The role of legumes in achieving net zero: reducing nitrogen losses and improving soil health

苏格兰政府承诺到2045年实现苏格兰温室气体净零排放目标，英国政府到2050年实现这一目标。然而，目前的农业做法通过硝酸盐浸出和温室气体一氧化二氮（N2O）的排放导致了大量氮(N)的损失。改良的农业做法可以防止土壤健康枯竭和过量施用合成氮肥。在作物系统中种植豆科植物，以捕获和利用生物形式的氮，为实现净零目标提供了一种基于自然的解决方案。包括固氮豆科植物（如红三叶草、黑苜蓿、苜蓿）在内的多种植物物种混合物目前正在有机农业中使用，但需要在传统农业中进一步发展，特别是了解不同物种混合物与单一栽培的氮循环和土壤温室气体释放。需要直接测量不同农业系统（覆盖作物、草/豆类混合物、间作、草本牧草）间氮转移过程的循证研究，以更好地了解植物-土壤相互作用及其操纵能力，以优化氮利用效率和减少温室气体排放，同时保持作物生产力。将制定一个试验方案，调查草豆科植物的物种多样性、组成和间作对固氮、氮库、氮吸收和生态响应的影响，如土壤健康状况和植物生产力。还将根据后续作物的净收益和损失以及更广泛的遗留影响来研究对残留物质量和掺入的影响。该项目将开发草/豆科植物管理指南，以优化氮利用效率，利用现有的试验田场地，与当前的群居放牧、碳固存潜力、温室气体监测和未来的RESAS研究活动相联系。学生将接受一系列分析技术（如连续流分析、气相色谱、同位素比质谱、遗传技术/分析）的培训，以探索氮库、温室气体排放和土壤微生物群落多样性。这些将提供关于植物-土壤N相互作用的详细信息，这对于将被纳入动态确定性模型以改进N循环预测的关系的发展至关重要。这个项目的导师都有丰富的博士指导经验（在一系列跨学科课题的领导和联合导师层面）。主管负责通过与学生积极沟通，了解学生的背景和相关经验，确定培训需求。为了确保所选博士生的优秀培训，在整个博士课程中都会对学生的进步和培训需求进行监控。

Scottish Government has pledged to meet a net-zero target for GHG emissions in Scotland by 2045 and the UK government by 2050. However, current agricultural practices result in high nitrogen (N) losses through nitrate leaching and emissions of the greenhouse gas (GHG) nitrous oxide (N2O). Improved agricultural practices can prevent soil health depletion and excess synthetic N fertiliser application. Implementing legumes into the crop system to capture and utilise biological forms of N provides a nature-based solution contributing to net zero targets. Diverse plant species mixtures that include N-fixing legumes (e.g. red clover, black medic, lucerne) are currently being used in organic agriculture but further development in conventional agriculture is needed, particularly understanding N cycling and soil GHG release in diverse species mixtures vs. monocultures. Evidence-based studies which directly measure N transfer-processes across contrasting agricultural systems (cover crops, grass/legume mixtures, intercropping, herbal leys) are needed to better understand plant-soil interactions and their ability to be manipulated for optimising N use efficiency and reducing GHG emissions whilst maintaining crop productivity. An experimental programme will be developed to investigate grass-legume species diversity, composition and intercropping effects on N fixation, N pools, N uptake and ecological responses, such as soil health status and plant productivity. Implications for residue quality and incorporation will also be studied in terms of net-gains and losses for the following crop and wider legacy effects. The project will develop grass/legume management guidance for optimal N use efficiency utilizing existing experimental field sites linked with current mob grazing, carbon sequestration potential, GHG monitoring and future RESAS research activities. The student will be trained in a range of analytical techniques (e.g. continuous flow analysis, gas chromatography, isotope ratio mass spectrometry, genetic techniques/analyses) to explore N pools, GHG emissions and soil microbial community diversity. These would provide detailed information about plant-soil N interactions which is vital for development of relationships that will be incorporated into dynamic deterministic models to improve the predictions of N cycling.Collectively supervisors on this project have extensive PhD supervision experience (at lead and co-supervisor levels on a range of interdisciplinary topics). The lead supervisor is responsible for identifying training needs through active communication with the student and awareness of the student's background and relevant experience. To ensure excellent training of the selected PhD student, the student's progress and training needs are monitored throughout the PhD programme.