Ecological intensification of soils in tropical agriculture: roles of soil biodiversity

Tropical agriculture is severely limited by low soil fertility and land degradation. In developing countries, food insecurity is exacerbated by economic, social and environmental constraints: population growth, economic marginalization, limited access to inputs, climate change and environmental degradation. Small-scale farmers are unable to break out of this negative spiral. which requires us to rethink our agricultural models and develop a form of agriculture that enables us to achieve sustainable development goals. One way of doing this is through the ecological, or agroecological, intensification of agriculture, also known as "sustainable agricultural intensification". Scientists generally recognize the need for ecological intensification of agricultural production by increasing the biodiversity and complexity of agrosystems, to rely more on natural functions, biotic interactions and ecological processes, and to amplify the services provided by living organisms. Generally at field and farm level, agroecological practices stimulate and optimize above-ground functional biodiversity, i.e. above the soil surface, while soil biodiversity and functions (below-ground environment) are rarely managed. The importance of soil functions in the performance of agroecological systems is widely recognized, and their restoration appears necessary. Unfortunately, due to the complexity of soil functioning and the limited knowledge of its determinism, soil is still given only scant consideration in the design of agricultural systems.

This ecologically intensive agriculture is mainly adapted to small-scale farming, which accounts for 70-80% of the population in Africa. These farms generally have small cultivated areas, very limited access to inputs, low yields and must make the best use of natural resources to produce their food using traditional techniques.

In this article, after recalling the main constraints on agriculture in tropical zones, we will first examine the potential offered by tropical soil organisms to ensure ecological functions in agrosystems, and then the various levers for restoring soil biodiversity and the ecological functions it carries. We will see that soil biodiversity, like above-ground biodiversity, can be managed to improve the provision of ecosystem services and the sustainability of tropical agrosystems.