NH3 emission responses to irrigation time and the initial moisture from urea applied to three soils in the North China Plain
2021
Dong, Wenxu | Xing, Hanbing | Chen, Suyan | Hu, Chunsheng
Water management affects NH₃ emission in complex ways due to its influence on nitrogen transformation and movement. This study aimed to determine the effect of irrigation timing on NH₃ emission from urea at different initial moistures. A pot experiment was conducted based on three typical soils (Fluvisols, Cambisols, and Luvisols) in the North China Plain. Each soil was treated to three levels of initial moisture (5%, 10%, and 15% w/w) and irrigated with 40 mm water 0, 6, and 12 hr after applying urea. The results showed that NH₃ loss ranged from 0.2 to 14.2 kg N ha⁻¹, with the greatest loss in Fluvisols, followed by Cambisols, and the lowest in Luvisols. The loss of NH₃ increased with initial moisture for all three soils. But there was no significant effect of irrigation time on NH₃ emission, although the contents of NH₄⁺ in surface soil were higher for delayed irrigation than for immediate irrigation. Additionally, the NO₃⁻ content was increased in Luvisols with delayed irrigation at a high initial water content, which may have promoted leaching. Therefore, delaying irrigation by up to 12 hr did not cause a significant increase in NH₃ emission. However, fertilization and irrigation should be carried out with lower moisture, especially for Luvisols to prevent ammonia emission or nitrate leaching.
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