Enhancing agroecosystem productivity with woody perennials in semi-arid West Africa. A meta-analysis
Félix, Georges F. ; Scholberg, Johannes M.S. ; Clermont-Dauphin, Cathy ; Cournac, Laurent ; Tittonell, Pablo - \ 2018
Agronomy for Sustainable Development 38 (2018)6. - ISSN 1774-0746
Agroforestry - Mulch - Sahel - Shrub-crop associations - Woody amendments
Soil degradation in semi-arid West Africa can be reversed through an intensified application of organic matter, especially on coarse soils. Woody perennials have been promoted in the region to secure organic matter sources and improve soil productive capacity, yet the mechanisms by which perennials provide benefits to soils and crops remain poorly understood, and no effective, generalizable agronomic recommendations exist. Here, we reviewed the effects of trees and shrubs on soil properties and on crop yields in semi-arid West Africa (1000 mm year−1). Specific objectives of this meta-analysis were to (i) describe and (ii) quantify the effects of the presence of woody perennials and of ramial wood amendments on crop productivity and soil characteristics, and (iii) identify general recommendations on the integration of perennials with crops. An iterative keyword search was conducted to gather relevant literature. The search string consisted of four parts: source, practice, responses, and countries of interest. In total, 26 references on agroforestry parklands and 21 on woody amendments were included in the meta-database (314 entries, 155 for parklands, and 159 for ramial wood). We show that (1) the presence of shrubs and trees on agricultural fields had an overall positive but variable effect on soil total C (i.e. + 20 to 75%); (2) millet and sorghum yields were often higher in the presence of shrubs (− 25 to + 120%); (3) more variability was observed in the presence of trees (− 100 to + 200%); and (4) the use of shrub- and tree-based ramial wood resulted in equal or higher cereal yields as compared to the control (− 30 to + 100%). Upscaling the use of biodiversity-driven processes in farming systems of West Africa may provide benefits to overall ecosystems, but species’ choice and trade-offs perceived at the farm level, including labour management and low ramial wood availability, should be addressed through future research.
Apports des typologies d'exploitations aux démarches de conception en agriculture de conservation: Une étude de cas dans le nord du Vietnam
Hauswirth, Damien ; Pham, Thi-Sen ; Wery, Jacques ; Tittonell, Pablo ; Jourdain, Damien ; Affholder, François - \ 2015
Cahiers Agricultures 24 (2015)2. - ISSN 1166-7699 - p. 102 - 112.
Cropping systems - Direct seeding - Farming systems - Mountain farming - Mulch - Sustainability
Conservation agriculture (CA) is considered a possible option for reducing the environmental impact of tilled maize on sloping land in two mountainous districts of northern Vietnam. Within this context, our study aimed at building a regional farm typology that can support the design of CA cropping systems, suiting different farm types. 411 maize-producing farms were surveyed. Using multivariate analysis, we identified 5 farm types with contrasting resources and sustainability performances. We discuss the range of possible CA systems to be designed for each type, according to its specific constraints and opportunities. We especially consider diverse intensification levels and kinds of cover plants. We propose the development of farm models to further explore the economic attractiveness of the options selected for each type.
Beyond conservation agriculture
Giller, K.E. ; Andersson, J.A. ; Corbeels, Marc ; Kirkegaard, John ; Mortensen, David ; Erenstein, Olaf ; Vanlauwe, Bernard - \ 2015
Frontiers in Plant Science 6 (2015)OCTOBER. - ISSN 1664-462X - 14 p.
Climate smart agriculture - Legumes - Mulch - Soil erosion - Sustainable intensification - Systems agronomy
Global support for Conservation Agriculture (CA) as a pathway to Sustainable Intensification is strong. CA revolves around three principles: no-till (or minimal soil disturbance), soil cover, and crop rotation. The benefits arising from the ease of crop management, energy/cost/time savings, and soil and water conservation led to widespread adoption of CA, particularly on large farms in the Americas and Australia, where farmers harness the tools of modern science: highly-sophisticated machines, potent agrochemicals, and biotechnology. Over the past 10 years CA has been promoted among smallholder farmers in the (sub-) tropics, often with disappointing results. Growing evidence challenges the claims that CA increases crop yields and builds-up soil carbon although increased stability of crop yields in dry climates is evident. Our analyses suggest pragmatic adoption on larger mechanized farms, and limited uptake of CA by smallholder farmers in developing countries. We propose a rigorous, context-sensitive approach based on Systems Agronomy to analyze and explore sustainable intensification options, including the potential of CA. There is an urgent need to move beyond dogma and prescriptive approaches to provide soil and crop management options for farmers to enable the Sustainable Intensification of agriculture.