ABSTRACT
The humid highlands of Eastern Africa (altitude ≥1,500 masl) are among the most populated areas in Africa, with densities ranging from 100 to 600 people/km2 (German et al. 2012). Available land/person ranges from 0.07 to 0.23 ha and although rainfall is high (>1,000 mm/year), agricultural production is low and poverty levels are high (Stroud and Peden 2005). In response to the dwindling land resources, smallholder farmers in the region are practising some form of agricultural intensification. However, most have failed to observe the basic principles of agricultural intensification, including the use of improved germplasm, fertilizers and the appropriate component integration that would lead to optimal system productivity. Intensification is seen only as increased frequency of cultivation and the growing of multiple crops on the same piece of land. As a result, yields of most crops are very low compared to what potentially can be produced (Mowo et al. 2007). The humid highlands of Eastern Africa are also characterized by steep slopes, hence soil conservation is vital; however, most farmers hardly ever practise soil conservation. Meanwhile, indiscriminate cutting of trees is common. Poor land preparation practices leave the soils exposed to agents of erosion, leading to excessive runoff, poor infiltration and limited recharge of underground water. Siltation of valley bottoms is common, rendering them unproductive as fertile soil is covered by infertile subsoils from the upper slopes. Springs which were once full of water have dried out due to poor land management and the removal of vegetation. Despite concerted efforts by both research and development partners to reverse the trend (Mansuri and Rao 2004), success has been limited to a few areas.
