• Energy Research

Sowing a second season crop following the harvest of a first crop (hereafter referred to as double cropping) is a practice that allows for temporal diversification of cropping systems to increase the efficiency of land use and yield per unit area while improving the ecosystem services. Sunflower is particularly suitable for double cropping, especially under the current context of Southern Europe. However, planting sunflower in double cropping may result in poor establishment as the crop is very demanding in terms of seedbed preparations. In addition, most sunflower varieties available to date belong to late maturity groups (MGs), which were bred for conventional cropping. Planting these varieties in double cropping may further exacerbate the risk of crop establishment failure. Here, we performed laboratory and growth chamber phenotyping of 11 hybrid oilseed sunflower varieties with contrasting MGs and assessed their field performance for two consecutive years (2020 and 2021). We measured the variables, such as seed germination, seedling emergence dynamics and final rates, and post-emergence damage, as these characteristics are important for a uniform and robust crop establishment. Under laboratory conditions, we found statistically significant effect of varieties on cardinal temperatures and water potential for germination. Under growth chamber conditions, the maximum heterotrophic growth of the hypocotyl was higher (i.e., 85 mm) compared to that of the radicle (i.e., 80 mm). The seedling mortality rates under soil aggregates ranged from 0 to 12%, depending on the size and spatial distribution of soil aggregates in the seedbed. Under field conditions, the final rates of seed germination ranged from 87 to 98% and from 99 to 100%, while those of the seedling emergence ranged from 58 to 87% and from 78 to 94%, in 2020 and 2021, respectively. The average final rates of postemergence damage ranged from 13 to 44% and from 3 to 18% in 2020 and 2021, respectively. Bird damage was the main cause of pre- and postemergence losses. We found that a good sunflower establishment in double cropping is possible in the southwestern conditions of France, provided that there is no water stress in the seedbed. An optimal seedbed moisture ensures a rapid crop emergence and limits pre-and postemergence damage due to birds, by reducing the duration of the crop establishment phase, which is highly vulnerable to bird damage.

La pratique d'une deuxième culture dans l’année, soit à la suite d’une récolte en début d’été (culture dérobée), soit par semis dans la culture primaire (culture en relais), permet une production supplémentaire, qu’elle soit destinée à l’alimentation animale ou humaine ou à vocation énergétique. Cette pratique de double culture peut générer un revenu supplémentaire tout en fournissant des services de soutien et de régulation. En tant que telle, elle peut être considérée comme une forme d'agriculture écologiquement intensive, mais aussi comme une opportunité offerte par le changement climatique. Le processus de prise de décision aboutissant à la double culture repose sur de nombreux facteurs liés aux conditions pédoclimatiques, mais aussi à l’espérance de gain et à la perception du risque. Le projet CASDAR "3C2A : Trois cultures en deux ans" (2019-2023) qui a regroupé 15 partenaires (agriculteurs, conseillers de chambres d’agriculture, ingénieurs d’instituts techniques, chercheurs) s'est efforcé de créer des références utiles pour la double culture dans le Sud-Ouest de la France, englobant les régions Nouvelle-Aquitaine et Occitanie. Cet article vise à illustrer l'intérêt potentiel du soja et du tournesol en tant que doubles cultures dans le Sud-Ouest de la France par une analyse qualitative des perceptions des agriculteurs sur les risques et les opportunités de cette pratique, complétée par une évaluation sur 4 ans des performances agronomiques et économiques de la double culture chez les agriculteurs (130 parcelles) ainsi qu’en station expérimentale où des gammes variétales ont été comparées pendant 3 ans. Avec l’appui de la simulation agronomique (SPA1 , STICS2 ), il a été possible d’évaluer la robustesse des conclusions (faisabilité, productivité) sur des séquences climatiques plus longues, pour des pédoclimats et des conduites culturales non expérimentées, et pour des scénarios de changement climatique, mais aussi d’apprécier les impacts environnementaux (besoins en eau, drainage, lixiviation du nitrate) des cultures dérobées dans le Sud-Ouest. Growing a second crop in a year, either following an early summer harvest (catch crop) or by sowing into the previous autumn-sown crop (relay crop), enables additional production, whether for feed, food or energy purposes. This practice of double cropping can generate additional income while providing support and regulation services. As such, it can be seen as an ecologically intensive form of agriculture, but also as an opportunity offered by climate change. The decision-making process leading to double cropping is based on a number of factors linked to soil and climatic conditions, but also to the expectation of gain and the perception of risk. The CASDAR project "3C2A: Three crops in two years" (2019-2023), which gathered 15 partners (farmers, advisors from chambers of agriculture, engineers from technical institutes, researchers), was set up to create useful references for double cropping in south-western France, encompassing the regions of Nouvelle-Aquitaine and Occitanie. The aim of this article is to illustrate the potential interest of soybean and sunflower as second crops in south-western France by means of a qualitative analysis of farmers' perceptions of the risks and opportunities of this practice, enriched by a 4- year on-farm assessment of the agronomic and economic performances of double cropping (130 fields) and at the experimental station, where a range of varieties were compared over a 3-year period. With the support of agronomic simulation (SPA1 , STICS2 ), it was possible to assess the robustness of the conclusions (feasibility, productivity) over longer climatic sequences, for unexperimented soils, climates and cropping practices, and for climate change scenarios. It was also possible to assess the environmental impacts (water requirements, drainage, nitrate leaching) of catch crops in the South-West.

