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

在全球气候变化情景下，挑战之一是保持农业生产力，以满足当前和预计的粮食生产趋势。 这一挑战，加上大规模的土壤和水退化，将对农业资源的长期和可持续生产构成挑战。 例如，施用到土壤中的有机残留物的量和化学组成的变化影响微生物过程和碳（C）的稳定，从而影响温室气体（GHG）如二氧化碳（CO2）的排放。 因此，土壤中的有机碳水平是作物残留物中的碳添加率与这些残留物微生物腐烂产生的CO2形式的碳损失率之间的平衡。 必须评估各种农业生态系统管理做法产生的温室气体排放，并实施增加土壤中碳储存量的土地使用制度。 然而，这种潜力尚未得到很好的量化，在复杂的农业生态系统中，如间作系统，调节土壤碳和氮（N）动态的相互作用机制，知之甚少。 这项研究提供了农业生态系统管理措施如何影响温室气体排放，以及长期的同化和稳定的C在复杂的农业生态系统的土壤中的信息。 该方法将涉及严格的土壤取样，并建立一个全面的数据集，用于模型的校准。 调查温室气体，土壤C和N动态与土壤生物物理特性同时增强了我们对农业生态系统管理的理解。从这项研究中获得的信息提供了进一步的见解农业生态系统的设计，系统地满足粮食生产的多重效益，并通过在土壤中的C的同化和稳定的环境目标，以帮助减轻温室气体通量。 这一信息将对各种利益攸关方具有价值，并促进国际协作努力。

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.