Agriculture Reference
In-Depth Information
Soil water regimes are dependent on both the amounts of water input to the soil
surface and its form. While water is normally acquired as rainfall (and snowfall in
the colder parts of the world) inputs as dew and fog may be significant to plants and O
horizon processes in drier areas. Other factors affecting the amounts of water entering
the soil are rainfall intensity in relation to the maximum rate at which the soil will accept
water (the infiltration capacity) and the temporal distribution of the rainfall at both short
term and seasonal time scales.
Soil factors affecting hydrological regimes include water holding capacity and profile
depth‚ both of which define the maximum store of soil water that may be held in any
given soil. Losses of water from the profile depend on soil hydraulic conductivities‚ site
drainage and the thermal regime of the site. The latter factor determines the evapo-tran-
spiration rate‚ which is the sum of evaporative losses from the soil surface and the water
lost by plants to the air by evaporation and transpiration. Finally‚ surface micro-relief
may slow water movement across the soil surface and thereby increase infiltration rates.
