水氮运筹影响高留残茬黑土稻田碳收支机理分析

为探明水氮运筹对稻田生态系统碳收支的影响，开展大田试验，设置浅湿干灌溉（D）和淹水灌溉（F）两种灌溉模式，及110kg/hm2（当地施肥标准，N1）、99kg/hm2（减氮10%，N2）和88kg/hm2（减氮20%，N3）3个施肥水平，观测高留残茬稻田水稻收获后不同器官的干物质量及碳含量，同时监测稻田CO2和CH4排放通量，计算水稻净初级生产力（NPP）和稻田净生态系统初级生产力（NECB）。结果表明：水氮运筹会影响稻株各器官干物质及碳含量，所有处理中DN2处理NPP最大（8918.02kg/hm2），浅湿干灌溉模式各处理NPP均大于淹水灌溉模式，分别增加12.13%、36.73%、8.01%；浅湿干灌溉模式增加了稻田土壤呼吸的CO2排放通量，减施氮肥则降低了CO2排放通量，浅湿干灌溉减施氮肥降低了CH4排放通量；两种灌溉模式下各处理CO2和CH4排放总量均随氮肥施用量减少而降低，淹水灌溉模式下各处理CH4排放总量均显著高于浅湿干灌溉模式（P＜0.05）；各处理稻田生态系碳净收支均为正值，黑土区高留残茬稻田生态系统表现为碳“汇”，其中DN2处理NECB最高，为1950.96kg/hm2。综合来看，浅湿干灌溉模式+减氮10%处理的稻田生态系统碳“汇”最强。研究可为寒地黑土保护提供理论参考和技术支撑。

Effect of Water and Nitrogen Management on Carbon Budget in Black Soil Rice Fields with High Residual Stubble

To investigate the impact of water and nitrogen management on the carbon budget of rice field ecosystems, field experiments were conducted, with two irrigation modes: dry-wet-shallow irrigation (D) and flooded irrigation (F), as well as three fertilization levels: 110kg/hm2 (local fertilization standard, N1), 99kg/hm2 (nitrogen reduction of 10%, N2), and 88kg/hm2 (nitrogen reduction of 20%, N3). The dry matter quality and carbon content of different organs of rice harvested in residual rice fields were observed, the CO2 and CH4 emissions fluxes from rice fields were simultaneously monitored, and the net primary productivity (NPP) of rice and the net ecosystem primary productivity (NECB) of rice fields were calculated. The results showed that water and nitrogen management would affect the dry matter and carbon content of various organs in rice plants. Among all treatments, the NPP of DN2 treatment was the highest (8918.02kg/hm2), and the NPP of dry-wet-shallow irrigation mode was greater than that of flooded irrigation mode, increasing by 12.13%, 36.73%, and 8.01%, respectively. The dry-wet-shallow irrigation mode increased the CO2 emission flux of rice field soil respiration, reduced the application of nitrogen fertilizer reduced the CO2 emission flux, and reduced the application of nitrogen fertilizer in dry-wet-shallow irrigation reduced the CH4 emission flux. The total emissions of CO2 and CH4 from each treatment under both irrigation modes dwere ecreased with the decrease of nitrogen fertilizer application. The total emissions of CH4 from each treatment under flooded irrigation mode were significantly higher than those under dry-wet-shallow irrigation mode (P<0.05). The net carbon budget of the rice field ecosystem under each treatment was positive,and the rice field ecosystem with high residual stubble in the black soil area showed a carbon “sink”, with the highest NECB of 1950.96kg/hm2 in the DN2 treatment. Overall, the carbon sink of the rice field ecosystem treated with dry-wet-shallow irrigation mode and 10% nitrogen reduction treatment was the strongest, and the research results can provide theoretical reference and technical support for the protection of black soil in cold regions.