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Madrid-2001

Le groupe de travail Conservation Agriculture de la FAO a coorganisé avec ECAF ce premier Congrès tenu en Espagne.

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application/pdf [402,76 kB] - 29/10/2002   Systèmes de culture et dynamiques de la matière organique : le semis direct sur couverture permanente, une révolution agricole (poster)

[ Résumé ]

En agriculture tropicale, le travail du sol accélère la destruction de la matière organique. Sa restauration est possible en quelques années grâce aux systèmes de culture sans travail du sol, en semis direct sur couverture végétale permanente. Le choix des plantes de couverture est déterminant. Le taux de carbone du sol peut atteindre alors celui des écosystèmes naturels, même en partant de conditions dégradées. Grâce au semis direct, l'agriculture agit comme stockeur net de CO2 et non plus comme producteur net. Le Cirad a travaillé sur de tels systèmes au Brésil, en Asie, à la Réunion et à Madagascar. Ce poster rapporte quelques résultats obtenus au centre-ouest du Brésil (secteur tropical humide).

application/pdf [122,64 kB] - 29/10/2002   Diagnostic agronomique et développement de techniques de semis direct (poster)

[ Résumé ]

Dans les montagnes du Nord Vietnam, avec une population croissant rapidement, la forte pression de l'élevage et l'évolution foncière, les systèmes traditionnels de défriche-brûlis ne sont plus durables et ont été bannis. Il est urgent de proposer aux agriculteurs des pratiques agronomiques et des systèmes de culture durables, simples, peu exigeants en intrants et permettant une sédentarisation à plus long terme après défriche de la forêt. Un diagnostic rapide mais précis a été conduit en 1998-1999. La plupart des types de culture et d'usage de la terre ont été identifiés

application/pdf [79,07 kB] - 27/10/2001   Developing sustainable cropping systems with minimal inputs in Madagascar: direct seeding on plant cover with "soil smouldering" (écobuage) techniques

[ Résumé ]

In the Hautes-Terres region of Madagascar, population pressure is accelerating the conversion of hilly areas with fragile and relatively infertile soils into cropland. As fertilizers are limited, crop yields remain low and erosion is destroying rice fields. Instead of clearing areas fallowed with Aristida sp. by burning, ibis biomass can be kept for use as mulch and for "soil smouldering" (écobuage). The effects of this strategy were found to be spectacular, i.e. boosting rainfed rice yields to levels that could bc achieved with high chemical fertilizer inputs-to which farmers have no access for financial reasons. All fuels used (Aristida sp. or barley straw, rice husks, and Acacia mearnsii branches) significantly inereased crop yields relative to the control (without soil smouldering). A residual effect was noted in the second year, especially on volcanic soils with high organic matter levels. Hence, sustainable cropping systems that fulfil farmers' needs while protecting their rice fields can be developed through the use of soil smouldering-performed just once to boost soil fertility-associated with direct seeding techniques.

application/pdf [49,39 kB] - 15/10/2001   Impacts des couvertures végétales sur la production de Pelargonium x Asperum et sur la biologie du sol (macrofaune) à l'Ile de La Réunion (Département Outre-Mer français)

[ Résumé ]

Dans les Hauts de l'Ouest de l'Ile de la Réunion, la culture du géranium rosat (Pelargonium x asperum) est confrontée à des problèmes de maintien de la fertilité des sols. L'abandon de la jachère, les pratiques culturales en sol nu (monoculture ou rotations) et une très forte sensibilité des andosols à l'érosion, ont abouti à la dégradation physique, chimique et biologique (macrofaune) des sols. Cette dégradation du milieu s'est traduite par une diminution sensible de la production en huile essentielle. Pour y remédier, des essais relatifs à l'utilisation des couvertures végétales ont été installés. Ces dernières ont été constituées à partir d'une biomasse soit importée (paille de canne à sucre, Saccharum officinarum) soit produite sur place à l'aide d'une espèce pérenne (Stenotaphrum secundatum.) cultivée en association avec le géranium. En comparaison avec la culture du géranium en sol nu, les résultats montrent une augmentation hautement significative de la production en biomasse aérienne du géranium ainsi qu'en essence obtenue après distillation. En parallèle, la biodiversité, la biomasse et la densité de la macrofaune du sol sont restaurées sous couvert végétal.

application/pdf [863,93 kB] - 06/10/2001   Systèmes de culture et dynamiques de la matière organique : le semis direct sur couverture permanente, une révolution agricole
application/pdf [25,74 kB] - 29/09/2001   Impact of cultivation practices (cover crops) on soil macrofauna in Réunion

[ Résumé ]

