In Veda’s water is defined as a life of the soil. If there is Waaphasa in the soil, the water is life. If there is no Waaphasa in the soil, water is death of the plant and soil biota. Waaphasa is that microclimate in the soil, by which the soil organisms and roots can live freely with availability of sufficient air and essential moisture in the soil. In one sentence, shortly, the Waaphasa means the mixture of 50 % air and 50 % water vapours in the cavities between two soil particles. Why water vapour ? Why not water ? Because, any root takes the molecules of water vapour. 92 % microorganisms and 88 to 95 % root hairs are working in the upper most 10 cm surface soil. So, the air must be circulating in this surface layer and vapour molecule must be available in this 10cm surface layer.
When this will happen? When, we give water outside the canopy of the plant. When you give water outside the canopy of the plant i.e. outside the shadow of the plant at 12 O’ clock, then only Waaphasa will be maintained. The roots that take water are situated at the outer canopy.
Source : http://palekarzerobudgetspiritualfarming.org/Waaphasa.aspx