Investigating soil carbon and nitrogen dynamics using stable isotopes in complex agroecosystems

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Under global climate change scenarios, one of the challenges is to maintain agricultural productivity in order to meet current and projected trends in food production.  This challenge, coupled with large-scale soil and water degradation, will challenge the long-term and sustainable production of agricultural resources.  For example, a change in the amount, and in the chemical composition of organic residues applied to the soil, influences microbial processes and the stabilization of carbon (C), affecting the emission of greenhouse gases (GHG) such as carbon dioxide (CO2).  Therefore, the level of organic C in soil is a balance between the rate of C addition from crop residues and C losses as CO2 from microbial decay of these residues.  It is essential to evaluate GHG emissions from various agroecosystem management practices, and implement land-use systems that increase the amount of carbon (C) stored in the soil.  However, this potential has not yet been well quantified, and the mechanisms of interaction that regulate soil C and nitrogen (N) dynamics in complex agroeocsystems, like intercropping systems, are poorly understood.  This study provides information on how agroecosystem management practices affect GHG emissions, and the long-term assimilation and stabilization of C in the soil in complex agroecosystems.  The methodological approach will involve rigorous soil sampling, and build a comprehensive data set for the calibration of models.  Investigating GHG, soil C and N dynamics concurrently with soil biophysical characteristics enhances our understanding of total agroecosystem management. Information gained from this study provides further insight on agroecosystem design, the multiple benefits that systematically meet food production, and environmental goals to help mitigate GHG fluxes through the assimilation and stabilization of C in the soil.  This information will be of value for a variety of stakeholders and also foster international collaborative efforts.