Conservation agriculture cropping systems in temperate and tropical conditions, performances and impacts. A review

Abstract

Nowadays, in a context of climate change, economical uncertainties and social pressure to mitigate agriculture externalities, farmers have to adopt new cropping systems to achieve a sustainable and cost-effective grain production. Conservation agriculture consists of a range of cropping systems based on a combination of three main principles: (1) soil tillage reduction, (2) soil protection by organic residues and (3) diversification in crop rotation. Conservation agriculture has been promoted as a way to reduce production costs, soil erosion and soil fertility degradation under both tropical and temperate conditions. Conservation agriculture-based cropping systems have diffused widely under Brazilian large-scale farms' conditions and more recently in Europe in the context of medium-size mechanized farms. Their diffusion, however, is still limited under small-scale non-mechanized farms' conditions of tropical countries. To assess the advantages and limits of such new cropping systems, this article compares experiences with conservation agriculture from the tropical Cerrado region of Brazil and from temperate conditions of Europe. It focusses on agronomic performances, environmental impacts and economical results. Conservation agriculture systems appear to be interesting options to achieve sustainable and intensive crop production under different agroecological environments because they use efficiently available resources and maintain soil fertility. However, this mostly results from the permanent presence of an organic mulch on the soil surface and the incorporation of cover crops in the rotations. Such modifications require a significant reorganization of the production process at farm level, and when facing technical or socioeconomic constraints, most farmers usually opt for applying only partially the three main principles of conservation agriculture. Investigating more fully the consequences of such partial implementation of conservation agriculture principles on its actual efficiency and assessing the most efficient participatory approaches needed to adapt conservation agriculture principles to local conditions and farming systems are top priorities for future research. (Résumé d'auteur

Response of a two-year sugar beet-sweet sorghum rotation to an agronomic management approach diversified by soil tillage and nitrogen fertilisation

“…The adoption of conservation agricultural practices favours a balanced distribution of fertilisers, meets crop nutrient requirements, and offers an efficient management of irrigation water (Kassam et al, 2012;Scopel et al, 2013). Among the soil management systems, reduced soil tillage can contribute to the reduction of erosion, the maintenance and/or improvement of soil fertility as well as the increase of biodiversity.…”

Sustainable Weed Management for Conservation Agriculture: Options for Smallholder Farmers

“…Indeed in many cases, in minimum and no-tillage, herbicides are considered as an alternative to the primary tillage, done in tillage-based systems, for pre-planting weed control [28][29][30][31][32][33][34][35][36]. Several authors indicate that herbicides have reduced reliance on traditional tillage methods to control weeds and have led to the adoption of minimum and no-tillage practices [37].…”

Adopción de prácticas de agricultura de conservación en Tlaxcala, México

“…La sostenibilidad de la agricultura según Kassam (2009) esta cuestionada por el aumento en el costo de los alimentos y de la energía, la escasez de agua, la degradación de los ecosistemas, el cambio climático, la biodiversidad, y la crisis financiera. En este contexto (Scopel et al, 2013) se exige que los cultivos sean más rentables, resistentes a condiciones adversas del entorno, de bajo riesgo, basados en tecnologías de bajo costo y con externalidades negativas mínimas.…”

“…The sustainability of agriculture as Kassam (2009) is challenged by the rising cost of food and energy, water scarcity, degradation of ecosystems, climate change, biodiversity, and the financial crisis. In this context (Scopel et al, 2013) are required to be more profitable crops resistant to adverse environmental conditions, low risk, based on low-cost technologies and minimum negative externalities.…”

“…La sostenibilidad de la agricultura según Kassam (2009) esta cuestionada por el aumento en el costo de los alimentos y de la energía, la escasez de agua, la degradación de los ecosistemas, el cambio climático, la biodiversidad, y la crisis financiera. En este contexto (Scopel et al, 2013) se exige que los cultivos sean más rentables, resistentes a condiciones adversas del entorno, de bajo riesgo, basados en tecnologías de bajo costo y con externalidades negativas mínimas.Para algunos autores (Cadena et al, 2009;Stagnari et al, 2010; Kassam y Friedrich 2011;Ndah et al, 2013) la AC es una combinación de medidas agronómicas, biológicas y mecánicas que mejoran la calidad del suelo; para otros (Knowler y Bradshaw 2007;Hobbs et al, 2008) es la integración formal de prácticas realizadas por los agricultores previo al surgimiento de la AC como forma de producción. Así, la AC puede entenderse como una innovación en el proceso de producción, o bien, como la integración de prácticas comunes realizadas de manera aislada.…”