加气灌溉对不同施氮水平的设施甜瓜土壤CO2和N2O排放的影响

为探讨不同加气灌溉施氮模式下设施甜瓜土壤CO₂和N₂O排放的动态变化规律及其与土壤温度、湿度的关系,本研究采用密闭静态箱-气相色谱法对加气灌溉不同施氮水平下土壤CO₂和N₂O排放进行监测,并分析了加气灌溉对不同施氮量下土壤CO₂和N₂O排放的影响.试验采用加气灌溉(AI)和不加气灌溉(CK)两种灌溉方式,施氮量设不施氮(N₁)、传统施氮量的2/3(150 kg·hm^-2,N₂)和传统施氮量(225 kg·hm^-2,N₃)3个施氮水平.结果表明:加气灌溉土壤CO₂和N₂O排放量高于不加气灌溉处理,但是差异不显著;相同灌溉模式下,CO₂和N₂O排放量随施氮量的增加而显著增加,施氮量是土壤CO₂和N₂O排放的主要影响因素.加气灌溉条件下,不同施氮处理N₂O排放通量与土壤温度和湿度呈显著正相关,CO₂排放通量与土壤温度呈显著正相关.加气减氮处理在氮肥减少1/3的情况下,甜瓜产量提高了6.9%,温室气体排放引起的增温潜势值从9544.82 kg·hm^-2下降到9340.72 kg·hm^-2.综上,通过加气灌溉减少氮肥施用量来抑制农业生产系统中温室气体排放是可行的.

Effects of aerated irrigation on CO2 and N2O emission from protected melon soils under different nitrogen application levels

To reveal the effects of coupling nitrogen (N) application and aerated irrigation on soil CO₂ and N₂O emission, and their relationship with soil temperature and moisture, an experiment was conducted in greenhouse melon fields by using the method of static chamber/gas chromatography to determine the CO₂ and N₂O emissions of different nitrogen rates under aerated irrigation. There were two irrigation factors (AI: aerated irrigation; CK: conventional irrigation) and three N levels (N₁: 0; N₂: 150 kg·hm^-2, the traditional nitrogen application rate was 2/3; N₃: 225 kg·hm^-2, traditional nitrogen application rate). The results showed that soil CO₂ and N₂O emissions in AI treatment were higher than those in CK, but no significant difference was observed between the two irrigation methods. Under the same irrigation method, soil CO₂ and N₂O emission significantly increased with the increases of N application rate, indicating that N application was the main influencing factor for CO₂ and N₂O emissions. There were significant positive relationships between soil N₂O emissions and soil temperature and water filled pore space (WFPS) under the AI treatment. Soil CO₂ emission were positively correlated with soil temperature. When N application reduced to N₂ rate under AI treatment, the yield was increased by 6.9% and the greenhouse warming potential was reduced from 9544.82 kg·hm^-2 to 9340.72 kg·hm^-2. Thus, it is feasible to reduce the amount of N fertilizer under AI treatment to mitigate greenhouse gas emission in agricultural production systems.