78 research outputs found
Innovative Approaches to Analysing Carbon Sequestration as a Mitigation Strategy in Tropical Pasture Landscapes in Two Emblematic Contexts, the Amazon and the West African Sahel
The relationship between ruminant production systems and climate change is complex. As a major contributor to greenhouse gas (GHG) emissions, the sector has been the subject of considerable controversy, with particularly severe criticism in the 2000s. However, ten years ago, the attitude towards grazing lands began to change. Their efficient use of non-renewable energy and their contribution to carbon (C) sequestration were considered as key factors in the new environmental challenge. The reality of this mitigation potential was recently called into question once again in the global agriculture and climate change debate, including that of sequestration in the soil where grazing lands occupy a major position (30-40% of the land surface representing 30% of the soil organic C of the world). Few scientific references are available on these questions in tropical regions, and the standard metrics and methods used may turn out to be unsuitable for the correct evaluation of grazed ecosystems in these regions. Significant work is therefore required to establish baselines and design strategies to ensure sustainable grazing in these regions where the global sequestration potential is high relative to the surface areas concerned.
To contribute to this debate, we focus on mitigation options offered by rangelands and grasslands and their management in two emblematic tropical contexts, humid and dry tropics, where field studies have been based on original and holistic approaches at different levels. In Amazonia, if curbing deforestation remains a priority, it needs to be accompanied by sustainable management of deforested areas. In the French Amazon (French Guiana), monitoring fields using chronosequences and flux towers has produced scientific knowledge on the significant mitigation capacities of grassland ecosystems. In the Brazilian Amazon, the spatial logic of the agro-ecological intensification of forage production has enabled a transition from individual extractive systems to farm management at communal levels. In the West African Sahelian region (Northern Senegal), an integrative study at landscape scale revealed the unexpected capacity of soil and shrubs for C sequestration that can offset the GHG emissions for which pastoralism in dry tropical zones is usually blamed
The input reduction principle of agroecology is wrong when it comes to mineral fertilizer use in sub-Saharan Africa
Can farmers in sub-Saharan Africa (SSA) boost crop yields and improve food availability without using more mineral fertilizer? This question has been at the center of lively debates among the civil society, policy-makers, and in academic editorials. Proponents of the “yes” answer have put forward the “input reduction” principle of agroecology, i.e. by relying on agrobiodiversity, recycling and better efficiency, agroecological practices such as the use of legumes and manure can increase crop productivity without the need for more mineral fertilizer. We reviewed decades of scientific literature on nutrient balances in SSA, biological nitrogen fixation of tropical legumes, manure production and use in smallholder farming systems, and the environmental impact of mineral fertilizer. Our analyses show that more mineral fertilizer is needed in SSA for five reasons: (i) the starting point in SSA is that agricultural production is “agroecological” by default, that is, very low mineral fertilizer use, widespread mixed crop-livestock systems and large crop diversity including legumes, but leading to poor soil fertility as a result of widespread soil nutrient mining, (ii) the nitrogen needs of crops cannot be adequately met solely through biological nitrogen fixation by legumes and recycling of animal manure, (iii) other nutrients like phosphorus and potassium need to be replaced continuously, (iv) mineral fertilizers, if used appropriately, cause little harm to the environment, and (v) reducing the use of mineral fertilizers would hamper productivity gains and contribute indirectly to agricultural expansion and to deforestation. Yet, the agroecological principles directly related to soil fertility—recycling, efficiency, diversity—remain key in improving soil health and nutrient-use efficiency, and are critical to sustaining crop productivity in the long run. We argue for a nuanced position that acknowledges the critical need for more mineral fertilizers in SSA, in combination with the use of agroecological practices and adequate policy support
Living territories to transform the world
What resources underpin the development of a territory? What does territorial management of resources mean? What specific characteristics and opportunities does territorial organization offer for agricultural production, regulation of sectors, and services? How are territorial public policies conceived and applied? But also, what are the limits of the territorial approach? How does a territorial approach refashion the frameworks of intervention for development? How do we implement and reinvent mechanisms to provide support, build skills, and promote production and good governance? How do we mobilize information systems, apprehend territorial dynamics, and encourage decentralized planning? Using a wide diversity of case studies, the book explores how actors, scales and scopes of intervention interact in the development of rural spaces in the countries of the Global South, both at the local level and in the global perspective of the objectives of sustainable development. The book brings together the experiences and views of more than 150 researchers and experts from CIRAD, AFD and their partners. It is aimed at researchers, engineers, professionals in the countries of the Global South, as well as students and the wider public
Living territories to transform the world
What resources underpin the development of a territory? What does territorial management of resources mean? What specific characteristics and opportunities does territorial organization offer for agricultural production, regulation of sectors, and services? How are territorial public policies conceived and applied? But also, what are the limits of the territorial approach? How does a territorial approach refashion the frameworks of intervention for development? How do we implement and reinvent mechanisms to provide support, build skills, and promote production and good governance? How do we mobilize information systems, apprehend territorial dynamics, and encourage decentralized planning? Using a wide diversity of case studies, the book explores how actors, scales and scopes of intervention interact in the development of rural spaces in the countries of the Global South, both at the local level and in the global perspective of the objectives of sustainable development. The book brings together the experiences and views of more than 150 researchers and experts from CIRAD, AFD and their partners. It is aimed at researchers, engineers, professionals in the countries of the Global South, as well as students and the wider public
Evaluating the sustainability of urban agriculture projects
Evaluating the sustainability of urban agriculture projects. 5. International Symposium for Farming Systems Design (AGRO2015
Livestock and sustainable nutrient cycling in mixed farming systems of sub-Saharan Africa. Volume II: Technical papers. Proceedings of an international conference
Achieving sustainable increases in agricultural production in sub-Saharan Africa is both a regional and a worldwide concern. High human and animal population densities in some areas have surpassed
land-carrying capacities causing environmental degradation and undermining the long-term stability of these production systems. In attempts to meet the increasing food demands of larger populations,
farmers are cultivating more land permanently, grazing lands have diminished and many traditional farming practices that formerly allowed land to rejuvenate are disappearing.
An efficient cycling of nutrients among crops, animals and soil is crucial to the sustained productivity of low-input mixed farming systems in sub-Saharan Africa. Access to agricultural inputs such as fertiliser and improved seed is limited. Nutrient balances, or the difference between nutrient inputs and harvests, are negative for many production systems. Although animal manures are perhaps the most important fertility amendment that many farmers apply to cropland, livestock can also contribute to these nutrient imbalances. Excessive removal of vegetation by grazing animals or
harvesting feeds can deplete soil-nutrient reserves and result in decreases in soil productivity. A major portion of nutrients consumed by livestock may also be unavailable for recycling due to volatilisation, erosion and leaching losses, and uneven deposition of nutrients by animals in the landscape.
The climatic and socio-economic changes currently taking place in many parts of sub-Saharan Africa suggest that sustainable increases in agricultural production from an increasingly fragile ecosystem require new and innovative crop, livestock, and soil-management strategies. To further this
objective, the International Livestock Centre for Africa (ILCA) and its cosponsors convened this conference to bring together national and international experts in livestock (cattle, sheep and goats)
nutrition and management, ecology, agronomy, soil science and socio-economics to address
fundamental issues of nutrient balances, agricultural productivity and the well being of the people, livestock and environment of sub-Saharan Africa
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