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Oil palm cultivation has environmental impacts, including those associated with nitrogen (N) losses. Improving management practices to optimise yield and N losses is critical. In order to identify the key management and site parameters driving yield and N losses, over a 25-year cycle, we undertook a Morris’s sensitivity analysis of the Agricultural Production Systems sIMulator oil palm model (APSIM-Oil palm), using 3 sites in Papua New Guinea. We selected 12 parameters and 3 outputs: yield, nitrous oxide (N2O) emissions and N leaching. The influence of the 12 parameters on the outputs depended on site characteristics, age of the palms, and climate. The most influential parameters for losses were N mineral fertiliser rate, drainage and fraction of legume in groundcover vegetation. The simulations suggested that APSIM-Oil palm is a useful tool for assessing management options for optimising yield and environmental outcomes in different environments. The results can also guide future measurements needed to improve N loss estimates, and further development of models and risk indicators.

Questions: What are the effects of abandonment on plant diversity in seminatural grasslands? Do the effects of abandonment on taxonomic and functional diversity vary along environmental gradients of climate and soil? Location: West and mid-Norway. Methods: Plant composition was surveyed in 110 subplots of 4 m2 in 14 sites across grazed and abandoned semi-natural grasslands. Climate data were extracted and soil composition analysed. To reduce the number of explanatory variables and deal with collinearity, we performed PCA. Data on the plant species vegetative height (H), leaf dry matter content (LDMC), specific leaf area (SLA), seed mass (SM) and number of seeds per plant (SNP) for 175 species were extracted from the LEDA database. Measures of plant diversity (species richness, CWM of functional traits and functional diversity (evenness and range)) were calculated for each subplot. To estimate the effects of abandonment on plant diversity and examine how these effects are moderated by gradients in soil and climate, we fitted mixed models to the data including site as a random effect. Results: Species richness in the subplots was lower in abandoned semi-natural grasslands, especially on more calcareous soils. CWM H, LDMC and SM were higher in abandoned semi-natural grasslands. CWM LDMC was only higher in the driest subplots. The ranges in H, SLA and SM, as well as evenness in LDMC were also higher in abandoned semi-natural grasslands,but the range in LDMC was lower. Conclusions: It is important to assess both taxonomic and functional diversity to understand ecosystem processes. The species pool in ecosystems influenced by a long history of intermediate grazing includes a high proportion of low stature, grazing-tolerant plant species. Abandonment of extensive land-use practices will cause a decline in taxonomic diversity (plant species richness) in such systems due to increased abundance of plants with high stature that outcompete the lower, grazing-tolerant plants. This process is predominant especially if moisture, soil fertility and pH are at intermediate levels. Changes in species communities due to abandonment will also influence ecosystem functioning, such as nutrient turnover and fodder production resilience.

International audience; Agricultural research has to tackle complex questions such as the design of sustainable cropping systems. System experiments are innovative approaches to address this challenge and a framework to iteratively design annual cropping systems has been proposed by Debaeke et al. (2009). However, specificities of some other cropping systems are not considered. Orchards are complex perennial agroecosystems formed of grass and tree layers aiming at the production of fresh fruit that require specific design and management over space and time. To identify orchard specificities and adapt the design framework to such perennial systems, we used two case studies of orchards aiming at decreasing pesticide use in temperate (apple, system experiment) and tropical (citrus, on-farm network) fruit productions. Specificities to take into account in the design framework are: (1) the spatial heterogeneity of the orchard with grass and tree layers, and tree rows and alleys; (2) the succession and interrelations among a young unproductive and then a productive stage; (3) the permanency of the fruit-tree crop constraining the management of soil fertility, (4) ground cover and (5) pest control, especially for pests that complete their lifecycle in the orchard and can build up important populations or inoculum across years. This is especially true in tropical areas where there is no dormant season. (6) Conversely, the permanency of the orchard habitats facilitates the sowing, planting or conservation of plant assemblages (e.g., ground covers, lining hedgerows) to enhance conservation biocontrol and/or compete weeds, provided non-disruptive practices are applied. Because of their longevity, orchards contribute to foster both plant-mediated (e.g., bottom-up) and natural enemy-mediated (e.g., top-down) processes in the foodweb to avoid direct measures against pests. Interactions among the orchard life stages, spatial and functional dimensions and practices need to be explicitly considered to optimize the efficiency of the system as a whole. Using the generic framework proposed by Debaeke et al. (2009) to design annual cropping systems, our framework includes adaptations to account for orchard specificities: (i) Agronomic objectives have to be fixed for each orchard stage; (ii) The cultivar choice and the composition and spatial arrangement of plants within the orchard are key elements to provide the expected services in the long term. This entails to include an additional step of perennial spatial design; (iii) Within-time and −space interactions have to be considered in the decisional system; (iv) Evaluation has to consider all the orchard stages in the global impact or performance, to account for carry-over effects and possible ‘paybacks’ of a given stage or period to the orchard whole lifetime. Last, to handle such complex interactions, design needs knowledge from many stakeholders in the food system (growers, advisors, scientists etc.) and requires more and renewed interactions among those stakeholders in a co-design process.

