Agricultural intensification and the functional capacity of soil microbes on smallholder African farms

1. Fertilization may impact ecosystem processes that sustain agriculture, such as nutrient cycling, by altering the composition of soil microbial communities that regulate such processes. These processes are crucial to low-input, smallholder tropical agriculture, which supports 900 million of the world's poorest people. Yet little is known about how efforts to increase crop yield on such farms will affect the capacity of soil microbial communities to carry out ecosystem processes. 2. We studied the diversity and functional capacity of microbial communities on smallholder farms in western Kenya. We measured functional capacity as the abundance of functional genes involved in several components of nutrient cycling as well as catabolism of multiple carbon substrates; taxonomic diversity was measured using metagenomic sequencing. Diversity and functional capacity were measured on short-term, experimental mineral fertilizer addition plots and on actively managed farms that have maintained fo...