【作者】 李洁静；

【导师】 潘根兴；

【作者基本信息】 南京农业大学 ， 土壤学， 2009， 硕士

【摘要】 农田生态系统碳循环是陆地生态系统碳循环的重要组成部分,也是受人类活动影响最为强烈的生态系统,对维持全球的碳平衡具有重要的贡献。稻田是农业土地利用类型的主要方式之一,在世界农业生产中起着举足轻重的作用,并且对陆地生态系统碳循环、大气温室气体的吸收／排放以及全球气候变化起着不容忽视的影响。稻田土壤与大气间CO2交换特征及其影响因素是碳循环研究的重要内容,其研究不仅是碳循环过程机理和调控机制以及模型模拟所必需的,而且可以为估算和评价稻田生态系统碳源／汇强度及其对大气CO2浓度变化的贡献提供科学依据。因此,本文以太湖稻-油轮作和红壤稻-稻生态系统为研究对象,利用历年作物产量、凋落物固碳、土壤有机碳含量、农田CO2排放等实测资料以及生态系统的物质投入和管理投入等调查资料,估算了该系统的年碳平衡和经济收益。同时,在实验室分析测定了太湖地区农田生态系统不同施肥处理下凋落物的碳含量,以期为完整的全碳分析提供数据支持。主要研究结果如下：1红壤地区供试稻田生态系统早稻季和晚稻季无论从碳投入-排放还是经济投入-收益上都没有显著差异,且均表现出有机无机肥配施>单施化肥>对照的效果。将红壤稻-稻系统和太湖稻-油轮作统作比较,红壤系统可以通过较小的碳投入和经济投入获得较高的碳汇效应,但经济收益不及太湖地区。综合比较可以得出,水田耕作相对于旱作有更高的碳汇效应及经济收益,并且,合理的有机无机肥配施可以达到经济效益和环境效益的双赢。2太湖供试稻田在水稻季和油菜季四种施肥处理下作物凋落物及根系含碳量都有一定的显著性差异。但无论水稻季还是油菜季,凋落物含碳量和根系含碳量没有一致的变化趋势。水稻季和油菜季NF处理的凋落物及根系固碳总量均远远低于其余三种施肥处理,化肥、常规、和秸秆处理的凋落物及根系固碳总量水稻季秸秆<常规<化肥,油菜季常规<化肥<秸秆。水稻季四种处理下凋落物及根系固碳量占作物固碳的百分比为4.0%(秸秆)-6.1%(无肥),油菜季为15.0%(常规)-24.4%(化肥)。3太湖地区供试土壤在4种施肥处理下的碳汇量和经济效益均存在显著差异。水稻季4种施肥处理均为碳汇,且有机肥处理高于化肥和无肥处理；油菜季无肥处理为弱的碳源,其余3种施肥处理为碳汇,但碳汇量低于水稻季；从全年总碳汇量来看,4种施肥处理的碳汇效应表现为：秸秆>常规>化肥>无肥。水稻季经济效益为施肥处理高于无肥处理,且有机肥处理的经济效益最好；油菜季无肥处理经济效益极低,其余3个处理经济效益为常规>秸秆>化肥；全年经济效益除无肥处理外,其余3个施肥处理均较高。总体来看,有机无机肥配施处理净碳汇效应明显高于无肥和化肥处理,而且可以取得更高的经济效益,因此,有机无机肥配施处理无论从作物产量,净碳汇量还是经济效益方面,都有较高的价值体现,是一种可持续的稻田管理措施。更多还原

【Abstract】 Carbon cycling of cropland ecosystem is an important part of terrestrial carbon cycling. Cropland ecosystem is also an ecosystem strongly influenced by human activities. It has great contributions to sustain Global carbon balancing. Paddy is a main style of agricultural land use. It plays an important role in world agricultural production, and is of significance in terrestrial carbon cycling, the adsorption/emission of greenhouse gas and global climate change. The CO2 exchange characteristics between paddy soil and atmosphere and related affecting factors are main contents in carbon cycling research. It is not only necessary in the mechanism of carbon cycling process, control mechanism and model simulation, but also provides scientific basis for estimating and evaluating the carbon source/sink density and its contribution to concentration varieties of atmospheric CO2 in cropland ecosystem. Therefore, taking long-term fertilized rice-rape rotation system in Tai Lake region and early rice-late rice ecosystem in red soil region as test objective, its annual carbon balance and economic benefit were estimated, based on the measurement of past years grain yield, litter C content, SOC and field CO2 emission as well as the investigation of material and management inputs. Meanwhile, determining and analyzing C contents in litters in cropland ecosystem in Tai Lake region under different fertilizer treatments was carried out in laboratory to provide data validation for full carbon analysis. Main conclusion can be summarized as follow:1 The experimental croplad ecosystem, not only in early rice season but also in late rice season for red soil, didn’t show significant difference in both carbon input-emission and economic cost-benefit, with the trend of combined inorganic/organic fertilization> chemical fertilizers only> no fertilization. Compared with the rice-rape rotation system in Tai Lake region, the rice-rice cultivation system in red soil region had less economic benefits while obtained higher carbon sink effect with less carbon and economic input. Above all, the underwater cultivation had higher carbon sink effect and economic benefits than dry cropping and reasonable inorganic/organic fertilization could promise win-win benefit for economy and environment.2 The carbon content in both litters and roots in rice and rape season in Tai Lake region had significant difference under four different fertilizer treatments. But it had no coincident varieties in each season. The carbon gross in roots under no fertilization was far lower than that under other three fertilizer treatments, and the trend was combined fertilization of chemical fertilizers with straw return< combined fertilization of chemical fertilizers with manure return< chemical fertilizers only in rice season, while it was combined fertilization of chemical fertilizers with manure return< chemical fertilizers only< combined fertilization of chemical fertilizers with straw return in rape season. The carbon sequestered in litters and roots accounted for 4.0%under combined fertilization of chemical fertilizers with straw return to 6.1%under no fertilization in carbon sequestered in crop in rice season, and was 15.0%under combined fertilization of chemical fertilizers with manure return to 24.4%under chemical fertilizers only that of rape season.3 Both the carbon sink and economic benefits have significant difference under four different fertilizer treatments in Tai Lake region. The four treatments were proved to be carbon sink in rice growing season, and the carbon sink under combined fertilization was higher than those under no fertilization and chemical fertilizers only; No fertilizer treatment was carbon source in rape growing season, the other 3 fertilizer treatments were carbon sink, but lower than that in rice season; as to the annual carbon sink, the effect of carbon sink was shown as:combined fertilization of chemical fertilizers with straw return> combined fertilization of chemical fertilizers with manure return> chemical fertilizers only> no fertilization. The economic benefits under fertilized treatments were higher than that under no fertilization, and combined inorganic/organic fertilization had highest economic benefits in rice season; the economic benefits under no fertilization was lowest, the other 3 treatments behaved as combined fertilization of chemical fertilizers with manure return> combined fertilization of chemical fertilizers with straw return> chemical fertilizers only in rape season; as to the annual economic benefits, all the treatments had higher benefits besides no fertilization treatment. Overall, the combined inorganic/organic fertilizer treatments obviously had higher net carbon sink than no fertilization and chemical fertilizers only, and could get higher economic benefits as well. Therefore, combined inorganic/organic fertilization was superior to the other treatments in yield, net carbon sink and economic benefits and could be taken as a sustainable cropland management countermeasure.更多还原