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Climate change models predict an increase in climate variability in the future, with more rainfall extremes and greater risks, causing a negative impact on crops produced by smallholders in West Africa. Conservation Agriculture (CA) systems can be effective in mitigating yield loss in environments with increased weather risk. This study aimed to evaluate CA cropping systems that can minimize both economic and climatic risks under erratic climatic conditions in West Africa. We tested upland rice-based CA systems and conventional systems with tillage (CT), in rotation with maize in some of the cases, without and with fertilization, at different sowing windows in the Bouaké region, Côte d'Ivoire, from 2015 to 2020. Sowing in June showed in a higher rice yield (1183 kg ha-1 and 1370 kg ha-1 without and with fertilization, on average over the 2017–2020 period) than in March (521 kg ha-1 and 495 kg ha-1 without and with fertilization) or in July or August (335 kg ha-1 and 498 kg ha-1 without and with fertilization). During the first four years, rice yields tended to be lower under the CA systems than under the CT systems, especially when water availability was not a major constraint. However, after this transition period, and especially when water stress occurred, as in 2020, rice yields under CA systems (1835–2021 and 2147–2254 kg ha-1 without and with fertilization) were higher than under CT systems (1350 kg ha-1 and 1435 kg ha-1 without and with fertilization). CA systems having relatively longer duration for growing cover crops tended to produce higher upland rice yield grown in the subsequent season. In both CT and CA systems, the impact of fertilization on rice yield was small over the study period, and the mean rice yield increase due to fertilization was on average 451 kg ha-1 even when rice was sown in the summer season, resulting in negative economic return. These results indicate that whereas low-input CA upland rice-based systems together with optimizing sowing window for rice could be promising options for sustaining rice yield and mitigating yield loss in environments with increased weather risk, further research is needed for reducing transition period to CA systems in order to enhance their adoption by smallholder farmers. Desirable cover crops should be less labor-demanding, generate incomes from their products, and produce large biomass under erratic climatic conditions.

Cropping systems with legumes play key roles in farming systems in sub-Saharan Africa. However, how commonly legume associations perform in low input-systems is not well-known. Here, we studied four legume species used in three systems in rotation with upland rice, i.e., groundnut monocropping, sorghum–cowpea intercropping, and velvet bean–crotalaria intercropping, in two fertilization managements on the previous rice, i.e., manure alone or complemented with mineral fertilization. Legume suitability was assessed using rhizobial and mycorrhizal colonization rates, plant biomass production, shoot N and P content, and biological N2 fixation based on their δ15N natural abundance. Shoot and root biomasses varied significantly between legume species and were positively correlated with nodule number (r = 0.49 and 0.74, p-value &lt, 0.05 and &lt, 0.001, respectively) and the amount of fixed N (r = 0.73 and 0.50, p-value &lt, 0.001 and &lt, 0.05, respectively). The proportion of plant N derived from N2 fixation also varied significantly between species, with a higher percentage for velvet bean (66%), compared to the other three species (50 to 60%). Legume roots were weakly colonized by AM fungi, with similar levels between species. Overall, fertilization management did not significantly impact legume biomass, symbioses, or N2 fixation, yet the organo-mineral fertilization significantly increased legume shoot P content. The lack of effect of mineral fertilization on N2 fixation and biomass could be due to other nutrient deficiencies (Ca, Mg, micronutrients), which can hamper symbioses with rhizobia and mycorrhizae.

