Collaborative Research: Disrupted Nitrogen Cycles in the Brazilian Amazon

为研究巴西亚马逊地区的氮循环提供了资金。该研究旨在量化新热带地区自然和农业环境中的氮转化和运输途径。农业的转变加上热带地区氮肥投入的增加，有可能导致一氧化二氮大量流失到大气中，或增加可溶性氮向河流和溪流的流动。拟议的实地研究将量化N2O通量和N的命运在渗流带，地下水和溪流在自然条件下（热带森林），单种大豆，大豆和玉米的双季种植。 遥感将被用来扩大结果从外地和模型到亚马逊地区，并纳入一个动态植被模型（IBIS）的研究结果，已参数化的亚马逊，并将用于估计氮排放量在不同的气候和土地利用管理方案的未来。这项工作将测试两个假设：（1）与天然林相比，增加氮肥将导致适度但不是很高的N2O排放，因为土壤排水良好，预计不会长时间厌氧积累N2O，和（2）流的N损失将在N中最小，施肥地块，因为玉米作物的高吸收率和保留任何残留的氮渗滤液在深，这项研究将有助于了解改变农业做法对亚马逊河流域温室气体排放和河流污染的影响。与巴西当地科学家的合作以及对美国和巴西学生的培训将对研究产生重要影响。将通过与巴西农业生产者和决策者建立联系，定期向巴西农业生产者和决策者介绍情况，以及支持一名美国记者访问长期生态和地球化学研究的研究现场，从而实现公共宣传和广泛传播成果。

Funds are provided to study nitrogen (N) cycles in the Brazilian Amazon. The research aims at quantifying N transformation and transport pathways in natural and agricultural settings in the Neotropics. The shift in agriculture combined with the increase in nitrogen fertilizer inputs in tropical regions have the potential to drive profound losses of nitrous oxide to the atmosphere, or increased movement of soluble N to rivers and streams. The proposed field research will quantify N2O fluxes and N fate in the vadose zone, groundwater and streams under natural conditions (tropical forest), single cropping of soybeans, and double cropping with soybeans and maize. Remote sensing will be used to scale up results from the field and model to the Amazon region, and incorporation of research results into a dynamic vegetation model (IBIS) that has been parameterized for the Amazon and will be used to estimate N emissions under different climate and land use management scenarios in the future. The work will test two hypotheses: (1) that increased N fertilization will lead to moderately but not greatly higher N2O emissions compared to natural forest because soils are well-drained and are not expected to go anaerobic long enough for accumulation of N2O, and (2) that N losses to streams will be minimal in N-fertilized plots because of high rates of uptake by maize crop and retention of any residual N leachates in deep, clay soils through anion exchange.The research will aid in understanding effects of changing agricultural practices on greenhouse gas emissions and stream pollution in the Amazon. Partnerships with local Brazilian scientists and training of US and Brazilian students will be important impacts from the research. Public outreach and broad dissemination of results will be achieved through regular presentations to agricultural producers and policy makers in Brazil through established contacts, as well as the support of a US journalist to visit the research field sites, which are locations of long-term ecological and biogeochemical research.