Pea–wheat intercrops in low-input conditions combine high economic performances and low environmental impacts

Intensive agriculture ensures high yields but can cause serious environmental damages. The optimal use of soil and atmospheric sources of nitrogen in cereal–legume mixtures may allow farmers to maintain high production levels and good quality with low external N inputs, and could potentially decrease environmental impacts, particularly through a more efficient energy use. These potential advantages are presented in an overall assessment of cereal–legume systems, accounting for the agronomic, environmental, energetic, and economic performances. Based on a low-input experimental field network including 16 site-years, we found that yields of pea–wheat intercrops (about 4.5 Mg ha−1 whatever the amount of applied fertiliser) were higher than sole pea and close to conventionally managed wheat yields (5.4 Mg ha−1 on average), the intercrop requiring less than half of the nitrogen fertiliser per ton of grain compared to the sole wheat. The land equivalent ratio and a statistical analysis based on the Price\u27s equation showed that the crop mixture was more efficient than sole crops particularly under unfertilised situations. The estimated amount of energy consumed per ton of harvested grains was two to three times higher with conventionally managed wheat than with pea–wheat mixtures (fertilised or not). The intercrops allowed (i) maintaining wheat grain protein concentration and gross margin compared to wheat sole crop and (ii) increased the contribution of N2 fixation to total N accumulation of pea crop in the mixture compared to pea sole crop. They also led to a reduction of (i) pesticide use compared to sole crops and (ii) soil mineral nitrogen after harvest compared to pea sole crop. Our results demonstrate that pea–wheat intercropping is a promising way to produce cereal grains in an efficient, economically sustainable and environmentally friendly way

Lagos: the ‘villagized’ city

This work examines some historical processes that have resulted in making Lagos hitherto the most urbanized center in Nigeria, a ‘villagized’ city. This work demonstrates how the city was made by people and also how the activities of people have been a major threat to the city. In addition, the paper has shown that what is striking to a visitor to Lagos is the site of a city marked by filthiness and degradation with slums and squatter settlements. This situation with its evident health hazards are now monumental that they are almost out of control. These problems are a result of fundamental neglect and poverty of urban governance. The collapse of critical public infrastructure such as roads, water, sewage and drainage systems, power supply and importantly, housing, essential for households and business concerns, increasingly characterize Lagos metropolis, thus making it a villagized city

Impact of nitrogen deposition on larval habitats: the case of the Wall Brown butterfly Lasiommata megera

Nitrogen deposition is considered as one of the main threats to biodiversity and ecosystem functioning. Three mechanisms have been proposed to explain the detrimental effect of excess nitrogen on butterflies: loss of host plants, deterioration of food plant quality and microclimatic cooling in spring. Here, we investigated whether these mechanisms might explain the dramatic recent decline of the Wall Brown butterfly Lasiommata megera. Monitoring data from the Netherlands indeed show a greater decline at higher critical load exceedance of nitrogen deposition. Loss of host plants is not a likely explanation of the decline for this grass-feeding species. In a greenhouse experiment, we only found beneficial effects of nitrogen fertilization on larval performance, which seems to rule out a nutritional cause; application of a drought treatment did not result in significant effects. Microclimatic conditions at overwintering larval sites of L. megera and the related but increasing Pararge aegeria provided a possible clue. In comparison with larval sites of P. aegeria, those of L. megera showed higher temperatures at the mesoscale and less plant cover and more dead plant material at the microscale. L. megera caterpillars were also found closer to the shelter of vertical structures. The greater dependence on warm microclimates suggests that microclimatic cooling through excess nitrogen contributes to the recent decline of L. megera

Protection Intégrée des rotations avec Colza et blé tendre : Conception et évaluation multicritères d’itinéraires techniques économes en produits phytosanitaires

Le projet PICOBLE avait pour objectif, en se plaçant à l’échelle de l’itinéraire technique, de contribuer à la recherche de solutions permettant de réduire l’usage de produits phytosanitaires dans les systèmes de culture à base de colza et de blé. Il a permis de concevoir et de tester des ITK innovants pour différentes situations. Les résultats obtenus concluent à la possibilité d’une réduction des produits phytosanitaires de 30 à 40% sans affectation de la marge de l’agriculteur sur la base des hypothèses de prix prises, mais avec une réduction du volume de production de 10% pouvant affecter l’économie des filières avales. Les connaissances acquises permettent d’envisager de nouvelles pistes de réduction à plus long terme mais elles nécessitent encore un travail considérable, il faudra en particulier aborder des échelles plus larges au niveau du système de culture ou du paysage.Integrated protection of crop rotation with winter oilseed rape (WOSR) and winter wheat: Conception and multicriteria evaluation of pesticides saver cropping practices The PICOBLE project was looking for knowledge and knowhow likely to contribute to a reduction of pesticides use in wheat and WOSR-based rotations, at the scale of annual cropping practices. New cropping techniques have been imagined, discussed and tested in the field before being assessed with a multi-criteria approach. A 30-40% reduction of the total amount of pesticides is possible, without X. Pinochet et al. 244 Innovations Agronomiques 28 (2013), 243-256 affecting the farmer economic result under given price hypothesis, but with a 10% reduction of the production, that might affect the economic competiveness of the connected industries. Results and knowledge produced during the project open new perspectives for further reductions on the longer term. Nevertheless, work is still needed and approaches have to be extended to cropping systems and landscapes scales

