典型水稻土有机碳分解特征及其影响因素研究

发布时间：2018-03-25 17:43

  本文选题：土壤有机碳库　切入点：水稻土　出处：《南京农业大学》2015年硕士论文

【摘要】：土壤有机碳(Soil Organic Carbon,SOC)库是陆地生态系统中最活跃的碳库,与全球碳循环密切相关,土壤有机碳的分解对大气中CO2浓度有重要影响。资料表明,水稻土约占我国耕地总面积的1/5,生产的粮食约占我国粮食总产量的4/5,且水稻土SOC分解过程与旱地土壤SOC分解不同,研究水稻土 SOC分解的规律在缓解我国固碳减排压力、缓解温室效应、稳定粮食产量等方面有重要意义。将湖南省桃源县水稻土剖面样品(0～100 cm)在25 ℃:下培养,将江苏省句容市水稻土表层样品(0～20cm)分别在5 ℃,15 ℃,25 ℃,35 ℃下培养,基于SOC三库一级动力学理论进行三库分离,从土层深度变化角度和培养温度变化角度研究水稻土 SOC分解的特征和活性碳(Active Organic Carbon,Ca)、缓效性碳(Slow Organic Carbon,Cs)、惰性碳(Passive Organic Carbon,Cp)三库参数的变化规律,并深入分析培养温度对SOC分解的温度敏感性系数(Q_(10))和三库拟合结果的影响。研究取得的主要结果如下:1.SOC分解速率和累计分解量随时间先快速变化,后慢速变化,最后稳定在一定水平上。按照CO2-C释放速率变化程度,可将土壤有机碳分解曲线划分为快速分解(平均约5.53d)、缓慢分解(平均约28 d)和平衡分解三个阶段。在同一培养温度下,随着土层加深,SOC分解速率和累积分解量逐层递减。同一土壤在5～35℃范围内,随着培养温度的升高,土壤SOC分解速率和累积分解量均升高,15、25和35℃时SOC累积分解量分别是5℃时的1.94倍、3.55倍、6.01倍。2.各土层中Ct(总有机碳,Total Organic Carbon)含量Cp含量Cs含量Ca含量,且Ca、Cs、Cp含量分别与土层深度成负相关关系,相关系数分别为0.841、0.833、0.773(P0.01),随着土层加深Ca/Ct减小,Cp/Ct增大,SOC的稳定性增大。SOC累积分解量与Ct含量、土壤全氮含量、碳氮比成显著正相关关系,与土壤pH值、粘粒含量成显著负相关关系。控制土层深度的偏相关关系表明,不同土层SOC各组分含量、SOC累积分解量与土壤全氮含量和土壤pH成显著偏相关关系,而与全磷、全钾、有效磷、速效钾、碳氮比和粘粒含量之间不存在显著偏相关关系。3.Q_(10)值取2时,SOC三库拟合结果受培养温度影响较大,Ca拟合值随培养温度的升高而增大,Cs拟合值随培养温度的升高而减小,其中Ca拟合值之间的差异最大,潴育、潜育、淹育水稻土 Ca拟合值的变异系数分别为64.9%、66.7%、48.5%,培养温度的设定对Ca拟合结果的影响较大。Q_(10)值按照定义式计算时,Q_(10)值随着培养温度的升高而降低、随着培养时间的增长而降低,Q_(10)变化范围为1.48～2.88,且Q_(10)值与SOC含量和SOC分解速率成正相关关系,与SOC累积分解量成负相关关系。采用按照Q_(10)定义式计算出的Q_(10)值对SOC三库进行拟合,得到的Ca和Cs拟合值与按照Q_(10)取固定值2拟合的结果没有差异,而得到的活性碳平均驻留时间(Mean Residue Time of Active Organic Carbon,MRTa)和缓效性破平均驻留时间(Mean Residue Time of Slow Organic Carbon,MRTs)的拟合值有差异。综上,表层以下的SOC以其缓慢的速度按照与表层相似的过程参与全球破循环,采取适当的措施可以增加其对碳的固定。表层SOC三库拟合值受培养温度的影响大,不能仅用25℃的培养结果确定三库值。按照定义式计算的Q_(10)值对拟合出的MRTa和MRTs影响大,而对拟合出的三库大小影响小,可以采用固定值2进行三库拟合。
[Abstract]:Soil organic carbon (Soil Organic Carbon, SOC) library is the most active carbon pool in terrestrial ecosystem, and is closely related to the global carbon cycle, the decomposition of soil organic carbon has important influence on the atmospheric concentration of CO2. The data showed that the paddy soil in China accounts for about 1/5 of the total area of arable land, the total grain production food production in China 4/5, and SOC in paddy soils and upland soil SOC decomposition process of paddy soil in different decomposition, SOC decomposition rules in ease China's carbon emission reduction pressure, alleviate the greenhouse effect, has important significance to stabilize grain yield. The rice in Taoyuan County of Hunan Province, soil samples (0~100 cm) in 25 C: culture, Jurong city in Jiangsu province paddy topsoil samples (0 ~ 20cm) respectively at 5 C, 15 C, 25 C, 35 C under cultivation, SOC three pool theory of three separated database based on the depth changes from culture angle and temperature change angle Study on paddy soil SOC decomposition characteristics and active carbon (Active Organic Carbon, Ca), slow carbon (Slow Organic Carbon Cs (Passive Organic), inert carbon Carbon, Cp) changes of the three reservoir parameters, and in-depth analysis of culture temperature on SOC decomposition temperature sensitivity coefficient (Q_ (10)) influence and fitting results of three libraries. The main results are as follows: 1.SOC decomposition rate and cumulative decomposition rate with time of rapid change, after the slow change, finally stabilized in a certain level. According to the degree of CO2-C release rate of change, the soil organic carbon decomposition curve is divided into rapid decomposition (average 5.53d) and the slow decomposition (approximately 28 d) and equilibrium dissociation in three stages. At the same temperature, with the increase of soil depth, SOC decomposition rate and decomposition rate of accumulation layer decreases. The same soil at 5~35 DEG C range, with the increase of culture temperature, soil SOC decomposition The decomposition rate and cumulative amount were increased, 15,25 and 35 degrees SOC cumulative solution quantity is respectively 1.94 times, 5 degrees 3.55 times, 6.01 times the depth of.2. in Ct (total organic carbon, Total Organic Carbon) Cp content Cs content Ca content, and Ca, Cs, Cp were negative correlation with soil depth, the correlation coefficients were 0.841,0.833,0.773 (P0.01), Ca/Ct decreased with the increase of soil depth, the increase of Cp/Ct, the stability of SOC increased.SOC accumulation decomposition rate and Ct content, the content of soil total nitrogen, carbon and nitrogen ratio was positively correlated with the soil pH, clay content, significant negative correlation between the partial. Correlation between the control of soil depth, soil SOC content, SOC content and accumulation of decomposition of soil total nitrogen content and soil pH significantly partial correlation, and total phosphorus, total potassium, available phosphorus, available potassium, no significant partial correlation between the presence of.3.Q_ carbon nitrogen ratio and clay content between (10)鍊煎彇2鏃，

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