SPAC

Soil Plant Atmosphere Continuum (SPAC):-

>  It is proposed by Huber in 1924.

> All components of field environment i.e. soil, plant and atmosphere, form a physically unified and dynamics networking system in which various water flow processes occur independently. This unified system is called the soil-Plant-Atmosphere-Continuum or SPAC.

 > The fundamental principle of SPAC is water moves from higher total water potential to regions of lower total water potential at a rate depending on the hydraulic resistance of the medium.