Affiliation: | 1. Department of Land Resource Management and Agricultural Technology (LARMAT) , University of Nairobi , PO Box 1253-0606, 00100, Nairobi, Kenya;2. World Agro forestry Centre (ICRAF) , PO Box 30677-00100, Nairobi, Kenya m.njenga@cgiar.org;4. Agriculture Learning and Impacts Network (ALINe), Institute of Development Studies at the University of Sussex , Brighton, BN1 9RE, UK |