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The Paris Climate Agreements and Sustainable Development Goals, signed by 197 countries, present agendas and address key issues for implementing multi-scale responses for sustainable development under climate change—an effort that must involve local, regional, national, and supra-national stakeholders. In that regard, Continental Carbon Sequestration (CoCS) and conservation of carbon sinks are recognized increasingly as having potentially important roles in mitigating climate change and adapting to it. Making that potential a reality will require indicators of success for various stakeholders from multidisciplinary backgrounds, plus promotion of long-term implementation of strategic action towards civil society (e.g., law and policy makers, economists, and farmers). To help meet those challenges, this discussion paper summarizes the state of the art and uncertainties regarding CoCS, taking an interdisciplinary, holistic approach toward understanding these complex issues. The first part of the paper discusses the carbon cycle’s bio-geophysical processes, while the second introduces the plurality of geographical scales to be addressed when dealing with landscape management for CoCS. The third part addresses systemic viability, vulnerability, and resilience in CoCS practices, before concluding with the need to develop inter-disciplinarity in sustainable science, participative research, and the societal implications of sustainable CoCS actions.
Tiphaine Chevallier; Maud Loireau; Romain Courault; Lydie Chapuis-Lardy; Thierry Desjardins; Cécile Gomez; Alexandre Grondin; Frédéric Guérin; Didier Orange; Raphaël Pélissier; Georges Serpantié; Marie-Hélène Durand; Pierre Derioz; Gildas Laruelle Goulven; Marie-Hélène Schwoob; Nicolas Viovy; Olivier Barrière; Eric Blanchart; Vincent Blanfort; Michel Brossard; Julien Demenois; Mireille Fargette; Thierry Heulin; Gil Mahe; Raphaël Manlay; Pascal Podwojewski; Cornélia Rumpel; Benjamin Sultan; Jean-Luc Chotte. Paris Climate Agreement: Promoting Interdisciplinary Science and Stakeholders’ Approaches for Multi-Scale Implementation of Continental Carbon Sequestration. Sustainability 2020, 12, 6715 .
AMA StyleTiphaine Chevallier, Maud Loireau, Romain Courault, Lydie Chapuis-Lardy, Thierry Desjardins, Cécile Gomez, Alexandre Grondin, Frédéric Guérin, Didier Orange, Raphaël Pélissier, Georges Serpantié, Marie-Hélène Durand, Pierre Derioz, Gildas Laruelle Goulven, Marie-Hélène Schwoob, Nicolas Viovy, Olivier Barrière, Eric Blanchart, Vincent Blanfort, Michel Brossard, Julien Demenois, Mireille Fargette, Thierry Heulin, Gil Mahe, Raphaël Manlay, Pascal Podwojewski, Cornélia Rumpel, Benjamin Sultan, Jean-Luc Chotte. Paris Climate Agreement: Promoting Interdisciplinary Science and Stakeholders’ Approaches for Multi-Scale Implementation of Continental Carbon Sequestration. Sustainability. 2020; 12 (17):6715.
Chicago/Turabian StyleTiphaine Chevallier; Maud Loireau; Romain Courault; Lydie Chapuis-Lardy; Thierry Desjardins; Cécile Gomez; Alexandre Grondin; Frédéric Guérin; Didier Orange; Raphaël Pélissier; Georges Serpantié; Marie-Hélène Durand; Pierre Derioz; Gildas Laruelle Goulven; Marie-Hélène Schwoob; Nicolas Viovy; Olivier Barrière; Eric Blanchart; Vincent Blanfort; Michel Brossard; Julien Demenois; Mireille Fargette; Thierry Heulin; Gil Mahe; Raphaël Manlay; Pascal Podwojewski; Cornélia Rumpel; Benjamin Sultan; Jean-Luc Chotte. 2020. "Paris Climate Agreement: Promoting Interdisciplinary Science and Stakeholders’ Approaches for Multi-Scale Implementation of Continental Carbon Sequestration." Sustainability 12, no. 17: 6715.
Nutrient availability is a major limitation of the production of West African mixed farming systems. The fertility of these systems was traditionally sustained by fallowing, and nutrient transfers by livestock from savanna to croplands. However, demographic growth and socio-economic constraints require the agro-ecological intensification of these systems. To understand how agricultural practices and landscape management affect crop production, we built a meta-ecosystem model of nitrogen stocks and fluxes, and we examined different scenarios of fallow management with or without livestock. Our results suggest that crop production is highly dependent on the source-sink dynamics of nitrogen. Without livestock, maximum crop production is obtained for an intermediate duration of fallowing, highlighting a trade-off between space devoted to production (cropland) and space devoted to fertility restoration (fallow). In presence of livestock, crop production is maximum for a shorter duration of fallowing; it is markedly higher with than without livestock. This result highlights the positive roles of livestock and fallows as pumps (vectors) of nitrogen from savanna rangeland to cropland, and from fallow land to cropland, respectively. However, it also highlights the negative relationship between livestock presence and fallowing, suggesting that the optimal configuration of livestock and fallow management is highly context-dependent. Overall, we argue that the meta-ecosystem approach is particularly relevant for the study of agro-ecosystems characterized by high spatial heterogeneity. This work can be seen as a first step toward an alternative approach, integrating tools from theoretical ecology for the study of agro-ecosystems which functioning strongly depends on spatial organisation.
Anne Bisson; Simon Boudsocq; Céline Casenave; Sébastien Barot; Raphaël J. Manlay; Jonathan Vayssières; Dominique Masse; Tanguy Daufresne. West African mixed farming systems as meta-ecosystems: A source-sink modelling approach. Ecological Modelling 2019, 412, 108803 .
AMA StyleAnne Bisson, Simon Boudsocq, Céline Casenave, Sébastien Barot, Raphaël J. Manlay, Jonathan Vayssières, Dominique Masse, Tanguy Daufresne. West African mixed farming systems as meta-ecosystems: A source-sink modelling approach. Ecological Modelling. 2019; 412 ():108803.
