[AGRIFOOD] Characterisation of microbiotic soil crusts in arable soil and their effect on pesticide fate and persistence

土壤通常在表面具有微生物结皮，其是生物形成的并且含有自养藻类和蓝细菌。由于这些层在土壤表面形成，它们在确定水分渗透和蒸发、侵蚀和气体交换方面具有相当重要的意义。目前评估作物保护产品（CPP）环境命运的监管指南是在黑暗中处理（筛分）土壤上进行的。因此，未评估微生物层中的群落对CPP降解的任何贡献。先正达和沃里克之间的合作工作表明，可耕地土壤表面的微生物层显著提高了作物保护产品（CPP）的降解速率。这些研究结果表明，微生物层可能在决定CPP的环境命运方面发挥重要作用，而这一点以前一直被忽视。学生将建立在早期的先正达-华威研究，以研究微生物层中农药降解速率改变的机制，环境和作物特征影响微生物层发育和特征的方式，以及CPP生物降解和通过土壤运输的后果。以下假设将被测试：1。光养生物是负责提高CPP生物降解率内的微生物结皮2。微生物结皮的结构和组成随季节变化3。不同冠层特征的作物具有不同结构、组成和空间分布的微生物结皮。微生物结皮结构和组成影响CPP的吸附和向土壤中的运输5.微生物结皮的结构和组成影响CPP生物降解工业合作伙伴将提供资金，让学生在第一年在先正达度过3个月的实习期，学习和应用先进的方案，使用14 C方法量化CPP和结合残留物。在工作的实验阶段之后，工业合作伙伴将支持学生在先正达再花3个月的时间，使用农药归宿建模方法（例如FOCUS模拟模型和情景）确定微生物结皮对不同作物类型下农药归宿和土壤持久性的重要性。此外，导师有一个既定的合作计划，弯曲，谢弗和马歇尔已经共同监督1博士生，弯曲和谢弗共同监督另外2博士生。

Soil usually possesses a microbiotic crust at the surface, which is biologically formed and contains autotrophic algae and cyanobacteria. Since these layers form at the soil surface, they have considerable importance in determining water infiltration and evaporation, erosion and gas exchange. Current regulatory guidelines to assess the environmental fate of crop protection products (CPP) are conducted on processed (sieved) soil in the dark. Hence, any contribution of communities in the microbiotic layer to CPP degradation is not assessed. Collaborative work between Syngenta and Warwick has indicated that microbiotic layers at the surface of arable soils significantly enhance degradation rates of crop protection products (CPP). These findings suggest that the microbiotic layer could have a major role in determining the environmental fate of CPP which has previously been overlooked. The student will build on earlier Syngenta-Warwick research to investigate the mechanisms underlying altered degradation rates of pesticides in the microbiotic layer, the way in which environmental and crop characteristics affect development and characteristics of the microbiotic layer, and the consequences of this for CPP biodegradation and transport through soil. The following hypotheses will be tested: 1. Phototrophic organisms are responsible for enhanced rates of CPP biodegradation within the microbiotic crust 2. The structure and composition of the microbiotic crust changes seasonally 3. Crops showing different canopy characteristics have microbiotic crusts with different structure, composition and spatial distribution 4. Microbiotic crust structure and composition affects sorption of CPP and transport into soil 5. Structure and composition of the microbiotic crust affects CPP biodegradation The industrial partner will provide funding to allow the student to spend a 3 month placement at Syngenta during year 1, learning and applying advanced protocols to quantify CPP and bound residues using 14C methodologies. Following the experimental phase of the work the industrial partner will support the student to spend a further 3 month placement at Syngenta to determine the significance of microbiotic crusts for pesticide fate and persistence in soil under different crop types, using pesticide fate modelling approaches (e.g. FOCUS simulation models and scenarios) The studentship provides interdisiplinary training in soil science, microbiology and the environmental chemistry. Furthermore the supervisors have an established collaborative programme, with Bending, Schafer and Marshall already co-supervsing 1 PhD student, and Bending and Schafer co-supervising a further 2 PhD students.