Question

Explain how soil is an open system as it interacts with the great systems of Earth: lithosphere, biosphere, atmosphere, and hydrosphere. Explain how soil receives energy or matter from each system.

Answer 1

An open system is one that has external interactions or which can allow the transfer of energy as well as mass across it's boundaries. Soil is an open system because it is not enclosed by anything and is in direct contact with the four spheres of Earth, namely the lithosphere, biosphere, atmosphere, and hydrosphere, where substances can be easily added and/or removed. There is no sharp boundary between weathered rock, undecomposed rock, soil and soil material. Rain directly rain falls on the soil, the wind blows the soil around, animals and people can move the soil. In addition to these, plants take mostly of of their nutrients from the soil and incorporates them within their tissues. When the plant dies, then those nutrients are again returned to the soil, maybe at a slightly different location. On the hilly slopes, soil usually moves downhill very slowly by the action of water(rain), wind and gravity whereas on the flat ground surface, wind and water can still transport the soil around. Soil receives energy or matter from each of these system. The geosphere mostly develops a layer of soil in which all of the nutrients become available to the living organisms, and which therefore provides an important ecological habitat and also the basis of many life fprms. The hydrosphere includes both freshwater and saltwater systems along with the moisture which is found in the soil (soil water) and within the pore spaces of the rocks (groundwater).