Climate change is threatening the ability to grow cotton (Gossypium hirsutum L.) under low input rainfed production areas in Sub-Saharan Africa. In Northern Cameroon, yield has been declining due to unsuitable cropping practices such as sub-optimal planting dates, along with an absence in genetic gain. The aim of this study was to use a cropping system model (DSSAT CSM-CROPGRO-Cotton) to identify the best cultivars (ideotypes) for Northern Cameroon that are adapted to low input rainfed productions systems for 2050 under RCP4.5 and RCP8.5. Calibration and evaluation of the CSM-CROPGRO-Cotton were performed with field observations for two cultivars (Allen Commun and L484). For RCP4.5 and RCP8.5, 50 replications for 2050 were generated based on an ensemble of 17 Global Circulating Models. In total, 3125 virtual cultivars representing existing genetic variability for phenology, morphology and photosynthesis were simulated. Thereafter, they were evaluated for performance under the projected future climate based on potential yield and the resilience of yield to sub-optimal planting date. The widely cultivated cultivar L484 will be unsuitable under projected future climate, due to boll opening during the middle of the rainy season (median: 10/09 under RCP4.5 and 12/09 under RCP8.5). None of the ideotypes tested could optimize both yield and resilience (Pearson correlation <−0.82). However, compared to the current cultivar L484, two virtual ideotypes were identified: (a) “Ideo_sub” had a wide planting window, especially in the 10 worst replications of 2050, up to +5 days in RCP8.5; (b) “Ideo_Pot” had a high potential yield trait with low resilience to sub-optimal planting date, in the 10 worst replications of 2050, +530 kg ha−1 in RCP4.5 and +591 kg ha−1 in RCP8.5. Both ideotypes had an earlier anthesis date, a longer reproductive duration, and increase in the maximum photosynthetic rate. Therefore, breeding programs should consider these traits suggested by this system analysis using a crop simulation model for the identification of suitable cultivars under the projected future climate. (Resume d'auteur)

Sustainability rests on the principle that we must meet the needs of the present without compromising the ability of future generations to meet their own needs. Starving people in poor nations, obesity in rich nations, increasing food prices, on-going climate changes, increasing fuel and transportation costs, flaws of the global market, worldwide pesticide pollution, pest adaptation and resistance, loss of soil fertility and organic carbon, soil erosion, decreasing biodiversity, desertification, and so on. Despite unprecedented advances in sciences allowing to visit planets and disclose subatomic particles, serious terrestrial issues about food show clearly that conventional agriculture is not suited any longer to feed humans and to preserve ecosystems. Sustainable agriculture is an alternative for solving fundamental and applied issues related to food production in an ecological way. While conventional agriculture is driven almost solely by productivity and profit, sustainable agriculture integrates biological, chemical, physical, ecological, economic and social sciences in a comprehensive way to develop new farming practices that are safe and do not degrade our environment. In that respect, sustainable agriculture is not a classical and narrow science. Instead of solving problems using the classical painkiller approach that treats only negative impacts, sustainable agriculture treats problem sources. As most actual society issues are now intertwined, global, and fast-developing, sustainable agriculture will bring solutions to build a safer world. This book gathers review articles that analyze current agricultural issues and knowledge, then propose alternative solutions. It will therefore help all scientists, decision-makers, professors, farmers and politicians who wish to build a safe agriculture, energy and food system for future generations.

