Mireille Navarrete

Agronomy for sustainable agriculture. A review

Sustainability rests on the principle that we must meet the needs of the present without compromising the ability of future generations to meet their own needs. Starving people in poor nations, obesity in rich nations, increasing food prices, on-going climate changes, increasing fuel and transportation costs, flaws of the global market, worldwide pesticide pollution, pest adaptation and resistance, loss of soil fertility and organic carbon, soil erosion, decreasing biodiversity, desertification, and so on. Despite unprecedented advances in sciences allowing us to visit planets and disclose subatomic particles, serious terrestrial issues about food show clearly that conventional agriculture is no longer suited to feeding humans and preserving ecosystems. Sustainable agriculture is an alternative for solving fundamental and applied issues related to food production in an ecological way (Lal (2008) Agron. Sustain. Dev. 28, 57–64.). While conventional agriculture is driven almost solely by productivity and profit, sustainable agriculture integrates biological, chemical, physical, ecological, economic and social sciences in a comprehensive way to develop new farming practices that are safe and do not degrade our environment. To address current agronomical issues and to promote worldwide discussions and cooperation we implemented sharp changes at the journal Agronomy for Sustainable Development from 2003 to 2006. Here we report (1) the results of the renovation of the journal and (2) a short overview of current concepts of agronomical research for sustainable agriculture. Considered for a long time as a soft, side science, agronomy is rising fast as a central science because current issues are about food, and humans eat food. This report is the introductory article of the book Sustainable Agriculture, volume 1, published by EDP Sciences and Springer (Lichtfouse et al. (2009) Sustainable Agriculture, Vol. 1, Springer, EDP Sciences, in press).

How do Farming Systems Cope with Marketing Channel Requirements in Organic Horticulture? The Case of Market-Gardening in Southeastern France

Organic market-gardening farming systems are extremely diverse, ranging from the extensive to the very intensive, although all follow organic standards. This study aimed to analyze the extent to which the diversity of farming systems in southeastern France may be explained by the marketing channels adopted by growers. Eighteen organic market gardeners were surveyed. Three types of growers were identified, differentiated by the way they combine farming and marketing systems: (1) growers selling a diversity of food products through local marketing channels, which allows them to increase plant species biodiversity and enhance natural regulations in accordance with agro-ecology principles; (2) specialized growers selling a limited number of food products through long marketing channels at the few periods most economically favorable with regard to the export-market, a questionable strategy in terms of environmental sustainability; and (3) intermediate growers combining short and long marketing channels, who potentially may reconcile environmental and economic components of sustainability. The study confirmed the importance of better understanding the relationships between farming practices and marketing channels so that commercialization does not to become an impediment to sustainability in organic farming.

SALADPLAN: a model of the decision-making process in lettuce and endive cropping

Market gardeners are facing new environmental, commercial and safety requirements and regulations that weigh heavily on their crop planting and management decisions. Producing high-quality products and simultaneously reducing the use of chemical products needs change in the multi-field planning of crops. In order to identify which cropping practice may be altered depending on each farm’s characteristics, we built a rule-based model that represents how market gardeners plan cropping cycles of lettuce and endive, here denoted as salad vegetables, on a farm scale. The model is adapted to the specificities of salad vegetable crops in the Mediterranean region, in particular the combination of several cycles per year and of open field and sheltered crops. The output variables are the developed areas allocated to the different salad types and the range of the harvest dates, which are two key factors for commercialisation. The model is based on identifying the successive decision steps of growers when building their farming systems; descriptive variables are the effective surface area and period for salad cultivation, the number of salad cycles per year, the developed surface area of each salad type and the dates of harvest. The decision-making rules leading to each descriptive variable are based on the agronomic characteristics of soil, climate and crops, farmers’ strategic objectives and organisation of farm resources. The cropping decisions were recorded in 38 farms in the large market-gardening region of Languedoc-Roussillon. In the sample, the number of salad types cultivated per farm varied from 1 to 8 and the harvesting period from 3 to 7 months. Our results demonstrate that the model can explain a substantial part of this variability, 26 and 28 farms among 38, respectively, being correctly classified by the model for the two variables. The original result of this work is to enhance the generality of a similar framework built earlier for arable cropping systems. From a practical point of view, this model can be used to determine the leeway available to the farmers for the introduction of technical change in salad cropping. It could therefore be used by agricultural advisors to plan salad crops either for individual farms or on the scale of a marketing structure.

