DISSERTATION RESEARCH: The effects of changing rainfall patterns on nitrogen cycling and leaching losses in agroecosystems

论文研究：降雨模式变化对农业生态系统氮循环和淋失损失的影响

• 批准号: 1501133
• 负责人: Pamela Matson
• 金额: $ 1.65万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1501133&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; effects; changing; rainfall

Rainfall patterns are currently changing in the midwestern U.S., with an increasing proportion of rain falling in very heavy rain events. This intensification of rainfall patterns may have important consequences for rain-fed agriculture. In particular, intensification of rainfall may alter the availability and losses of soil nitrogen. Nitrogen is an essential crop nutrient, but it is also very mobile. Only about half the nitrogen added to soil in fertilizer is taken up by crops, with much of the remainder lost to the environment. Leaching is one of the most important pathways through which nitrogen is lost, with possible negative consequences including groundwater contamination and algae blooms and dead zones in rivers, lakes, and the coastal ocean. This research explores how more intense rainfall patterns may affect nitrogen leaching from Midwestern agricultural ecosystems. The project also seeks to identify management practices which may mitigate enhanced nitrogen leaching in the face of climate change. This research will be conducted using an ecosystem-scale rainfall manipulation experiment at the Kellogg Biological Station Long Term Ecological Research (LTER) site in southwest Michigan. Agricultural fields under conventional and no-till management are exposed to ambient rainfall as well as rainfall patterns with extended dry periods and large, simulated rainfall events. Leaching will be estimated with tension lysimeters to measure soil water nitrogen concentrations, and a model to estimate soil water flux. Deep soil sampling to 1.2m will trace the movement of nitrate down the soil profile over the course of a year and in response to individual rainfall events. The results will be shared with extension specialists, policymakers, and other local stakeholders and will provide opportunities for mentoring undergraduates.

美国中西部的降雨模式正在发生变化，在非常强的降雨事件中，降雨的比例增加。降雨模式的这种加剧可能对依赖雨水的农业产生重要影响。 特别是，降雨量的增加可能会改变土壤氮素的有效性和损失。氮素是一种重要的作物养分，但它也是非常移动的。 只有大约一半的肥料中添加到土壤中的氮被作物吸收，其余的大部分流失到环境中。淋溶是氮流失的最重要途径之一，可能造成的负面后果包括地下水污染、藻类大量繁殖以及河流、湖泊和沿海海洋中的死区。这项研究探讨了更强烈的降雨模式如何影响中西部农业生态系统的氮淋失。该项目还寻求确定在气候变化的情况下可能减轻氮淋溶增加的管理做法。 这项研究将在密歇根州西南部的凯洛格生物站长期生态研究（LTER）现场进行生态系统规模的降雨控制实验。在传统和免耕管理下的农田暴露于环境降雨以及降雨模式与延长干旱期和大，模拟降雨事件。 将使用张力蒸渗仪来测量土壤水氮浓度，并使用模型来估计土壤水通量。深至1.2米的土壤采样将追踪硝酸盐在一年中以及对个别降雨事件的反应中沿土壤剖面的移动。研究结果将与推广专家、政策制定者和其他当地利益攸关方分享，并将为指导本科生提供机会。