International audience; Lengthening and diversifying crop rotations is an efficient strategy to reduce the use of fertilizers and pesticides, thereby improving the sustainability of cropping systems. To test this assumption, six innovative cropping system prototypes were designed, each introducing one or more agroecological practices, as alternatives to the 2-year sunflower (Helianthus annuus L.)-durum wheat (Triticum turgidum L. subsp. durum) rotation widespread in southwestern France. Two 3-year rotations were implemented at INRAE, Toulouse, from 2011 to 2016. The six prototypes were composed of two low-input cropping systems (with/without cover crops) and four very low-input cropping systems (including cultivar or species mixtures, each with/without cover crops). As compared to the sunflower-wheat rotation, the prototypes aimed at reducing the use of N fertilizers by 25% (low-input) and 50% (very low-input) and pesticides by 50%. A set of agronomic, environmental, technical, and socio-economic indicators was calculated to assess the different components of sustainability. The introduction of agroecological principles resulted in a clear reduction of the use of synthetic inputs as compared to the sunflower-wheat rotation. The treatment frequency index was decreased by 56, 18 and 39% for the low-input cropping systems, very low-input cropping systems with cultivar mixtures, and very low-input cropping systems with species mixtures, respectively. However, the profitability decreased with the diversification of cropping systems as the semi-net margin decreased for the three previous cropping systems (745, 696, and 438 euro center dot ha(-1), respectively, vs. 963 euro center dot ha(-1) for the sunflower-wheat rotation). Despite the costs of inputs, the short rotation remained the most profitable. Agroecological practices succeeded in reducing the dependence of cropping systems on synthetic inputs, but their implementation needs to be improved to achieve better economic performance, using both scientific knowledge and know-how of innovative farmers.

International audience; This paper investigates the perceptions of a diversity of stakeholders supporting smallholders in the eastern Brazilian Amazon about ecosystem services and agricultural practices. Our results come from 30 semi-structured interviews with key stakeholders in two contrasting municipalities in this region (Paragominas and Irituia). We identified 17 different ecosystem services and 15 agricultural practices. Using a multidimensional scaling (MDS), we differentiated the stakeholders’ perceptions of co-production of ecosystem services. The most mentioned ecosystem services are food supply, regulation of water cycles, soil fertility and erosion prevention. Overall, there is a positive perception that agricultural practices are providing ecosystem services. Biodiversity-based practices are associated with the provision of a broad range of ecosystem services whereas mechanical-chemical practices are mainly linked to food supply. Use of fire, deforestation and use of chemical pesticides are perceived as having most negative effects on the provision of ecosystem services. The type of activity performed by the stakeholders and their municipality are the main factors influencing their perception of ecosystem services co-production. In conclusion, the concept of co-production of ecosystem services related to agroecosystems is relevant as local actors recognize a diversity of effects of agricultural practices on service provision.; Cette étude analyse les perceptions relatives aux services écosystémiques et aux pratiques agricoles, de différents acteurs venant en appui aux agriculteurs familiaux en Amazonie brésilienne orientale. Nos résultats se fondent sur 30 entretiens semi-directifs avec des acteurs clés de deux municipalités contrastées de cette région (Paragominas et Irituia). Dix-sept services écosystémiques différents et 15 pratiques agricoles ont été identifiés. Un positionnement multidimensionnel (MDS) a permis de différencier la perception des acteurs sur la coproduction de services écosystémiques. La production de nourriture, la régulation des cycles de l’eau, la fertilité des sols et la prévention de l’érosion, sont les services écosystémiques les plus mentionnés. Globalement, les pratiques agricoles sont perçues de manière positive en termes de fourniture de services écosystémiques. Les pratiques basées sur la biodiversité (principalement l’introduction de différentes plantes) sont associées à une grande diversité de services, tandis que les pratiques basées sur les intrants chimiques et l’énergie mécanique sont principalement associées à la production de nourriture. L’utilisation du feu, la déforestation et l’utilisation des pesticides chimiques sont considérées comme ayant principalement des effets négatifs sur la fourniture de services écosystémiques. Le type d’activité exercée par les acteurs et la municipalité sont les principaux facteurs influençant leur perception de la co-production de services écosystémiques. En conclusion, le concept de co-production lié aux agroécosystèmes est pertinent, car les acteurs locaux reconnaissent une diversité d’effets des pratiques agricoles sur la fourniture de services.

