Soil carbon pool in China and its global significance

Soil organic carbon density and its related characteristics of 41 soil types all over China were analyzed by using data of 745 soil profiles , and size of soil carbon pool was estimated. As a result, area-weighted averages of these 41 soil types for bulk density, profile depth, organic carbon content and profile carbon were 1. 24 tC/m3, 86. 2 cm, 3. 04% and 19. 7 kg C/m2 respectively. Total size of soil carbon pool was 185. 68 × 1009tC, which is 29 times of that in terrestrial biomass of China and 12. 6% of global soil carbon pools. Because of its huge carbon pool, soil of China plays an important role in global carbon cycle.

Soil carbon pools of six ecological regions of the United States

Mineralisable soil organic carbon(SOC)pools vary with ecosystem type in response to changes in climate,vegetation and soil properties.Understanding the effect of climate and soil factors on SOC pools is critical for predicting change over time.Surface soil samples from six ecoregions of the United States were analyzed for permanganate oxidizable C(KMnO4-C)and mineralizable C pools.Variations of SOC ranged from 7.9 mg g^-1(Florida site)to 325 mg g^-1(Hawaii site).Mineralisable C pools and KMnO4-C were highest in soils from the Hawaii site.Mean annual precipitation explains SOC and resistant C pool variations.Clay content was related to mineralisable active C pools and bacterial abundance.Mean annual precipitation and clay content are potential variables for predicting changes in SOC pools at large spatial scales.

Biochar Serves as a Long-term Soil Carbon Pool

Biochar is a carbon-rich(】60%)organic material derived from incomplete combustion of fossil fuels and biomass.It consists of a continuum ranging from slightly charred material through char and charcoal to soot,and is ubiquitous in the atmosphere,marine sediment,soil and water.Moreover,】80%of biochar produced ends up in soils,where it resides for hundreds to thousands of years.Because of its resistance to biological and chemical breakdown, biochar can serve as a pool of C with long residence time in the soil.As a result,there has been increasing attention given to the potential of biochar to sequestrate carbon and counteract

Effects of Nitrogen Application Rate to Late Rice on Greenhouse Gas Emissions and Soil Carbon Pool During the Growing Season of Winter Chinese Milk vetch

It is of important referential values for the further understanding of the effects of fertilization on greenhouse gas emissions and the effects of winter green manure on soil carbon pool to study the effects of fertilization on the greenhouse gas emissions and soil carbon pool during the growing season of winter Chinese milk vetch in the process of rice cultivation.This study investigated the effects of nitrogen application in late rice season on the yield of the succeeding Chinese milk vetch and greenhouse gas emissions as well as the soil carbon pool characteristics after the winter planting of Chinese milk vetch with the winter idling of no nitrogen application as the control.The results showed that the yield of Chinese milk vetch was the highest under the nitrogen application of 225 kg/hm^2 in the late rice season,reaching up to 18 388.97 kg/hm^2,which was significantly different from other treatments( P <0.05).Nitrogen application in late rice season increased the emissions of N_2 O,CH_4,CO_2 and global warming potential( GWP) in the growing season of Chinese milk vetch.Compared with the winter idling treatment,winter planting of Chinese milk vetch significantly increased the soil organic carbon and soil carbon pool management index.The yield of Chinese milk vetch was significantly positively correlated with N_2O and CH_4 emissions( P < 0.05),while it presented extremely significant positive correlations with CO_2 emissions,GWP,active organic carbon,and carbon pool management index( P < 0.01).Nitrogen application in the late rice season increased the emissions of N_2 O,CH_4,CO_2,and enhanced the greenhouse gas emission potential during the growing season of Chinese milk vetch.Therefore,without reducing the yield of rice,reducing the amount of nitrogen fertilizer in rice could reduce the greenhouse gas emissions in the growing season of succeeding Chinese milk vetch.

Pool Sizes and Turnover of Soil Organic Carbon of Farmland Soil in Karst Area of Guilin

The three-pool and first-order model separates the mineralizable organic carbon into active,slow,and passive carbon pools.This paper used the model and decomposition curves of the soil organic carbon to fit the active pool and its decomposition rate,slow pool and its decomposition rate.The results showed that the size of the active pool from different profiles accounted for 2.09%-3.08% of the total soil organic carbon and the mean residue time was 3.57-17.21 days.And the size of the slow pool accounted for 3.19%-43.55% and the mean residue time was 1.12-4.94 years.Acid hydrolysis（6M HCl） was used to fractionate the passive organic carbon,which accounted for 50.83%-94.44% of the total soil organic carbon.

