Soil heat and water flow with a partial surface mulch

Abstract

A computer model using the alternating direction implicit (ADI) finite difference method to study two‐dimensional coupled soil heat and water flow with a partial surface mulch cover is developed. A new, simplified computational procedure, which has only tridiagonal matrix problems, for the ADI method is introduced. The model uses a soil surface energy balance equation to determine soil surface boundary conditions for both heat and water flow. The inputs required for the computer simulations are weather data, soil thermal and hydraulic properties, and mulch data. Numerical experiments are performed to examine the effects of soil type, mulch width, and weather conditions on soil heat and water movement. For continuous evaporation and drainage, 10‐day simulations were performed for each combination of clay, loam, and sand soil and fractions of mulch cover of 0, 0.5, 0.8, and 1.0 of the row interval width. For repetitive evaporation and infiltration, 15‐day simulations were performed. The mulch cover greatly reduces evaporation loss and the amplitude of daily soil temperature, water content, and pressure head variations. Large spatial variations in temperature and soil water content are predicted near the interface of mulch and bare soil surface. The soil hydraulic properties have important roles in controlling soil surface water content. The present model reasonably describes the soil thermal and hydrologic environments and thus can be applied successfully in soil science and groundwater hydrology and can be extended to related disciplines.

Fate of the antibiotic sulfadiazine in natural soils: Experimental and numerical investigations

“…The water flow and heat transport equations are solved in a fully coupled way. The equation of Chung and Horton (1987) was used to describe the thermal conductivity k (W/m/K) as a function of the volumetric water content:…”

“…Parameters of the empirical function that describes the thermal conductivity as a function of the volumetric water content were calculated using the Chung and Horton (1987) equation based on the two dominant grain sizes of the soils. All thermal conductivity parameters were fixed during the calibration.…”

Evaluation of the impact of surface residue cover on single and dual crop coefficient for estimating soybean actual evapotranspiration

“…have also shown that crop residue that only partially covers soil surface has less effect on E s because of greater surface temperature and larger drying gradients between bare soil and soil under residue covered areas (Willis, 1962;Chung and Horton, 1987;Steiner, 1989;Klocke et al, 2009).…”

Modeling Coupled Water and Heat Transport in the Root Zone of Winter Wheat under Non-Isothermal Conditions

“…The presence of a soil temperature gradient affects not only the transfer of soil water by affecting the physical properties of soil water, but also affects the redistribution of soil water [5,6]. The thermodynamic characteristics of soil are therefore altered, consequently affecting heat flow in soil [7]. This phenomenon shows that a coupling relationship exists between water and heat transfer in soil [8].…”