Anne-Sophie Voisin

Precision agriculture is a reality in agriculture and is playing a key role as the industry comes to terms with the environment, market forces, quality requirements, traceability, vehicle guidance ...

Triazole fungicides are widely used to treat fungal pathogens in field crops, but very few studies have investigated whether fields of these crops constitute hotspots of azole resistance in Aspergillus fumigatus. Soil samples were collected from 22 fields in two regions of eastern France and screened for triazole residues and azole-resistant A. fumigatus (ARAf). Real-time quantitative PCR (qPCR) was used to quantify A. fumigatus in these soil samples. All the plots contained tebuconazole at concentrations from 5.5 to 19.1 ng/g of soil, and 5 of the 22 plots also contained epoxiconazole. Only a few fungal isolates were obtained, and no ARAf was detected. A. fumigatus qPCR showed that this fungal species was, on average, 5000 times more common in soil from flowerbeds containing ARAf than in soil from field crops. Thus, field-crop soils do not appear to promote A. fumigatus development, even if treated with azole fungicides, and cannot be considered hotspots of resistance. Indeed, our results suggest that they are instead a coldspot of resistance and highlight how little is known about the ecological niche of this species.

Hand-held chlorophyll meters or leaf-clip-type sensors indirectly and instantaneously measure leaf N content. They can provide an N nutrition index (NNI) value that is crucial information for adjusting the amount of N fertilizer to the actual N status of the plant. Although these measurements are non-invasive and non-destructive, they require numerous repetitions at the canopy scale. The objective of this work was to explore the potential of visible images to predict nitrogen status in winter wheat crops from estimating NNI and to compare these results with those deduced from classical methods. Based on a dark green colour index (DGCI), which combines hue, saturation and brightness, a normalized DGCI (nDGCI) was proposed as the ratio between the measurements of the study microplot and those of the over-fertilized microplot. The methodology was performed on winter wheat microplots with a nitrogen gradient. Half of the microplots were grown with a single cultivar (LG Absalon) and the other half with a mixture of four wheat cultivars. The impact of optical device (digital camera or smartphone), the white balance (Manual or Automatic), the crop growth stage (two-nodes or heading) and cultivars (single or mixed) on the relationship between (DGCI, nDGCI) and NNI was evaluated. The results showed a close correlation between the nDGCI values and the NNI_NTester values, especially on a single cultivar (LG Absalon; R² = 0.73 up to 0.91 with smartphone). It suggested that the relationship is highly sensitive to the wheat cultivar. This approach with no specific calibration of images is promising for the estimation of N requirements in wheat field.

Legumes provide several ecological services to agroecosystems, but there is a lack of references on services related to N flows for a wide range of legume crops. N2O emissions were measured in two field experiments using a two-year legume-cereal crop sequence. In the first year (2014 and 2016), different legume crops were grown (lupin, pea, fava bean, common bean, soybean, chickpea) and compared to fertilized cereals (barley and sorghum). Once the seeds were harvested and the residues incorporated in the soil, unfertilized wheat was sown and harvested in the second year (2015 and 2017). N2O emissions, as well as soil temperature and moisture, were measured continuously using an automated chamber method during the two years of each experiment. Daily N2O emissions were less than 10 g N-N2O ha-1 d-1, with higher values (ranging from 10 to 90 g N-N2O ha-1 d-1) being measured during exceptionally rainy conditions. Daily N2O emissions were mainly influenced by climatic conditions for field experiments and far less by inorganic N content, except for N-fertilized cereals. For both field experiments, cumulative N2O emissions during legume and cereal pre-crops + fallow period between pre-crop harvest and wheat sowing (1st year) (mean values 365.4 and 318.1 g N-N2O ha-1 for experiment I and II, respectively) were higher than during wheat crop cultivation (2nd year) (155.8 and 101.5 g N-N2O ha-1 for experiment I and II, respectively). For field experiment II, N2O emissions were slightly higher for the N fertilized cereal pre-crops (529.8 and 523.3 g N-N2O ha-1 for barley and sorghum, respectively) compared to legume pre-crops (mean values 380.6 and 417.2 g N-N2O ha-1 for legumes sown in March and May, respectively), while no significant difference was measured for field experiment I. There was no difference in N2O emissions during the cultivation of the different legume species. Furthermore, when wheat was grown after legumes or N fertilized cereals, N2O emissions were comparable for the different experimental treatments with no relation established with the amounts of N present in crop residues or their C: N ratios. Despite the small differences in emissions between N-fertilized cereals and grain legumes, introducing these leguminous species in crop rotation and in these pedoclimatic conditions makes it possible to substitute synthetic N fertilizer and mitigate the greenhouse gases emitted from these cropping systems. However, further research is still needed to clarify and quantify the value of legumes in mitigating and reducing greenhouse gas emissions from cropping systems.

Diversification of cropping systems has been proposed as a major mechanism to move towards sustainable cropping systems. To date, a diversification option that has received little attention is introduction of ley pastures into cropping systems, but the use of ley pastures is challenged by most future-oriented scenarios aiming to feed the world sustainably. In these scenarios, ruminant livestock feed only on permanent pastures, while cropping systems focus completely on production of crop-based human food. Diversification of cropping systems with ley pastures is thus compromised by knowledge gaps and future-oriented policy options. Here, we review ecosystem services provided by introducing ley pastures into cropping systems to increase sustainability of agriculture, discuss types of ley pastures and their management liable to promote these services, and raise future challenges related to introducing ley pastures into cropping systems. We conclude that (1) ley pastures provide a large set of input (soil conservation, nutrient provision and recycling, soil water retention, biological control of pests) and output (water purification, climate regulation, habitat provision for biodiversity conservation, forage production) ecosystem services of primary importance to cropping systems and society, respectively, as long as their spatial and temporal insertion within cropping systems is well-managed; otherwise, disservices may be produced. (2) To benefit from ecosystem services provided by ley pastures in cropping systems while limiting their disservices, it appears necessary to define a safe operating space for ley pastures in cropping systems. Moving towards this space requires changing plant breeding programs towards multiservice ley pastures, producing knowledge about emerging ways of introducing ley pastures into cropping systems (e.g., living mulch, green manure) and better quantifying the bundles of ecosystem services provided by ley pastures in cropping systems.

Grain-legume crops are important for ensuring the sustainability of agrofood systems. Among them, pulse production is subject to strong lock-in compared to soya, the leading worldwide crop. To unlock the situation and foster more grain-legume crop diversity, scientific research is essential for providing new knowledge that may lead to new development. Our study aimed to evaluate whether research activity on grain-legumes is also locked in favor of soya. Considering more than 80 names grouped into 19 main grain-legume species, we built a dataset of 107,823 scholarly publications (articles, book, and book chapters) between 1980 and 2018 retrieved from the Web of Science (Clarivate Analytics) reflecting the research activity on grain-legumes. We delineated 10 scientific themes of interest running the gamut of agrofood research (e.g., genetics, agronomy, and nutrition). We indexed grain-legume species, calculated the percentage of records for each one, and conducted several analyses longitudinally and by country. Globally, we found an unbalanced research output: soya remains the main crop studied, even in the promising field of food sciences advanced by FAO as the “future of pulses”. Our results raise questions about how to align research priorities with societal demand for more crop diversity.