International audience; Agroforestry systems provide diverse ecosystem services that contribute to farmer livelihoods and the conservation of natural resources. Despite these known benefits, there is still limited understanding on how shade trees affect the provision of multiple ecosystem services at the same time and the potential trade-offs or synergies among them. To fill this knowledge gap, we quantified four major ecosystem services (regulation of pests and diseases; provisioning of agroforestry products; maintenance of soil fertility; and carbon sequestration) in 69 coffee agroecosystems belonging to smallholder farmers under a range of altitudes (as representative of environmental conditions) and management conditions, in the region of Turrialba, Costa Rica. We first analyzed the individual effects of altitude, types of shade and management intensity and their interactions on the provision of ecosystem services. In order to identify potential trade-offs and synergies, we then analyzed bivariate relationships between different ecosystem services, and between individual ecosystem services and plant biodiversity. We also explored which types of shade provided better levels of ecosystem services. The effectiveness of different types of shade in providing ecosystem services depended on their interactions with altitude and coffee management, with different ecosystem services responding differently to these factors. No trade-offs were found among the different ecosystem services studied or between ecosystem services and biodiversity, suggesting that it is possible to increase the provision of multiple ecosystem services at the same time. Overall, both low and highly diversified coffee agroforestry systems had better ability to provide ecosystem services than coffee monocultures in full sun. Based on our findings, we suggest that coffee agroforestry systems should be designed with diversified, productive shade canopies and managed with a medium intensity of cropping practices, with the aim of ensuring the continued provision of multiple ecosystem services.

International audience; Harvest residue management is a key issue for the sustainability of Eucalyptus plantations established on poor soils. Soil microbial communities contribute to soil fertility by the decomposition of the organic matter (OM), but little is known about the effect of whole-tree harvesting (WTH) in comparison to stem only harvesting (SOH) on soil microbial functional diversity in Eucalyptus plantations. We studied the effects of harvest residue management (branches, leaves, bark) of Eucalyptus grandis trees on soil enzymatic activities and community-level physiological profiles in a Brazilian plantation. We measured soil microbial enzymatic activities involved in OM decomposition and we compared the community level physiological profiles (CLPP) of the soil microbes in WTH and SOH plots. WTH decreased enzyme activities and catabolic potential of the soil microbial community. Furthermore, these negative effects on soil functional diversity were mainly observed below the 0-5 cm layer (5-10 and 10-20 cm), suggesting that WTH can be harmful to the soil health in these plantations.

Basé sur des cas d'étude au Sénégal, ce chapitre dresse le bilan de 15 années de recherches sur le fonctionnement des sols d'agrosystèmes associant plantes cultivées (mil-arachide) et arbustes natifs au Sahel. Les travaux, publiés pour la plupart, ont montré que Guiera senegalensis et Piliostigma reticulatum redistribuent l'eau dans le sol, stimulent les microorganismes du sol et génèrent des îlots de fertilité au bénéfice de la culture associée. Ainsi, les rendements des cultures sont augmentés, y compris en absence de fertilisants : jusqu'à +137 % pour le mil en présence de P. reticulatum à Nioro-du-Rip. Cela justifie l'intérêt de maintenir ces arbustes dans les champs en appliquant une gestion agroécologique.

This work showed for the first time that organic nutrient transformation techniques based on locally available materials (manure, green waste and advanced biochar) can increase fertilizing efficiency of the resulting substrate by a factor of three compared with other organic amendments without biochar. We used three different composting methods to investigate the techniques of organic nutrient transformations; i) conventional composting (composting process completed without turning the piles) ii) aerobic composting (composting process with manual turning of piles) and iii) bokashi composting (anaerobic lacto-fermentation). Composting was carried out in the absence (compost alone) and the presence of biochar (co-composted). Biochar was produced locally from an invasive forest shrub ‘Eupatorium adenophorum’. A pot trial with maize grown in silty loam soil was carried out to investigate the agronomic effect produced using three above-mentioned composting methods that were compared with conventional mineral fertilizers (NPK). Significant effects of co-composted bokashi-biochar (60 t ha−1) were observed on maize growth, which increased biomass by 243% compared to mineral NPK, also showing better growth effects than conventional and aerobic composting amendments. Improved soil available nutrients (available P and other exchangeable base cations (K+, Ca2+ and Mg2+)) were probably the cause of the superior growth effect of co-composted bokashi-biochar.

Made available in DSpace on 2019-10-04T12:35:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-19 Aiming to comprehend the relationship among restoration techniques and soil attributes, we compared the soil attributes of four forest stands: three regarding an experiment initiated eight years ago with distinct techniques: perch, abandonment and transposition, and one that was pristine forest used as a reference. In each local, five soil samples were taken at 0-20 cm, and another sample was taken in a profile (layers: 20-40, 40-60 and 60-80 cm) for analysis of the major physical, chemical and isotopic attributes. The soil density varied from 1.20 to 1.24 g.cm(-3). The different values of chemical attributes among the treatments and reference revealed that the yet the areas are no longer degraded, they cannot be considered restored (reasons explained in the text). Evaluating the characteristics of the soils and making specific silvicultural and soil-related practices before implementing the intervention, is a prerequisite that should be considered by managers in restoration projects. Univ Estadual Paulista, Dept Environm Engn, Sorocaba, SP, Brazil CIRAD, UMR Eco & Sols, Montpellier, France Univ Estadual Paulista, Dept Forest Sci, Campus Botucatu, Botucatu, SP, Brazil Eucatex Corp Fazenda Santa Terezinha, Bofete, SP, Brazil Univ Estadual Paulista, Dept Environm Engn, Sorocaba, SP, Brazil Univ Estadual Paulista, Dept Forest Sci, Campus Botucatu, Botucatu, SP, Brazil