Chicago/Turabian StyleAnne Bisson; Simon Boudsocq; Céline Casenave; Sébastien Barot; Raphaël J. Manlay; Jonathan Vayssières; Dominique Masse; Tanguy Daufresne. 2019. "West African mixed farming systems as meta-ecosystems: A source-sink modelling approach." Ecological Modelling 412, no. : 108803.
Restoring degraded soils to support food production is a major challenge for West African smallholders, who have developed local innovations to counter further degradation. The objective of this study was to evaluate a local farmer's technique that uses ramial wood (RW) as soil amendment (Piliostigma reticulatum shrub species). Three treatments were applied in an experimental plot in Burkina Faso: control (no amendment), low‐RW (3 Mg FM ha‐1 yr‐1), and high‐RW (12 Mg FM ha‐1 yr‐1), RW was chipped to <5 cm pieces and either buried or mulched. Topsoil carbon (C), nitrogen (N) and phosphorus (P) in control and low‐RW treatments declined after seven years of continuous sorghum cultivation. Use of high‐RW amendment stabilized soil C content while N and P declined, thus not replenishing nutrient exports. Net contribution to soil C in the 0‐15 cm layer was 15% of the applied C in the high‐RW amendments. Although biomass and grain yields were higher in high‐RW treatments, crop productivity declined throughout the experiment for all treatments. Termite casts on RW treatments evidenced the potential role of wood‐foraging termites in diluting the impact of RW on soil fertility build‐up and soil water content. We conclude that mitigating soil degradation under semi‐arid conditions in Burkina Faso would require large amounts of woody amendments, particularly if the level of termite activity is high. Additional nutrient sources would be needed to compensate for removal in exported products so that biomass and grain production can be stabilized or increased.
Georges F. Félix; Cathy Clermont-Dauphin; Edmond Hien; Jeroen C.J. Groot; Aurélien Penche; Bernard G. Barthès; Raphaël J. Manlay; Pablo Tittonell; Laurent Cournac. Ramial wood amendments (Piliostigma reticulatum) mitigate degradation of tropical soils but do not replenish nutrient exports. Land Degradation & Development 2018, 29, 2694 -2706.
AMA StyleGeorges F. Félix, Cathy Clermont-Dauphin, Edmond Hien, Jeroen C.J. Groot, Aurélien Penche, Bernard G. Barthès, Raphaël J. Manlay, Pablo Tittonell, Laurent Cournac. Ramial wood amendments (Piliostigma reticulatum) mitigate degradation of tropical soils but do not replenish nutrient exports. Land Degradation & Development. 2018; 29 (8):2694-2706.
Chicago/Turabian StyleGeorges F. Félix; Cathy Clermont-Dauphin; Edmond Hien; Jeroen C.J. Groot; Aurélien Penche; Bernard G. Barthès; Raphaël J. Manlay; Pablo Tittonell; Laurent Cournac. 2018. "Ramial wood amendments (Piliostigma reticulatum) mitigate degradation of tropical soils but do not replenish nutrient exports." Land Degradation & Development 29, no. 8: 2694-2706.
Greenhouse gas (GHG) emissions from the surface soils and surface water receiving animal excreta may be important components of the GHG balance of terrestrial ecosystems, but the associated processes are poorly documented in tropical environments, especially in tropical arid and semi-arid areas. A typical sylvo-pastoral landscape in the semi-arid zone of Senegal, West Africa, was investigated in this study. The study area (706 km² of managed pastoral land) was a circular zone with a radius of 15 km centered on a borehole used to water livestock. The landscape supports a stocking rate ranging from 0.11 to 0.39 tropical livestock units per hectare depending on the seasonal movements of the livestock. Six landscape units were investigated (land in the vicinity of the borehole, natural ponds, natural rangelands, forest plantations, settlements, and enclosed plots). Carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) fluxes were measured with static chambers set up at 13 sites covering the six landscape units, and the 13 sites are assumed to be representative of the spatial heterogeneity of the emissions. A total of 216 fluxes were measured during the one-year study period (May 2014 to April 2015). At the landscape level, soils and surface water emitted an average 19.8 t C-CO2 eq/(hm²•a) (CO2: 82%, N2O: 15%, and CH4: 3%), but detailed results revealed notable spatial heterogeneity of GHG emissions. CO2 fluxes ranged from 1148.2 (±91.6) mg/(m²•d) in rangelands to 97,980.2 (±14,861.7) mg/(m²•d) in surface water in the vicinity of the borehole. N2O fluxes ranged from 0.6 (±0.1) mg/(m²•d) in forest plantations to 22.6 (±10.8) mg/(m²•d) in the vicinity of the borehole. CH4 fluxes ranged from–3.2 (±0.3) mg/(m²•d) in forest plantations to 8788.5 (±2295.9) mg/(m²•d) from surface water in the vicinity of the borehole. This study identified GHG emission “hot spots” in the landscape. Emissions from the surface soils were significantly higher in the landscape units most frequently used by the animals, i.e., in the vicinity of the borehole and settlements; and emissions measured from surface water in the vicinity of the borehole and from natural ponds were on average about 10 times higher than soil emissions.
Mohamed Habibou Assouma; Dominique Serça; Frederic Guerin; Vincent Blanfort; Philippe Lecomte; Ibra Touré; Alexandre Ickowicz; Raphaël Manlay; Martial Bernoux; Jonathan Vayssières. Livestock induces strong spatial heterogeneity of soil CO2, N2O and CH4 emissions within a semi-arid sylvo-pastoral landscape in West Africa. Journal of Arid Land 2017, 9, 210 -221.
