Topsoil
It also plays host to significant bacterial, fungal and entomological activity without which soil quality would degrade and become less suitable for plants.
Bacteria and fungi can be essential in facilitating nutrient exchange with plants and in breaking down organic matter into a form that roots can absorb.
It condenses and settles over time in different ways depending upon conditions such as beneath roadbeds and foundations vs uncovered and exposed to the elements.
[6] A Victorian open-cut coal mine was rehabilitated with low-quality artificial topsoil made from local materials.
Organisations such as the British Standards Institution (BSI) and the North Carolina Department of Agriculture publish guidelines for soil quality and the desired levels of topsoil nutrients broadly suitable for many plants.
[10] Alternatively the BSI relates the following values: The preceding tables are for a multipurpose grade and certain levels can alter with regard to soil pH.
In order to protect against flooding the International Residential Code requires a 2% slope (2.4 in (61 mm)) for the first ten feet away from the home.
Commercially available topsoil (manufactured or naturally occurring) in the United Kingdom must be classified to British Standard BS 3882, with the current version dated 2015.
The standard has several classifications of topsoil with the final classification requiring material to meet certain threshold criteria such as nutrient content, extractable phytotoxic elements, particle size distribution, organic matter content, carbon:nitrogen ratio, electrical conductivity, loss on ignition, pH, chemical and physical contamination.
The estimated annual costs of public and environmental health losses related to soil erosion in the United States exceed $45 billion.
[14] Conventional industrial agriculture practices such as ploughing and spraying high quantities of synthetic liquid fertilisers can degrade the quality of the soil.
Algae blooms can occur when high quantities of nutrients flood rivers, lakes or oceans often as a result of farm runoff or from sewage.
[15] Sustainable techniques attempt to slow erosion through the use of cover crops in order to build organic matter in the soil.