Poor soil fertility and erratic rainfall constrain crop production in rain-fed smallholder farming systems in sub-Saharan Africa. Integration of drought tolerant and N2-fixing crops into maize-based cropping systems is a risk-averse strategy that also improves nitrogen cycling. A field experiment was carried out during the 2017/18 and 2018/19 cropping seasons in Goromonzi district in Zimbabwe. The trials were established on 14 farms, and on two field types (homefields and outfields), with eight treatments from a combination of cropping systems (maize and cowpea monocrops or maize/cowpea intercrops) and with or without nitrogen fertilizer (+N; -N). The trials were implemented on the same field plots for the two consecutive seasons. An improved cowpea variety and a landrace were used. The objectives were to determine 1) the productivity of the different cropping systems under variable soil fertility conditions, 2) N2-fixation of the two cowpea types when planted as monocrops or intercrops, and 3) mineral composition of maize and cowpea grains from intercrops and sole crops. Contrary to expected results, soil properties were not significantly different (P > 0.05) between field types. The land equivalent ratios (LER) were >1 for both seasons, implying improved land productivity under intercropping. Intercropping significantly reduced cowpea nodulation and active nodules, but not the total nodule weight, resulting in similar proportion of nitrogen derived from the atmosphere (%Ndfa) for cowpea grown as monocrop or in intercropping with maize. However, the total amount of fixed nitrogen was reduced in intercropping systems due to the smaller cowpea biomass compared to monocropping. Maize and cowpea grain mineral contents (Fe, Zn, Mn, Cu, Ca, Mg, P, K) were significantly affected by the cropping season only. We showed that intercropping maize with cowpea generally increases system productivity, in addition to substantial amounts of nitrogen being added to the system through N2-fixation. However, intercropping was not an agronomic biofortification option in these nutrient-depleted soils. Finally, annual variation in grain mineral quality can be larger than the annual variation in grain yield, potentially posing serious challenges to human nutrition.

International audience; En Amérique du Sud, les politiques publiques s’intéressent de près aux technologies alternatives aux intrants chimiques agricoles (pesticides et engrais). Certains pays sud-américains soutiennent les intrants biologiques, dits aussi biointrants, avec des programmes nationaux incitatifs et la transformation des réglementations. L’Argentine, le Brésil et la Colombie occupent un rôle pilote. Cette promotion des biointrants n’est néanmoins pas pensée dans une optique de rupture avec les modèles industriels de production agricole, dont les États tirent une grande partie de leurs recettes fiscales grâce aux exportations. Ils cherchent plutôt à aménager une coexistence entre intrants chimiques et biologiques dans le cadre d’une transition tournée vers la bioéconomie. La promotion des biointrants rencontre en ce sens les attentes de nombreux agriculteurs sud-américains et celles de l’industrie des intrants agricoles, qui se diversifie depuis une dizaine d’années dans ces technologies. Cette dynamique industrielle vient en partie se heurter à des mouvements d’agriculteurs défendant la production à la ferme des intrants biologiques.

International audience; Reducing the use of synthetic inputs by shifting to alternative practices is becoming a growing priority in the agricultural sector. This study aims to understand how farmers manage this shift on diversified horticultural farms. The implementation of alternative practices at the crop level was analyzed on 28 farms on La Réunion Island (France). The surveys conducted combined interviews with farmers and the use of a dedicated indicator. Implementation of alternative practices depends on (i) the specificities of each production case (PC) defined as the combination of a crop with its biological features, a production mode and an economic environment (available technical support and market specifications), and (ii) links between PC within a farm. Five clusters of PC were identified based on their specificities. Links between PC take the form of competition over farm resources or, conversely, exchanges of biomass, inputs, equipment and skills acquired on each PC. These results provide an analytical framework to help advisors better support the diversity of farm involvement in shifting from synthetic inputs to alternative practices.

