The importance of these issues to the world community were underscored in the landmark 1992 United Nations Conference on Environment and Development held in Rio de Janeiro, Brazil, where the Convention on Biological Diversity (CBD), was presented and signed by 159 governments and the European Union."Up to the present, about 180 nations have ratified the "Convention, that addresses the ways in which biodiversity can be effectively conserved, managed and used.

The objectives of the convention are (Article 1): "the conservation of biological diversity, the sustainable use of its components and the fair and equitable sharing of the benefits arising out of the utilization of genetic resources, including the appropriate access to genetic resources and by appropriate transfer of relevant technologies, taking into account all rights over those resources and to technologies, and by appropriate funding."
The sustainable use of biodiversity, as stated in the CBD involves "the use of components of biodiversity in a way that does not lead to the long term decline of biodiversity, thereby maintaining its potential to meet the needs and aspirations of present and future generations."

The impact of agricultural activities on biodiversity of plants and animals has a long history, which began when humans first started the domestication process over 7000 years ago (Solbrig and Solbrig, 1994). By selecting a few seemingly more useful or edible species, these ancient agriculturists began the selection process which still continues today as farmers, researchers and companies look for more productive plants and animals. This process necessarily involves a reduction and simplification of the immense biological diversity of nature, at both the species and genetic level. However, since the first farmers selected their preferred plants and cultivated their land with the few simple tools and mostly organic inputs available at a local (small) scale, their activities were, in general, of low impact or at least of a limited geographical scale. There are still examples today of cultures that continue to practice this small-scale, limited impact agriculture (Denevan, 1995; Redford and Mansour, 1996).

With the advent of large cities and major civilizations, large areas were dedicated to agricultural activities, using animal traction, irrigation canals and other intensification techniques. The need to produce large quantities of food to supply the growing (mostly urban) populations, and the later advent of industrialization spurred on the development of modernized agricultural techniques with the use the moldboard plow, motorized tractors, hybrid cultivars, inorganic fertilizers and pesticides that created new pressures on the land, dramatically increasing the influence of agricultural practices on biodiversity. Furthermore, as the amount of land available for agricultural use continues to decrease worldwide, the demands of human populations (especially urban) are simultaneously increasing, putting more pressure on the soil resource base and the environment (Lavelle, 2000; Young, 1998).

Today, some 6 billion humans rely on biodiversity for its goods and services, the population having doubled since 1950. This may reach 9 billion by the year 2050. More significantly, the demands on natural reesources are growing even faster, the global economy having quintupled in the last 50 years.

Botanists estimate there are about 350,000 plant species and about 300,000 of these grow on land (Burger, 1981). The dominant and most important are the 195,000 flowering species, most of which produce edible parts potentially useful to people. The world's food supply is obtained either directly or indirectly from the abundance of plant species, but fewer than 100 are used for food (Burger, 1981). World-wide, about 50 species are cultivated actively, and as few as 17 species provide 90% of man's food supply and occupy about 75% of the total tilled land on earth (Biswas and Biswas, 1976; Harlan, 1976). They include wheat (Triticum aestivum), rice (Oryza sativa L.), corn (Zea mays L.), potato (Solanum tuberosum), barley (Hordeum vulgare), sweet potato (Ipomoea batatos), cassava (Manihot esculenta), soybean (Glycine max), oat (Avena sativa), sorghum (Sorghum bicolor), millet (Pennisetum typhoides), rye (Secale cereale), peanut (Arachis hypogaea), field bean (Dolichos lab-lab var. purpurius), pea (Pisum sativum), banana (Musa paradistaca), and coconut (Cocos nucifera). Eight cereal grains - wheat, barley, oat, rye, rice, maize, sorghum and millet provide 56% of the food energy and 50% of the protein consumed on earth (Stoskoph, 1985).

The "Green Revolution", so called because of the large increases in plant production that were obtained by using its techniques, relied on overcoming soil constraints through the application of external inputs such as inorganic fertilizers, and other amendments, in order to meet plant requirements (Sanchez, 1994; 1997). These practices, still under use in a large part of the world’s surface, primarily in developed nations, have greatly benefited humankind, being responsible for important increases in per-capita food production worldwide. However, the vast majority of the world´s farmers do not have access to or can afford the external inputs (agro-chemicals, improved crop varieties, hybrid seeds, ready access to cash and credit), required to apply the principles and practices of high external input agriculture (HEIA) (Vandermeer et al., 1998). Furthermore, the misuse or overuse of practices associated with HEIA have been associated with soil and environmental degradation (i.e., depletion or loss of soil fertility and its physical and biological components, contamination of surface and ground water) and declines in productivity in certain areas of the world (Shiva, 1991).

What is needed therefore is the development and implementation of an integrated soil management approach to agriculture of an integrated approach to agriculture that considers the potential impacts of agriculture on the environment and optimizes the ecological interactions and synergies between biological components of the ecosystem and the biological efficiency of soil processes in order to maintain soil fertility, productivity and crop protection (Altieri, 1995; Woomer and Swift, 1994; Lavelle, 2000).

The challenge of this approach is to show that not only gains in agricultural productivity can be made by optimising biological processes, including the manipulation of soil biota, but also that biological management of soil fertility can be integrated profitably into the rest of the farming enterprise (Swift, 1999) and can simultaneously serve to conserve biologically important populations and species.

This approach can be used in modern commercial agriculture, but has been considered especially useful in marginal lands prior to degradation (i.e. by preventing damage), in degraded lands in need of reclamation and in regions where the availability, access to or use of external inputs is limited (thus leading to a predominance of biological processes in the maintainance of soil fertility) (Anderson, 1994; Sanchez, 1997, Swift, 1999; Senapati et al., 1999).

At technical and policy levels, the challenges to be overcome have to do mostly with demonstrating that the long-term social, economic and conservation benefits of an integrated biological management of soil outweigh the short-term costs (if any), so that specifically designed policies that promote integrated soil biological management can be created and implemented at different hierarchical levels.

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