Simulation of soil water dynamics in structured heavy soils with respect to root water uptake

Abstract

Abstract:In agricultural lands has the soil moisture uptake from the root system a significant effect on the water regime of the soil profile. In texturally heavy soils, where preferential pathways are present, infiltrated precipitation and irrigation water with diluted fertilizers quickly penetrate to a significant depth and often reach an under-root zone or even the groundwater level. Such a scenario is likely to happen during long summer periods without rain followed by heavy precipitation events, when a part of the water may flow through desiccated cracks. Since 2001 the effects of drip irrigation and nitrogen fertilization of potatoes (Solanum tuberosum L., cultivar Agria) have been monitored within the frame of a research project at the experimental site Valecov (Czech Republic). Based upon the measured data an attempt has been made to simulate the water regime of the soil profile at a selected experimental plot, considering the impact of preferential flow and root water uptake. The dual-permeability simulation model S 1D Dual (VOGEL et al., 2000) was used for the simulation. The soil hydraulic parameters were inversely determined using LevenbergMarquardt method. Measured and simulated pressure heads were utilized in the optimization criterion. The scaling approach was applied to simplify the description of the spatial variability of the soil profile.The results of simulations demonstrate that during particular rainfall events the water reaches significant depths of the soil profile via preferential pathways. The effect of the root zone is dominant during dry periods, when capillary water uptake from the layers below roots becomes important. This should be taken in account into the optimization of the drip irrigation and nitrogen fertilization schedule.

Dual permeability soil water dynamics and water uptake by roots in irrigated potato fields

“…The simulations presented here embrace a period from 21 May to 18 July 2004. Similar simulations were presented by Zumr et al (2006), but there the assumed root zone depth was larger and constant, the evapotranspiration was constant over particular days and the irrigated treatment (T5) was not simulated.…”

A review of model applications for structured soils: a) Water flow and tracer transport

“…DPM simulation results improved only slightly compared to those using a one-domain (Richards) model, and the water transfer rate parameters in the DPM could not be identified (Ludwig et al, 1999). Zumr et al (2006) applied the 1D counterpart of the DPM S_2D_Dual for the Levenberg-Marquardt estimation of soil hydraulic parameters using measured pressure heads below a plot with pseudogley soil containing desiccated cracks, biopores and interaggregate fractures. Problems with reproducing observations were attributed to the uncertainty of allocating tensiometer values to the matrix or macropores (Zumr et al, 2006).…”

“…Zumr et al (2006) applied the 1D counterpart of the DPM S_2D_Dual for the Levenberg-Marquardt estimation of soil hydraulic parameters using measured pressure heads below a plot with pseudogley soil containing desiccated cracks, biopores and interaggregate fractures. Problems with reproducing observations were attributed to the uncertainty of allocating tensiometer values to the matrix or macropores (Zumr et al, 2006). Gérard et al (2004) tried to predict 4 years of daily measurements of soil water content in a forest soil plot with PF in a capillary pore network.…”

Field and laboratory ad hoc calibrations of Virrib and ThetaProbe dielectric sensors for soil moisture measurements

“…A more detailed description of the site and the design of experiments can be found, for example, in Plauborg (2006). Some information is also contained in the papers by Doležal et al (2005) and Zumr et al (2006). The soil type is deep Stagnosol (IUSS Working Group WRB 2007) on weathered paragneiss.…”