AMA StyleMohamed Habibou Assouma, Dominique Serça, Frederic Guerin, Vincent Blanfort, Philippe Lecomte, Ibra Touré, Alexandre Ickowicz, Raphaël Manlay, Martial Bernoux, Jonathan Vayssières. Livestock induces strong spatial heterogeneity of soil CO2, N2O and CH4 emissions within a semi-arid sylvo-pastoral landscape in West Africa. Journal of Arid Land. 2017; 9 (2):210-221.
Chicago/Turabian StyleMohamed Habibou Assouma; Dominique Serça; Frederic Guerin; Vincent Blanfort; Philippe Lecomte; Ibra Touré; Alexandre Ickowicz; Raphaël Manlay; Martial Bernoux; Jonathan Vayssières. 2017. "Livestock induces strong spatial heterogeneity of soil CO2, N2O and CH4 emissions within a semi-arid sylvo-pastoral landscape in West Africa." Journal of Arid Land 9, no. 2: 210-221.
In Sudano-Sahelian agriculture, organic amendments are often limited by resource availability. Small branches (ramial wood, RW) represent an organic resource found in many landscapes but little is known about their effects. This field trial (2007–2009) studied the effects of RW or straw at low application rate (0.69 Mg C ha−1 year−1) on topsoil carbon (C), nitrogen (N) and available phosphorus (P, Pav), termite cast abundance, and sorghum yield. Straw and RW were chopped and either buried (StBu, WoBu) or mulched (StMu, WoMu). Mineral fertilizers were added to straw so that RW- and straw-amended plots received similar applications of C, N, P, and potassium. Another treatment had RW buried with additional N (WoBuN), and there was a control (Ctrl). Branches came from Piliostigma reticulatum, very common in the area. The treatments had little significant effect on topsoil and crop, owing to the low application rate and spatial variability. However, Pav was significantly lower with buried than mulched amendments in 2009, and decreased significantly over time in Ctrl and with buried amendments. Topsoil C also decreased significantly with time in WoMu. Significantly more termite casts were observed with RW. The sorghum yield averaged 0.87 Mg DM ha−1 in 2007 and then decreased. The treatments affected yield significantly in 2008 only: it was higher in WoBuN and StBu than in Ctrl. In 2009, the yield was mainly affected by initial topsoil Pav. These results suggest that RW stimulated biological activity, leading to P immobilization and C mineralization, but had little effect on yields.
Bernard G. Barthès; Aurélien Penche; Edmond Hien; Philippe Deleporte; Cathy Clermont-Dauphin; Laurent Cournac; Raphaël Manlay. Effect of ramial wood amendment on sorghum production and topsoil quality in a Sudano-Sahelian ecosystem (central Burkina Faso). Agroforestry Systems 2014, 89, 81 -93.
AMA StyleBernard G. Barthès, Aurélien Penche, Edmond Hien, Philippe Deleporte, Cathy Clermont-Dauphin, Laurent Cournac, Raphaël Manlay. Effect of ramial wood amendment on sorghum production and topsoil quality in a Sudano-Sahelian ecosystem (central Burkina Faso). Agroforestry Systems. 2014; 89 (1):81-93.
Chicago/Turabian StyleBernard G. Barthès; Aurélien Penche; Edmond Hien; Philippe Deleporte; Cathy Clermont-Dauphin; Laurent Cournac; Raphaël Manlay. 2014. "Effect of ramial wood amendment on sorghum production and topsoil quality in a Sudano-Sahelian ecosystem (central Burkina Faso)." Agroforestry Systems 89, no. 1: 81-93.
A large proportion of the tropical rain forests of central Africa undergo periodic selective logging for timber harvesting. The REDD+ mechanism could promote less intensive logging if revenue from the additional carbon stored in the forest compensates financially for the reduced timber yield. Carbon stocks, and timber yields, and their associated values, were predicted at the scale of a forest concession in Gabon over a project scenario of 40 yr with reduced logging intensity. Considering that the timber contribution margin (i.e. the selling price of timber minus its production costs) varies between 10 and US$40 m −3, the minimum price of carbon that enables carbon revenues to compensate forgone timber benefits ranges between US$4.4 and US$25.9/tCO 2 depending on the management scenario implemented. Where multiple suppliers of emission reductions compete in a REDD+ carbon market, tropical timber companies are likely to change their management practices only if very favourable conditions are met, namely if the timber contribution margin remains low enough and if alternative management practices and associated incentives are appropriately chosen.
Michel Ndjondo; Sylvie Gourlet-Fleury; Raphaël J Manlay; Nestor Laurier Engone Obiang; Alfred Ngomanda; Claudia Romero; Florian Claeys; Nicolas Picard. Opportunity costs of carbon sequestration in a forest concession in central Africa. Carbon Balance and Management 2014, 9, 1 -13.
AMA StyleMichel Ndjondo, Sylvie Gourlet-Fleury, Raphaël J Manlay, Nestor Laurier Engone Obiang, Alfred Ngomanda, Claudia Romero, Florian Claeys, Nicolas Picard. Opportunity costs of carbon sequestration in a forest concession in central Africa. Carbon Balance and Management. 2014; 9 (1):1-13.
Chicago/Turabian StyleMichel Ndjondo; Sylvie Gourlet-Fleury; Raphaël J Manlay; Nestor Laurier Engone Obiang; Alfred Ngomanda; Claudia Romero; Florian Claeys; Nicolas Picard. 2014. "Opportunity costs of carbon sequestration in a forest concession in central Africa." Carbon Balance and Management 9, no. 1: 1-13.
