High population growth and rapid depletion of soil fertility in smallholder farms are the main causes for decline per capita food production in sub Saharan Africa. Decreasing soil fertility in the highlands of Kenya is a result of imbalance between nutrient inputs, harvest removal erosion and leaching and is reaching critical proportions. Because small-scale farms in this region cannot be expanded due to limited frontiers and shrinking arable land, farmers make decisions about land use and improvement that fundamentally affect the soil fertility and crop productivity of their farms. These results to either carefully diversified profitable mixed enterprise agriculture or backslide into worsening poverty, with soil fertility management playing a crucial role in either outcome. This paper will present results from a study that was carried out as part of a larger research program on poverty dynamics in the smallholder farms of the highlands of Kenya to characterize farm enterprises soil fertility and assess effect of enterprise/crop, household income and number of cattle on soil fertility. Soils were sampled (0-10cm) from 123 and 113 farms in Madzuu (966 plots) and Embu(1036 plots) respectively and analysed using spectral reflectance approach. Madzuu and Embu were selected as being representative of the dominant smallholder-farming scenario in the eastern and western Kenya highlands respectively. This kind of information is vital for major players in the agricultural sector when designing soil fertility management policies and strategies geared towards alleviating social, economic and environmental problems afflicting the rural poor population of the highlands of Kenya.

Key words: smallholder, soil fertility, and farm income