In-soil trophic interactions between plants, rhizosphere bacteria and nematodes: improving availability of soil phosphorus

磷肥是农业生产的重要组成部分，但全球磷矿供应是有限的，而且受到地理限制；因此，更好地利用磷供应至关重要。许多农业土壤含有大量的磷，但主要是有机形式的（尤其是植酸盐），这通常被认为是植物无法获得的。一些植物可以同时分泌有机酸和酶，它们可以潜在地动员和水解土壤有机磷。然而，这些过程的有效性在许多土壤中是有限的，开发利用这些有机磷储备的系统是全球农业可持续集约化的一个重要挑战。接种某些土壤微生物可提高植物对植酸磷的利用。此外，研究表明，线虫在草地地下根系的摄食促进了养分的流动，并影响了根际微生物群落的组成。同样，最近的研究表明，当线虫的细菌放牧促进了有机磷的释放时，松树幼苗对有机磷的利用得到了改善。了解这些土壤营养相互作用对设计未来可持续农业系统的重要性，对粮食安全至关重要。我们的目标是建立1)根际线虫和细菌之间的营养相互作用是否增加了从琼脂到土壤等一系列复杂系统中植物对磷的利用；2)植物和土壤细菌衍生的酶和有机酸的功能作用及其与线虫放牧的相对相互作用，以提高有机磷的利用率。为了实现这一目标，该项目最初将包括a)受控环境实验，在琼脂中种植一系列植物，以各种形式提供磷(Pi，植酸盐和磷酸糖)，并添加全因子组合的细菌（天然土壤群落和特定的磷酸盐增溶细菌）和线虫（天然土壤群落，细菌食草动物和真菌食草动物）；b)土壤复杂性增加的实验-从Balruddery可持续发展平台（可持续与传统）的两种处理中提取的土壤将进行灭菌，并使用增加复杂性的附加处理范围重新接种。这将包括对线虫和细菌群落结构组合的评估以及有机磷库的测量；c)线虫和细菌组合的评估，以及在现有处理的洛桑ltte和从档案中提取的适当样品中有机P库的测量；d)在苏格兰政府部门咨询秘书处实习，以深入了解政策和研究如何相互作用。

Phosphorus (P) fertiliser is an important component for agricultural production, but global supplies of rock phosphate are finite and geographically restricted; hence better use of P supplies is vital. Many agricultural soils contain large amounts of P, but mostly in organic forms (especially phytate), which are generally considered unavailable to plants. Some plants can exude both organic acids and enzymes, which together can potentially mobilise and hydrolyse soil organic P. However, the effectiveness of these processes is limited in many soils, and developing systems to utilise these organic P reserves is an important challenge in global sustainable intensification of agriculture. Plant utilisation of P from phytate is improved when inoculated with certain soil micro-organisms. Additionally, it has been demonstrated that below-ground root herbivory by nematodes in grasslands promoted nutrient flux and influenced the composition of the rhizospheric microbial community. Similarly, recent research has shown improved plant utilisation of organic P by pine seedlings when bacterial grazing by nematodes facilitated the release of P from organic sources. Understanding the importance of these soil trophic interactions under arable crops in order to design future sustainable agricultural systems is important for food security. We aim to establish 1) whether trophic interactions between rhizospheric nematode and bacteria increases plant utilisation of P in systems of a range of complexity from agar to soil; and 2) the functional role of plant- and soil bacteria derived enzymes and organic acids and their relative interaction with nematode grazing for enhanced utilisation of organic P.To achieve this the project will initially include a) controlled environment experiments, growing a range of plants in agar with P supplied in various forms (Pi, phytate and sugar phosphates) with addition of a full factorial combination of bacteria (natural soil community and specific phosphate solubilising bacteria) and nematodes (natural soil community, bacterial grazers and fungal grazers); b) experiments of increasing complexity in soil - soils taken from both treatments of the Balruddery Sustainability Platform (Sustainable vs Conventional) will be sterilised and re-inoculated with an additive range of treatments of increasing complexity. This will include an assessment of the nematode and bacterial community structure assemblages alongside measurement of organic P pools ; c) an assessment of the nematode and bacteria assemblages, alongside measurements of organic P pools in existing treatments of the Rothamsted LTEs and in appropriate samples taken from the archive; d) an internship with the Scottish Government Department Advisory Secretariat to gain an insight into how policy and research interface.