Sustainable Agriculture Volume 2

Contents: SECTION 1 - NOVEL CONCEPTS Emerging agroscience; Ants and sustainable agriculture; Agroecology as a science, a movement and a practice; Adaptiveness to enhance the sustainability of farming systems; Economics of biosecurity across levels of decision-making; Describing and locating cropping systems on a regional scale. SECTION 2 - FOOD SECURITY Nutritional quality and safety of organic food; Minerals in plant food: effect of agricultural practices and role in human health; Fertiliser trees for sustainable food security in the maize-based production systems of East and Southern Africa; Cereal landraces for sustainable agriculture; Mineral sources of potassium for plant nutrition; Glandless seed and glanded plant research in cotton; Micronutrient-efficient genotypes for crop yield and nutritional quality in sustainable agriculture; Multi-criteria decision models for management of tropical coastal fisheries. SECTION 3 - SOCIOLOGY AND ECONOMICS Farmer responses to climate change and sustainable agriculture; The use of the marasha ard plough for conservation agriculture in Northern Ethiopia; Biological nitrogen fixation and socioeconomic factors for legume production in sub-Saharan Africa; Conventionalisation of organic farming practices: from structural criteria towards an assessment based on organic principles; Conservation tillage in Turkish dryland research. SECTION 4 - CLIMATE CHANGE Biofuels, greenhouse gases and climate change; Agronomic and physiological performances of different species of Miscanthus, a major energy crop; Changes in atmospheric chemistry and crop health; Modelling soil carbon and nitrogen cycles during land use change; Greenhouse gases and ammonia emissions from organic mixed crop-dairy systems: a critical review of mitigation options; Water deficit and nitrogen nutrition of crops; Validation of biophysical models: issues and methodologies; Cold stress tolerance mechanisms in plants. SECTION 5 - ALTERNATIVE PEST CONTROL Defence mechanisms of Brassicaceae: implications for plant-insect interactions and potential for integrated pest management; Ionising radiation and area-wide management of insect pests to promote sustainable agriculture; Biodiversity and pest management in orchard systems; Pathogenic and beneficial microorganisms in soilless cultures; Allelopathy in Compositae plants. SECTION 6 - SOIL HEALTH Assessing the productivity function of soils; Long-term effects of organic amendments on soil fertility; Tillage management effects on pesticide fate in soils; Sustainable cow-calf operations and water quality; Biogeography of soil microbial communities: a review and a description of the ongoing french national initiative. SECTION 7 - ALTERNATIVE FERTILISATION Nitrogen rhizodeposition of legumes; Models of biological nitrogen fixation of legumes; Arbuscular mycorrhizal networks: process and functions; Efficient N management using winter oilseed rape; Improving nitrogen fertilization in rice by site-specific N management; Solid–liquid separation of animal slurry in theory and practice

Crop management, labour organization, and marketing: three key issues for improving sustainability in organic vegetable farming

Most market-garden farms that have converted to organic farming (OF) in the last few decades in France are small and diversified. Larger farms usually specialize in a few vegetable species and frequently face technical and economic problems when they convert to organics. Diversifying production may be a means of increasing sustainability due to larger crop rotations and varied marketing outlets, but it has various implications on farm management, especially labour organization and marketing. In the present study, we examined how an acceptable degree of species diversification can act as a lever to develop organic vegetable production by combining sociologist and agronomist points of view. Multidisciplinary surveys of 30 market-garden farms varying in usable surface area and degrees of crop diversification were carried out. Consequences on crop management, labour organization and skills, and marketing implications were described, and farm sustainability was assessed. Specialized farms of the sample had a rather industrial organization of labour and marketing and benefited from economy of scale to produce vegetables. But in the long term, they may suffer from low agronomical sustainability because of narrow crop rotations and intensive crop management. Diversified farms were more sustainable according the criteria studied, but they suffered from the extremely complex management of cropping systems. These results are discussed on both the farm and territorial levels. Collective marketing initiatives and social networks might help reach an acceptable degree of species diversification at the farm level. Potential innovative organizations are identified, which could facilitate the transition to OF.

