免耕对广东典型稻区早稻稻田甲烷排放特征的影响

发布时间：2018-07-12 17:05

本文选题：免耕 + 甲烷　；参考：《甘肃农业大学》2017年硕士论文

【摘要】：甲烷(CH_4)是造成温室效应的主要温室气体。相同分子数的CH_4温室效应比二氧化碳更高,变暖潜力是二氧化碳的25倍,严重影响着人类的生存环境。而稻田是CH_4的重要排放源,如何减少稻田CH_4的排放对消减温室气体的排放具有重要意义。本研究选取典型亚热带季风性湿润气候区的广东省双季稻区进行定位试验,设置了免耕和常规耕作两种模式,包括常规不施肥、常规施肥、免耕不施肥、免耕施肥4个处理,观测各处理CH_4排放通量的日变化及生育期变化,探究免耕施肥对早稻稻田CH_4排放的影响,并分析了温度、风速、湿度、土壤有机质、土壤pH、土壤酶活等对稻田CH_4排放的影响机制。结果如下:1.水稻分蘖期稻田CH_4排放有明显的日变化特征,各处理稻田CH_4排放趋势一致,排放峰值出现在下午15:00,最低排放值出现在夜晚21:00。CH_4日平均排放量大小为:常规施肥(48.56mg/m~2·h)常规不施肥(24.47mg/m~2·h)免耕施肥(8.88mg/m~2·h)免耕不施肥(1.97mg/m~2·h)。水稻抽穗期稻田CH_4排放的日变化特征不明显,各处理CH_4排放峰值与最低值出现不一致,各处理CH_4日平均通量大小次序为:常规不施肥(19.43 mg/m~2·h)免耕施肥(16.06 mg/m~2·h)免耕不施肥(5.34 mg/m~2·h)常规施肥(4.67 mg/m~2·h)。2.在整个生育期内,免耕处理稻田CH_4的排放通量低于常规处理。各处理稻田CH_4排放的动态变化表现为多峰模式,稻田CH_4排放最高值出现在分蘖期,最低值出现在晒田时(移栽后41天),整个生育期各处理稻田CH_4排放通量均值大小关系为:常规不施肥常规施肥免耕施肥免耕不施肥,分别为25.68mg/m~2·h,19.55 mg/m~2·h,11.67 mg/m~2·h,4.54 mg/m~2·h,免耕处理稻田CH_4排放量比常规处理稻田CH_4排放量低64.16%。3.免耕提高了土壤酶活性,且有利于培肥地力。与常规耕作比较,免耕脲酶、酸性磷酸酶活性分别提高了5.27%-10.85%和5.26%-6.56%,脲酶活性在孕穗期和抽穗期免耕的主效应达到显著水平(P0.05),酸性磷酸酶活性在孕穗期、抽穗期和成熟期免耕的主效应达到显著水平(P0.05)。土壤养分测试结果表明,免耕提高了土壤有机质、铵态氮、硝态氮含量。土壤有机质含量免耕比常规耕作模式提高4.00%-8.92%,并在分蘖期、孕穗期、抽穗期和成熟期的主效应达到显著水平(P0.05);土壤铵态氮含量免耕比常规耕作模式提高16.50%-24.88%,并在孕穗期和抽穗期的主效应达到显著水平(P0.05);土壤硝态氮含量免耕比常规耕作模式提高17.73%,并在孕穗期、抽穗期和成熟期的主效应达到显著水平(P0.05)。但免耕有降低土壤pH的趋势。4.免耕和常规耕作模式稻田CH_4气体的日尺度排放与气温、地表温度、5cm土温、草面温度、绝对湿度、风速等呈正相关关系。土壤pH、土壤有机质、土壤铵态氮含量及土壤脲酶活性均与CH_4排放通量为正相关关系,土壤硝态氮含量与稻田CH_4排放量相关性不显著。
[Abstract]:Methane (CH4) is the main greenhouse gas that causes Greenhouse Effect. CH4 Greenhouse Effect with the same molecular number is higher than carbon dioxide, and the warming potential is 25 times higher than that of carbon dioxide, which seriously affects the living environment of human beings. The rice field is an important source of CH4 emission. How to reduce CH4 emission from paddy field is of great significance to reduce the greenhouse gas emission. In this study, two models of no-tillage, conventional tillage, no-tillage and no-tillage fertilization were established. The effects of no-tillage fertilization on CH4 emission from early rice paddy field were investigated by observing the diurnal variation of Ch _ 4 emission flux and growth period of various treatments, and the temperature, wind speed, humidity and soil organic matter were analyzed. Effects of soil pH and soil enzyme activity on CH4 emission from paddy field. The result is as follows: 1. CH4 emission from rice field at tillering stage showed obvious diurnal variation, and the CH4 emission trend of all treatments was the same. The emission peak appeared at 15: 00 in the afternoon, and the lowest emission value appeared at 21: 00.CH4 at night. The average emission value was: conventional fertilization (48.56mg/m~2 h), conventional no-tillage fertilization (24.47mg/m~2 h), no-tillage fertilization (8.88mg/m~2 h), no-tillage fertilization (1.97mg/m~2 h). H). The diurnal variation of CH4 emission in rice field at heading stage was not obvious. The order of the average fluxes of Ch _ 4 in each treatment was as follows: no fertilization (19.43 mg/m~2 h), no-tillage fertilization (16.06 mg/m~2 h), no-tillage fertilization (5.34 mg/m~2 h), conventional fertilization (4.67 mg/m~2 h) .2. During the whole growth period, Ch _ 4 emission flux of no-tillage treatment was lower than that of conventional treatment. The dynamic change of Ch _ 4 emission in paddy field was multi-peak mode, and the highest value of Ch _ 4 emission in paddy field appeared at tillering stage. The mean value of CH4 emission flux of rice field in the whole growth period was: conventional fertilization, no-tillage, no-tillage and no fertilization. The CH4 emission of no-tillage treatment rice field was 64.16% lower than that of conventional rice field. No tillage increased soil enzyme activity and was beneficial to fertility. Compared with conventional tillage, the activities of urease and acid phosphatase in no-tillage were 5.27-10.85% and 5.26-6.56, respectively. The main effect of no-tillage was significant at booting stage and heading stage (P0.05), and the activity of acid phosphatase was at booting stage. The main effect of no-tillage at heading stage and ripening stage was significant (P0.05). The results of soil nutrient test showed that the content of organic matter, ammonium nitrogen and nitrate nitrogen were increased by no-tillage. The content of soil organic matter in no-tillage was 4.00-8.92 higher than that in conventional tillage, and it was increased at tillering stage and booting stage. The main effects at heading stage and ripening stage were significant (P0.05), the content of soil ammonium nitrogen in no-tillage was 16.50-24.88 higher than that in conventional tillage, and the main effect was significant at booting stage and heading stage (P0.05); No-tillage of soil nitrate content was higher than that of conventional tillage (P0.05). The pattern was increased by 17.73, and at booting stage, The main effects at heading stage and mature stage were significant (P0.05). But no-tillage had the tendency of decreasing soil pH. The diurnal emission of CH4 gas was positively correlated with air temperature, surface temperature (5cm), grass surface temperature, absolute humidity, wind speed and so on. Soil pH, soil organic matter, soil ammonium nitrogen content and soil urease activity were positively correlated with Ch _ 4 emission flux, but no significant correlation was found between soil nitrate nitrogen content and Ch _ 4 emission from paddy field.
【学位授予单位】：甘肃农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X712;S511.31

【相似文献】