Associations céréale-légumineuses multi-services

Depuis plusieurs décennies, l’évolution de l’agriculture en France est, dans un certain nombre de régions de grande culture et d’élevage marquée fortement par la simplification des assolements accompagnée d’un usage accru des intrants et la standardisation des itinéraires techniques. Le challenge est maintenant de concevoir des agroécosystèmes plus diversifiés dans l’objectif d’une gestion écologique des parcelles cultivées devant se traduire par une amélioration de la productivité et la stabilité des systèmes face à divers aléas et la fourniture de différents services éco-systémiques. Ce projet a exploré l’augmentation de la diversité cultivée au sein de la parcelle via des associations céréale-légumineuse. Il a montré la diversité des services que l’on peut en attendre en agriculture biologique et en agriculture conventionnelle, en système céréalier et en système d’élevage. Ces associations permettent de répondre à la fois à des enjeux de production, de réduction des intrants, de réduction des impacts environnementaux des cultures, de stabilité face à des aléas biotiques et abiotiques. Le cœur du projet a consisté a testé différents leviers d’actions pour aider à l’orientation des performances de ces associations pour différents objectifs. Les atouts et contraintes d’adoption à l’échelle des filières (notamment pour les collecteurs) ont été aussi mis en évidence et quantifiés

An interdisciplinary approach to increase wheat within-field diversity and promote agro-ecosystem services

International audienceOne major challenge for increasing agriculture sustainability is to better mobilize crop genetic diversity, as prone by agroecology. A simple way to increase within-field diversity is to use cultivar mixtures, and this has been successfully applied to a few crops in the past. Despite numerous scientific papers documeting the value of cultivar mixtures in wheat and other cereals, especially to control diseases, their cultivation has remained marginal throughout the world. To understand the origin of this gap between scientific knowledge and agricultural practices, the French project Wheatamix explored the synergies mobilized by cultivar mixtures, their impact on various ecosystem services, and their potential to reinforce the sustainability, resilience, and multi-functionality of agriculture. It focused on the agro-ecological and socio-economic impacts of variety associations at different scales, from the plant level up to the wheat supply chain. The project aims at developing new blending and breeding methods to design performing mixtures.To understand how plant-to-plant interactions shape wheat mixtures performances, Wheatamix has set five objectives: 1) describe the variability of morphological and ecological traits in a panel of 57 varieties; 2) explore variability by blending 16 contrasted varieties from the panel into 72 mixtures, composed of 2, 4, and 8 components; 3) study the ecosystem services provided; 4) assess the technical and economic performances in farmer conditions; 5) evaluate the impact of cultivar mixtures on the wheat supply chain. To achieve these goals, this project has developed an interdisciplinary approach, mobilizing agronomy, ecology, economics, ecophysiology, epidemiology, genetics, and management sciences. The project brought together scientists from 10 labs, as well as agricultural advisers and farmers from 6 French counties. The project first described the functional diversity of 57 varieties, highlighting the effects of modern breeding on trait variability, that lowered variability of traits subject to direct selection, and impacted both plant architecture, physiological traits as nutrient absorption, but also trade-off between traits. Wheatamix then surveyed how variation in mixture diversity impacted wild communities. A first result highlighted the low abundance of macro-organisms in this experiment: no relationship was found between the number of varieties in a mixture and the diversity/abundance of earthworms, weeds, mycorrhizae, springtails, beetles, nematodes. However, a significant effect of mixture diversity on the abundance of some spiders, and on nitrifying bacteria, was observed. Coming to ecosystem services, disease regulation (rust and septoria) has been confirmed as the most strongly and positively affected by varietal associations, raising also the strong effects of architectural variability of the canopy (septoria). Diversity also contributed to higher predation rates on aphids. Lastly, soil nitrification and denitrification activities were significantly affected by mixture diversity on 4 surveyed sites, contributing to a shift in plant nutrition and positive effect of greenhouse gas emission.Co-design of variety mixtures was carried out with farmers, technical advisers, and scientists. For three years, 30 farmers in the Paris basin proposed varietal blends and measured their performance on their farms. This exchange first highlighted that the first goals for farmers was to i) secure their production ii) simplify plot management. Then co-design workshops allowed to propose assembly rules and design mixtures, resulting in a wide diversity of sown mixtures. Field trials revealed that in more than 70% of the cases, the mixture had a higher yield than the mean of its components. This work highlighted farmers needs and resulted in a Multicriteria Evaluation Tool, helping farmers and advisers to design mixtures. The survey of the wheat supply chain finally highlighted the need for a concerted innovation among the various actors. Finally, Wheatamix also developed new statistical method to infer mixing ability, allowing both to blend the best mixers, and also to propose new breeding methods.Coupling various disciplines and approaches, such as ecophysiological modeling of plant competition (FSPM WALTer), field and controlled experiments, theoretical framework in ecology (sampling vs complementarity effects, functional traits and tradeoff), and mixture co-design and surveys with stakeholders, Wheatamix has allowed to understand the interest of cultivar mixtures for farmers. Wheat cultivar mixtures are experiencing an exponential growth: they only represented 2% of bread wheat sown in 2010, and are presently at 8%, raking at the first position on the cultivar list. Wheatamix emphasizes the need for an interdisciplinary approach when addressing agroecological subjects, and illustrates the strong mutual benefices between agronomic and ecological sciences