Sustainable Soil Fertility Management Alternatives and Approaches for Small Scale Farmers in Africa.

Degrading soil fertility is widely recognized as the underlying cause of declining crop production in much of Africa. While the application of fertilizers is seen by many as a direct means for correcting this situation, questions surround the ability of most smallholders to purchase sufficient amounts of fertilizer to meet crop needs. Several alternative “best-bet” recommendations for soil fertility management of maize-legume intercrops were examined in Western Kenya in on-farm trials over 4 years.    These recommendations were generated by various research organizations working independently of one another and included capital-intensive “Green Revolution” technologies, labor-and-resource-intensive “Organic” managements, land-extensive fallows and information-intensive (technically complex) “Integrated” solutions.   The trials were conducted through a network of six different Non-Governmental Organizations (NGOs) strategically located in Western and Nyanza provinces of Kenya with each responsible for 20 or 40 on-farm trials.  Data was assembled on crop yield, inputs costs, economic returns and soil chemical properties into a database and subjected to statistical analyses.

The largest yields and greatest returns are obtained when mineral inputs were applied to soil in the FURP, PREP and MBILI treatments.  Part of the economic advantage of the best two treatments (PREP and MBILI) is the significantly greater legume yields (p<0.005).  The Best Bet Network documented the legitimacy and limitations of several alternative approaches to maize-legume intercropping but it also has quantified the failure of those technologies to serve many farmers’ needs.  This study reports on the findings of this study and raises general issues and questions that surround the sustainable soil fertility management by smallholder farmers in Africa and suggests the way forward.