Among a wide range of possible applications of nanotechnology in agriculture, there has been a particular interest in developing novel nanoagrochemicals. While some concerns have been expressed regarding altered risk profile of the new products, many foresee a great potential to support the necessary increase in global food production in a sustainable way. A critical evaluation of nanoagrochemicals against conventional analogues is essential to assess the associated benefits and risks. In this assessment, recent literature was critically analysed to determine the extent to which nanoagrochemicals differ from conventional products. Our analysis was based on 78 published papers and shows that median gain in efficacy relative to conventional products is about 20-30%. Environmental fate of agrochemicals can be altered by nanoformulations, but changes may not necessarily translate in a reduction of the environmental impact. Many studies lacked nano-specific quality assurance and adequate controls. Currently, there is no comprehensive study in the literature that evaluates efficacy and environmental impact of nanoagrochemicals under field conditions. This is a crucial knowledge gap and more work will thus be necessary for a sound evaluation of the benefits and new risks that nanoagrochemicals represent relative to existing products.

Biochar is obtained by pyrolyzing biomass and is, by definition, applied in a way that avoids its rapid oxidation to CO2. Its use in agriculture includes animal feeding, manure treatment (e.g. as additive for bedding, composting, storage or anaerobic digestion), fertilizer component or direct soil application. Because the feedstock carbon is photosynthetically fixed CO2 from the atmosphere, producing and applying biochar is essentially a carbon dioxide removal (CDR) technology, which has a high‐technology readiness level. However, for swift implementation of pyrogenic carbon capture and storage (PyCCS), biochar use in agriculture needs to deliver co‐benefits, for example, by improving crop yields and ecosystem services and/or by improving climate change resilience by ameliorating key soil properties. Agronomic biochar research is a rapidly evolving field of research moving from less than 100 publications in 2010 to more than 15,000 by the end of 2020. Here, we summarize 26 rigorously selected meta‐analyses published since 2016 that investigated a multitude of soil properties and agronomic performance parameters impacted by biochar application, for example, effects on yield, root biomass, water use efficiency, microbial activity, soil organic carbon and greenhouse gas emissions. All 26 meta‐analyses show compelling evidence of the overall beneficial effect of biochar for all investigated agronomic parameters. One of the remaining challenges is the standardization of basic biochar analysis, still lacking in many studies. Incomplete biochar characterization increases uncertainty because adverse effects of individual studies included in the meta‐analyses might be related to low‐quality biochars, which would not qualify for certification and subsequent use (e.g. high content of contaminants, high salinity, incomplete pyrolysis, etc.). In summary, our systematic review suggests that biochar use in agriculture has the potential to combine CDR with significant agronomic and/or environmental co‐benefits.

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To protect themselves, plants can produce toxic secondary metabolites (phytotoxins) that appear with widely varying structures and negative effects. These phytotoxins often show similar properties as known aquatic micropollutants in terms of mobility, persistence, toxicity, and possibly also ecotoxicity. However, their occurrence in surface waters remains largely unknown, which is also due to unknown ability of available screening approaches to detect them. Therefore, we performed a target and suspect screening based on a persistence-mobility prioritization for phytotoxins in small Swiss creeks using high resolution mass spectrometry. In total, three of 26 targets were detected, three of 78 suspects tentatively identified, and six suspects fully confirmed by reference standards. To the best of our knowledge, it is the first time that three different plant secondary metabolite classes are detected in the same surface water sample. Estrogenic isoflavones were detected at 73% of the sites with formononetin as main toxin, which is in agreement with previous studies. Furthermore, pyrrolizidine alkaloids and the indole alkaloid gramine were detected. Especially pyrrolizidine alkaloids might be critical due to their production by various plants including the invasive Senecio inaequidens, and their known importance in food and feed safety. Based on these first screening results, different phytotoxin classes should be assessed for their ecotoxicological effects and considered in future water monitoring.

Fusarium head blight is one of the most noxious cereal diseases. Worldwide, F. graminearum (FG) and the mycotoxin deoxynivalenol (DON) is the most dominant species/mycotoxin in barley and wheat. Barley is often produced as on farm feed and thus routine mycotoxin analyses similar to those of cereals for human consumption are not performed. Hence, an early prediction of mycotoxin levels is important for farmers to minimise the risk of contaminated feed but also of contaminated cereals entering the cereal supply chain. Therefore, climate chamber experiments with artificial FG infection of barley investigating the influence of different temperatures (10°C, 15°C, 20°C) and durations (4 h, 8 h, 12 h) at 99% relative humidity were conducted to accumulate data to develop a forecasting system. An up to three times higher DON contamination in the 15°C treatments for the feed barley variety Ascona was detected compared with the 10°C and 20°C treatments. For the malting barley variety Concerto, the prolonged humidity durations had a stronger effect under all tested temperatures and resulted in up to two times higher DON contaminations. In addition, field experiments where spore deposition during anthesis as well as disease incidence, fungal amount and mycotoxins were observed, showed that the overwintered straw treatment resulted, depending on the year, in a three times higher FG incidence and DON content compared with the control and freshly inoculated straw treatment.