Phenology is critical in simulating crop production and hydrology and must be sufficiently robust to respond to varying environments, soils, and management practices. Phenological algorithms typically focus on the air temperature response function and rarely quantify the phenological responses to varying water deficits, particularly for versions of the Environmental Policy Integrated Climate model (EPIC)‐based plant growth component used in many agroecosystem models. Three EPIC‐based plant growth components (Soil Water Assessment Tool [SWAT], Wind Erosion Prediction System [WEPS], and the Unified Plant Growth Model [UPGM]) have been incorporated into the spatially distributed Agricultural Ecosystems Services model [AgES], and only the UPGM includes a phenological response to varying water deficits. These three plant components were used to evaluate the phenological responses of winter wheat (Triticum aestivum L.) to varying water deficits and whether having a water stress factor in UPGM improves the simulation of phenology. A 3‐yr irrigation study and a 4‐yr study across a rainfed landscape were used in the evaluation. Only the UPGM simulated all five of the developmental stagesmeasured. The UPGM was the only component that simulated a phenological response to variable water deficits, resulting in better prediction of phenology. For example, the RMSE (days) and relative error (RE, days) decreased and index of agreement (d) increased in predicting maturity from SWAT (RMSE = 18.4; RE = 9.2; d = 0.34) to WEPS (RMSE = 6.2; RE = 1.0, d = 0.63) to the UPGM (RMSE = 6.1; RE = 0.1; d = 0.70). Incorporating phenological responses to varying water deficits improves the accuracy and robustness of predicting phenology, which is particularly important in spatially distributed agroecosystem models. Core Ideas Phenology is critical in accurately simulating crop production and hydrology. The AgES watershed model evaluated three EPIC‐based plant growth components. Only UPGM was able to simulate phenological responses to varying water deficits. The results promote more robust simulation of phenology in varying environments.

N ational and international openaccess agricultural research databases are needed to help solve problems at watershed, regional, and national scales, and to connect productivity, soil health, and environmental quality to food quantity and quality. There are some established, openaccess agricultural research networks with extensive research data in the United States, but there is a major need to improve connections between those networks and the emerging data in order to address complex questions. Improving the connections and flow of information among agricultural research networks will enhance the scientific community's ability to simultaneously increase crop yield, sustainability of natural resources, and environmental quality, as well as food, feed, and forage quality, and thus human and animal health. Establishing a network of agricultural databases is crucial for facilitating information flow among different research disciplines. Doing so will also enhance multidisciplinary research opportunities and help build transdisciplinary teams that can provide answers to complex, whole-system research questions and thus solve some of the globe's greatest challenges. GLOBAL CHALLENGES The ever-growing human population is facing one of the greatest challenges of the twenty-first century: to ensure the sustainability of agricultural and natural systems. Both are under the pressure of a changing climate and the increase in extreme events that accompanies it. A statement by the United Nations (UN) Secretary General about a special climate change report recently released by the UN Intergovernmental Panel on Climate Change, warns the global community that climate change is occurring at a faster rate than humanity is addressing it and that environmental consequences, including more extreme weather and sea level rise, will continue impacting humanity in the years to come (United Nations 2018).

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