Observing Changes in Riparian Buffer Strip Soil Properties Related to Land Use Activities in the River Njoro Watershed, Kenya E. M. Enanga & W. A. Shivoga & C. Maina-Gichaba & I. F. Creed Received: 19 February 2010 / Accepted: 14 October 2010 # Springer Science+Business Media B.V. 2010 Abstract Riparian buffer strip guidelines are under scrutiny in the River Njoro Watershed in Kenya. This study investigated soil properties (bulk density, carbon, nitrogen, and phosphorus) in different land use types (small scale agriculture in recent settlements, mixed agriculture in established peri-urban settlements, large- scale commercial agriculture, and the gazetted forest reference condition) and their adjacent buffer strips. Bulk density, carbon, nitrogen, and phosphorus within 30-m riparian buffer strips adjacent to recent settlement land use areas were similar to those of the gazetted forest reference condition, but only bulk density of the buffer strips adjacent to peri-urban and commercial agriculture land use areas were similar to the gazetted forest reference condition. Phosphorus is a sensitive indicator of the impacts of human activity, as increased concen- trations were observed with increasing scale of land use activity. For riparian buffers adjacent to recent settle- ments, soil phosphorus was significantly higher in buffers narrower than 30 m (5.01 mg P kg -1 ) than gazetted forest (3.40 mg P kg -1 ) but not significantly different for riparian buffers wider than 30 m (3.81 mg P kg -1 ) compared to gazetted forest. Based on the research, it is recommended that policies governing riparian buffer strips become (1) stricter, with the current “maximum” of 30 m considered a minimum; and (2) adaptive, with 30 m used in small- scale agricultural areas, and wider riparian buffer strips used in medium- and large-scale agricultural areas. Keywords Riparian area . Buffer strip . Soil properties . River Njoro . Kenya 1 Introduction Water sustainability depends on ecosystem structure and function; and in Kenya, water policy tends to ignore water as an ecosystem service (Baldyga 2005). In recent years, rural communities are increasingly encroaching on forest reserves, riparian areas, and commercial agricultural areas for their own pasture and crop production. This trend has persisted in the face of persistent dry conditions and decreasing water flows in rivers serving Kenyan rangelands, despite the recognition that these actions will impact the communities that depend on the rivers’ ecosystem services (Chemilil 1995). Riparian buffer strips have become an integral part of watershed management in American and European Water Air Soil Pollut DOI 10.1007/s11270-010-0670-z E. M. Enanga : W. A. Shivoga Department of Environmental Science, Egerton University, Nakuru, Kenya C. Maina-Gichaba Department of Geology, University of Nairobi, Nairobi, Kenya E. M. Enanga (*) : I. F. Creed Department of Biology, The University of Western Ontario, 1151 Richmond St. N, London, ON N6A 5B7, Canada e-mail: eenanga@uwo.ca