Process-based vegetative growth model for cereal rye winter cover crop using object-oriented programming and linked-list data structure

Authors: WANG, ZHUANGJI - University Of Maryland; Timlin, Dennis; THAPA, RESHAM - Tennessee State University; Fleisher, David; BEEGUM, SAHILA - University Of Nebraska; Han, Eun Jin; Schomberg, Harry; Mirsky, Steven; SUN, WENGUANG - Colorado State University; Reddy, Vangimalla; HORTON, ROBERT - Iowa State University; TULLY, KATHERINE - University Of Maryland

Submitted to: Agriculture, Ecosystems & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2025
Publication Date: 1/27/2025
Citation: Wang, Z., Timlin, D.J., Thapa, R., Fleisher, D.H., Beegum, S., Han, E., Schomberg, H.H., Mirsky, S.B., Sun, W., Reddy, V., Horton, R., Tully, K. 2025. RYESIM: Process-based vegetative growth model for cereal rye winter cover crop using object-oriented programming and linked-list data structure.. Agriculture, Ecosystems and Environment. 231(2025):109964. https://doi.org/10.1016/j.compag.2025.109964.
DOI: https://doi.org/10.1016/j.compag.2025.109964

Interpretive Summary: Many environmental factors can affect the management of a cereal rye cover crop. Simulation models can be an important tool to assess the cereal rye biomass accumulation and nitrogen update during the cover crop period. RYESIM is a newly developed crop growth model for a cereal rye winter cover crop. RYESIM uses advanced data structures and programming approaches to model the growth of cereal rye organs (e.g., leaf, internode, and tiller), as well as the plant photosynthesis and root nitrogen (N) uptake over a whole field. Time-continuous tiller number, leaf area, biomass, and N mass can be simulated over the entire winter cover crop season, and RYESIM can provide reasonable simulation results compared to field measurements and existing datasets. The plant simulations illustrate the growing of cereal rye and provide information for the cover crop management. The RYESIM model structure can also be a reference point for future cash crop model development (especially for “multi-tiller plants,” such as wheat and rice). Therefore, RYESIM presented in this study is important for model developers, model users and experimental scientists in agroecosystem and agricultural production.

Technical Abstract: Cereal rye (Secale cereale L.) as a winter cover crop has been extensively studied in conservation agriculture using experimental and modeling approaches. However, previous studies generally modeled cereal rye as a cover crop by modifying existing cash crop models (e.g., wheat). We present a newly developed cereal rye vegetative growth model. The new model, namely RYESIM, employs object-oriented programming techniques and a linked-list data structure to present the emergence order of cereal rye organs (e.g., leaf, internode, and tiller). Individual organs are abstracted as “classes,” which encapsulate organs’ morphological features and emergence-growth-senescence processes as member variables and functions. Multiple organs are assembled based on the tiller hierarchy to formulate the cereal rye plant architecture. RYESIM also contains “representative plant” as an average among multiple individual plants. The representative plant bridges individual organs’ growth and field-scale averaged plant morphology, as well as ensuring plant-level biomass and nitrogen (N) mass balance. Existing soil (2DSOIL) and biochemical photosynthesis models are incorporated to estimate soil water-nutrient supply, carbon assimilation and transpiration. RYESIM is evaluated using published field data measured in the Mid-Atlantic region of the USA. Compared to observed values, the relative mean absolute errors of RYESIM for tiller number, aboveground biomass and N mass are within 0.3, 0.4 and 0.5 (with exceptions), and in general, the RYESIM simulated values are within the value ranges from literature results. Therefore, RYESIM provides effective simulations on cereal rye vegetative growth, and the RYESIM model structure also provides a paradigm for future “multi-tiller” cash crop model development.