International audience; Smallholder farmers in sub-Saharan Africa (SSA) currently grow rainfed maize with limited inputs including fertilizer. Climate change may exacerbate current production constraints. Crop models can help quantify the potential impact of climate change on maize yields, but a comprehensive multimodel assessment of simulation accuracy and uncertainty in these low-input systems is currently lacking. We evaluated the impact of varying [CO2], temperature and rainfall conditions on maize yield, for different nitrogen (N) inputs (0, 80, 160 kg N/ha) for five environments in SSA, including cool subhumid Ethiopia, cool semi-arid Rwanda, hot subhumid Ghana and hot semi-arid Mali and Benin using an ensemble of 25 maize models. Models were calibrated with measured grain yield, plant biomass, plant N, leaf area index, harvest index and in-season soil water content from 2-year experiments in each country to assess their ability to simulate observed yield. Simulated responses to climate change factors were explored and compared between models. Calibrated models reproduced measured grain yield variations well with average relative root mean square error of 26%, although uncertainty in model prediction was substantial (CV = 28%). Model ensembles gave greater accuracy than any model taken at random. Nitrogen fertilization controlled the response to variations in [CO2], temperature and rainfall. Without N fertilizer input, maize (a) benefited less from an increase in atmospheric [CO2]; (b) was less affected by higher temperature or decreasing rainfall; and (c) was more affected by increased rainfall because N leaching was more critical. The model intercomparison revealed that simulation of daily soil N supply and N leaching plays a crucial role in simulating climate change impacts for low-input systems. Climate change and N input interactions have strong implications for the design of robust adaptation approaches across SSA, because the impact of climate change in low input systems will be modified if farmers intensify maize production with balanced nutrient management.

Maximizing the comparative advantage of grain quality in low-yielding rainfed lowland rice (RLR) growing areas of lower northeast Thailand could be a key intervention option for favoring technological and organizational changes towards more sustainable and remunerative rice-based production systems in this relatively poor part of the kingdom where RLR production is by far the dominant type of land use. In the recent past, several mono-disciplinary studies were carried out that determined separately the effects of factors and environmental conditions on grain quality of Thai aromatic rice from this region. An attempt was made to integrate already available knowledge and major findings from different scientific disciplines, as well as expert assessment, to assess the regional distribution of grain quality potentials for the well-known Khao Dok Mali 105 (KDML105) aromatic rice variety across lower northeast Thailand. GIS techniques were used to integrate mapped information on several factors having major influence on aroma production and to prolong aroma in the grain through harvest and storage of the paddy. Three main climatic factors are taken into account: (i) the probability of drought at milky stage, (ii) the average lowest temperature in late November-early December, and (iii) the probability of occurrence of late storms at ripening stage. The possible impact of current changes in harvesting techniques (from rice harvest by sickle and thresher to the increasing use of small combine harvesters) is also considered. This paper reports preliminary results from the GIS analysis and the validation of these outputs by an expert. The outputs of this research could help policy-makers in their search for adapted rules to be applied for the certification of the origin of quality rice from this part of the kingdom.

IFDC, CIRAD et leurs partenaires Africains proposent un passage à grande échelle du transfert des technologies qui visent une utilisation plus efficace et plus rentable des intrants externes. Dans l'espace de quelques années, l'introduction participative de la gestion intégrée de la fertilités des sols et des nuisances augmentera la marge des producteurs de coton après remboursement d'intrants de près de 60.000 F CFA/ha/an; à terme une augmentation de 75.000 F CFA peut être envisagé. En d'autres termes, la marge des producteurs pourrait être augmentée de 50% sur la base des prix de 2003.

Les concepts de développement technique largement utilisés en agriculture bananière intensive sont basés sur la mise au point d'une agriculture raisonnée de plus en plus performante. L'objectif affiché est clairement de maintenir ou de faire progresser les rendements tout en limitant les intrants en pesticides et en engrais. Au delà de l'approche triviale qui consisterait à vouloir justifier chaque apport nutritif ou produit phytosanitaire (limitation des intrants par abolition des apports systématiques), le Cirad-flhor a développé des outils de diagnostic agricole, des technologies et des techniques culturales utilisables à l'échelle de la parcelle ou du bassin de production.

