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不同水肥管理措施对新疆绿洲棉田土壤CO2排放的影响
牛百成
学位类型硕士
导师冯广龙 ; 赵成义
2016
学位授予单位中国科学院大学
学位授予地点北京
学位专业水土保持与荒漠化防治
关键词绿洲棉田 秸秆还田 干湿交替 施氮肥 土壤co2排放
摘要目前,农田管理措施对农田生态系统碳循环和全球变暖的影响已成为研究的热点。如果能长期和准确的测定农田管理措施对于农田土壤碳库的影响,就能为评价陆地生态系统碳源、汇以及全球气候变化等方面提供强有力的依据。本研究基于新疆阿克苏站,以绿洲棉田土壤为研究对象,开展不同还田方式对棉花秸秆腐解速率的影响,棉花秸秆下土壤CO2时空分布特征,干湿交替(灌溉引起的)及秸秆和氮肥对土壤CO2排放影响的研究。本研究主要得出以下结论: 1基于尼龙网袋法研究不同还田方式对棉花秸秆腐解速率的影响,结果表明:1)棉花秸秆还田后腐解速率均表现为前期较快,后期较慢的特点;2)还田量对秸秆腐解速率无显著影响(P>0.05)。3)秸秆还田后90d内,表现为粉碎度越小,越有利于腐解,但在此后,粉碎度对秸秆腐解速率已无显著影响(P>0.05)。4)从棉花秸秆还田深度对秸秆腐解百分率的影响看,表层处理的腐解百分率最小,埋深10cm处理的腐解百分率居中,埋深20cm处理的秸秆腐解百分率最高。 2基于静态箱法和气井法,研究棉花秸秆还田下绿洲棉田土壤CO2浓度和通量的时空分布特征。结果表明:棉花秸秆还田下土壤CO2浓度与通量具有明显的时空变化特征。均表现为7月份出现峰值,10月份出现低值,但与NS(对照组)相比,棉秆还田处理的土壤CO2浓度与通量在5月份也出现峰值。土壤CO2浓度随土壤深度的增加而增加,但棉秆还田对土壤CO2浓度的垂直分布影响不大(0~30cm)。土壤CO2浓度和通量均随秸秆还田量的增加而增加,但加倍量棉秆还田的土壤CO2浓度和通量均显著高于其他处理(P < 0.05)。此外,不同处理的土壤CO2浓度与通量之间均呈现显著相关(P < 0.05),相关系数随棉秆还田量的增大而增大,即土壤CO2通量强烈依赖于土壤CO2浓度。 3通过室内模拟土壤含水量和干湿交替对土壤CO2排放的影响,结果表明:1)与60%WFPS(土壤充水孔隙度)处理相比,40%WFPS处理对土壤CO2排放起到显著抑制作用(P < 0.05), 而80%WFPS处理对土壤CO2排放速率影响较小(P>0.05)。2)多次干湿交替循环后,干湿交替处理的土壤CO2累积排放量显著低于恒湿处理(P < 0.05)。在不同干旱强度处理中, SD(强度干旱)处理对土壤CO2排放速率造成的影响变化幅度显著大于MD(适度干旱)处理,但多次干湿交替循环后,SD处理的土壤CO2累积排放量却显著小于MD处理。随干湿交替循环次数的增加,对土壤CO2排放速率造成的影响幅度显著降低。干湿交替能降低土壤CO2排放量,降低量随干旱强度增大而增大。 4通过室内模拟秸秆和氮肥对土壤CO2排放的影响,结果表明:1)施加棉花秸秆显著增加了土壤CO2排放量和土壤有机碳含量(P <0.05),而施氮肥对土壤CO2排放量及土壤有机碳含量无显著影响(P > 0.05)。2)以CO2形式排放出去的碳占秸秆腐解产生总碳量的百分比来看,在MS(适量秸秆)和LN(低氮量)水平下最高,分别为48.71和50.72%,而在H1S(高量秸秆)和0N(不施氮肥)水平下最低,分别为46.68和45.94%。3)从秸秆还田量和施氮量对EF(秸秆碳排放系数)的影响来看,在MS和0N水平下最高,分别为36.68和35.71%,而在H1S和HN(高氮量)水平下最低,分别为33.53和34.86%,但从每个处理来看EF不是一个常数。
其他摘要The effects of farmland managements on soil CO2 emissions have become one of the important part of the global carbon cycle and global warming researches. If the effects of farmland managements on farmland soil carbon library measure by long time and accurate measurements would provide prerequisite and foundation of assessing the function of terrestrial ecosystem in carbon source and carbon sink and predicting response of ecosystem to climate change. This study was conducted at Aksu station in Xinjiang,and oasis cotton soil was selected as the subject in this thesis. To carry out the effect of different cotton straw returned ways on decomposition, and the spatial and temporal distribution characteristic of soil CO2 under cotton straw returned, and drying-wetting alteration (caused by irrigating) and straw and nitrogen application on soil CO2 emissions, the main results were listed as follows: 1 To study the effects of different cotton straw returned ways on decomposition rates, using the nylon mesh bags method, we found that: 1) The decomposition rate of cotton straw returned was faster at the initial stage decomposition but then slowed down right through the final stage of decomposition. 2) There was no significant effects of cotton straw returned amounts on decomposition rates (P>0.05). 3) After 90d’s straw returned, the less length of cotton straw was beneficial to decompose. But then, there was no significant effect cotton straw returned of length on decomposition rates (P>0.05). 4) The effects of different depths of cotton straw returned on decomposition rates showed that the decomposition ratios of surface was minimum, the depth of 10cm was mediate, and the depth of 20cm was maximum. 