水炭运筹对黑土稻田N2O排放与氮肥利用的影响

为揭示水炭运筹下稻田N2O排放规律，以及各阶段施入氮肥的利用和损失对N2O排放的影响，设置两种水分管理模式(浅湿干灌溉、常规淹灌)和4个秸秆生物炭施用量水平(0、2.5、12.5、25t/hm2)，采用田间小区和15N示踪微区结合的方法，研究不同水炭运筹下稻田N2O排放规律，以及基肥、蘖肥和穗肥的吸收利用率和损失率，并分析了N2O排放量与各阶段施入氮肥的利用率和损失率之间的关系。结果表明：两种灌溉模式水稻本田生长期N2O排放规律不同，浅湿干灌溉模式N2O累积排放量显著高于常规淹灌模式(P<0.05)，施加生物炭能够有效地减少水稻本田生长期N2O排放总量。两种灌溉模式在分蘖期和拔节孕穗期N2O累积排放量较大，浅湿干灌溉模式的各生育期N2O累积排放量均高于常规淹灌，施加生物炭降低了N2O各生育期累积排放量。浅湿干灌溉模式水稻植株对基肥的吸收利用率低于常规淹灌模式，而对蘖肥和穗肥的吸收利用率显著高于常规淹灌(P＜0.05)，施加适量的生物炭能够增加各阶段施入氮肥的吸收利用率。相关性分析表明，浅湿干灌溉模式下N2O排放总量与蘖肥、穗肥吸收利用率呈显著负相关(P<0.05)，与基肥吸收利用率呈极显著负相关(P<0.01)，常规淹灌模式下N2O排放总量与基肥、蘖肥和穗肥吸收利用率均呈极显著负相关(P<0.01)；两种灌溉模式N2O排放总量与基肥和蘖肥损失率均达到显著正相关(P<0.05)。

Effects of Water and Biochar Management on N2O Emission and Nitrogen Use Efficiency in Black Soil Paddy Field

In order to reveal the rule of N2O emission from paddy fields under water and biochar management and the effects of nitrogen use and loss in different stages on N2O emission, two water management modes (dry-wet-shallow, conventional flooding irrigation) and four straw biochar application levels (0t/hm2, 2.5t/hm2, 12.5t/hm2 and 25t/hm2) were set up. The N2O emission from paddy fields, as well as the absorption and utilization efficiency and loss rate of basal fertilizer, tiller fertilizer and panicle fertilizer, were studied by combining field plot and 15N tracer micro plot. The relationship between N2O emission and the use and loss of nitrogen fertilizer in each stage was analyzed. The results showed that the N2O emission patterns of the two irrigation modes were different. The cumulative N2O emissions of the dry-wet-shallow irrigation mode were significantly higher than that of the conventional flooding irrigation mode (P<0.05). The cumulative N2O emissions of the two irrigation modes were larger at tillering stage and jointing booting stage. The cumulative N2O emission of dry-wet-shallow irrigation mode was higher than that of conventional flooding irrigation. The application of biochar reduced the cumulative N2O emission in each growth stage. The absorption and utilization efficiency of basic fertilizer was lower in dry-wet-shallow irrigation mode than that in conventional flooding irrigation mode, but the absorption and utilization efficiency of tiller and panicle fertilizer was significantly higher than that of conventional flooding irrigation (P<0.05). The application of appropriate amount of biochar could increase the absorption and utilization efficiency of nitrogen fertilizer applied in each stage. The correlation analysis showed that the total N2O emission was significantly and negatively correlated with the absorption and utilization efficiency of tiller and panicle fertilizer (P<0.05), and significantly and negatively correlated with the absorption and utilization rate of base fertilizer (P<0.01), and significantly and negatively correlated with the absorption and utilization efficiency of base fertilizer, tiller fertilizer and ear fertilizer under the conventional flooding irrigation mode (P<0.01);the total N2O emission under the two irrigation modes was significantly and negatively correlated with the loss of base fertilizer and tiller fertilizer. The loss rates were significantly and positively correlated (P<0.05).