Can conservation agriculture improve phosphorus (P) availability in weathered soils? Effects of tillage and residue management on soil P status after 9 years in a Kenyan Oxisol - Margenot, Andrew J.; Paul, Birthe K.; Sommer, Rolf; Pulleman, Mirjam Margreet; Parikh, Sanjai J.; Fonte, Steven J. (Elsevier, 2017)