The influence of biochar and digestate on short term nitrogen transformations in three contrasting soils.

In recent times agricultural production has placed an emphasis the maximisation of yield rather than on effects on the wider environment which has caused a shift in the nitrogen cycle leading to deleterious consequences in agricultural systems and beyond. Agronomic consequences include declining soil organic matter content, pH and increasing soil erosion which has led to decreasing yields. Environmental consequences include increased greenhouse gas emission. Two potential solutions to these challenges are the use of pyrolyzed or digested organic materials, including waste organic material. Pyrolyzed organic material results in a carbonaceous product called biochar and anaerobic digestion results in a product called digestate. Biochar offers the advantage of storing carbon in soil to mitigate climate change, and digestate is a nutrient rich fertiliser. However, they both have their disadvantages. Biochar is low in fertilising value which limits its use to crops, and digestate is low in carbon which limits its use in improving soil carbon stocks. This thesis explores whether combining these amendments in different soils results in a shift in the nitrogen cycle such that more nitrogen compounds are retained in the soil for crop use, and less nitrogenous gases are emitted to cause environmental pollution. Incubation experiments were conducted on three different soils, predominantly silt, sand or clay, to investigate the effect of the addition of a hardwood biochar or maize digestate applied as single amendments or together on a range of parameters of agronomic and environmental concern. Those parameters included soil mineral nitrogen accumulation and mineralisation rates, total and organic nitrogen and carbon concentration, pH, cation exchange capacity, electrical conductivity, ammonia, nitrous oxide and carbon dioxide emission. Whether or not combining biochar with digestate improved agronomic factors and reduce negative environmental ones depended, in large part, on soil type. In the silt soil pH and cation exchange capacity was not influenced by either biochar or digestate, also when co-applied. The addition of digestate generally increased mineralisation of ammonium, however, there was some evidence that, when combined with biochar, this process was reduced. Given the lack of change in other soil parameters, it was concluded that biochar brought about a shift in the micro-organism population such that mineralisation processes were suppressed. The emission of carbon dioxide and nitrous oxide were all increased with digestate amendments, but not with biochar alone. When in combination with biochar, there was no significant statistical difference between digestate alone treatments. Hence, in the silt soil, combining biochar with digestate did not reduce greenhouse gas emission. In the sand soil, both pH and electrical conductivity increased as a result of digestate application, alone and co-applied with biochar but not with biochar alone. Due to the low carbon and nitrogen concentrations in the sand soil it was possible to detect a greater shift in total nitrogen and carbon levels, with a significant change in the C:N ratio. Again, digestate application promoted mineralisation rates, but the addition of biochar appeared to reduce them such that there was a higher accumulation of ammonium after one week. There were significant differences in carbon dioxide emission from the sand soil treated with digestate compared to control, and this was not mitigated by biochar emission. However, there was some evidence that the co-application of biochar did reduce nitrous oxide emission from digestate amended soils. Unsurprisingly, in the fertile clay soil biochar did not influence pH, cation exchange capacity or electrical conductivity, however, digestate did, resulting in an increase in pH. There was also some evidence that biochar decreased nitrous oxide emission from digestate amended soils. This research has contributed new insights into the use of digestate and biochar in agricultural production to meet agronomic and environmental requirements. It has provided an important perspective on the potential and limitations of combining these two amendments in different soil types. Overall, in these incubation experiments, biochar did not quite prove to be the useful ‘sponge’ for the nitrogen supplied by digestate that was anticipated. However, this thesis provides some important indicators which may guide the co-application of a biochar and digestate to land, not only for field scale experimentation but also for future application in food production. Firstly, different soil textures respond differently to the co-applied amendment, and it may be that farmers on sandy or clay soils may reap more direct agronomic benefits and, secondly, be able to show evidence of environmental benefits (and therefore earn more subsidy) as co-applied biochar and digestate saw a decrease in nitrous oxide emissions over digestate alone. <br/

Place-Based Pathways to Sustainability: Exploring Alignment between Geographical Indications and the Concept of Agroecology Territories in Wales

Geographical Indications (GIs) are regarded as important endogenous rural development mechanisms by the European Union. GIs have proven successful for some producers in some regions, delivering higher added value and safeguarding a product&rsquo;s identity and heritage through the notion of terroir. Within the context of a gradual &ldquo;greening&rdquo; of GIs, this paper opens up questions about what potential they might have for transitions to agroecology territories, which are spaces engaged in a transition process towards sustainable agri-food systems. Using the Food and Agricultural Organization&rsquo;s 10 elements of agroecology as a lens, we discuss whether GIs can serve as levers in delivering sustainable agri-food transitions, drawing on the case of the devolved nation of Wales. We base our narrative on a content analysis of GI product specification documents and data from interviews with GI stakeholders. Our case study illustrates that the discourse within the regulatory framework of some Welsh GIs has shifted from one of technicality towards the integration of some agroecology elements in more recent GI product specifications. In this respect, we argue that there is evidence of a &ldquo;first generation&rdquo; and &ldquo;second generation&rdquo; assortment of GIs in Wales. However, any potential for levering an overall transition within this scheme towards an agroecology territory remains constrained by the piecemeal embedding of agroecology. The incorporation of agroecology is emerging primarily from the ground-up&mdash;driven by independent organizational and place-based collective action, but unaccompanied, as yet, by any parallel shift amongst supporting administrative and regulatory authorities. We also discuss the importance of reflexive governance if GIs are to be viable pathways for sustainability transitions. As such, the capacity for GIs to facilitate quality-led place-based food systems that enhance increasingly threatened environmental resources is contingent upon stakeholders adopting a territorial, reflexive governance approach

Using biodiversity to persuade: A discourse analysis

Using biodiversity to persuade: A discourse analysis. Insights from the biodiversity discourse in Europe

Report on biodiversity and related concepts perceptions. Delivrable number: D1.1

• This report provides insight into the biodiversity discourse by biodiversityrelevant actor groups in Europe • The absence of a common understanding of biodiversity allows actor groups to choose rhetoric strategically • Biodiversity discourse is used strategically to persuade, gather custom or support, or justify action or inaction • Anthropocentric values are mostly used when arguing both for and against biodiversity conservation • The biodiversity discourse is dominated by rhetoric of warning, persuading, calling for action, accusing, and informing • The rhetoric used in biodiversity discourse differs between countries • Knowledge of societal discourses are valuable to tailor interventions to promote biodiversity, such as those in PLANET4B case studie