*INRA, URD, BP 29, Le Rheu Cedex Diffusion du document : INRA, URD, BP 29, Le Rheu Cedex; Bilan d'azote à l'échelle de l'exploitation.. Programme Systèmes Terre et Eau 199461999

National audience

National audience

Selon les dernières estimations des Nations Unies, la population urbaine atteindra 5,34 billions d'individus au niveau mondial en 2025 (2,76 billions d'individus en 1995) et plus de la moitié habiteront l'Asie. Parmi les villes d'Asie du Sud-Est pour les quelles une explosion démographique est attendue, trois villes (Ho Chi Minh City au Vietnam, Cagayan de Oro aux Philippines et Vientiane au Laos), qui présentent un niveau d'urbanisation différent, ont été retenues pour évaluer les differents facteurs et contraintes qui influent ou limitent la production maraîchère des petites ou moyennes exploitation agricoles (SMEs) en zone urbaine ou peri-urbaine. En partenariat avec l'Allemagne et la France, les instituts de recherches des Philippines, du Vietnam et du Laos introduiront et developperont des techniques de production en accord avec les situations socio-économique et anthropologiques des sites retenus. Seront abordés en particulier, la fertilisation organique à partir des déchets urbains, les techniques de protection intégrées à l'aide d'organismes utiles ou de biopesticides, la gestion de l'eau adaptée aux saisons sèches et pluvieuses. Des semences adaptées au climat et présentant une résistance/tolérance aux principales maladies seront également testées

Two fertilizer levels (LN = 0 and HN = 80 kg N ha−1 before and after the first cut in spring 1991) were compared on a second cut (30 days old) of perennial ryegrass using a cross-over design with four fistulated cows producing 20 kg of milk at the beginning of the experiment. Grass was cut daily and given ad libitum in three meals per day. The absence of nitrogen fertilizer resulted in a reduction in the nitrogen content of grass from 24 to 17 g kg−1 dry matter. In addition, nitrogen intake was reduced from 367 to 263 g day−1, whereas organic matter intake (14 kg day−1) and milk output were not affected. When LN grass was fed, organic matter digestibility was slightly reduced, from 0.81 to 0.79 (P < 0.05) but the site of digestion was unaffected. Organic matter truly digested in the rumen was 0.94 of digestible organic matter intake. Fibre digestibility was reduced by 0.06 unit (P < 0.01) using the unfertilized grass. Non ammonia nitrogen supplied to the duodenum (366 and 349 g day−1 for HN and LN grass respectively) was slightly different (P < 0.05) between diets. Lower nitrogen fertilization affected neither microbial synthesis (21.2 g kg−1 digestible organic matter intake) nor microbial nitrogen flow and did not lead to any significant change in the amount of feed nitrogen escaping rumen degradation. Non ammonia nitrogen flow was equal to nitrogen intake in the fertilized grass but was substantially higher than nitrogen intake (+ 86 g day−1) in the unfertilized grass. This difference in net nitrogen recycling between the two diets matched the quantity of urea-nitrogen excreted in urine, which was reduced by 81 g day−1 using the unfertilized grass. The results suggest that although lowering the amount of nitrogen fertilizer alone has only a minor effect on dairy cow nutrition, it has a great effect on nitrogen metabolism, thus producing a much lower urinary nitrogen output.

Développement durable et recherches agronomiques; National audience

National audience

Rapport final. Contrat de branche 1994-1996 *INRA, Rennes-Documentation, BP 29, 35653 Le Rheu Cedex Diffusion du document : INRA, Rennes-Documentation, BP 29, 35653 Le Rheu Cedex

Ministère de l'Environnement, Service de la Recherche *INRA Rennes, Service documentation, BP 29, 35653 Le Rheu Cedex Diffusion du document : INRA Rennes, Service documentation, BP 29, 35653 Le Rheu Cedex; National audience

National audience

International audience