International audienceCarbon is an important determinant of the sustainability of West African farming systems and of the atmospheric greenhouse effect. Given the complexity of C dynamics, various simulation models have been developed. Few include socioeconomic factors or handle system heterogeneity. This study pro- poses a generic, multi-agent model for the analysis of C dynamics at village level. It assumes that a better analysis of carbon dynamics at village level requires account to be taken of social, economic, physical and biological factors as well as of the actions of individuals and their interdependence. The Carbon of Territory Multi-Agent Simulator (CaTMAS) model is based on the Organization-Role-Entity-Aspect (OREA) meta-model and the Multi-Agent Systems (MAS) approach. OREA enables C dynamics to be studied from various points of view through the roles played by entities within organizations and also allows various entities to play the same role in various ways through the notion of aspects. The model was coupled with the Century model and a geographical information system to provide a realistic representation of C dynamics. CaTMAS provides not only a framework for the explicit description of the carbon dynamics of farming systems but can also be used to assess the viability of farming systems using various socioeconomic and biophysical scenarios. The model includes interactions between human activities and the environment. Simple simulations involving two cropping systems and focusing on the impact of population growth and different climate regimes on the C dynamics indicate that CaTMAS accounts realistically for the relationships between population, agriculture, climate and SOC dynamics. In simulation, population growth, which drives food demand, leads to agricultural expansion, land scarcity and decrease in fallow duration. These effects are accentuated by increasing temperature and decreasing rainfall which affect the SOC dynamics controlling soil fertility and thus crop production. Improvements to the model should make it possible to extend the scale of the simulation of C dynamics and include refinements such as the inclusion of the trading of carbon credits
Mahamadou Belem; Raphaël J. Manlay; Jean-Pierre Müller; Jean-Luc Chotte. CaTMAS: A multi-agent model for simulating the dynamics of carbon resources of West African villages. Ecological Modelling 2011, 222, 3651 -3661.
AMA StyleMahamadou Belem, Raphaël J. Manlay, Jean-Pierre Müller, Jean-Luc Chotte. CaTMAS: A multi-agent model for simulating the dynamics of carbon resources of West African villages. Ecological Modelling. 2011; 222 (20-22):3651-3661.
Chicago/Turabian StyleMahamadou Belem; Raphaël J. Manlay; Jean-Pierre Müller; Jean-Luc Chotte. 2011. "CaTMAS: A multi-agent model for simulating the dynamics of carbon resources of West African villages." Ecological Modelling 222, no. 20-22: 3651-3661.
Impacts of two land-management systems on soil C content and stocks and their dynamic were assessed in two agro-ecosystems of South-West Burkina Faso. The study was carried out on 26 pedological profiles and 112 farmers’ plots for a precise study compared to four plots in a close forest. The study goal was to assess differences between two cropping systems in terms of organic resources management. The itinerant one, based on yam production, developed by the native population and the permanent one based on cotton production, developed by the migrant population. The results show similarities as well as differences: (1) C content and stocks in soil are highly related to textural factors (clay content + tiny silt, %) in both systems; (2) for all uses the average stocks for all plots for the top 20 cm (0–10 and 10–20 cm) of soils are 14 and 12 t C ha–1 and (3) significant differences in C stocks occurred mainly in the 0–10-cm soil layer with higher stocks in the permanent cropping system than in the itinerant system or forest. No significant difference was noticed between cultivated and noncultivated plots. These are the main points of our study. This implies that management factor, as Cultural Intensity (CI) or the position of the plot in the cultural succession (POSISSUC) does not significantly improve C stocks prediction. Similarly texture does not improve C stocks prediction but participates in the variability of C stocks. Lastly, in order to simulate C stocks at the village territory level, taking into account different scenarios including biophysical or socio-economical parameters, the main stock data and equations are to be considered herein. The equations were established for the horizons 0–10 and 10–20 cm for cultivated and noncultivated plots, in permanent and itinerant cropping systems.
S. Youl; E. Hien; R.J. Manlay; D. Masse; V. Hien; C. Feller. Natural and Entropic Determinants of Soil Carbon Stocks in Two Agro-Ecosystems in Burkina Faso. Innovations as Key to the Green Revolution in Africa 2011, 539 -551.
AMA StyleS. Youl, E. Hien, R.J. Manlay, D. Masse, V. Hien, C. Feller. Natural and Entropic Determinants of Soil Carbon Stocks in Two Agro-Ecosystems in Burkina Faso. Innovations as Key to the Green Revolution in Africa. 2011; ():539-551.
Chicago/Turabian StyleS. Youl; E. Hien; R.J. Manlay; D. Masse; V. Hien; C. Feller. 2011. "Natural and Entropic Determinants of Soil Carbon Stocks in Two Agro-Ecosystems in Burkina Faso." Innovations as Key to the Green Revolution in Africa , no. : 539-551.
Bernard G. Barthès; Raphaël Manlay; Olivier Porte. Effets de l'apport de bois raméal sur la plante et le sol: une revue des résultats expérimentaux. Cahiers Agricultures 2010, 19, 280 -287.
AMA StyleBernard G. Barthès, Raphaël Manlay, Olivier Porte. Effets de l'apport de bois raméal sur la plante et le sol: une revue des résultats expérimentaux. Cahiers Agricultures. 2010; 19 (4):280-287.
Chicago/Turabian StyleBernard G. Barthès; Raphaël Manlay; Olivier Porte. 2010. "Effets de l'apport de bois raméal sur la plante et le sol: une revue des résultats expérimentaux." Cahiers Agricultures 19, no. 4: 280-287.
On the eve of the 15th climate negotiations conference in Copenhagen, the pressure to assess all climate mitigation options is mounting. In this study, a bio-physic model and a socio-economic model were designed and coupled to assess the carbon sequestration potential of agricultural intensification in Senegal. The biophysical model is a multiple linear regression, calibrated and tested on a dataset of long-term agricultural trials established in West Africa. The socio-economic model integrates both financial and environmental costs related to considered practice changes. Both models are spatially explicit and the resulting spatial patterns were computed and displayed over Senegal with a geographic information system. The national potential from large-scale intensification was assessed at 0.65–0.83 MtC. With regards to local-scaled intensification as local projects, the most profitable areas were identified in agricultural expansion regions (especially Casamance), while the areas that meet the current financial additionality criteria of the Clean Development Mechanism were located in the northern part of the Peanut Basin. Using the current relevant mode of carbon valuation (Certified Emission Reductions), environmental benefits are small compared to financial benefits. This picture is radically changed if “avoided deforestation”, a likely consequence of agricultural intensification, is accounted for as the greenhouse gases sink capacity of projects increases by an average of a hundred-fold over Senegal.
