Concerns about sustainability and high environmental costs of agriculture in developed and developing countries are pertinent. Here, we focus on how the interactions between organic materials, mineral nitrogen inputs and the dynamics of soil aggregates control carbon and nitrogen cycling in natural and agricultural systems across different climate zones (i.e. African Humid Forest zone, Moist Savanna zone, and Dry Savanna zone). An understanding of these interactions is needed for an integrated and ecological sound management of organic (OR) and mineral resources (MR). It is postulated that aggregate turnover plays a fundamental role in the interactions between OR and MR by the multitude of regulatory effects aggregates have on processes in the soil system, like the protection of soil organic matter, determining microbial community structure, limit O₂ diffusion, regulate water flow, influence nutrient ad- and desorption, and reduce erosion. Fundamental knowledge of N synchrony, C turnover and C plus N storage in soil across a wide range of ecosystems is central to our ability to predict ecosystem behavior and develop sustainable ecosystem management practices. The combined use of OR plus MR is a holistic approach in soil fertility research that embraces the full range of biological, physical, chemical, social, economic and political factors influencing the sustainability of the soil system. However, to fully benefit from this approach, the mechanistic linkage between soil structural dynamics and resource use efficiency need to be understood.

For more information contact Johan Six (jwsix@ucdavis.edu) or Roberta Gentile (rgentile@ucdavis.edu) or Pauline Nhamo (ppnhamo@ucdavis.edu)