Most farming practices are detrimental to soil organic matter reserves, leading to a significant decrease in biological activity and an increased risk of erosion. Soil invertebrate populations (macrofauna) are also sharply reduced in annual crop systems. The role of macrofauna in pedological processes and in the regulation of microbial activity has been fully described (Lavelle et al., 1999). Some agroecological practices and especially plant covers straw mulch or perennial plants intercropped with annual crops can enhance the sustainability of tropical cropping systems (Séguy et al., 1996). This study was aimed at assessing the effects of two plant covers (greater bird's food trefoil, Lotus uliginosus, and oat, Avena sativa) on soil macrofauna populations in Réunion (Indian Ocean).

application/pdf [116,57 kB] - 21/09/2001   Agronomic diagnosis and development of direct sowing techniques Upland rice-based cropping systems in mountainous areas of Northern Vietnam
application/pdf [37,38 kB] - 20/09/2001   Direct seeding on plant cover with "soil smouldering" techniques
application/pdf [76,42 kB] - 12/09/2001   Conservation tillage effects on runoff reduction in rainfed maize of semi-arid zones of western Mexico

[ Résumé ]

Between 1994 and 1999, a series of studies were done to try to quantify and to modelize the effects of conservation tillage (direct drilling of seeds into a residue mulch-CT) and particularly of a partial residue mulch on water dynamics in the soil-plantatmosphere system under semi-arid conditions of western Mexico. They showed that with even a very minimal amount of residue (1.5 t/ha), CT begins to give worthwhile improvements in productivity (Scopel, 1994; Scopel et al., 1999), illustrating the important role of runoff reduction (30% less than with traditional tillage) in explaining benefits of this technique. This study set out to explain the mechanisms involved in this reduction of runoff losses, trying to separate the short term effects on water movement on the soil surface and the long term effects on water infiltration capacity ( Antoine Findeling 2001).

application/pdf [74,09 kB] - 09/09/2001   Effects of direct seeding techniques on soil fertility indicators under equatorial climatic conditions

[ Résumé ]

I n the Boumango agroindustrial area (2°S, 13°E) of Gabon, 2000 ha has been intensively cropped since 1980 under mechanized conditions, with an annual sequence of maize and soybean. New alternative cropping systems are now required to solve the cultivation problems that have arisen. Experiments were carried out to test systems involving direct seeding on plant cover that were initially developed in central-western Brazil. Several soil fertility indicators were monitored over a 3-year period, their evolution under three different crop management sequences and two fertilizer levels are reported.

application/pdf [365,85 kB] - 08/09/2001   Cropping systems and organic matter dynamics: direct seeding on plant cover, an agricultural revolution

[ Résumé ]

Tillage accelerates organic matter destruction under tropical agriculture conditions. No-till cropping systems involving direct seeding on permanent plant cover enable short-term soil restoration. Cover plant choices are crucial. Soil carbon can thus be boosted to levels generally found in natural ecosystems, even when starting from degraded soils. Direct seeding systems promote net CO2 storage rather than net production. CIRAD has been working on such systems in Brazil, Asia, Réunion and Madagascar. This poster reports some results obtained in central-western Brazil (hot humid tropical area).

application/pdf [434,29 kB] - 06/09/2001   Towards large-scale adoption of no-tillage in central Mexico: a participatory, multi-institutional approach to technology development and diffusion

[ Résumé ]

Conservation tillage (CT) has been adopted in Mexico on less than 500,000 ha (only 3% of the national cropped area), in contrast with Brazil, Argentina, or Paraguay (Derpsh, 1998). Reasons include: - Uncoordinated efforts by the various institutions involved. - Use of top-down, rigid transfer approaches. - Technology not adequately tailored to farmer conditions and constraints. - Limited access to CT drills. - Insufficient training of farmers and technicians. - Virtually no technical assistance for farmers.

application/pdf [74,71 kB] - 05/09/2001   Trophic control of tillering rate of three rice cultivars (Oryza sativa L. and O. glaberrima Steud.) under different drought levels

[ Résumé ]

T illering capacity of rice depends on the genotype, on resources available for growth and the level of physiological stresses. The aim of this work is to examine tillering dynamics of three genetically contrasting rice cultivars: IAC47 (upland-adapted, O. sativa, japonica, low-tillering), Javaé (lowland-adapted, O. sativa, indica, high-tillering) and CG14 (broadly adapted, O. glaberrima)

application/pdf [299,92 kB] - 04/09/2001   Differential adoption of direct-seeding in Guanajuato Mexico : a baseline diagnostic

[ Résumé ]

Mexico who are facing increased competition from world markets. Conservation tillage (CT) has been promoted as a productivity enhancing and resource conserving technology that benefits grain farmers, but despite its advantages has not been widely adopted. Some information exists on CT adoption rates but the information is incoherent and divergent. This study examines CT adoption among farmers in Guanajuato, Mexico. A diagnostic survey was designed to procure baseline information for a participatory research development program to develop sustainable farming practices based on CT principles.