斜发沸石对干湿交替灌溉驱动下稻田氨挥发和氮素淋失的影响机理研究

As a big rice production country, China’s water consumption of rice production accounts for about half of the total water consumption. Excessive fertilizer in paddy field is one of the main causes being responsible for a series of pollution problems of water and soil resources. This study is intended to be conducted at two sites located in central Liaoning and coastal areas, respectively. Clinoptilolite zeolite (CZ) effects of rice crop nitrogen uptake and nitrogen loss under alternate wetting and drying irrigation (AWD) are emphatically evaluated in order to reveal influence mechanism of reduced ammonia volatilization and N leaching by CZ application under AWD after primary understanding of the characteristics of the nitrogen cycle under continuous flood irrigation in paddy field. Oxidation reduction potential, field moisture capacity of water, soil nitrogen mineralization and nitrogen loss characteristics under AWD are mainly observed under different CZ treatments (different dosage and particle size) to elucidate the incentives mechanisms for reducing N loss and the potential of water and fertilizer saving. In addition, ammonia volatilization and N leaching under different CZ cycles are analyzed to clarify the after-effect and long-term effects of CZ. It concludes that it is of importance to conduct this study to provide theoretical basis and technical support for reducing water and nitrogen fertilizer as well as ensuring the sustainability of water and nitrogen fertilizer.

我国是水稻生产大国，水稻生产耗水约占我国农业年耗水量的一半。水稻田化肥的大量施用也是造成水、土资源污染的主要成因之一。为减少稻田用水量和化肥施用量，本研究拟在辽宁中部地区和滨海地区两个灌溉试验站，采用干湿交替灌溉技术,在掌握稻田持续淹灌条件下氮循环特征的基础上，重点研究斜发沸石对水稻氮吸收和稻田氮素损失的影响，探索斜发沸石降低氨挥发和减少氮素淋失的响应机理。通过研究干湿交替灌溉驱动下稻田土壤氧化还原电位、田间持水能力、土壤矿化氮以及氮素流失等特征，阐明在干湿交替灌溉驱动下斜发沸石（不同用量和粒径）降低氮素流失的机制和节水节肥潜力；观察不同斜发沸石施用周期下氨挥发和氮素淋失的差异，摸清斜发沸石的长效性机制，为减少水稻生产用水和氮肥用量并保障水稻生产的可持续性提供理论基础和技术支撑。

为降低水稻生产系统的资源和环境代价，本研究将斜发沸石应用到AWD稻田，通过AWD实现水稻节水，用沸石来减缓稻田氮损失和提高产量，进一步实现水稻绿色高产高效栽培。本研究通过测坑采用裂区试验设计，研究了两种灌溉模式（CF和AWD）和三种沸石量（0 t·ha-1, 5 t·ha-1, 10 t·ha-1）下的田面水氮素变化，氨挥发和氮素淋溶特征；植株和土壤中氮素变化特征；水稻产量和水分利用率。主要研究结果如下：（1）两种灌溉模式下，田面水NH4+-N浓度均随沸石量的增加而显著降低。AWD处理小幅度降低了氨挥发总量。沸石降低了各施肥期的氨挥发量，ICFZ10和IAWDZ10处理分别较ICFZ0处理减少35.1%~36.5%和38.5%~40.6%。（2）在水稻生长季大部分时期，AWD处理淋溶液中氮浓度均大于CF。然而，两种灌溉模式下，淋溶液中氮浓度均随沸石量增加而显著降低，沸石施入缓解了AWD引起的氮素淋失增加的风险。（3）与CF相比，AWD提高了土中无机氮含量，却降低了氮素积累量和转运量。沸石提高了整个水稻生长季0~30 cm土中无机氮含量，进而显著提高了拔节孕穗期后的氮积累和氮转运量。（4）与CF相比，AWD降低了根系伤流强度，叶片SPAD值，拔节孕穗期后的地上部干物质积累量。沸石增加了根系伤流强度，叶片SPAD值，拔节孕穗期后的干物质积累及转运量。（5）与CF相比，AWD显著提高了水分生产率；无沸石施入时，AWD稻田的产量在2016年相对于CF无显著差异，在2017年AWD显著降低了产量。沸石提高了水稻产量和水分生产率。当稻田施用5 t·ha-1沸石时，AWD稻田的产量显著低于CF，而施用10 t·ha-1沸石时，CF和AWD间的产量无显著差异。由此说明AWD条件下需施入更多的沸石来提高产量和水分生产率。（6）与传统的稻田管理模式相比，AWD与施用10 t·ha-1沸石相结合的模式降低了氨挥发损失38.5%~40.6%，且未增加氮素淋失，促进了植株氮素积累，进而提高了产量6.2%~8.3% 和水分生产率19.4%~21.3%。研究结果为实现水稻高产/稳产的前提下，减少水稻生产用水、氮资源消耗和环境代价提供了一种新途径。