Valentin Bellassen; Raphaël Manlay; Jean-Pierre Chéry; Vincent Gitz; Assize Touré; Martial Bernoux; Jean-Luc Chotte. Multi-criteria spatialization of soil organic carbon sequestration potential from agricultural intensification in Senegal. Climatic Change 2009, 98, 213 -243.
AMA StyleValentin Bellassen, Raphaël Manlay, Jean-Pierre Chéry, Vincent Gitz, Assize Touré, Martial Bernoux, Jean-Luc Chotte. Multi-criteria spatialization of soil organic carbon sequestration potential from agricultural intensification in Senegal. Climatic Change. 2009; 98 (1):213-243.
Chicago/Turabian StyleValentin Bellassen; Raphaël Manlay; Jean-Pierre Chéry; Vincent Gitz; Assize Touré; Martial Bernoux; Jean-Luc Chotte. 2009. "Multi-criteria spatialization of soil organic carbon sequestration potential from agricultural intensification in Senegal." Climatic Change 98, no. 1: 213-243.
While Carbon (C) sequestration on farmlands may contribute to mitigate CO2 concentrations in the atmosphere, greater agro-biodiversity may ensure longer term stability of C storage in fluctuating environments. This study was conducted in the highlands of western Kenya, a region with high potential for agroforestry, with the objectives of assessing current biodiversity and aboveground C stocks in perennial vegetation growing on farmland, and estimating C sequestration potential in aboveground C pools. Allometric models were developed to estimate aboveground biomass of trees and hedgerows, and an inventory of perennial vegetation was conducted in 35 farms in Vihiga and Siaya districts. Values of the Shannon index (H), used to evaluate biodiversity, ranged from 0.01 in woodlots through 0.4–0.6 in food crop plots, to 1.3–1.6 in homegardens. Eucalyptus saligna was the most frequent tree species found as individual trees (20%), in windrows (47%), and in woodlots (99%) in Vihiga and the most frequent in woodlots (96%) in Siaya. Trees represented the most important C pool in aboveground biomass of perennial plants growing on-farm, contributing to 81 and 55% of total aboveground farm C in Vihiga and Siaya, respectively, followed by hedgerows (13 and 39%, respectively) and permanent crop stands (5 and 6%, respectively). Most of the tree C was located in woodlots in Vihiga (61%) and in individual trees growing in or around food crop plots in Siaya (57%). The homegardens represented the second C pool in importance, with 25 and 33% of C stocks in Vihiga and Siaya, respectively. Considering the mean total aboveground C stocks observed, and taking the average farm sizes of Vihiga (0.6 ha) and Siaya (1.4 ha), an average farm would store 6.5 ± 0.1 Mg C farm−1 in Vihiga and 12.4 ± 0.1 Mg C farm−1 in Siaya. At both sites, the C sequestration potential in perennial aboveground biomass was estimated at ca. 16 Mg C ha−1. With the current market price for carbon, the implementation of Clean Development Mechanism Afforestation/Reforestation (CDM A/R) projects seems unfeasible, due to the large number of small farms (between 140 and 300) necessary to achieve a critical land area able to compensate the concomitant minimum transaction costs. Higher financial compensation for C sequestration projects that encourage biodiversity would allow clearer win–win scenarios for smallholder farmers. Thus, a better valuation of ecosystem services should encourage C sequestration together with on-farm biodiversity when promoting CDM A/R projects.
M. Henry; P. Tittonell; Raphaël Manlay; Martial Bernoux; A. Albrecht; B. Vanlauwe. Biodiversity, carbon stocks and sequestration potential in aboveground biomass in smallholder farming systems of western Kenya. Agriculture, Ecosystems & Environment 2009, 129, 238 -252.
AMA StyleM. Henry, P. Tittonell, Raphaël Manlay, Martial Bernoux, A. Albrecht, B. Vanlauwe. Biodiversity, carbon stocks and sequestration potential in aboveground biomass in smallholder farming systems of western Kenya. Agriculture, Ecosystems & Environment. 2009; 129 (1-3):238-252.
Chicago/Turabian StyleM. Henry; P. Tittonell; Raphaël Manlay; Martial Bernoux; A. Albrecht; B. Vanlauwe. 2009. "Biodiversity, carbon stocks and sequestration potential in aboveground biomass in smallholder farming systems of western Kenya." Agriculture, Ecosystems & Environment 129, no. 1-3: 238-252.
Soil organic matter (SOM) is understood today as the non-living product of the decomposition of plant and animal substances. Because it is now recognised that SOM tightly controls many soil properties and major biogeochemical cycles its status is often taken as a strong indicator of fertility and land degradation. Nonetheless the building of the SOM concept has not been easy. A reason for this is that the SOM concept is the product of interdisciplinary cognitive production as well as of a cultural moving context. Historically, three periods involving SOM in relation to cropping sustainability can be distinguished. (1) Until 1840, some still believed that plant dry matter was mainly derived from uptake of matter supplied by SOM, which was termed humus at that time. Agriculturists who believed this based the management of cropping systems fertility on the management of humus, i.e. through organic inputs. In 1809 Thaër proposed a “Humus Theory” that remained very influential for 30 years, as well as a quantified assessment of the agro-ecological and economic sustainability of farming systems. (2) From the 1840s to the 1940s, Liebig's “mineral nutrition theory”, progressive abandonment of recycling of nutrients between cities and country, and breakthroughs in the processes of fertilizer industry paved the way for intensive mineral fertilization as a substitute for organic practices. Although understanding of SOM and soil biological functioning was improving it had little impact on the rise of new mineral-based cropping patterns. (3) Since the 1940s, SOM has been gaining recognition as a complex bio-organo-mineral system, and as a pivotal indicator for soil quality and agro-ecosystems fertility. This has resulted from: (a) methodological and conceptual breakthroughs in its study, leading to significant scientific developments in characterising the role of humus as an ecosystem component; (b) a growing societal demand for the assessment of the environmental cost of intensification in modern agricultural practices, which has led to growing interest in organic farming, agroforestry, conservation tillage, and the use of plant cover; (c) investigation of the potential of SOM as a sink for greenhouse gas carbon in response to concerns about global climate change. In summary the interest in SOM over time, both from the viewpoint of scientific concept and that of field practices, can be described by a sine curve. Its definition and the recognition of its functions have gained both much from the combination of holistic and reductionist approaches and from the progressive amplification of the scale at which it has been considered.
