水氮管理对黑土稻作土壤碳氮磷化学计量特征的影响

为阐明不同水氮管理模式对黑土稻作产量和土壤碳氮磷化学计量特征的影响。设置3种灌溉模式（常规淹灌、浅湿灌溉、控制灌溉）和4种氮肥梯度（0、85、110、135 kg/hm2）,探究水稻产量、土壤碳氮磷含量、化学计量比及层化率对不同水氮管理模式的响应规律。结果表明：控制灌溉模式下,水稻通过形成足量大穗提高库容,小幅增加结实率,从而显著提高产量（p<0.05）。稻田土壤有机碳（SOC）、土壤总氮（STN）、土壤总磷 (STP) 含量随土层深度增加而降低,施氮处理可显著提升SOC、STN含量并降低STP含量（p<0.05）。常规淹灌模式增加SOC、STN含量,控制灌溉模式增加STP含量。土壤C/N随施氮量增加而降低,土壤C/P、N/P随施氮量增加而升高,施氮能提升不同土层平均C/N层化率,降低C/P、N/P层化率。相比常规淹灌,控制灌溉模式能提升不同土层SOC、STP含量层化率,在一定程度上说明控制灌溉配施适宜氮肥可以改善土壤质量,综合考虑CN2为最优水氮管理方式。

Effects of water and nitrogen management on stoichiometric characteristics of soil carbon, nitrogen and phosphorus in black soil rice farming area

In order to elucidate the effects of different water and nitrogen management modes on rice yield and soil carbon, nitrogen and phosphorus stoichiometry characteristics in black soil. 3 irrigation modes (conventional flooding irrigation, shallow wet irrigation, controlled irrigation) and 4 nitrogen gradients (0, 85, 110, 135 kg/hm2) were set up to explore the response of rice yield, soil carbon, nitrogen and phosphorus content, stoichiometric ratio and stratification rate to different water and nitrogen management modes.The results showed that under controlled irrigation mode, the storage capacity of rice was increased by forming sufficient large panicles,and the seed setting rate was slightly increased, which significantly increased the yield (p<0.05). The content of soil organic carbon (SOC), soil total nitrogen (STN), and soil total phosphorus (STP) in paddy soil decreased with increasing soil depth. Nitrogen application treatments significantly increased SOC and STN contents and decreased STP content(p<0.05). SOC and STN contents were increased in conventional flooding irrigation mode, and STP content was increased in controlled irrigation mode. Soil C/N decreased with the increase of nitrogen application rate, and soil C/P and N/P increased with the increase of nitrogen application rate. Nitrogen application could improve the average C/N stratification rate of different soil layers, and reduce the C/P and N/P stratification rates. Compared with conventional flooding irrigation, the controlled irrigation mode could improve the stratification rates of SOC and STP contenst in different soil layers. To some extent, it indicated that controlled irrigation with appropriate nitrogen fertilizer could improve soil quality. Overall, CN2 was considered as the optimal water and nitrogen management method.