SWDF30 is the soil water stress affecting tiller development, weighted in the upper 30 cm of soil:

where SWi, LLi and DULi are the soil water content (m3 m-3), permanent wilting point (m3 m-3), field capacity (m3 m-3) of the i-th layer respectively. L is the total number of layer within the upper 30 cm of soil, and TBL is the depth from the surface to the bottom of the L-th layer and DLi is the thickness of the i-th layer.

The SWDF factors influencing root development are evaluated at each i-th soil layer and they differ for root length density and root depth processes.

The root depth         is reduced by the stress factor only if root bottom edge belongs to a stressed soil layer (i.e., SWDFi < 1).

Created with the Personal Edition of HelpNDoc: Write EPub books for the iPad