Soil Quality as Affected by Intensive versus Conservative Agricultural Managements
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Environmental Science. Please check back later for the full article.
Soils, the Earth’s skin, are at the intersection of lithosphere, hydrosphere, atmosphere, and biosphere. The persistence of life on our planet depends on the maintenance of soils, as they constitute the biological engines of Earth. Human population has increased exponentially in recent decades, along with the demand for food, materials, and energy. These needs have caused a shift from a low-yield and improvised agriculture to a more productive, high-cost, and intensive one. However, soils are fragile ecosystems and require centuries to develop; thus, within the human timescale, they are not renewable. Modern agriculture, ever more intensive, suggests serious concern about the conservation of soil as living organism, of its capacity to perform the vast number of biochemical processes needed to complete the biogeochemical cycles of plant nutrients, such as nitrogen and phosphorus, crucial for crop primary production. Most practices related to intensive agriculture determine an over-exploitation of soils as living organisms, with deterioration even in the short-middle term of their biological properties, which cumulatively can be called “soil quality.” Recent trends turn towards styles of agriculture management that are more sustainable or conservative for soil quality.
In general, any anthropogenic exploitation of soils tends to disturb or divert them from a more “natural” development that, by definition, represents the best comparison term for measuring the relative shift from soil sustainability. The continuous degradation of soil health and quality due to abuse of land potentiality or intensive management has been occurring for decades. Soil microbiota, being “the biological engine of the Earth” provide pivotal services in the functioning of the soil ecosystem. Hence, management practices protecting soil microbial diversity and resilience should be pursued. Besides, any abnormal change in rate of innumerable biochemical soil processes, as mediated by microbial communities, may constitute an early and sensitive warning of soil homeostasis alteration and, therefore, may diagnose a possible risk for soil sustainability. Among the vast number of soil biochemical processes and related attributes (bioindicators) potentially able to assess the sustainable use of soils, those related to the mineralization or immobilization of major nutrients (C and N), including enzyme activity (functioning) and composition (community diversity) of microbial biomass, have paramount importance due to their centrality in soil metabolism. Comparing, in various pedoclimates, the impact of different agricultural factors (fertilization, tillage, etc.), under intensive and sustainable managements of soil microbial community, diversity and functioning by both classical and molecular soil quality indicators allow us to outline the most reliable biochemical soil attributes for assessing risky shifts from soil sustainability.