Cocoa is among the most desirable and palatable food in the world. Soil under cacao trees in Papua New Guinea (PNG) is fertile, however, it's been identified that to sustainably reach a production goal of 310,000 t by 2030, PNG needs soil-based recommendations. For this purpose, a cost-effective, rapid and non-invasive soil testing approach using near infrared diffuse reflectance spectroscopy (NIR-DRS), to cater for soil testing needs of numerous small landholdings was assessed. This study investigated whether spectral data collected from smallholder farms across provinces can be used to estimate soil conditions for cacao farming. To assess this, a spectral library was generated by measuring 17 different soil parameters and spectral reflectance data over visible to near-infrared region (350–2500 nm) in 507 soil samples collected from four production systems in Autonomous region of Bougainville (AroB), New Ireland province (NIP), East New Britain province (ENB) and East Sepik province (ESP). Analysis of spectral data showed that the shallow limestone soil of NIP is dominantly montmorillonite mixed with kaolinite clay minerals, while the three other sampling sites are mostly vermiculite with mixed illite type of clay. Among Cubist, partial-least-square regression (PLSR), and support vector regression (SVR) chemometric approaches, Cubist model outperformed both SVR and PLSR. Most soil properties were estimated with high accuracy (concordance coefficient ≥ 0.7) using the Cubist model, except for pH, electrical conductivity (EC), available K and B. The high quality of the prediction models maybe owing to the variability in properties of the four different soils captured through conditioned Latin hypercube sampling. Results from this study also suggest that soil samples collected from multiple depths may be used for predicting both surface (0–30 cm) and sub-surface (30–90 cm) soil properties. Thus, this tool can help reduce the cost of laboratory analysis, even if it requires analysis of samples for calibration for the development of a successful spectral library across provinces.

The multifunctional classification of grasslands in the Massif Central aims to characterise the diversity of grasslands and structure our knowledge about their processes and potential. The tool described here provides information to help livestock farmers transition towards more sustainable, grass-based production. The classification system currently covers 60 different grassland types, and the classification key is based on simple criteria such as field characteristics and farming practices. Here, we discuss 6 common and representative grassland types utilised in PDO cheese production in the Massif Central: we compared agronomic productivity (forage quantity and quality), environmental properties (species richness and the occurrence of rare species), and ecosystem services (carbon storage levels and cheese quality). The impact of farming practices was also analysed; the results can help inform discussions with farmers, to help them better match their practices with the production potential of their grasslands.; La richesse et la diversité des prairies du Massif central sont le résultat d’une longue histoire entre facteurs du milieu et pratiques des agriculteurs. La typologie multifonctionnelle des prairies du Massif central permet de caractériser la diversité des prairies et d’organiser les connaissances sur le fonctionnement et les potentiels agro-écologiques de ces surfaces. Cet outil contribue ainsi à accompagner la transition des systèmes d’élevage vers des modes de production plus durables et basés sur la ressource herbe. Les 60 types recensés actuellement sont organisés dans une clé basée sur des critères simples de milieux et de pratiques. Sur la base de 6 types emblématiques des zones AOP du Massif central, nous comparons les performances agronomiques (quantité et qualité de la production) et environnementales (richesse et rareté de la flore) de chacun, ainsi que les services rendus (stockage de carbone et qualité des fromages). L’analyse de l’impact des pratiques au regard des performances et services de chaque type constitue un support de discussion avec les éleveurs pour envisager les adaptations de leurs pratiques aux potentiels de production de leurs prairies.

Au coeur de l'Amazonie, des travaux archéologiques ont fait émerger les vestiges de cultures intensives et de sociétés structurées datant de l'époque précolombienne, faisant voler en éclats le mythe de la forêt vierge.

International audience; Cocoa agroforestry systems (cAFS) in Central Cameroon are established on lands which were either forest or savannah. The functioning and ecosystem services (ES) delivery of an agroecosystem can be influenced by past land-use. We hypothesised that savannah-derived cocoa agroforestry systems (S-cAFS) and forest-derived cocoa agroforestry systems (F-cAFS) would (i) progressively drift away from past land-use, and (ii) eventually converge and support comparable levels of ecosystem services. We selected 25 ecosystem attributes directly related to at least one of the following six ecosystem (dis)services (ES): species conservation, carbon storage, crop production, nutrient cycling, soil quality and soil pollution. We followed their temporal evolution in S- and F-cAFS along >70-year chronosequences. Our results showed that the attributes and services studied followed typical temporal trajectories in S- and F-cAFS while generally tending to reach comparable levels on the long run. However, the time needed to do so varied strongly and ranged from 20 to 30 years for perennial species diversity to more than 70 years for C storage or some components of soil quality. The results also demonstrated that S-cAFS could sustainably improve many of the studied attributes and ES. Regarding the attributes related to the cocoa stand, both S- and F-cAFS seemed influenced by their previous land-use up until 15 and 30 years, respectively, after their establishment. With respect to soil quality, nutrient cycling and carbon storage, only S-cAFS could be significantly distinguished from their past land-use, after 15 to 30 years.