2 The spatial and temporal distributions of soil CO2 concentration and efflux under cotton straw returned were conducted by using closed chamber method and diffusion chamber technique in oasis arid areas. The soil CO2 concentration and efflux of temporal variations exhibited similar pattern, with a peak in July and a minimum in October, but compared to NS (control), soil CO2 concentration and efflux also reached a peak in May under cotton straw returned. The vertical distributions of soil CO2 concentration were increased with the increase of soil depth, but no significant effect on soil CO2 concentration of vertical distribution under cotton straw returned. Inherence, cotton straw returned played an important role in soil CO2 concentration and efflux under different treatments, and soil CO2 concentration and efflux were significantly higher in double amounts of cotton straw returned than other treatments (P<0.05). In addition, the soil CO2 concentration and efflux were significant correlation (P < 0.05), which increased with the amounts of cotton straw returned, indicating that the soil CO2 efflux strongly depends on the soil CO2 concentration. 3 To evaluate the effects of soil moisture content and drying and wetting alternation on soil CO2 emissions were carried out in laboratory incubation. The results showed that: 1) Compared with 60% WFPS (water filling soil porosity), 40% WFPS was inhibitory on soil CO2 emissions (P<0.05), while 80% WFPS existed no significant influence on soil CO2 emissions (P>0.05). 2) After alternation cycles of many times, the soil CO2 accumulative emissions were lower than constant moisture treatment (P<0.05). Under different drought intensity, severe drought was higher than moderate drought for the effects of range of on soil CO2 emission rate, but after many times, severe drought was lower than moderate drought for the accumulation of soil CO2 emissions. As the times of drying and wetting alternation increased, the soil CO2 emission rates were reduced significantly, especially for the maximum of soil CO2 emission rate. 4 According to the effects of straw and nitrogenous fertilizer on soil CO2 emissions in an incubation, we found that: 1) Cotton straw returned significant increased soil CO2 emissions and soil organic carbon (P<0.05), but applying nitrogenous fertilizer had no significant effects on soil CO2 emissions and soil organic carbon (P > 0.05). 2) In the form of CO2 emissions of carbon accounts for percentage total carbon of straw decomposed, the maximum were 48.71 and 50.72% under moderate straw and Low nitrogen level, and the minimum were 46.68 and 45.94% under double straw+ no fertilizer level. 3)The effect of amount of cotton straw returned and nitrogen application on EF(emission factor of straw carbon), the maximum of emission factor of straw carbon were 36.68 and 35.71 under moderate straw and no fertilizer level, and the minimum of EF were 33.53 and 34.86% under double straw and high nitrogen level, but EF was not a constant under different treatments.
学科领域水土保持与荒漠化防治
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14692
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
牛百成. 不同水肥管理措施对新疆绿洲棉田土壤CO2排放的影响[D]. 北京. 中国科学院大学,2016.
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