Soil surface water flow as runoff has been recognized as an important component in agricultural water management. Surface flow has the potential to carry extra fertilizer to nearby water bodies, can be a critical factor for soil erosion, and affects the water balance. 

A new 2DSoil module was developed for soil surface water flow with the following three components:

• Movement of water along the soil surface
• Accumulation of water in depressions
• Water fluxes across the soil-water interface, i.e., the infiltration.

The advantages of the new soil surface water module are:

• Heavyside function and its derivative, Dirac delta function, are used to present the water boundary conditions on soil surface
• Overland flow was simulated using a kinetic wave approximation.

Root Growth

Knowledge of root density and its spatial distribution can enhance our understanding of plant adaption to the soil environment and the impacts of agricultural management. A new method in 2DSoil was developed to simulate the root system of a corn plant. A diffusive root growth model is applied to represent corn root distributions. Soil water content, temperature, soil density and aeration are considered as the ambient factors for root growth. The program can estimate the effects of water and nutrients on root growth and crop yield.

 Mulch

Knowledge of the impacts on residue mulch and surface runoff on surface soil is important for agricultural field management. We developed a new method to simulate the moisture and thermal regimes on soil surface with residue mulch and/or surface runoff using a computer program. The computer program can also present the surface runoff and residue decomposition. The program can estimate the nitrogen and carbon (organic matter) exchanges between residue mulch and surface soil. This information will be useful to scientists, agricultural managers and consultants.

 Soil Vapor

In soil, water can evaporate in warm regions, move to colder zones in vapor phase, and then condense. Such a process can be a predominant component of soil water transfer when the soil is relatively dry. A new vapor transfer is developed in 2DSOIL to compensate the vapor effects on soil water and heat dynamics. With this update, liquid water, water vapor and heat transfer in 2DSOIL are coded into three separate modules, which enables a flexible control on each transfer component. This research is useful to soil scientists, hydrologists, agronomists, and agricultural managers interested in quantifying evaporation, plant water uptake and drainage of water input into soil as irrigation or rainfall.