Investigating the fundamental mechanisms that regulate nitrogen transformations and nitrous oxide emissions in complex agroecosystems

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The conversion of undisturbed ecosystems to intense agricultural production has negatively affected levels of soil organic matter, which has has led to a decline in soil carbon (C) and nitrogen (N) stocks and has resulted in the emission of greenhouse gases (GHG). Additionally, our increasing dependence on N fertilizers to maintain agricultural productivity has augmented the emission of N2O, a GHG with a global warming potential 296 times greater than that of CO2. Currently, soils contribute 70% of the total global N2O emissions, but further increases are expected as agricultural production intensifies with increasing reliance on N fertilizers to meet current and future global demands for food, fiber and fuel. If N can be managed more effectively through the implementation of complex agroecosystems, such as intercrop systems, then the need for surplus N additions decreases. However this potential is poorly understood, and the mechanisms that regulate the transformation of N in complex agroecosystems has not yet been quantified. This research program provides information on soil N transformations and C stabilization in intercrops compared to sole crops, in addition to how these processes are affected by an increase in the concentration of atmospheric CO2 and temperature. The methodological approach involves rigorous soil sampling to quantify soil C and N in intercrops and sole crops; and provides data that is valuable for the calibration of models. Use of novel stable isotope techniques will help to determine the sources of N2O and the rate gross soil nitrogen mineralization and immobilization. Information gained from this research program provides further insight into the management of N in complex agroecosystems, and contribute to the current lack of information on N2O partitioning and the application of stable isotope techniques in different agricultural production systems. This research program addresses the multiple benefits that systematically meet environmental goals through mitigating GHG emissions, but also addresses the current issue of maintaining global food security over the long-term. This information is of value for a variety of stakeholders and will foster international collaborative efforts.