改性生物炭施用双减稻田NH3挥发与N2O排放效果及机制研究

Ammonia (NH3) volatilization and nitrous oxide (N2O) emission are the main nitrogen loss paths in rice paddy field, which result in lower nitrogen usage efficiency and threat the water and air quality. Therefore, it is imperative to control the NH3 and N2O losses from rice paddy，especially find a counter measure which can simultaneously reduce the NH3 volatilization and N2O emission. Modified biochar, which can effectively adsorb the nitrogen, improve the soil prosperity and the microbial community structure and function, has the potential of reducing the NH3 volatilization and N2O emission from rice paddy soil simultaneously. However, it is unclear what the impacts and mechanisms of modified biochar on reducing the NH3 volatilization and N2O emission in field-scale. In this study, we will examine the effect of amendment of modified biochar on simultaneously reducing NH3 volatilization and N2O emission from rice paddy soil through a two-year consecutive field trial and a 15N-labeled experiment on two sites (Yixing and Changshu with Typic Hapli-Stagnic Anthrosols and Hapli-Stagnic Anthrosols, respectively). Meanwhile, a proper modified biochar applied rate will be proposed. During the key rice growth stage when NH3 volatilization and N2O emissions occurred, soil and water samples will be collected for determination of physical and chemical properties of water-soil interface, nitrogen nitrification-denitrification potential and the change of nitrogen cycling related functional microbes. Based on these results, the impact of modified biochar application on simultaneously reducing NH3 volatilization and N2O emission from flooded rice paddy will be well-known and the influence mechanisms will be defined. The findings will provide reliable scientific basis and data support for reducing the NH3 volatilization and N2O emission from rice paddy field.

氨（NH3）挥发与氧化亚氮（N2O）排放是稻田土壤氮素损失的重要途径，不仅降低氮素利用率，而且严重影响水体与大气环境，因此减控NH3挥发与N2O排放意义重大。找寻一种能够双减二者损失的措施是研究的关键点。改性生物炭可有效吸附氮，并具有改良土壤，改善微生物群落结构与功能的能力，有实现双减稻田NH3挥发与N2O排放的潜力，但其田间应用效果及机制需要评价与明确。本研究拟在太湖地区通过两年两点（宜兴：黄泥土；常熟：乌栅土）田间小区试验及微区15N标记试验评价改性生物炭对NH3挥发与N2O排放的影响规律及双减效果，并提出适宜施用量。主要对NH3挥发与N2O排放发生关键时期的水土界面理化性质、土壤氮硝化-反硝化势、土壤脲酶活性与氮循环功能微生物结构进行重点测定与分析，以阐明改性生物炭施用双减稻田NH3挥发与N2O排放的作用机制。研究结果将为实现稻田NH3挥发和N2O排放的双减提供科学依据和数据支撑。

氨（NH3）挥发与氧化亚氮（N2O）排放是稻田土壤氮素损失的重要途径，不仅降低氮素利用率，而且严重影响水体与大气环境，因此减控NH3挥发与N2O排放意义重大。找寻一种能够双减二者损失的措施是研究的关键点。改性生物炭可有效吸附氮，并具有改良土壤，改善微生物群落结构与功能的能力，有实现双减稻田NH3挥发与N2O排放的潜力，但其田间应用效果及机制需要评价与明确。本研究拟通过两年连续观测试验评价改性生物炭对NH3挥发与N2O排放的影响规律及双减效果，并提出适宜施用量。主要对NH3挥发与N2O排放发生关键时期的水土界面理化性质及氮循环功能微生物结构进行重点测定与分析，以阐明改性生物炭施用双减稻田NH3挥发与N2O排放的作用机制。该项目通过2年连续试验，证明不同用量改性生物炭的施用均可有效地同时减少2类稻田土壤的稻季氨挥发与氧化亚氮排放，减排效率可达16.5‒62.5%和33.3‒43.6%，其中施用当季的氨挥发减排效果优于第二季。改性生物炭发挥双减作用的关键机制是调控土壤/田面水的pH值，及NH4+-N/NO3‒-N含量等。改性生物炭的施用有利于土壤氮素的固持减排，而且具有提升第二季水稻产量的益处。该项目研究成果为适量生物炭可持续地应用于稻田生态系统，实现氮素高效利用与环境减排提供了技术支撑与理论依据。