[Towards a renewable and sustainable agriculture. Biological agriculture: from marginal vanguard to spearhead of the agriculture of the future].

This work seeks to demonstrate how different types of organic agriculture can meet the need for renewable and sustainable agriculture, rural development, and management of the land and water resources. An obstacle to the spread of organic agriculture is the widespread perception that without intensive factors of production, demographic growth will necessarily outstrip the available food resources. Calculation of economic costs and benefits at present carries greater weight in planning than do soil erosion, deforestation, extinction of species, disappearance of habitats, and similar environmental damage. The different types of organic agriculture do not follow rigid rules and are not defined solely by the nonuse of nitrogenous fertilizers and pesticides. One of the main principles or organic agriculture is to respect local soil and climatic conditions. Self-sufficiency regarding external factors of production and an emphasis on recycling and optimal use of natural resources were concept ahead of their time when they initially were introduced in the 1920s. The specialization which restructured agriculture over the past century has seriously damaged the system of mixed agriculture and the chain of food production. The solution will be to seek for each region an appropriate balance linking animals and agricultural production in an organic process. The objective of organic agriculture, also known as autonomous ecosystem management, is to preserve as far as possible the balance between needs for food and fiber on the 1 hand and the potential of local ecosystems on the other. General principles of organic agriculture include mixed exploitation in which both plants and animals have specific functions in the context of their local soil and climatic characteristics. Different types of crop rotation are practiced to optimize mutual interactions between crops, and the varied organic cycles are also optimized within the framework of anorganic management in accord with nature. The adoption of alternative agricultural practices will require new attitudes and new training for agricultural workers and extension agents. Organic agriculture was highly marginal until the 1970s, but several European universities have created department or sections for organic agriculture, and governmental or quasi-governmental organizations have been created in several countries. Negative prejudices regarding results of organic agriculture remain a major obstacle to their wider acceptance. Detailed research is needed on the positive and negative effects of a change from current chemically based agriculture to an alternative form more attuned to the principles of organic agriculture.