Validation of a spatial–temporal soil water movement and plant water uptake model

Abstract

Management and irrigation of plants increasingly relies on accurate mathematical models for the movement of water within unsaturated soils. Current models often use values for water content and soil parameters that are averaged over the soil profile. However, many applications require models to more accurately represent the soil-plant-atmosphere continuum, in particular, water movement and saturation within specific parts of the soil profile. In this paper a mathematical model for water uptake by a plant root system from unsaturated soil is presented. The model provides an estimate of the water content level within the soil at different depths, and the uptake of water by the root system. The model was validated using field data, which includes hourly water content values at five different soil depths under a grass/herb cover over one year, to obtain a fully calibrated system for plant water uptake with respect to climate conditions. When compared quantitatively to a simple water balance model, the proposed model achieves a better fit to the experimental data due to its 2 ability to vary water content with depth. To accurately model the water content in the soil profile, the soil water retention curve and saturated hydraulic conductivity needed to vary with depth.

Use of a coupled soil-root-leaf model to optimise phosphate fertiliser use efficiency in barley

“…16 and 17) we are able to estimate (belowground only) the water and P concentrations in the soil by solving Eqs. 1-15, as in Heppell et al 2014.…”

“…where P is a function of temperature (T), humidity (H) and a base line pressure (p r 0 ) for fitting parameters λ 1 , λ 2 and λ 3 , (see Heppell et al 2014 for the procedure to estimate them), i.e.…”

“…for fitting parameters δ, α, β and γ (see Heppell et al 2014 for how these values were estimated). In addition, we have a zero flux boundary condition for the concentration of P (c) at the soil surface,…”

Modelling the optimal phosphate fertiliser and soil management strategy for crops

“…This allows for a more accurate calculation of the plant transpiration rate and the movement of water inside the soil and within the plant. These adaptations are made in Heppell et al (2014) and successfully capture the movement of water within the soil profile and plant transpiration rate.…”

“…Roose and Fowler (2004b) advanced the model by tracking the movement of water and P spatially. In this paper, for the first time, we extend the model of Roose and Fowler (2004b) and Heppell et al (2015) by adding the effect of climate, via surface water flux and xylem pressures as in Heppell et al (2014). This extension allows comparison of the model output, plant P uptake (kg P ha −1 ), against two sets of field trial data for barley, for different environmental conditions.…”