Phosphorus mobilization in artificially drained agricultural landscapes

以农业为主导的集水区的非点源磷出口是一个全球性问题，也是加拿大许多地区的优先领域，在这些地区，湖泊中有害和讨厌的藻类大量繁殖的现象越来越频繁。尽管实施了保护措施以减少磷的损失，但在某些地区，磷负荷并没有减少，而是增加了。一些磷的加速流失与农业用地的人工排水有关，这可以从最近施用的肥料和景观中的遗留储存中迅速输送养分。在气候变化的情况下，随着预期的水文循环的加剧，瓷砖排水正在整个北美扩大。我们目前对瓦片排水中磷运移的概念理解在不同的景观、气候和管理方案中过于笼统。因此，需要更清楚地了解与瓷砖排水相关的营养损失风险。这项提案的目标，以及我的研究计划的短期目标是提高对农业景观中瓦片排水对磷供应和运输过程的影响的科学认识。在接下来的五年里，我的研究团队将更好地了解通过不饱和渗透带向瓦片排水渠（瓦片尺度）调动磷的情况，并更好地了解不同水文条件下瓦片排水区（即内部排水差，地下水相互作用少，与地下水相互作用浅的可变源区水文）调动磷的差异。拟议的工作将在一系列景观和环境条件下描述P动力学的复杂性。实地调查将与新颖的实验相结合，作为这项工作的一部分，将至少培训五名研究生。该项目将对环境和经济产生重大影响，因为它解决了与土地管理（瓷砖排水）以及气候（和气候变化）相关的问题，这些问题与农业和粮食安全有关。这项研究基于数据驱动的实地观测，并包括冬季，在冬季期间，对过程的理解较弱，数据匮乏，因此解决了一个重大的知识差距。这将对土壤排水对磷损失的贡献提供一种创新的理解，这对平衡作物产量和水质至关重要，从而确保未来的粮食和水安全。

Phosphorus (P) export from non-point sources in agriculture-dominated catchments is a global issue, and a priority area for many regions in Canada, where harmful and nuisance algal blooms have been observed in lakes with increasing frequency. Despite the implementation of conservation practices to reduce P loss, P loads are not decreasing and are increasing in some regions. Some of the accelerated losses of P have been linked to the artificial (tile) drainage of agricultural lands, which can rapidly deliver nutrients from recently applied fertilizers as well as legacy stores in the landscape. With the anticipated intensification of the hydrological cycle under a changing climate, tile drainage is expanding throughout North America. Our current conceptual understanding of P mobilization in tile drainage is overgeneralized across different landscapes, climates and management scenarios. Thus, a clearer understanding of the risks of nutrient loss associated with tile drainage is needed. The goal of this proposal, and the short-term objective of my research program is to improve scientific understanding of the impacts of tile drainage on P supply and transport processes from agricultural landscapes. Over the next five years, my research team will provide an improved understanding of P mobilization through the unsaturated vadose zone into tile drains (tile scale) and an improved understanding of differences in P mobilization in tile drained fields with contrasting hydrology (ie poor internal drainage with little groundwater interaction vs variable source area hydrology with shallow groundwater interaction). The proposed work will characterize the complexities of P dynamics across a range of landscapes and environmental conditions. Field investigations will be coupled with novel experiments, and a minimum of five graduate students will be trained as part of this work. This program will have significant environmental and economic impacts as it addresses issues related to land management (tile drainage) as well as climate (and climate change), which are relevant to agriculture and food security. This research is based on data-driven field observations and includes the winter period, during which there is a weak understanding of processes and a paucity of data, and therefore addresses a significant knowledge gap. This will provide an innovative understanding of the contributions of tile drainage to P losses, which is important to balance both crop yields and water quality and thus ensure to future food and water security.