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Soils Database Table
The Soils Database provides a collection of basic soils and artificial materials used to construct soil profiles. You do not access items from this table in your simulations directly, but you refer to them through the definition of soil profiles.
Type of Material
Defines if the soil material is a Natural soil or an Artificial material. The main difference between the two is that natural soils allow the exchange of water inside the soil layers and - if used at the surface- allow natural transpiration. The thermal properties are calculated dynamically based on the actual water content of the soil. In addition, Water Body is supported as a special material to include still water bodies of substantial depth. Note: If “Water Body” is chosen, all other parameters are not required as the physical properties of water are fixed in ENVI-met.
Water Content (Natural soils only)
The volumetric water content defines the amount of liquid water per cube meter soil. For the ENVI-met simulations, three different critical threshold points need to be defined for a given soil:
- Water content at Saturation: The (theoretical) maximum amount of water inside the soil when each pore in the soil matrix is filled with water. In practise, this amount can only be reached if the soil cannot drain water to lower soil layers and is completely watered.
- Water content at Field Capacity: At Field capacity the soil holds the maximum amount of liquid water the soil matrix can hold against gravity without loosing water through drainage. Not every pore of the soil matrix is filled with water
- Water content at Wilting Point: The (permanent) wilting point is the lowest threshold defined for a drying soil. This is the minimum water content required, so that plant roots can extract water out of the soil. If the soil water content is lower than the wilting point value, the soil still contains water, but it cannot be used by the plants for transpiration.
These values are a constant property of the soil and its texture matrix and are normally available for a limited list of soils.