Forests dominate carbon (C) exchanges between the terrestrial biosphere and the atmosphere on land. In the long term, the net carbon flux between forests and the atmosphere has been significantly impacted by changes in forest cover area and structure due to ecological disturbances and management activities. Current empirical approaches for estimating net ecosystem productivity (NEP) rarely consider forest age as a predictor, which represents variation in physiological processes that can respond differently to environmental drivers, and regrowth following disturbance. Here, we conduct an observational synthesis to empirically determine to what extent climate, soil properties, nitrogen deposition, forest age and management influence the spatial and interannual variability of forest NEP across 126 forest eddy-covariance flux sites worldwide. The empirical models explained up to 62% and 71% of spatio-temporal and across-site variability of annual NEP, respectively. An investigation of model structures revealed that forest age was a dominant factor of NEP spatio-temporal variability in both space and time at the global scale as compared to abiotic factors, such as nutrient availability, soil characteristics and climate. These findings emphasize the importance of forest age in quantifying spatio-temporal variation in NEP using empirical approaches. ISSN:1748-9326 ISSN:1748-9318

International audience; The growth response of Phaseolus vulgaris to dual inoculation with arbuscular mycorrhizal (AM) fungi and rhizobia was studied in a low-fertility tropical soil in Madagascar. Two isolates of AM fungi identified as Acaulospora sp. and Glomus sp., respectively, along with a cocktail of ten Rhizobium spp. strains were used to conduct a greenhouse experiment in a fully randomized block design with two factors. The Phaseolus vulgaris seedlings received one of the following inoculation treatments: no inoculation, separate inoculation with each of the three microbial symbionts (the two AM fungal isolates and the rhizobia), and co-inoculation with each of the two AM fungal isolates and the mix of rhizobium strains. The results showed an additive effect of co-infection by AM fungi and rhizobia on plant growth and on the total N content of the plants, along with a synergistic effect on the total P content, the number of nodules and the mycorrhizal rate of the plants. Dual symbiosis with native strains contributes to the success of legumes, especially in harsh environments and low-fertility tropical soils.

The productivity of smallholder farming systems is held back by poor soil fertility, low input levels and erratic rainfall distribution in the sorghum-based cropping systems of the Sudano-Sahelian zone of West Africa. We assessed the sensitivity of current agricultural practices to climate change and to improved management practices: (i) increased fertilizer application combined with increased plant populations and (ii) use of improved sorghum varieties. We applied the Decision Support Systems for Agro-Technological Transfer (DSSAT) Cropping Systems Model, and the Agricultural Production Systems sIMulator (APSIM), for a multiple-farm assessment (i.e. diverse types of management and soils) in Koutiala (Mali) and Navrongo (Ghana), which are representative sites for West African sorghum production systems. Baseline climate data from observed weather (1980–2009) and future climates from five Global Circulation Models (GCMs: 2040–2069) in two Representative Concentration Pathways (RCP 4.5 and 8.5) were used as inputs for crop models. In Navrongo, under current management, sorghum yields either decreased or increased compared to the baseline, depending on the crop models and the GCMs; changes in management options induced a yield increase of up to 256%. The addition of genetic improvement resulted in further yield increases (24%). In Koutiala, sorghum yield changes for future climates ranged from −38 to +8% assuming current management. Shifting to an improved cultivar had a marginal effect on grain yields, while increased fertilizer rates resulted in grain yield increases ranging of 20% and 153% for DSSAT and APSIM, respectively, assuming the current climate. We conclude that in the Sudano-Sahelian zone of West Africa sorghum, as it is cultivated today, appears moderately vulnerable to climate change, while doubling fertilizer inputs with an adjusted planting density, in the current climate, would more than double yields. However, by exploring farm diversity we established that, under certain conditions, the effect of the future climate might be as important as the effect of management changes in the current climate, hinting at the importance of locally-relevant management practices.

Little is known regarding how the increased diversity of nitrogen-fixing bacteria contributes to the productivity and diversity of plants in complex communities. However, some authors have shown that the presence of a diverse group of nodulating bacteria is required for different plant species to coexist. A better understanding of the plant symbiotic organism diversity role in natural ecosystems can be extremely useful to define recovery strategies of environments that were degraded by human activities. This study used ARDRA, BOX-PCR fingerprinting and sequencing of the 16S rDNA gene to assess the diversity of root nodule nitrogen-fixing bacteria in former bauxite mining areas that were replanted in 1981, 1985, 1993, 1998, 2004 and 2006 and in a native forest. Among the 12 isolates for which the 16S rDNA gene was partially sequenced, eight, three and one isolate(s) presented similarity with sequences of the genera Bradyrhizobium, Rhizobium and Mesorhizobium, respectively. The richness, Shannon and evenness indices were the highest in the area that was replanted the earliest (1981) and the lowest in the area that was replanted most recently (2006).

Made available in DSpace on 2018-12-11T16:39:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01 Unlike Eucalyptus monocultures, nitrogen fixing trees are likely to improve the soil nutrient status through the decomposition of N-enriched litter. The Home Field Advantage (HFA) hypothesis states that plants can create conditions that increase the decomposition rates of their own litter. However, there may not be any HFA when most of the decomposers are generalists. A reciprocal transplant decomposition experiment of fine roots and leaves of Acacia mangium and Eucalyptus grandis was undertaken in monocultures of these two species to test the HFA hypothesis using a complete randomized design with three blocks. Three litterbags containing leaf or fine root residues of each species were collected every 3 months from each plot over 12 months for fine roots and 24 months for leaves. The litter mass and C, N and P concentrations were measured at each sampling date. The concentrations of C-compounds were measured 0, 12 and 24 months from the start of the experiment. There was no evidence of HFA for either the leaves or the fine roots of either species. The decomposition rates were slower for Acacia litter than for Eucalyptus litter even though initial N concentrations were 1.9-2.9 times higher and P concentrations were 1.5-3.3 times higher in the Acacia residues. N:P ratios were greater than 20-30 for the residues of both species, with the highest values for Acacia. Litter decomposition depended partly on the C quality of the litter, primarily in terms of water soluble compounds and lignin content. As shown recently in tropical rainforests, these results suggest that the activity of decomposers is limited by energy starvation in tropical planted forests. Decomposer activity may also have been limited by P availability which may not have been directly related to the P concentrations or C:P ratios in the residues. USP CENA, 303 Av. Centenario USP ESALQ, 11 Av. Padua Dias CIRAD UMR Eco and Sols, 2 Place Viala INRA UR BEF, Rue de l'Arboretum CIRAD UMR AGAP, Avenue Agropolis UNESP Ciência Florestal, 1780 Rua José Barbosa de Barros UNESP Ciência Florestal, 1780 Rua José Barbosa de Barros