Temporal variation of soil carbon stock and its controlling factors over the last two decades on the southern Song-nen Plain,Heilongjiang Province

Against the current background of global climate change, the study of variations in the soil carbon pool and its controlling factors may aid in the evaluation of soil＇s role in the mitigation or enhancement of greenhouse gas. This paper studies spatial and temporal variation in the soil carbon pool and their controlling factors in the southern Song-nen Plain in Heilongjiang Province, using soil data collected over two distinct periods by the Multi-purpose Regional Geochemical Survey in 2005-2007, and another soil survey conducted in 1982-1990. The study area is a carbon source of 1479 t/km2 and in the past 20 years, from the 1980s until 2005, the practical carbon emission from the soil was 0.12 Gt. Temperature, which has been found to be linearly correlated to soil organic carbon, is the domi- nant climatologic factor controlling soil organic carbon contents. Our study shows that in the relevant area and time period the potential loss of soil organic carbon caused by rising temperatures was 0.10 Gt, the potential soil carbon emission resulting from land-use change was 0.09 Gt, and the combined potential loss of soil carbon （0.19 Gt） caused by warming and land-use change is comparable to that of fossil fuel combustion （0.21 Gt）. Due to the time delay in soil carbon pool variation, there is still 0.07 Gt in the potential emission caused by warming and land-use change that will be gradually released in the future.

Characteristics of soil organic carbon mineralization and influence factor analysis of natural Larix olgensis forest at different ages

Soil organic carbon(SOC)mineralization is closely related to carbon source or sink of terrestrial ecosystem.Natural stands of Larix olgensis on the Jincang forest farm,Jilin Province were selected to investigate the dynamics of SOC mineralization and its correlations with other soil properties in a young forest and mid-aged forest at soil depths of 0–10,>10–20,>20–40 and>40–60 cm.The results showed that compared with a mid-aged forest,the SOC stock in the young forest was 32%higher.Potentially mineralizable soil carbon(C0)in the young forest was 1.1–2.5 g kg^-1,accounting for 5.5–8.1%of total SOC during the 105 days incubation period and 0.3–1.5 g kg^-1 in the mid-aged forest at different soil depths,occupying 2.8–3.4%of total SOC.There was a significant difference in C0 among the soil depths.The dynamics of the SOC mineralization was a good fit to a three-pool(labile,intermediate and stable)carbon decomposition kinetic model.The SOC decomposition rate for different stand ages and different soil depths reached high levels for the first 15 days.Correlation analysis revealed that the C0 was significantly positively related with SOC content,soil total N(TN)and readily available K(AK)concentration.The labile soil carbon pool was significantly related to SOC and TN concentration,and significantly negatively correlated with soil bulk density.The intermediate carbon pool was positively associated with TN and AK.The stable carbon pool had negative correlations with SOC,TN and AK.

Topsoil organic carbon mineralization and CO_2 evolution of three paddy soils from South China and the temperature dependence

Carbon mineralization and its response to climatic warming have been receiving global attention for the last decade. Although the virtual influence of temperature effect is still in great debate, little is known on the mineralization of organic carbon （SOC） of paddy soils of China under warming. SOC mineralization of three major types of China＇s paddy soils is studied through laboratory incubation for 114 d under soil moisture regime of 70% water holding capacity at 20℃ and 25℃ respectively. The carbon that mineralized as CO2 evolved was measured every day in the first 32 d and every two days in the following days. Carbon mineralized during the 114 d incubation ranged from 3.51 to 9.22 mg CO2-C/gC at 20℃ and from 4.24 to 11.35 mg CO2-C/gC at 25℃ respectively; and a mineralizable C pool in the range of 0.24 to 0.59 gC/kg, varying with different soils. The whole course of C mineralization in the 114 d incubation could be divided into three stages of varying rates, representing the three subpools of the total mineralizable C： very actively mineralized C at 1-23 d, actively tnineralized C at 24--74 d and a slowly mineralized pool with low and more or less stabilized C mineralization rate at 75-114 d. The calculated Q10 values ranged from 1.0 to 2.4, varying with the soil types and N status. Neither the total SOC pool nor the labile C pool could account for the total mineralization potential of the soils studied, despite a well correlation of labile C with the shortly and actively mineralized C, which were shown in sensitive response to soil warming. However, the portion of microbial C pool and the soil C/N ratio controlled the C mineralization and the temperature dependence. Therefore, C sequestration may not result in an increase of C mineralization proportionally. The relative control of C bioavailability and microbial metabolic activity on C mineralization with respect to stabilization of sequestered C in the paddy soils of China is to be further studied.

