摘要
摘要:砂姜黑土是黄淮海平原重要的中低产土壤, 由于其剖面含有砂姜层, 易产生裂隙, 影响了氮素在土壤剖面的迁移分布, 可能导致砂姜黑土的N₂O排放存在一定的独特性。基于此, 本研究以砂姜黑土小麦-玉米轮作体系为研究对象, 设置4个处理, 分别为不施肥(CK)、传统施肥(TR)、优化施肥(OPT)和再优化施肥(ZOPT), 通过静态箱-气相色谱法结合常规土壤参数的监测与分析, 探究砂姜黑土不同施氮条件下N₂O排放特征、累积排放量及关键驱动因素。结果显示, 砂姜黑土小麦季的N₂O平均排放通量为14.2~21.6 μg·m^?2·h^?1, 累积排放量为0.82~1.24 kg(N)·hm^?2; 玉米季的N₂O平均排放通量为14.4~24.5 μg·m^?2·h^?1, 累积排放量为0.42~0.71 kg(N)·hm^?2; 不同处理小麦季的N₂O累积排放量均高于玉米季。小麦季追肥期与基肥期的N₂O累积排放量分别为0.27~0.41 kg(N)·hm^?2和0.55~0.83 kg(N)·hm^?2, 玉米季分别为0.18~0.30 kg(N)·hm^?2和0.24~0.41 kg(N)·hm^?2, 追肥期N₂O累积排放量均高于基肥期。相关性分析结果显示, CK处理的N₂O排放量与土壤温度、含水量和硝酸盐含量均表现出明显的多元线性相关(P<0.05), TR、OPT和ZOPT仅与土壤硝酸盐含量呈极显著多元线性相关(P<0.01), 而与土壤温度和土壤含水量未表现明显的相关性, 说明施肥条件下, 土壤硝酸盐含量的高低成为影响砂姜黑土农田土壤N₂O排放最关键的影响因素。除此之外, 不同施氮量的N₂O累积排放量差别明显(P<0.05), TR处理的N₂O排放量最高, 小麦玉米季分别为1.24 kg(N)·hm^?2和0.71 kg(N)·hm^?2, 显著高于OPT处理[0.99 kg(N)·hm^?2和0.51 kg(N)·hm^?2]和ZOPT处理[0.82 kg(N)·hm^?2和0.42 kg(N)·hm^?2]。无论小麦季还是玉米季N₂O的累积排放量均随施氮量的增加而呈指数增加趋势, 相关性系数分别达0.997和0.977 (P<0.05), 说明砂姜黑土传统施氮N₂O存在过量排放问题。总而言之, 尽管与其他土壤相比, 砂姜黑土不属于N₂O高排土壤, 但传统施氮量导致的N₂O排放量仍不可忽视。
关键词:砂姜黑土/
N₂O排放/
施氮量/
土壤硝酸盐含量/
静态箱-气相色谱法/
小麦-玉米轮作
Abstract:Lime concretion black soil is an important medium and low-yield soil in the Huanghuaihai Plain. It is prone to cracks because containing a high clay and sand ginger layer, making it unique in nitrogen transport. This study used the wheat and corn rotation system in lime concretion black soil as the research object, researching the N₂O emission characteristics and key driving factors by static box-gas chromatography methods. The experiment included four treatments: no fertilization (CK), traditional fertilization (TR), optimized fertilization (OPT), and re-optimized fertilization (ZOPT). Results showed that the average emission flux of N₂O in the wheat season ranged from 14.2 to 21.6 μg?m^?2?h^?1, and the cumulative emission amount ranged from 0.82 to 1.24 kg(N)?hm^?2; the average emission flux of N₂O in the corn season ranged from 14.4 to 24.5 μg?m^?2?h^?1, the cumulative emission amount ranged from 0.42 to 0.71 kg(N)?hm^?2; the N₂O emission in the wheat season was higher than that in the corn season, and the N₂O emission in the top dressing period of the two seasons was higher than that in the basal fertilizer period, demonstrating that the wheat season and top dressing period were high N₂O emission periods for lime concretion black soil. The correlation analysis results showed that N₂O emission of CK showed a significant multiple linear correlation with soil temperature, water content, and NO₃^?-N content (P<0.05); whereas that of TR, OPT, and ZOPT only showed a significant multiple linear correlation with soil nitrate (P<0.01). There was no significant correlation between soil temperature and soil water content (except in individual cases), indicating that under fertilization conditions, the level of soil nitrate content was the most critical factor affecting N₂O emissions from the farmland of lime concretion black soil. In addition, the cumulative N₂O emissions of different nitrogen application rates were significantly different (P<0.05), and the N₂O emissions of the TR treatment were the highest, which were 1.24 kg(N)?hm^?2 and 0.71 kg(N)?hm^?2, respectively, in the wheat and corn seasons, significantly higher than those of OPT treatment [0.99 kg(N)?hm^?2 and 0.51 kg(N)?hm^?2] and ZOPT treatment [0.82 kg(N)?hm^?2 and 0.42 kg(N)?hm^?2]. The cumulative emissions of N₂O in both the wheat and corn seasons showed an exponentially increasing trend with the increase in nitrogen application, with the correlation coefficients reaching 0.997 and 0.977 (P<0.05), respectively, indicating that the traditional lime concretion black soil nitrogen application had the problem of excessive emissions of N₂O. Overall, compared with other soils, although lime concretion black soil is not a high-emission soil of N₂O, the N₂O emission caused by higher nitrogen application cannot be ignored.
Key words:Lime concretion black soil/
N₂O emission/
Nitrogen fertilizer amount/
Soil nitrate content/
Static chamber-gas chromatography/
Wheat and corn rotation



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