Soil microbial biomass carbon (MBC), β-glucosidase, acid phosphatase and fluorescein diacetate (FDA) activities and bacterial community structure were assessed in a long-term (26 years) experiment, at physiological stages of sorghum growth, comparing different management methods for organic (manure, straw residues) and inorganic (urea) amendments at the INERA field station in Saria (Burkina Faso). Annual application of manure led to the highest soil microbial biomass and enzyme activities. Investigations indicated that only microbial biomass and β-glucosidase activities were affected during the cropping season. Phosphatase and FDA enzyme activities did not depend on the crop development stages. The application of N fertilizer modified phosphatase and FDA enzyme activities, the activities being higher in soils amended with N fertilizer. The bacterial community structure was analyzed by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) targeting the eubacterial 16S rRNA gene. Cluster analysis of PCR-DGGE patterns showed two major clusters, the first containing the mineral fertilization and straw treatments and the second, the straw + urea, manure and manure + urea treatments. Sorghum grain yields were the highest for manure treatments. In this long-term experiment, applying straw did not produce a better grain yield than that obtained in the un-amended plot.

9 pages; International audience; It has been repeatedly argued that mineral fertiliser application combined with in situ retention of crop residue biomass can sustain long-term productivity of West African soils. Using 20-year experimental data from southern Togo, a biannual rainfall area, we analysed the effect of two rates of mineral NPK fertiliser application to maize–cotton rotation on the long-term dynamics of soil C and nutrient contents, as compared with two control treatments. Mineral fertiliser treatments consisted of application to both maize (first season) and cotton (second season) the research-recommended NPK rates (Fertiliser-RR) and 1.5 times these rates (Fertiliser-1.5 RR). Control treatments consisted of cropping maize and cotton without fertiliser use (No-Fertiliser) and of double annual soil tillage (as done for planted treatments) without planting a crop (Tillage-NoCrop). Maize residue biomass was every year returned to the soil of crops planted treatments, whereas cotton stems were uprooted, piled and burnt on the experimental plots as done locally for phyto-sanitary reasons. Treatment effects were analysed through a long-term change in crop productivity, in soil C and nutrient contents. Our results indicate that productivity of maize and notably of cotton cannot be sustained in this Ferralsol without nutrient inputs. On average, maize yields without fertilisers decreased from 2 t ha−1 after woodland clearing to 0.5 t ha−1 after 10 years of cultivation, while cotton yields decreased from 1.5 to 0.5 t ha−1 only after 5 years. In spite of the need of mineral fertiliser use to sustain productivity of this soil, there was little justification to increase inputs of mineral fertiliser over the research recommended rate. Over 20-year experiment, both maize and cotton while received N, P and K inputs at the research-recommended rates produced virtually the same yields as when these rates were increased by 50%. Although C inputs to soil under RR and 1.5 RR were greater than in the No-Fertiliser control (nil for Tillage-NoCrop), and the N input was more favourable for 1.5RR, the rates in which contents of soil C and N decreased over time did not differ substantially between treatments. Soil available P decreased for all treatments, while exchangeable K concentration increased under RR and 1.5 RR and decreased in unfertilised treatments (No-Fertiliser and Tillage-NoCrop). In fertilised plots and in tillage no-planted plots, soil pH decreased more than in No-Fertiliser plots. A decline of soil pH was associated with a decline of exchangeable Ca and Mg, which were on average 20 and 40% higher in fertilised plots than in No-Fertiliser plots. We conclude that soil C and N decline in this Ferralsol was more determined by a change in soil conditions due to woodland clearance and continuous tillage than by the quantities of C or N inputs added annually.

To study food production systems of six communities located on six different islands of Vanuatu we selected villages in zones of low and high population pressures. We measured land availability, soil fertility, genetic resources, average yields of food gardens, their plant densities, traditional knowledge richness (TKR), and household incomes and expenses. We analyzed a total of 224 plots belonging to 30 farmers and identified 13 root crop species with the total number of cultivars in communities ranging from 74 to 261. Surprisingly, villages under high population pressure have shorter fallow periods but higher yields. In both zones, women have higher TKR. In high population pressure villages there are signs of soil fertility reduction and mineral depletion but no signs of significant decrease in soil fertility after the first year of cultivation, indicating that root crop species remove limited amounts of total N and minerals per year. The purchase of imported foods is associated with a sociocultural change in diets rather than pressures on land or soils. Our quantitative and integrative methodology allows clear differentiation between villages under different pressures and can be used to assess levels of resilience and vulnerability.