Raphaël J. Manlay; Christian Feller; M.J. Swift. Historical evolution of soil organic matter concepts and their relationships with the fertility and sustainability of cropping systems. Agriculture, Ecosystems & Environment 2007, 119, 217 -233.
AMA StyleRaphaël J. Manlay, Christian Feller, M.J. Swift. Historical evolution of soil organic matter concepts and their relationships with the fertility and sustainability of cropping systems. Agriculture, Ecosystems & Environment. 2007; 119 (3-4):217-233.
Chicago/Turabian StyleRaphaël J. Manlay; Christian Feller; M.J. Swift. 2007. "Historical evolution of soil organic matter concepts and their relationships with the fertility and sustainability of cropping systems." Agriculture, Ecosystems & Environment 119, no. 3-4: 217-233.
Soil organic matter (SOM) contributes significantly to the chemical, physical and biological ecosystem functions of soil. It influences on plant growth, thus contributing to agricultural production, and performs environmentally valuable services such as carbon sequestration, regulation of the water cycle and detoxification of pollutants. Identification of the functions and services provided by SOM has a long and tumultuous history of scientific discoveries and struggles against false assumptions. This work reports the major steps of this history, with emphasis on two services secured by SOM: (1) the role of SOM in plant production and its connection to soil fertility and thence to the sustainability of cropping and farming systems; and (2) the recognition and assessment of the contribution of SOM to climate-change regulation. Finally, the work explores how SOM, as a multifunctional resource, may be allocated an economic value as a way of promoting its conservation.
C. Feller; Raphaël Manlay; M. J. Swift; Martial Bernoux. Functions, services and value of soil organic matter for human societies and the environment: a historical perspective. Geological Society, London, Special Publications 2006, 266, 9 -22.
AMA StyleC. Feller, Raphaël Manlay, M. J. Swift, Martial Bernoux. Functions, services and value of soil organic matter for human societies and the environment: a historical perspective. Geological Society, London, Special Publications. 2006; 266 (1):9-22.
Chicago/Turabian StyleC. Feller; Raphaël Manlay; M. J. Swift; Martial Bernoux. 2006. "Functions, services and value of soil organic matter for human societies and the environment: a historical perspective." Geological Society, London, Special Publications 266, no. 1: 9-22.
Fallowing is a common practice for the management of soil fertility in low-input cropping systems of the West-African savanna, but has been threatened by the growing need for land in the sub-region for the past few decades. Proposals for alternatives to traditional fallowing must rely on a proper understanding of the soil biochemical dynamics occurring after fallow conversion to cropping. Two mesh-bag experiments were thus conducted in two sites (dry and sub-humid tropical climates) in Senegal to assess the role of site-related factors (climate, macrofaunal activity) and root-related factors (tree species, root diameter) on the decomposition of tree roots after clearing of fallow vegetation as measured from mass loss. Root decomposition was fastest – and even faster than predicted from a global model – in the wettest site (first order disappearance rate: 1.00 y−1 and 1.46–1.49 y−1 under dry and sub-humid conditions, respectively). Macrofauna accounted for half of root mass loss in the sub-humid site, with biomass removal occurring even during the dry season. Fastest disappearance for roots with ∅<5 mm occurred for Dichrostachys cinerea, and Combretum glutinosum. The influence of root chemical composition on decomposition patterns among tree species and root diameter classes was not clear, with effects of cell wall composition and nutrient content changing throughout the incubation period. Fast disappearance of dead roots suggests that cropping practices that allow conservation of live stumps, such as no-tillage and direct sowing, be promoted wherever possible to ensure soil conservation. It also suggests the possible management of tree species composition and, to a much lesser extent, of macrofauna during the fallow period to control root decomposition patterns and related nutrient transfers to crop biomass after fallow conversion.
Raphaël J. Manlay; Dominique Masse; Tiphaine Chevallier; Anthony Russell-Smith; Dominique Friot; Christian Feller. Post-fallow decomposition of woody roots in the West African savanna. Plant and Soil 2004, 260, 123 -136.
AMA StyleRaphaël J. Manlay, Dominique Masse, Tiphaine Chevallier, Anthony Russell-Smith, Dominique Friot, Christian Feller. Post-fallow decomposition of woody roots in the West African savanna. Plant and Soil. 2004; 260 (1/2):123-136.
Chicago/Turabian StyleRaphaël J. Manlay; Dominique Masse; Tiphaine Chevallier; Anthony Russell-Smith; Dominique Friot; Christian Feller. 2004. "Post-fallow decomposition of woody roots in the West African savanna." Plant and Soil 260, no. 1/2: 123-136.
Raphaël Manlay; Alexandre Ickowicz; Dominique Masse; Christian Floret; Didier Richard; Christian Feller. Spatial carbon, nitrogen and phosphorus budget of a village in the West African savanna—I. Element pools and structure of a mixed-farming system. Agricultural Systems 2004, 79, 55 -81.
