Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada; Department of Bioresource Engineering, McGill University, Sainte-Anne-de-Bellevue, QC, Canada.
Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada.
Sci Total Environ. 2020 Aug 1;728:138845. doi: 10.1016/j.scitotenv.2020.138845. Epub 2020 Apr 22.
Assessment of the impact of climate change on agricultural sustainability requires a robust full system estimation of the interdependent soil-plant-atmospheric processes coupled with dynamic farm management. The simplification or exclusion of major feedback mechanisms in modelling approaches can significantly affect model outcomes. Using a biogeochemical model, DNDCv.CAN, at three case-study locations in Canada, we quantified the impact of using commonly employed simplified modelling approaches on model estimates of crop yields, soil organic carbon (SOC) change and nitrogen (N) losses across 4 time periods (1981-2010, 2011-2040, 2041-2070, and 2071-2100). These approaches included using climate with only temperature and precipitation data, annual re-initialization of soil status, fixed fertilizer application rates, and fixed planting dates. These simplified approaches were compared to a more comprehensive reference approach that used detailed climate drivers, dynamic planting dates, dynamic fertilizer rates, and had a continuous estimation of SOC, N and water budgets. Alternative cultivars and rotational impacts were also investigated. At the semi-arid location, the fixed fertilizer, fixed planting date, and soil re-initialization approaches reduced spring wheat (Triticum aestivum L.) yield estimates by 40%, 25%, and 29%, respectively, in the 2071-2100 period relative to the comprehensive reference approach. At both sub-humid locations, the re-initialization of soil status significantly altered SOC levels, N leaching and N runoff in all three time periods from 2011 to 2100. At all locations, SOC levels were impacted when using simplified approaches relative to the reference approach, except for the fixed fertilizer approach at the sub-humid locations. Results indicate that simplified approaches often lack the necessary characterization of the feedbacks between climate, soil, crop and management that are critical for accurately assessing crop system behavior under future climate. We recommend that modellers improve their capabilities of simulating expected changes in agronomy over time and employ tools that consider robust soil-plant-atmospheric processes.
评估气候变化对农业可持续性的影响需要对土壤-植物-大气过程进行稳健的全系统估计，并结合动态农场管理。在建模方法中简化或排除主要反馈机制会显著影响模型结果。本研究使用生物地球化学模型 DNDCv.CAN，在加拿大的三个案例研究地点，量化了在四个时间段（1981-2010 年、2011-2040 年、2041-2070 年和 2071-2100 年）内，使用常用简化建模方法对作物产量、土壤有机碳（SOC）变化和氮（N）损失的模型估计的影响。这些方法包括使用仅包含温度和降水数据的气候、土壤状态的年度重新初始化、固定施肥率和固定种植日期。这些简化方法与更全面的参考方法进行了比较，该方法使用详细的气候驱动因素、动态种植日期、动态肥料率，并对 SOC、N 和水预算进行连续估算。还研究了替代品种和轮作的影响。在半干旱地区，与综合参考方法相比，固定施肥、固定种植日期和土壤初始化方法分别导致春小麦（Triticum aestivum L.）产量在 2071-2100 期间减少了 40%、25%和 29%。在两个亚湿润地区，土壤状态的初始化在 2011 年至 2100 年的所有三个时间段内显著改变了 SOC 水平、N 淋溶和 N 径流。在所有地点，与参考方法相比，使用简化方法都会对 SOC 水平产生影响，除了亚湿润地区的固定施肥方法。结果表明，简化方法通常缺乏对气候、土壤、作物和管理之间反馈的必要描述，这对于准确评估未来气候下作物系统的行为至关重要。我们建议建模者提高随时间模拟农业变化的能力，并使用考虑稳健土壤-植物-大气过程的工具。
