Kerina , Arnold, et al. “ Response of Three Legumes to Inorganic Fertilizer Application in Different Agro-Ecological Zones in Makueni County Kenya ”. African Journal of Education,Science and Technology (AJEST), vol. 4, no. 1, Aug. 2017, pp. Pg 14-25, http://ajest.org/index.php/ajest/article/view/168.