Jashanjeet Kaur Dhaliwal, Dinesh Panday, G Philip Robertson, Debasish Saha
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引用次数: 0
Abstract
Soil nitrous oxide (N2O) emissions exhibit high variability in intensively managed cropping systems, which challenges our ability to understand their complex interactions with controlling factors. We leveraged 17 years (2003-2019) of measurements at the Kellogg Biological Station Long-Term Ecological Research (LTER)/Long-Term Agroecosystem Research (LTAR) site to better understand the controls of N2O emissions in four corn-soybean-winter wheat rotations employing conventional, no-till, reduced input, and biologically based/organic inputs. We used a random forest machine learning model to predict daily N2O fluxes, trained separately for each system with 70% of observations, using variables such as crop species, daily air temperature, cumulative 2-day precipitation, water-filled pore space, and soil nitrate and ammonium concentrations. The model explained 29%-42% of daily N2O flux variability in the test data, with greater predictability for the corn phase in each system. The long-term rotations showed different controlling factors and threshold conditions influencing N2O emissions. In the conventional system, the model identified ammonium (>15 kg N ha-1) and daily air temperature (>23°C) as the most influential variables; in the no-till system, climate variables such as precipitation and air temperature were important variables. In low-input and organic systems, where red clover (Trifolium repens L.; before corn) and cereal rye (Secale cereale L.; before soybean) cover crops were integrated, nitrate was the predominant predictor of N2O emissions, followed by precipitation and air temperature. In low-input and biologically based systems, red clover residues increased soil nitrogen availability to influence N2O emissions. Long-term data facilitated machine learning for predicting N2O emissions in response to differential controls and threshold responses to management, environmental, and biogeochemical drivers.
期刊介绍:
Articles in JEQ cover various aspects of anthropogenic impacts on the environment, including agricultural, terrestrial, atmospheric, and aquatic systems, with emphasis on the understanding of underlying processes. To be acceptable for consideration in JEQ, a manuscript must make a significant contribution to the advancement of knowledge or toward a better understanding of existing concepts. The study should define principles of broad applicability, be related to problems over a sizable geographic area, or be of potential interest to a representative number of scientists. Emphasis is given to the understanding of underlying processes rather than to monitoring.
Contributions are accepted from all disciplines for consideration by the editorial board. Manuscripts may be volunteered, invited, or coordinated as a special section or symposium.