Transitions Towards Organic Farming at the Farm and at the Local Scales: The Role of Innovative Production and Organisational Modes and Networks

In a context of growing environmental constraints and economic uncertainties, how is it possible to facilitate transitions towards more ecological forms of agriculture? In this chapter, changes in practices from conventional agriculture towards organic farming (OF) are investigated by combining sociological and agronomical studies of farmers’ trajectories conducted in the fruit and vegetable sectors. We specifically explore the potential of combinations of systems, both at the level of production and in terms of marketing outlets. We analyse the processes of adoption of alternative crop protection strategies using the Efficiency-Substitution-Redesign grid developed by biological and agricultural scientists. The combination of diversified systems of production (including organic and IPM) and marketing channels (including short and long food supply chains) might provide promising transition pathways for organic farmers. We also examine the conditions that enable such transitions, involving learning processes, collective and territorial dynamics and the ability of the networks to overcome the classical frontier between organic and conventional agricultures. Our three French case studies, which cover a wide range of marketing networks and diversification levels, show that a robust ecologisation of agricultural practices requires the redesign of both technical agricultural systems, as well as the larger interactions within agri-food systems and non-agricultural networks.

Modelling spatial extension of vegetable land use in urban farms

Increasing vegetable production to meet the growing urban demand is essential in developing countries. This article proposes a new model to analyse farm land use for market gardening in tropical urban agriculture and to evaluate the capacity of farmers to increase their vegetable surface area. It is based on a decision model simulating crop sequences and crop location initially validated for temperate arable and vegetable productions. In this study, the leafy vegetables land use model (LYLU) was first adapted to suit the specificities of urban leafy vegetable production: short crop cycles; wide crop diversity; instability of the cultivated area during a season, in our case due to flood recession; manual labour and close relationships with retailers. The output variables of the model were then compared to observations collected on an 11 farms sample. The model estimates the surface area for each leafy vegetable, depending on plant species requirements, farm resources and relations with retailers. This is the first model that simulates the spatial and temporal variation of the farm land and the exploitable surface areas over the cropping season depending on the dynamics of water availability and labour force. In some cases, up to half of the surface remained uncultivated because of slow fields’ drainage at the end of the rainy season and/or lack of water in the wells in the dry season. Moreover, the available labour force on farm and the way vegetables were sold greatly affected the intercrop period, which in turn contributed to reducing the cultivated area. Finally the model was used to quantify farmers’ room for manoeuvre in order to increase their vegetable cultivation area. Opportunities to overcome them were discussed both at farm and territorial levels. This is an innovative approach that could be useful to face the growing urban demand in developing as well as in Western countries.

Diversity of experimentation by farmers engaged in agroecology

Agroecology questions the production of generic knowledge. Rather than searching for the best practices for large-scale transfer, it would be more efficient to help farmers find their own solutions. A promising activity for farmers is experimentation because it answers their needs and helps them learn. However, how agroecological practices are tested by farmers in their own experiments is still poorly known. In this study, we examined the short-term experimental activity, i.e., experiments carried out at a yearly scale in pre-defined fields. Seventeen farmers in south eastern France were surveyed. The farmers practiced conventional or organic farming and cultivated either arable or market garden crops. Experiments on agroecological practices were characterized, located along a timeline, and discussed with them. To conduct the interviews with the farmers, each experiment was described in three stages: (1) designing the experiment, (2) managing it in real time, and (3) evaluating the results of the experiment. The data collected in the interviews were first analyzed to build a descriptive framework of farmers’ experiments, after which hierarchical cluster analysis was used to analyze the diversity of the farmers’ experiments. Here, we propose for the first time a generic framework to describe farmers’ experiments at a short time scale based on the consistency between the Design, Management, and Evaluation stages. We used the framework to characterize the diversity of farmers’ experiments and identified four clusters. The originality of this work is both building a descriptive framework resulting from in-depth analyses of farmers’ discourse and using statistical tools to identify and interpret the groups of experiments. Our results provide a better understanding of farmers’ experiments and suggest tools and methods to help them experiment, a major challenge in the promotion of a large-scale agroecological transition.