不同水氮管理模式下黑土稻田碳固定与碳减排效应分析

为探寻不同水氮管理模式对黑土稻田碳固定与碳减排效应的影响，进行了田间试验研究。设置常规淹灌(F)与控制灌溉(C)两种灌溉模式，选用110 kg/hm²(N)、99 kg/hm²(N1,减氮10%)、88 kg/hm²(N2,减氮20%)3种施氮量，测定了6种水氮管理模式下的水稻土壤呼吸CO₂排放强度和CH₄排放强度，水稻收获后各器官干物质量、碳含量及固碳量，并计算了净土壤碳收支情况。结果表明，不同水氮管理模式下，各处理土壤呼吸CO₂排放量呈现单峰值变化，并在分蘖期达到峰值；各处理甲烷排放量呈现双峰值变化且在分蘖期与穗肥施入后达到峰值。相同灌溉方式下，随着施氮量的减少，土壤呼吸CO₂排放强度与甲烷排放强度也显著减少(P<0.05)。相同施氮量下，控制灌溉相比常规淹灌有效地降低了甲烷排放强度，但提高了土壤呼吸CO₂排放强度。不同水氮管理模式下，水稻收获后总固碳量为319.37～489.00 g/m^2<...

Carbon Fixation and Carbon Emission Reduction Effects of Different Water and Nitrogen Management Modes in Black Soil Paddy Fields

In order to explore the effects of different water and nitrogen management modes on carbon fixation and carbon emission reduction in black soil paddy fields, a field experiment was conducted. Two irrigation modes of conventional flooding irrigation (F) and controlled irrigation (C) were set up, and three nitrogen application rates of 110kg/hm2(N), 99kg/hm2(N1,10% nitrogen reduction) and 88kg/hm2 (N2,20% nitrogen reduction) were selected. The CO2 emission intensity and CH4 emission intensity of rice soil respiration under six water and nitrogen management modes were measured, and the dry matter quality, carbon content and carbon sequestration of each organ after rice harvest were calculated. The results showed that under different water and nitrogen management modes, the soil respiration CO2 emission intensity of each treatment showed a single peak change, and reached the peak at the tillering stage. The methane emission of each treatment showed a double peak change and reached the peak at the tillering stage and the two time periods after the application of panicle fertilizer. Under the same irrigation method, with the decrease of nitrogen application rate, soil respiration CO2 emission intensity and methane emission intensity were also decreased significantly (P<0.05). Under the same nitrogen application rate, compared with conventional flooding irrigation, controlled irrigation effectively reduced methane emission intensity, but increased soil respiration CO2 emission intensity. Under different water and nitrogen management modes, the total carbon sequestration after rice harvest was 319.37~489.00g/m2. The carbon sequestration of each organ after rice harvest from small to large was leaf, root, stem and spike, which were 5.16%~6.72%, 5.71%~10.78%, 28.62%~36.66% and 49.53%~58.70% of the total carbon sequestration of the plant, respectively. Compared with conventional flooding irrigation, controlled irrigation effectively improved the carbon sequestration capacity of plants. Under different water and nitrogen management modes, the net primary productivity (NPP) and gross primary productivity (GPP) of rice reached the highest in the treatment of 10% nitrogen reduction. Under the same irrigation method, with the increase of nitrogen application rate, the trend showed increase first and then decrease; at the same nitrogen application rate, NPP and GPP under controlled irrigation were higher than those under conventional flooding irrigation. Controlled irrigation had higher production potential than conventional flooding irrigation. Except that the net soil carbon budget of CN treatment was negative, the other treatments were positive, that was, except for CN treatment, the other treatments showed the effect of net soil carbon gain. At the same nitrogen application rate, the net soil carbon gain under conventional flooding irrigation was higher than that under controlled irrigation, but the difference was not significant (P>0.05). With the decrease of nitrogen application rate, the soil carbon budget of each treatment was increased first and then decreased under the same irrigation system. Considering comprehensively, CN1 treatment can improve soil carbon sequestration capacity and reduce soil carbon loss and greenhouse gas emissions from paddy fields under high production capacity.