International audience; Crop losses caused by pests and diseases decrease the incomes and threaten the livelihoods of thousands of families worldwide. A good example of the magnitude of these impacts are the massive crop losses experienced by coffee farmers in Central America due to coffee leaf rust. Coffee farmers need agroecosystems that are capable of regulating the negative impacts of pests and diseases while providing other ecosystem services on which their households and society depend. In this study, we aimed to identify the most promising coffee agroforestry systems for regulating diseases and ensuring the provision of other ecosystem services. During two years, in a research network of 61 coffee plots under a wide variety of shade and management conditions in Turrialba, Costa Rica, we quantified primary and secondary coffee losses (yield and economic losses) and indicators of three other ecosystem services: provisioning of agroforestry products (bananas, plantains, other fruits, and timber), maintenance of soil fertility and carbon sequestration. We then performed an analysis of the relationships between losses and ecosystem service indicators. Based on the results of relationships and on three criteria, we identified the coffee agroforestry systems that had the lowest losses due to diseases and that provided desirable levels of agroforestry products, soil fertility and carbon sequestration. We found multiple significant relationships between losses and ecosystem services (including both tradeoffs and synergies) which allowed us to derive recommendations for better management strategies to reduce yield losses. We identified six coffee agroforestry systems (CAFs) as the most promising ones for reducing losses while simultaneously providing other ecosystem services. One of these CAFs was a simple agroforestry system (dominated by service trees), three were medium diversified CAFs and two were highly diversified CAFs (systems including service trees, timber trees, fruit trees and musaceas). The six CAFS differed in their cropping practices and farmer profitability objectives. The six CAFs offer several options for the design of new coffee plantations or for the transformation of existing plantations. Several of this promising CAFs use little fungicides, which is an indicator that the reduction of chemical inputs could be possible. Our results suggest that the regulation of diseases and associated losses in agroforestry systems should be based on, and take advantage of, the positive effects of plant biodiversity, adequate shade cover, good soil fertility, and minimal use of fungicides.

Made available in DSpace on 2020-12-10T20:01:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01. Added 1 bitstream(s) on 2021-07-15T15:25:04Z : No. of bitstreams: 1 S1980-50982020000100117.pdf: 1255717 bytes, checksum: cb32f05c60784ed1d46889ded03b66f3 (MD5) Anglo American Arauco Arborgen ArcelorMittal Cenibra CMPC Copener Duratex Eldorado Fazenda Campo Bom Fibria Florestal Itaquari Forestal Gerdau GMR International Paper Jari Klabin Lwarcel Montes del Plata Plantar Rigesa Suzano Vallourec Veracel University of Sao Paulo - Brazil State University of Sao Paulo - Brazil Federal University of Lavras - Brazil Federal University of Rio Grande do Norte - Brazil Colorado State University - USA North Carolina State University - USA USDA Forest Service Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The present study aimed to evaluate the correlations between productivity and eucalyptus drought (DR) response between soil attributes in two distinct climatic types in Brazil. For this, 24 experiments were installed in Brazil with four common clones in all the experiments to obtain strong edaphoclimatic contrasts, and, thus, to measure the productivity and the response to drought and to describe its relationship with the attributes of the soils. Two climatic groups were evaluated: Wet (precipitation rate: evapotranspiration between 1.0 to 2.5) and Sub-Humid (precipitation rate: evapotranspiration between 0.5 to 1.0). The attributes of the evaluated soils were: Sand, Silt, Clay, organic matter (O.M.), cation exchange capacity (CEC). For sites located in the wet climate class, CVWB correlated negatively with O.M. and clay, and positively with the sand. For DR, the correlations were observed for the Sub-Humid climate for the CEC and Sand variables, and for the Humid climate, no correlations were observed between the attributes of soils with DR. Univ Estadual Paulista, VIMEF Solucoes Florestais, Av Brasil Sul 56, BR-15385000 Ilha Solteira, SP, Brazil Univ Estadual Paulista, Dept Fitossanidade Engn Rural & Solos, Fac Engn Ilha Solteira, Av Brasil Sul 56, BR-15385000 Ilha Solteira, SP, Brazil Univ Montpellier, Montpellier SupAgro, Eco & Sols, CIRAD,INRA,IRD, 389 Ave Agropolis, F-34980 Montpellier, France Univ Estadual Paulista, Dept Ciencias Exatas, Fac Ciencias Agr & Vet, Campus Jaboticabal, BR-14884900 Jaboticabal, SP, Brazil Eldorado Brasil Celulose, BR-158,Km 231 S-N, BR-79641300 Tres Lagoas, MS, Brazil Univ Estadual Paulista, VIMEF Solucoes Florestais, Av Brasil Sul 56, BR-15385000 Ilha Solteira, SP, Brazil Univ Estadual Paulista, Dept Fitossanidade Engn Rural & Solos, Fac Engn Ilha Solteira, Av Brasil Sul 56, BR-15385000 Ilha Solteira, SP, Brazil Univ Estadual Paulista, Dept Ciencias Exatas, Fac Ciencias Agr & Vet, Campus Jaboticabal, BR-14884900 Jaboticabal, SP, Brazil