Des systèmes de culture climato-intelligents doivent combiner (i) réduction des émissions de gaz à effet de serre (GES), (ii) adaptation au changement et à la variabilité climatique et (iii) sécurisation de la production alimentaire. L’agriculture peut améliorer le bilan des émissions de GES via trois leviers : (i) moins d’émissions de N2O, CH4 et CO2, (ii) plus de stockage du carbone, (iii) de la production d’énergie verte (biocarburants, biogaz). Réduire l’application d’engrais minéral ou augmenter la proportion de légumineuses dans la rotation permet de réduire les émissions de N2O. La réduction des émissions de CH4 en riziculture inondée impose de revoir la gestion de l’eau (drainage, irrigation). Stocker plus de carbone dans le sol et la biomasse passe par la culture sans labour (moins d’énergie, paillage avec les résidus de récolte), l’utilisation de plantes de couverture, l’introduction ou le maintien de prairies et la pratique de l’agroforesterie. La sélection de variétés mieux adaptées aux chocs thermiques et à la sécheresse est la principale adaptation à long terme au changement climatique. Des stratégies à court terme ont été identifiées à partir des pratiques actuelles, tirant profit de conditions de croissance plus favorables ou compensant les impacts négatifs par le décalage des dates de semis, l’introduction de nouvelles espèces et cultivars, la diversification des rotations, de nouvelles pratiques de gestion du sol et de la fertilisation, l’introduction ou l’expansion de l’irrigation. Certaines cultures pourraient également migrer vers des zones de culture plus appropriées. Des outils basés sur les modèles et l’agriculture de précision devraient être développés afin d’aider les agriculteurs face à un contexte plus incertain et plus risqué. La plupart des options d’adaptation et d’atténuation sont compatibles, mais des arbitrages devront être faits : ainsi augmenter la part des légumineuses ne sera possible que si des efforts de sélection importants sont conduits. Climate-smart cropping systems should be designed with three objectives: reducing greenhouse gas (GHG) emissions, adapting to changing and fluctuating climate and environment, and securing food production sustainably. Agriculture can improve the net GHG emissions balance via three levers: less N2O, CH4 and CO2 emissions, more carbon storage, and green energy production (agrifuels, biogas). Reducing the application of mineral N fertilizer is the main option for reducing N2O emissions either directly or by increasing the proportion of legumes in the rotation. The most promising options for mitigating CH4 emissions in paddy fields are based on mid-season drainage or intermittent irrigation. The second option is storing more carbon in soil and biomass by promoting no-tillage (less fuel, crop residues), sowing cover crops, introducing or maintaining grasslands and promoting agroforestry. Breeding for varieties better adapted to thermal shocks and drought is mainly suggested as long-term adaptation to climate change. Short-term strategies have been identified from current practices to take advantage of more favorable growing conditions or to offset negative impacts: shifting sowing dates, changing species, cultivars and crop rotations, modifying soil management and fertilization, introducing or expanding irrigation. Some crops could also move to more suitable locations. Model-based tools and site-specific technologies should be developed to optimize, support and secure farmer's decisions in a context of uncertainty and hazards. Most of the adaptation and mitigation options are going in the same way but tradeoffs will have to be addressed (e. g. increasing the part of legumes will be possible only with significant breeding efforts). This will be a challenge for designing cropping systems in a multifunctional perspective.

The European Union has a high demand for plant proteins for food and feed. Its self-sufficiency rate is about 5% for soya crude proteins. The European Union and its Member States have launched initiatives for reducing soya imports that come mainly from South America and promoting domestic production of protein-rich crops. In the future, climate suitability for soybean cultivation is likely to increase in oceanic and continental Europe. The recent AE2050 study (INRAE. 2020. Role of European agriculture in world trade by 2050: Balancing climate change and global food security issues. Summary report of the study. INRAE (France), 12 p; Tibi A, Forslund A, Debaeke P, et al. 2020. Place des agricultures européennes dans le monde à l’horizon 2050 : entre enjeux climatiques et défis de la sécurité alimentaire. Rapport de synthèse de l’étude. INRAE (France), 159 p + Annexes) concluded that, in some parts of Europe (defined here as the European Union-27 plus other Balkan countries, Switzerland, Norway and the United Kingdom), cropland requirements in 2050 may be lower than “2010” cropland areas given possible changes in European food demand (related to glooming demographic growth and under the assumption of healthy diets) and in crop yields (influenced by technological developments and climate change). In this study, we examine to what extent this “cropland surplus” could be used to increase soybean production in Europe and reduce the dependency ratio on protein imports. Only in the case of a Healthy Diets scenario (less meat consumption, inducing less animals fed with cakes), substantial soybean acreages could be envisaged to reduce the European reliance on imports. In addition to the surplus allowed by increasing yields, land surplus was also made available by the reduction of livestock production and its grain feed requirements. The best-case scenario, combining healthy diets and trend-based yield growth, would reduce European imports to only 15% of its total domestic requirements versus 45% for the Trend-based Diets scenario. This can be compared to a dependency rate of 51% in our base year “2010”, and of 53%–54% for the two 2050 scenarios without growing soybean on cropland surplus. If the range of these quite optimistic estimations of surplus land dedicated to soybean was reduced to more plausible levels (limited to 10% of annual field cropland in 2050) and considering current soybean yield levels (“2019” instead of “2010”), the decrease in Europe’s oil cake imports levels would be lower. However, its dependency rate could still be reduced from 54% to 46% in the Trend-based Diets scenario, and from 53% to 38% in the Healthy Diets scenario. One important conclusion is that adopting healthy diets would allow a significant reduction of imports of soybean cakes from abroad with expected environmental benefits in Europe and overseas. On the supply side, challenges for a higher self-sufficiency rate of proteins in Europe resulting from the development of soybean domestic production will come from both available and suitable crop areas, attainable yields and relative profitability.