AMA StyleRaphaël Manlay, Alexandre Ickowicz, Dominique Masse, Christian Floret, Didier Richard, Christian Feller. Spatial carbon, nitrogen and phosphorus budget of a village in the West African savanna—I. Element pools and structure of a mixed-farming system. Agricultural Systems. 2004; 79 (1):55-81.
Chicago/Turabian StyleRaphaël Manlay; Alexandre Ickowicz; Dominique Masse; Christian Floret; Didier Richard; Christian Feller. 2004. "Spatial carbon, nitrogen and phosphorus budget of a village in the West African savanna—I. Element pools and structure of a mixed-farming system." Agricultural Systems 79, no. 1: 55-81.
International audienceThe identification of quantitative fertility indicators for evaluating the sustainability of cropping and farming systems has become a major issue. This question has been extensively studied by the German agronomist Albrecht Daniel Thaer at the beginning of the 19(th) century. In this paper Thaer's work is set in its historical background, from the end of the 16(th) century (Palissy, 1580) to the middle of the 19(th) century (Liebig, 1840). Then the paper focuses on Thaer's quantitative and complex fertility scale (expressed in "fertility degrees"), which was based on soil properties, on the requirement of nutrients by plants, and on the cropping system (including crop rotation). Thaer expressed soil fertility and economic results as a function of rye production in "scheffel of rye per journal" (ca. 200 kg per hectare). He also proposed a scale to describe the intrinsic fertility of soil. Thaer used this approach to assess the effect of major German cropping systems on soil fertility. He applied it to eight theoretical systems and nine existing systems in a true modeling approach. Thaer completed the fertility evaluation for the nine existing systems with a detailed economical analysis commenting the limits and potentialities of each system. Thaer's approach was used with success during half a century as it combined numerous empirical findings on soils and fertilization with organic substances in a sophisticated model. Unfortunately and despite effective practical applications, the scientific foundations of Thaer's "Humus Theory" proved definitively false as soon as 1840 when Sprengel and Liebig published on mineral nutrition of plants. Thaer's work deserves to be rediscovered since it approaches the modern issue of the sustainability of cropping and farming systems
Christian L. Feller; Laurent J.-M. Thuriès; Raphaël J. Manlay; Paul Robin; Emmanuel Frossard. ”The principles of rational agriculture” by Albrecht Daniel Thaer (1752–1828). An approach to the sustainability of cropping systems at the beginning of the 19th century. Journal of Plant Nutrition and Soil Science 2003, 166, 687 -698.
AMA StyleChristian L. Feller, Laurent J.-M. Thuriès, Raphaël J. Manlay, Paul Robin, Emmanuel Frossard. ”The principles of rational agriculture” by Albrecht Daniel Thaer (1752–1828). An approach to the sustainability of cropping systems at the beginning of the 19th century. Journal of Plant Nutrition and Soil Science. 2003; 166 (6):687-698.
Chicago/Turabian StyleChristian L. Feller; Laurent J.-M. Thuriès; Raphaël J. Manlay; Paul Robin; Emmanuel Frossard. 2003. "”The principles of rational agriculture” by Albrecht Daniel Thaer (1752–1828). An approach to the sustainability of cropping systems at the beginning of the 19th century." Journal of Plant Nutrition and Soil Science 166, no. 6: 687-698.
The assessment of carbon (C), nitrogen (N) and phosphorus (P) in agro-ecosystems of West African savannas (WAS) may be a useful tool to define sustainable intensification schemes needed to respond to the rapid increase in local populations as well as global change issues. Changes in soil properties, and particularly in the soil organic matter status, under semi-permanent cultivation were thus examined through a groundnut crop-fallow chronosequence in southern Senegal. The effect of fallowing was mainly restricted to the 0–20 cm soil layer and hardly affected soil physical properties. In this layer, steady improvements were recorded for Mg and Ca contents. Carbon and N amounts increased by 30%, and by 50% for available P (POD) within the very first year of fallow and then remained steady (C and N) or dropped back to levels recorded for crops (POD). The rapid initial change in organic status after crop abandonment was attributed to fast recovery of woody vegetation. The steady soil organic matter (SOM) content in oldest fallows compared to young fallows probably resulted from poor protection of soil organic matter from oxidation during biological activity. This hypothesis was confirmed by mesh-bag experiments, which indicated that >40–60% of decaying woody root biomass disappeared after 6 months of in situ incubation. In fallow systems in southern Senegal, soil fertility may in fact rely at least as much on fast organic matter cycling in soil food webs as on SOM build-up. Carbon storage in the soil-plant system of mature fallow ecosystems was only 27 t C ha−1 higher than in crops and consisted mainly of pools with fast turnover. Consequently, the potential of semi-permanent cultivation for C sequestration in the WAS will be rather indirect, by a shift to more intensified practices, thus avoiding the conversion of dense forests to cropping in more humid areas.
Raphaël J Manlay; Dominique Masse; Jean-Luc Chotte; Christian Feller; Maguette Kairé; Joël Fardoux; Roger Pontanier. Carbon, nitrogen and phosphorus allocation in agro-ecosystems of a West African savanna: II. The soil component under semi-permanent cultivation. Agriculture, Ecosystems & Environment 2002, 88, 233 -248.
AMA StyleRaphaël J Manlay, Dominique Masse, Jean-Luc Chotte, Christian Feller, Maguette Kairé, Joël Fardoux, Roger Pontanier. Carbon, nitrogen and phosphorus allocation in agro-ecosystems of a West African savanna: II. The soil component under semi-permanent cultivation. Agriculture, Ecosystems & Environment. 2002; 88 (3):233-248.
Chicago/Turabian StyleRaphaël J Manlay; Dominique Masse; Jean-Luc Chotte; Christian Feller; Maguette Kairé; Joël Fardoux; Roger Pontanier. 2002. "Carbon, nitrogen and phosphorus allocation in agro-ecosystems of a West African savanna: II. The soil component under semi-permanent cultivation." Agriculture, Ecosystems & Environment 88, no. 3: 233-248.
