Long-term data assessing the status of yields and SOC are required to make objective inferences about the SI nature of various soil management paradigms and are unfortunately in short supply, especially for sub-Saharan Africa.
