The modified Richard’s equation for assessing the impact of drought and salinity in arid and semi-arid zones. part two: a soil hydraulic capacitance

The soil hydraulic capacitance, a tank like the plant water reservoir, is being controlled by signals, valves like the switches. Three types of signaling devices, Geo, Bio, and weather controlled were discussed. The soil hydraulic capacitance property was first discovered by the author when modeling the wheat root water uptake under saline and drought conditions. Under the latter extreme conditions, treating plants with silica products was the common managerial practice used for enhancing uptake and plantation.  A split-split plot experimental design with four replicates was used to conduct the research in Oraby Village, Maryout area, Alexandria, Egypt in the last year of the most water-scarce decade. The aim of the experiment was to put the sink/ source term of Richard’s equation, S, into consideration under a macroscopic electrical modeling, AMUN_SHC. The S-shaped relative stress response function was used to describe the relation SSI= f (h, z, t). AMOUN_SHC showed that the sink term of Richard’s equation is the product of multiplying the soil hydraulic capacitance and soil stress index.  The soil stress index, plant stress index and strain of straw sap were calculated. The soil hydraulic capacitance was derived estimated and discussed. The effect of silicon as a beneficial element on the soil hydraulic capacitance and therefore the winter wheat water uptake was estimated and discussed. The brilliant result from the model is that the property soil hydraulic capacitance controls the compensated root water uptake under drought and saline conditions in accordance with stress, strain and weather controlled relationships. See the graphical abstract in Fig (1) supplementry file.