Abstract:

The rain-fed potato (Solanum tuberosum) field in dryland is an important source of nitrous oxide (N₂O) emission, and one of the current research hotspots of agricultural greenhouse gas emission. Under the promotion of potato as staple food, the potato planting area is expanding continuously. Plastic film mulching and ridge tillage are two important planting methods, but the characteristics of N₂O emission in potato fields under these cultivation practices are not clear. In this study, potato fields under natural precipitation conditions in Wuchuan County, Inner Mongolia Autonomous Region were selected as experimental objects. Four treatments were set up: flat tillage with mulching, ridge tillage with mulching, flat tillage without mulching, and ridge tillage without mulching. Static chamber (dark box)-gas chromatography was used to monitor the N₂O emission flux, and its emission characteristics was analyzed. Real-time fluorescence quantitative PCR technology (q-PCR) was used to detect the abundance of nitrifying bacteria and denitrifying bacteria related to N₂O emissions at different stages, and soil elements were determined to explore the microbial mechanism affecting the characteristics and regularity of N₂O emission from rain-fed potato fields under the conditions of plastic film mulching and ridge tillage. The results showed that the rain-fed potato field was the source of N₂O emissions, with an average cumulative N₂O emission of (0.47±0.08) kg N∙hm⁻² during the whole growth period. In this study, there was a significant positive correlation between N₂O emission flux and soil temperature and moisture content (P<0.05). Ammonia−oxidizing archaea (AOA), rather than ammonia-oxidizing bacteria and denitrifying bacteria, dominated N₂O emission during the whole potato growth period (P<0.05). Both plastic film mulching and ridge tillage can directly or indirectly change the physical properties of soil, leading to changes in the rhizosphere ecological microenvironment, affecting the activities of nitrifying bacteria and denitrifying bacteria, and finally changing the N₂O emission. Among the treatments, the ridging mulching treatment had the highest cumulative N₂O emissions and emission intensity, while the ridging no mulching treatment had the lowest emissions (P<0.05), with accumulations ranging from 0.401 to 0.515 kg∙hm⁻². Therefore, from the perspective of emission reduction without reducing yield, the planting method of ridge tillage without mulching has the most significant effect. This paper aims to provide the theoretical basis for the sustainable development of dryland agricultural production.

Key words: plastic film mulching, ridge tillage, nitrous oxide, potato, impact factor, emission flux

摘要：

旱地雨养马铃薯（Solanum tuberosum）田是一个重要的氧化亚氮（N₂O）排放源，是当前农业温室气体排放的研究热点之一。在马铃薯主粮化战略的推动下，马铃薯种植面积不断扩大，覆膜和垄作栽培是其中两种重要的种植方式，但其栽培下的马铃薯田N₂O排放规律尚不十分明确。选择内蒙古自治区武川县自然降水条件下的马铃薯田为试验对象，设置平作覆膜、垄作覆膜、平作不覆膜和垄作不覆膜4种处理，采用静态箱（暗箱）-气相色谱法监测N₂O的排放通量并分析其排放特征，运用实时荧光定量PCR技术（Real-time quantitative PCR，q-PCR）检测不同时期与N₂O排放相关的硝化菌和反硝化菌丰度，并测定相关的土壤要素，进而探究在覆膜和垄作条件下，影响雨养马铃薯田N₂O排放特性和规律的微生物机理。结果表明，雨养马铃薯田是N₂O排放源，其全生育期内平均N₂O累积排放量为N (0.47±0.08) kg∙hm⁻²。N₂O排放通量与土壤温度、水分含量之间具有显著的正相关关系（P<0.05）。在整个马铃薯生育期，氨氧化古菌（Ammonia-oxidizing Archaea，AOA）基本起到了控制N₂O排放的作用（P<0.05），而不是氨氧化细菌和反硝化菌。覆膜和垄作都可以直接或间接改变土壤物理性质使根际生态微环境发生变化，进而影响硝化菌和反硝化菌的活性，最终使N₂O排放发生变化。其中，覆膜垄作处理的N₂O累积排放量及排放强度最高，且垄作不覆膜处理的排放最少（P<0.05），累积量达到了0.401-0.515 kg∙hm⁻²。因此，从减排和不减产的角度来看，采用垄作不覆膜的种植方式效果最显著，旨在为旱地农业生产的可持续发展提供理论依据。

关键词: 覆膜, 垄作, 氧化亚氮, 马铃薯, 影响因子, 排放通量