A diffusive model of maize root growth in MAIZSIM and its applications in Ridge-Furrow Rainfall Harvesting

Authors: WANG, ZHUANGJI - University Of Maryland; Timlin, Dennis; LI, SANAI - Oak Ridge Institute For Science And Education (ORISE); Fleisher, David; DATHE, ANNETTE - Cornell University; LUO, CHENYI - Beijing University Of Chinese Medicine; DONG, LIXIN - China Meteorological Administration; Reddy, Vangimalla; TULLY, KATHERINE - University Of Maryland

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2021
Publication Date: 6/1/2021
Citation: Wang, Z., Timlin, D.J., Li, S., Fleisher, D.H., Dathe, A., Luo, C., Dong, L., Reddy, V., Tully, K. 2021. A diffusive model of maize root growth in MAIZSIM and its applications in Ridge-Furrow Rainfall Harvesting. Agricultural Water Management. 254:106966. https://doi.org/10.1016/j.agwat.2021.106966.
DOI: https://doi.org/10.1016/j.agwat.2021.106966

Interpretive Summary: Knowledge of corn root density and its spatial distribution can enhance our understanding of plant adaption to the soil environment and the impacts of agricultural management. We developed a new method to simulate the root system of a corn plant using a computer program. The computer program can represent corn root distributions in soil and above ground plant growth as affected by soil water content, temperature and soil density. The program can estimate the effects of water and nutrients on root growth and crop yield. This information will be useful to scientists, agricultural managers and consultants as well as policy makers.

Technical Abstract: The root system is a critical vegetative organ in maize (Zea mays). Knowledge of root density and its spatial distribution can enhance our understanding of plant adaption to the soil environment and agricultural management. Numerical simulation is widely applied in the study of root growth. Architectural and diffusive (spatially continuous) models are two common approaches to simulate two and three-dimensional root growth. The diffusive model omits root structure and treats root development as a diffusion process of carbon, which greatly simplifies computation but retains the ability to simulate root functions, such as water and nutrient uptake. MAIZSIM is a simulator for the growth and development of a maize plant with a 2-D finite element representation of soil physical and chemical processes. However, MAIZSIM currently uses a simple numerical model of 2-D root growth. Therefore, the objectives of this study are to (1) develop a new diffusive root growth model in MAIZSIM; and (2) verify the accuracy and flexibility of the root growth model in describing maize root distributions with respect to experimental data and numerical examples based on literature results, under a variety of climate conditions and agricultural managements. The new root model was written into three modules, which (1) allocates total carbon from plant photosynthesis for root growth based on soil water availability and transpiration demand; (2) assigns new carbon for root growth to selected spatially locations in soil, represented by finite element nodes and pre-defined favorability indices; and (3) calculates the spatial root distribution as a diffusive process of existing roots. Numerical experiments based on published field experiments were performed to assess the validity of this model. The simulated maize root distributions were similar to the observed ones under the influences of soil strength and a variety of soil water conditions, with mass balance errors of carbon <0.5%.Therefore, the root growth model is able to reproduce realistic maize root distributions. Potential applications of this model are provided to demonstrate the versatility of the diffusive root model under specific agricultural management practices, such as “Ridge Furrow Rainfall Harvesting (RFRH)”. The results indicated the simulated root distributions were adaptive to the changes of soil conditions induced by artificial managements. In conclusion, the new diffusive root model developed within MAIZSIM provided an accurate and stable way to simulate maize root growth. This model can be used to evaluate the root growth in response to climate changes or management practices and support comprehensive agricultural simulators that included crop or root growth simulations.