A Compensated Root Water Uptake Model for Crops under Stress from Water
Availability
Abstract
The agricultural sector is a major consumer of water for irrigation
purposes. Precise quantification of irrigation water requirements will
help in achieving sustainable water management. Root water uptake (RWU)
is driven by transpiration demand exerted by crops and is influenced by
factors such as weather and leaf area index (LAI). The root water uptake
at a particular depth in the root zone depends on the local moisture
content, soil type, and root density. Under certain conditions, lack of
availability of soil moisture at a certain depth may be compensated by
more water being drawn into the roots from wetter portions of the soil.
To incorporate this mechanism, this study presents a compensated root
water uptake model (CRWU) with application to maize crops grown in
Indian climatic conditions. Irrigation field experiments were conducted
at seven field plots with the same soil by adjusting the irrigation
supplied to simulate different degrees of water stress. Daily soil
moisture data recorded at different depths in the root zone, crop yield
and biomass data help in assessing model performance and identifying a
critical water stress index that governs the extent of compensation in
RWU.