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

未受干扰的生态系统向集约化农业生产的转变对土壤有机质水平产生了负面影响，导致土壤碳(C)和氮(N)储量下降，并导致温室气体（GHG）排放。此外，我们越来越依赖氮肥来维持农业生产力，这增加了一氧化二氮的排放，一种温室气体，其全球变暖潜能值是二氧化碳的296倍。目前，土壤占全球一氧化二氮排放总量的70%，但随着农业生产的加强和对氮肥的日益依赖，以满足当前和未来全球对粮食、纤维和燃料的需求，预计这一数字将进一步增加。如果可以通过实施复杂的农业生态系统（如间作系统）更有效地管理氮，那么对剩余氮补充的需求就会减少。然而，人们对这种潜力知之甚少，而且在复杂的农业生态系统中调节氮转化的机制尚未被量化。该研究项目提供了间作与单作相比土壤氮转化和碳稳定的信息，以及这些过程如何受到大气二氧化碳浓度和温度增加的影响。方法方法包括严格的土壤取样，以量化间作和单作作物的土壤C和N；并为模型的标定提供了有价值的数据。使用新的稳定同位素技术将有助于确定N2O的来源和总土壤氮矿化和固定速率。从该研究项目中获得的信息为深入了解复杂农业生态系统中N的管理提供了进一步的见解，并有助于解决目前缺乏的N2O分配和稳定同位素技术在不同农业生产系统中的应用的信息。该研究项目致力于通过减少温室气体排放系统地实现环境目标的多重效益，同时也解决了长期维持全球粮食安全的当前问题。这些信息对各种利益攸关方都有价值，并将促进国际合作努力。

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.