Institute of African Studies - Columbia University

Stephen Wood

Recent efforts to increase food security in sub-Saharan Africa have focused on providing farmers with high-yielding seeds and mineral fertilizers. Although these interventions have led to short-term increases in yield, it is unclear how they will affect ecosystems. For example, very little research has examined how soil microbial communities respond to the application of mineral fertilizers, and no studies to date have been conducted in sub-Saharan Africa. These soil microbial communities regulate nearly every ecosystem process necessary for sustained food production (e.g., decomposition and organic matter formation).

During my time in Kenya, I examined:

  1. the effect of mineral fertilizers on the composition and functional capacity of soil microbial communities and
  2. the potential consequences this has for ecosystem processes, decomposition and organic matter formation required for sustainable food production in sub-Saharan Africa.

My research was conducted in the Sauri Millennium Villages Project site in western Kenya. I collected soils from three different types of farms (mineral fertilizer, no fertilizer, and fallows that use fast-growing, nitrogen-fixing trees to add nutrients and organic matter to the soil). To understand the composition of the microbial community, I extracted DNA for genetic analysis to determine the microorganisms that are present in the soil. To understand the functional capacity of the soil, I tested for the ability of the soil to consume various carbon substrates. To understand the potential consequences on soil organic matter dynamics, I analyzed soils for amount and type of soil organic matter and the amount of microbial biomass present, which is one of the most important sources of soil organic matter formation.


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