Humans are dependent on healthy soils for nutrition:
-
Microbes, invertebrates and vertebrates break down organic matter to provide soil structure, rich humus content, drainage, water up-take and nutrient release.
-
Roots stabilise soils, facilitate mineralisation, including biological nitrogen fixation (BNF) and aeration.
-
Canopies intercept rainfall, allowing water to gently percolate into soils.
In one gram of healthy soil there can be more than 10,000 species and over a billion living micro-organisms which decompose organic matter and unlock nutrients and minerals so plants can use them.
An “ecosystem approach to soils”, ensures that the natural processes soils need to maintain health are provided. Natural soil improvement can be provided through: buffer strips, shade plants, hedgerows, shelter strips, mixed cropping, fallow periods, minimal ploughing etc.
Case Study:-Yerba Mate, Paraguay
Yerba maté (Ilex paraguariensis) a popular tea in southern South America, is grown under native intact forest canopies in Reserva Privada Estancia Itabo, Paraguay. The crops benefit from healthy soils under the native trees as well as from invertebrate pest control from native bird species.
Artificial fertilisers depend upon fossil fuels, energy and the mining of dwindling nutrients (e.g. phosphates) and contribute to eutrophication of water ways and thus expenditure on nutrient stripping of portable water.
“Soil erosion is one of the world’s greatest disasters” ..as…”it takes 500 years to form one inch (2.5cm) of topsoil, yet worldwide we are losing 75 billion tons of soil each year”
– David Pimentel, Professor of Ecology and Agricultural Sciences at Cornell University
“We have already lost in the vicinity of 30% of the world’s topsoil and much of it caused by human activities such as deforestation, intensive chemical farm practices and development”.
– Bruce Wilkinson, Professor of Geological Sciences, University of Michigan.
“The nation that destroys its soil destroys itself”.
– Franklin D. Roosevelt
http://e360.yale.edu/feature/phosphate_a_critical_resource_misused_and_now_running_out/2423/
http://www.chooseorganics.com/organicarticles/soil_organics.htm
http://www.fao.org/DOCREP/005/Y4586E/y4586e10.htm