Forest soil fertility can be defined as a combination of physical, chemical and biological factors characterising the biomass production capacity of the soil. However, numerous ecological variables affect tree growth and the aim of the present study was to investigate the specific influence of soil chemical properties on tree productivity at 49 acidic forest sites. A standardized tree productivity index based on tree height expressed as dominant height of the studied stand divided by maximum tree height observed at the same age for the same species in the same climatic region was firstly computed at each site. This index is assumed to limit the influence of species, ages and climate. A soil database was also compiled with data on soil properties from 47 temperate (France) and two tropical (Congo, Brazil) sites. Data included seven tree species, varying in age from 1 to 175 years. Commonly used indicators such as C:N ratio, soil pH, as well as available and total pools of soil nutrients were compared to the standardized tree productivity index, to find the most reliable indicator(s). Nutrient pools at fixed mineral soil depths (down to 100 cm) were used, as well as (for 11 stands) the depth comprising 95% of fine roots. Our results show that none of the common soil chemical parameters tested in this paper could individually explain stand productivity. Combinations of different parameters were also tested using PCA and they could better explain the variability of the data set but without being able to separate the sites according to their standardized tree productivity index. Moreover, random Forests performed on our dataset were unable to properly predict the standardized tree productivity index. Our results reinforce the idea that the influence of the soil chemical fertility on stand productivity is complex and the soil chemical parameters alone (individually or combined) are poor predictors of tree productivity as assessed by the H0:Hmax index. In this paper we focused on static soil chemical indicator and more dynamic indictors, such as nutrient fluxes involved in the biogeochemical cycles, could better explain stand productivity. A companion paper (Legout et al., 2020) focuses on the connection between productivity and different components of the biogeochemical cycle, using data from 11 of the stands presented in this paper.

Dans un hectare de sol cultivé, un entrelacs de racines abrite 1,5 tonnes de bactéries et 3,5 tonnes de champignons microscopiques. Sans compter les vers de terre, insectes, acariens… et toute une faune qui peut peser de 1 à 5 tonnes ! Cette biodiversité très riche fait la valeur de nos sols, participe à leur fertilité et contribue donc à la qualité de notre alimentation. Élément clé du bon fonctionnement de notre environnement, elle favorise la régulation du climat, le stockage du carbone, la qualité de l’eau… Interviews vidéos. Le sol est au carrefour du bon fonctionnement de notre agriculture, de notre alimentation et de notre environnement… S’il a longtemps été vu comme un support inerte, son patrimoine biologique est aujourd’hui apprécié pour tous les services qu’il rend aux communautés humaines. À l’Inra, il mobilise de nombreux chercheurs. Dans cette interview vidéo Pierre-Alain Maron, Inra Bourgogne Franche-Comté, Mickaël Hedde, Inra Occitanie-Montpellier et Antonio Bispo, Inra Val de Loire en livrent quelques enjeux qu’ils partageaient lors du Carrefour de l’Innovation agronomique sur la fertilité biologique des sols, le 18 octobre dernier.

(IF 3.95; Q1); International audience; The rapid expansion of perennial crops is a major threat to biodiversity in Southeast Asia. The biodiversity losses related to the conversion of forest lands to oil palm or rubber plantations (RP) are well documented by recent studies. However, the impact of the conversion from intensively managed annual crops to perennial crops on soil biodiversity has not yet been addressed. This study aims at assessing the impact on soil biodiversity of a) the short-term effect of land use conversion from cassava crop to RP, and b) the long-term effect of RP ageing. Soil biodiversity (bacterial, fungal and macrofaunal), microbial activities and pedoclimatic characteristics were measured over a chronosequence of 1–25 years old of RP compared to cassava fields, the former crop, in Thailand. The conversion from cassava to young RP (1–3 yr) had a significant effect on microbial biomass and activities and fungal composition, but did not impact the bacterial and macrofaunal diversity. This effect of land use conversion could be explained by the change in land management due to the cultivation of pineapple in the inter-row of the young RP. Canopy closure appeared to be the main driver of soil biota shifts, as most of the biotic parameters, composition, abundance and activities were significantly modified after 7 years of RP. The changes of composition in older rubber plantations originated from the dominance of Trichoderma (fungi), Firmicutes (bacteria), and earthworms. Old rubber plantations (23–25 yr) harboured the highest microbial and macrofaunal biomass; however, they were also characterised by a significant decrease in bacterial richness. The change in pedoclimatic conditions across the rubber chronosequence, i.e. increase in soil moisture, litter and organic carbon content, was a stronger driver of soil biota evolution than land use conversion. The macrofaunal composition was more resistant to land use conversion than the bacterial composition, whereas the microbial biomass was sensitive to land use conversion, but showed resilience after 20 years. However, bacterial, fungal and macrofaunal diversity, macrofaunal and microbial biomass and microbial activities were all sensitive to RP ageing.

International audience; Service crops are crops grown with the aim of providing non-marketed ecosystem services, i.e. differing from food, fiber and fuel production. Vineyard soils face various agronomic issues such as poor organic carbon levels, erosion, fertility losses, and numerous studies have highlighted the ability of service crops to address these issues. In addition to their ability to increase soil organic matter and fertility, and reduce runoff and erosion processes, service crops provide a large variety of ecosystem services in vineyards such as weed control, pest and disease regulation, water supply, water purification, improvement of field trafficability and maintenance of soil biodiversity. However, associating service crops with grapevines may also generate disservices and impair grape production: competition for soil resources with the grapevine is often highlighted to reject such association. Consequently, vinegrowers have to find a balance between services and disservices, depending on local soil and climate conditions, on their objectives of grape production and on the nature and temporality of the ecosystem services they expect during the grapevine cycle. This study proposes a review of the services and disservices provided by service crops in vineyards, and a framework for their management. Vinegrowers' production objectives and pedoclimatic constraints form the preliminary stage to consider before defining a strategy of service crop management. This strategy assembles management options such as the choice of species, its spatial distribution within the vineyard, the timing of its installation, maintenance and destruction. These management options, defined for both annual and long-term time scales, form action levers which may impact cropping system functioning. Finally, we underline the importance of implementing an adaptive strategy at the seasonal time scale. Such tactical management allows adapting the cropping system to observed climate and state of the biophysical system during the grapevine cycle, in order to provide targeted services and achieve satisfactory production objectives.

