ORIGINAL ARTICLE Arbuscular mycorrhizal fungi with different soil fertility amendment practices in agricultural landscapes of Kenyan highlands John Nyaga . Joyce M. Jefwa . Catherine W. Muthuri . Viviene N. Matiru . Peter M. Wachira . Sheila A. Okoth Received: 15 April 2015 / Accepted: 5 October 2015 / Published online: 8 October 2015 Ó Springer Science+Business Media Dordrecht 2015 Abstract Several interrelated and site-specific agro- nomic factors ranging from agroecological conditions to systems management practices have been shown to variably affect arbuscular mycorrhizal fungi (AMF) diversity in the soil. Also, there have been various attempts in the past to evaluate the potential of AMF field inoculation but a majority focussed on the use of exotic strains, disregarding the potential of the existing naturally occurring strains. In an attempt to address these problems, our study aimed to develop ‘best-bet practice’ based on soil fertility amendment practice (SFAP) that encourages occurrence and diversity of AMF in the soil. Control treatment (no application) was compared with three (3) SFAP used singly or in combination with AMF or two other soil nutrients enhancing organisms (Bacillus and Trichoderma) which included the following: (1) Mavuno (macro- and micronutrients and secondary nutrients) fertilizer, (2) calcium ammonium nitrate (CAN) plus triple super phosphate (TSP) and (3) cattle manure. Maize (Zea mays L.) and common bean (Phaseoli vulgaris L.) were planted at on-station and on-farm plots for two consecutive cropping seasons with the experiment replicated in two benchmark sites of Embu and Taita- Taveta Districts. Embu site recorded a lower soil pH and also very low phosphorus levels compared to Taita site. The number of AMF spores per kg of soil was very low, ranging from 30 to 100, at Embu in the first season and application of SFAP resulted in no significant difference. However, in the second season, use of Trichoderma ? CAN plus TSP was shown to significantly stimulate AMF species in the soil, with a 250 % increase in species density compared to use of Bacillus ? Manure. At Taita, after the first cropping season, significant change in spore density was only recorded from AMF applied singly with a 66.1 % J. Nyaga (&) Á C. W. Muthuri Á V. N. Matiru Botany Department, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000-00100, Nairobi, Kenya e-mail: nyaga09@gmail.com; jnyaga@cgiar.org C. W. Muthuri e-mail: cmuthuri@cgiar.org V. N. Matiru e-mail: viviene.matiru@yahoo.com J. Nyaga Á C. W. Muthuri World Agroforestry Centre (ICRAF), United Nations Avenue, Gigiri, P.O. Box 30677-00100, Nairobi, Kenya J. M. Jefwa Tropical Soil Biology and Fertility-CIAT, P.O. Box 30777, Nairobi, Kenya e-mail: jjefwa@cigar.org P. M. Wachira Á S. A. Okoth School of Biological Sciences, University of Nairobi, P.O. Box 30197-001000, Nairobi, Kenya e-mail: wachirapm@yahoo.com S. A. Okoth e-mail: dorisokoth@yahoo.com 123 Nutr Cycl Agroecosyst (2015) 103:229–240 DOI 10.1007/s10705-015-9744-z