Leaching is the process where soluble materials (including nutrients and salts) in the soil are washed down the soil profile by water.

Glacial till is sediment ground up beneath a glacier and deposited as 'sub-glacial till', or glacial till deposited at the 'terminus' as a 'terminal moraine'. Till is a j [..]

Fossil fuels can release chemicals such as sulphur when they are burnt (as petrol is in a car, or coal is in a power station). These chemicals can dissolve in atmospheric water and make rainfall unnat [..]

An aerated soil is a soil with a good movement of air through the soil structure. The opposite is a wet waterlogged soil, where the soil pores are filled with water.

Aggregates' in the soil are just soil lumps of a range of differing sizes. The word is also often used to describe gravel used to build roads.

Alluvium is a deposit made by a river or running water. This leads to an 'alluvial deposit' forming in the water. Alluvial soils are rich agricultural lands. Glaciers may also deposit sedime [..]

Anaerobic soils have very little oxygen present - for instance the wet, waterlogged, marshy soils in a bog. While anaerobic conditions are important for some processes, such as bacterial reduction of [..]

A negatively charged ion. The most commonly found anions in soil waters include bicarbonates, sulphates, carbonates, chlorides and nitrates.

Arid conditions are dry! Where rainfall is less than about 200 mm/year an area is 'semi-arid', rainfall below below this leads to arid conditions such as deserts.

Autotrophic bacteria can take carbon in from the atmosphere through the fixation, reduction and incorporation of carbon dioxide.