National audience; Plusieurs éléments généraux ressortent des observations. Tout d'abord, la structure du sol sous le cavaillon reste préservée des fortes dégradations et est favorable à l'enracinement de la vigne. Un second résultat générique est que la mécanisation des pratiques d'entretien des interrangs peut causer des changements de structure des sols irréversibles. Un troisième résultat est que des dégradations structurales des sols viticoles peuvent persister longtemps sous le cavaillon et au milieu des interrangs.

International audience; Livestock-driven nutrient flows are the main sources of soil and crop fertilization in West African agro-sylvo-pastoral landscapes. They result from nutrient recycling between farm activities and the spatial transfer of nutrients within the landscape. “Extensive” systems, based on livestock mobility are tending to be replaced by more “intensive” systems based on in-barn livestock fattening. We built an agent-based model to compare these systems in terms of nitrogen cycling at land plot, herd, household and village levels. Model evaluation, based on field-data from two real contrasted villages, showed that the model satisfactorily reproduces the differences between an “extensive” and an “intensive” system with key parameters such as variability among households and soil fertility gradients. Simulations highlighted bottlenecks along the nitrogen (N) cycle like accumulation of N in manure heaps and housing areas, reducing N recycling efficiency, especially in “intensive” systems. The model can be further used to explore improved agro-sylvo-pastoral landscapes.

International audience; Soil organic carbon (SOC) balance is an important component of the terrestrial carbon (C) budget. However, effect of cropland management changes on SOC dynamics has not been recently assessed in the tropics. Studies were compiled in the tropics where SOC stocks were measured in the topsoil (0–20 or 0–30 cm depth) after the adoption of management practices that are expected to enhance SOC stocks, including tillage reduction, crop rotation, exogenous organic amendments, restitution of crop residues, mineral amendments, and combinations of these practices. Random forest regression was used to identify the determinants of SOC accumulation rates (ΔSOC) depending on the climate, soil characteristics and changes in management practices. 214 cases were identified in 48 studies in 13 different countries. The average ΔSOC was 0.41 ± 0.03 Mg C ha−1 yr−1 (significantly greater than zero), for an average experiment duration of 13.6 ± 0.6 years. Although a large part of the variability remained unexplained due to methodological bias in the studies or a lack of relevant predictors. The strongest predictors of ΔSOC were C inputs, duration of the experiments, and the management practices, whereas neither soil characteristics (soil type, clay content, and initial SOC stock) nor climate variables (mean annual temperature and rainfall, aridity index) affected ΔSOC. The SOC accumulation rates increased linearly with C inputs, and the conversion rate of C inputs to SOC was 8.2 ± 0.8%. Given the competing uses of organic matter on many tropical farms, the benefits of using changes in management practices for climate change mitigation might be overrated. As ΔSOC decreased with the duration of the experiments, ΔSOC would probably be smaller if a period of 20 years were considered, as recommended by the IPCC guidelines. The management practice with the greatest ΔSOC was diversified crop rotation. Cropping systems where diverse practices were combined resulted in higher ΔSOC than individual practices such as reduced tillage and mineral fertilization on their own. The adoption of improved management practices that increase C inputs is still relevant for meeting the challenges of food security and adaptation to climate change.

International audience; Soil bacterivorous nematodes are key plant mutualists that increase nutrient availability for plants either by enhancing the mineralization of organic compounds (the “mineralization pathway”) or by increasing plant lateral root branching following shifts in internal plant metabolism, and subsequently leading to a higher volume of soil prospected by the roots (the “hormonal pathway”). The effects of these organisms on the nutrition of plants growing in strongly nutrient-deficient ferrallitic soils, especially in soils with limited available inorganic phosphorus (P), are poorly known, as are the pathways involved. In our study, using Oryza sativa (Poaceae) and Acrobeloides sp. (Cephalobidae), we tested the “mineralization” and “hormonal” hypotheses in an acidic P-depleted Ferralsol from the Madagascar highlands. We assessed the effect of nematode inoculation on (i) inorganic P flow from soil to plant using the 32P labelling technique and (ii) plant root architecture using a rhizobox device. We showed that the ability of Acrobeloides sp. to enhance P uptake in plants is strongly limited in Ferralsols. However, when the soil pH was corrected with dolomite, Acrobeloides sp. increased plant P uptake probably through the “mineralization” pathway (higher microbial turnover). Indeed, the L-value increased by 49% in the presence of nematodes and dolomite, suggesting the production of unlabelled plant-available P, probably through a higher net P mineralization when the nematodes were inoculated. Using the rhizobox technique, we also observed increased root length in the presence of nematodes but the specific root length, the tip number and the root branching density did not increase in the presence of nematodes, suggesting that nematodes did not increase plant P uptake and growth in this soil as proposed by the “hormonal” hypothesis. From an ecological intensification perspective, to promote agro-ecological development in tropical regions, our results suggest that amending ferrallitic soils with P-rich organic matter and correcting soil pH with an appropriate amount of dolomite may constitute suitable agronomic actionable triggers to drive the mutualistic activity of bacterivorous nematodes.