Working Document Series Open Access Effectiveness of White Lupin (Lupinus albus) and Chickpea (Cicer arietinum ) in Enhancing Phosphorus Release from Rock Phosphate J.J. Lelei · R.N. Onwonga · J.P. Ouma Smallholder farming systems are characterised by application of suboptimal rates or non utilisation of inorganic fertilisers due to their exorbitant prices vis-à-vis low financial return from crops. Minjingu rock phosphate (MPR) would be a… RUF-32687 2012 CC BY 4.0 18 May 2014