As a rainfed spring-sown crop, sunflower is increasingly exposed to negative impacts of climate change, especially to high temperatures and drought stress. Incremental, systemic and transformative adaptations have been suggested for reducing the crop vulnerability to these stressful conditions. In addition, innovative cropping systems including low input systems, organic farming, soil and water conservation, intercropping, double cropping, and agroforestry are under strong development in agriculture. Due to its plasticity and low input requirements (nitrogen, water, pesticides), sunflower crop is highly concerned by these new agroecological systems. Apart from current production outputs (yield, oil), ecosystemic services are now expected from the crop and non-food industrial uses are emerging.All these changes should deeply modify crop management and the usual characteristics of genotypes that are grown in the main production areas. After reviewing these changes, we will identify how innovative cropping systems and new environments could modify the traits classically considered up to now, especially in relation to expected ecosystemic services. We will discuss the methods that research could provide for helping to identify adapted traits and design ideotypes.

Contents: SECTION 1 - NOVEL CONCEPTS Emerging agroscience; Ants and sustainable agriculture; Agroecology as a science, a movement and a practice; Adaptiveness to enhance the sustainability of farming systems; Economics of biosecurity across levels of decision-making; Describing and locating cropping systems on a regional scale. SECTION 2 - FOOD SECURITY Nutritional quality and safety of organic food; Minerals in plant food: effect of agricultural practices and role in human health; Fertiliser trees for sustainable food security in the maize-based production systems of East and Southern Africa; Cereal landraces for sustainable agriculture; Mineral sources of potassium for plant nutrition; Glandless seed and glanded plant research in cotton; Micronutrient-efficient genotypes for crop yield and nutritional quality in sustainable agriculture; Multi-criteria decision models for management of tropical coastal fisheries. SECTION 3 - SOCIOLOGY AND ECONOMICS Farmer responses to climate change and sustainable agriculture; The use of the marasha ard plough for conservation agriculture in Northern Ethiopia; Biological nitrogen fixation and socioeconomic factors for legume production in sub-Saharan Africa; Conventionalisation of organic farming practices: from structural criteria towards an assessment based on organic principles; Conservation tillage in Turkish dryland research. SECTION 4 - CLIMATE CHANGE Biofuels, greenhouse gases and climate change; Agronomic and physiological performances of different species of Miscanthus, a major energy crop; Changes in atmospheric chemistry and crop health; Modelling soil carbon and nitrogen cycles during land use change; Greenhouse gases and ammonia emissions from organic mixed crop-dairy systems: a critical review of mitigation options; Water deficit and nitrogen nutrition of crops; Validation of biophysical models: issues and methodologies; Cold stress tolerance mechanisms in plants. SECTION 5 - ALTERNATIVE PEST CONTROL Defence mechanisms of Brassicaceae: implications for plant-insect interactions and potential for integrated pest management; Ionising radiation and area-wide management of insect pests to promote sustainable agriculture; Biodiversity and pest management in orchard systems; Pathogenic and beneficial microorganisms in soilless cultures; Allelopathy in Compositae plants. SECTION 6 - SOIL HEALTH Assessing the productivity function of soils; Long-term effects of organic amendments on soil fertility; Tillage management effects on pesticide fate in soils; Sustainable cow-calf operations and water quality; Biogeography of soil microbial communities: a review and a description of the ongoing french national initiative. SECTION 7 - ALTERNATIVE FERTILISATION Nitrogen rhizodeposition of legumes; Models of biological nitrogen fixation of legumes; Arbuscular mycorrhizal networks: process and functions; Efficient N management using winter oilseed rape; Improving nitrogen fertilization in rice by site-specific N management; Solid–liquid separation of animal slurry in theory and practice