Organic matter (OM) is both a commodity and a means of production in low-input farming systems of sub-Saharan Africa. Since this resource is becoming increasingly scarce in West African savannas (WAS), there is a need to assess OM, carbon (C), nitrogen (N), and phosphorus (P) allocation in local ecosystems related to land management. Carbon, N and P storage under semi-permanent cultivation in savannas in southern Senegal was thus measured through a chronosequence including 25 groundnut (Arachis hypogaea L.) crops and plots left to fallow for 1–26 years. The amounts of C, N and P in cropped plots were 5.5 t C, 106 kg N and 5.9 kg P ha−1, they increased to 17.7 t C, 231 kg N and 19.6 kg P ha−1 in fallow plots aged 1–9 years. A threshold was reached after 10 years of fallow. Beyond it biomass amounts remained steady. Older fallow plots stored 29 t C, 333 kg N and 33.8 kg P ha−1. Highest increases in woody components were found within the very first year following crop abandonment, and were achieved at the expense of the herbaceous layer. Carbon and nutrient allocation to woody below-ground biomass occurred only later. Massive nutrient losses were expected to occur at clearing due to both burning and wood exportation. Because storage in woody and herbaceous biomass remained steady in fallows aged more then 10 years, young fallows were found to have the highest productivity for wood and forage. However, plant productivity relied on the high resprouting capacity of local tree species, and thus on the maintenance of long breaks of fallow needed for the maintenance of perennial rooting systems. One of the aims of programs to improve the management of fallows, or to replace them with agroforestry techniques, should thus be to preserve perennial rooting systems by any means that are possible in the cropping systems of the WAS.
Raphaël J. Manlay; Maguette Kairé; Dominique Masse; Jean-Luc Chotte; Gilles Ciornei; Christian Floret. Carbon, nitrogen and phosphorus allocation in agro-ecosystems of a West African savanna: I. The plant component under semi-permanent cultivation. Agriculture, Ecosystems & Environment 2002, 88, 215 -232.
AMA StyleRaphaël J. Manlay, Maguette Kairé, Dominique Masse, Jean-Luc Chotte, Gilles Ciornei, Christian Floret. Carbon, nitrogen and phosphorus allocation in agro-ecosystems of a West African savanna: I. The plant component under semi-permanent cultivation. Agriculture, Ecosystems & Environment. 2002; 88 (3):215-232.
Chicago/Turabian StyleRaphaël J. Manlay; Maguette Kairé; Dominique Masse; Jean-Luc Chotte; Gilles Ciornei; Christian Floret. 2002. "Carbon, nitrogen and phosphorus allocation in agro-ecosystems of a West African savanna: I. The plant component under semi-permanent cultivation." Agriculture, Ecosystems & Environment 88, no. 3: 215-232.
Carbon (C) and associated nutrient budgets related to land use in agro-ecosystems in West African savannas (WAS) are a matter of both local (sustainability of farming systems) and global (C balance) concern. In a mixed-farming system in southern Senegal, patterns of C, nitrogen (N) and phosphorus (P) allocation in the plant–soil system (down to a 40 cm soil depth) were compared at harvest in 14 plots, six being under semi-permanent cultivation with groundnut (Arachis hypogaea L.), others being under continuous cultivation with millet (Pennisetum glaucum L.), maize (Zea mays L.) or rice (Oryza sativa L.). Carbon stored in the plant–soil system amounted to 25.0, 27.4, 34.9 and 71.9 t per ha, respectively, in groundnut, millet, maize and rice fields. Ninety percent of C and P (total in plant Pt, available P in soil (POD)) and 95% of N of the whole ecosystem were stored in the soil. The high C and nutrient amounts found in rice plots were attributed to the clayey texture of the soil and to seasonal flooding. The lower values for C, N and POD found in soils in the bush ring (groundnut crops) compared to those of the compound ring (millet and maize crops) stemmed from land management. Higher values for C, N and POD in soils in the compound ring were maintained under continuous cultivation thanks to higher organic and nutrient inputs originating from crop residue recycling, manuring and, in the maize plots, spreading of household wastes. In the compound ring, the amount of C stored seemed to depend as much on the amount of C input as on the chemical richness of organic inflow. The effect of land management (bush versus compound ring) on soil properties was generally restricted to the 0–20 cm layer (except for P, cations and pH), and the better soil status in the compound ring was linked to nutrient depletion of the bush ring. From the perspective of global change, the estimated potential of the WAS for C sequestration under continuous cultivation was found to be low. From a methodological point of view, soil carbon status may be considered as a relevant indicator for the fertility of agro-ecosystems in the WAS belt, provided that its biotic components are included, and that both the quality and dynamics of soil organic matter (assessment of seasonal variations, and C flows) and soil texture are characterised.
Raphaël J. Manlay; Jean-Luc Chotte; Dominique Masse; Jean-Yves Laurent; Christian Feller. Carbon, nitrogen and phosphorus allocation in agro-ecosystems of a West African savanna: III. Plant and soil components under continuous cultivation. Agriculture, Ecosystems & Environment 2002, 88, 249 -269.
AMA StyleRaphaël J. Manlay, Jean-Luc Chotte, Dominique Masse, Jean-Yves Laurent, Christian Feller. Carbon, nitrogen and phosphorus allocation in agro-ecosystems of a West African savanna: III. Plant and soil components under continuous cultivation. Agriculture, Ecosystems & Environment. 2002; 88 (3):249-269.
Chicago/Turabian StyleRaphaël J. Manlay; Jean-Luc Chotte; Dominique Masse; Jean-Yves Laurent; Christian Feller. 2002. "Carbon, nitrogen and phosphorus allocation in agro-ecosystems of a West African savanna: III. Plant and soil components under continuous cultivation." Agriculture, Ecosystems & Environment 88, no. 3: 249-269.