Labile and stabile soil organic carbon fractions in surface horizons of mountain soils–relationships with vegetation and altitude

Global and local climate changes could disturb carbon sequestration and carbon stocks in forest soils. Thus, it is important to characterize the stability of soil organic matter and the dynamics of soil organic carbon(SOC) fractions in forest ecosystems. This study had two aims:(1) to evaluate the effects of altitude and vegetation on the content of labile and stabile forms of organic carbon in the mountain soils; and(2) to assess the impact of the properties of soil organic matter on the SOC pools under changing environmental conditions. The studies were conducted in the Karkonosze Mountains(SW Poland, Central Europe). The content of the most labile fraction of carbon(dissolved organic carbon,DOC) decreases with altitude, but the content of fulvic acids(FA), clearly increases in the zone above 1000 m asl, while the stabile fraction(humins, nonhydrolyzing carbon) significantly decreases. A higher contribution of stabile forms was found in soils under coniferous forests(Norway spruce), while a smaller-under deciduous forests(European beech) and on grasslands. The expected climate change and the ongoing land use transformations in the zone above1000 m asl may lead to a substantial increase in the stable humus fraction(mainly of a non-hydrolyzing carbon) and an increase in the SOC pools, even if humus acids are characterized by a lower maturity and greater mobility favorable to soil podzolization.In the lower zone(below 1000 m asl), a decrease in the most stable humus forms can be expected,accompanied by an increase of DOC contribution,which will result in a reduction in SOC pools. Overall,the expected prevailing(spatial) effect is a decreasing contribution of the most stable humus fractions,which will be associated with a reduction in the SOC pools in medium-high mountains of temperate zone of Central Europe.

Fractal Kinetics Parameters Regulating Carbon Decomposition Rate under Contrasting Soil Management Systems

Agricultural soils can sequester and release large amounts of carbon. Accessibility of soil carbon to microbial attacks depends on biological, chemical, and physical protection mechanisms such as organic matter composition and particle size, soil aggregation, and chemical protection through the silt-clayorganic matter complex. While soil and organic matter are fractal objects controlling exposure of reactive surfaces to the environment, soil aggregation and biomass production and quality are regulated by agricultural practices. Organic matter decomposition in soil is generally described by the classical first-order kinetics equations fitted to define distinct carbon pools. By comparison, fractal kinetics assigns a coefficient to adjust time-dependent decomposition rate of total soil carbon to protection mechanisms. Our objective was to relate fractal parameters of organic matter decomposition to soil management systems. Retrieving published data, the decomposition of organic matter was modeled in a silt loam soil maintained under pasture, annual cropping or bare fallow during 11 years. The classical first-order kinetics model returned quadratic relationships indicating that reactive carbon decreased with time. Fractal kinetics rectified the relationships successfully. Initial decomposition rate (k 1 at t = 1) was 7 × 10-4 for pasture, 1 × 10-4 for annual cropping, and 0.5 × 10-4 for bare-soil fallow. Fractal coefficients h were 0.71, 0.45, and 0.25 for pasture, annual cropping and fallow, respectively. Due to aggregation, physical protection against microbial attacks was highest under pasture management, leading to higher carbon sequestration despite higher biomass production and “priming” effects. Parameters k 1 and h proved to be useful indicators for soil quality classification integrating the opposite effects of labile carbon decomposition and carbon protection mechanisms that regulate the decomposition rate of organic matter with time as driven by soil management practices.

Predicting dynamics of soil organic carbon mineralization with a double exponential model in different forest belts of China

The dynamics of soil organic carbon （SOC） was analyzed by using laboratory incubation and double exponential model that mineralizable SOC was separated into active carbon pools and slow carbon pools in forest soils derived from Changbai and Qilian Mountain areas. By analyzing and fitting the CO2 evolved rates with SOC mineralization, the results showed that active carbon pools accounted tor 1.0% to 8.5% of SOC with an average of mean resistant times （MRTs） for 24 days, and slow carbon pools accounted for 91% to 99% of SOC with an average of MRTs for 179 years. The sizes and MRTs of slow carbon pools showed that SOC in Qilian Mountain sites was more difficult to decompose than that in Changbai Mountain sites. By analyzing the effects of temperature, soil clay content and elevation on SOC mineralization, results indicated that mineralization of SOC was directly related to temperature and that content of accumulated SOC and size of slow carbon pools from Changbai Mountain and Qilian Mountain sites increased linearly with increasing clay content, respectively, which showed temperature and clay content could make greater effect on mineralization of SOC.

夏闲期耕作下旱地土壤有机碳库与温度和含水量季节变化及关系研究

为明确夏闲期耕作下土壤有机碳(SOC)库与温度和含水量的季节变化及其相互关系,设置夏闲期免耕、翻耕和深松3种耕作处理,分析了黄土高原旱地麦田SOC和易氧化有机碳(POxC)含量的季节变化、土壤含水量和温度的季节变化、以及碳库与温度和含水量变化的关系。结果表明,在冬小麦生育期内,随着生育进程的推进,翻耕和深松处理0~5和5~10 cm土层SOC含量呈先升高后降低的变化趋势,而POxC含量呈“降低—升高—再降低”的变化趋势;土壤质量含水量变化均呈“增加—降低—再增加”的变化趋势,而土壤温度呈先降低后升高的变化趋势。回归分析发现,5~10 cm土层土壤质量含水量与SOC含量呈线性关系(P<0.05),与POxC含量呈二次多项式关系(P<0.05),尤其与免耕和深松处理相比,翻耕处理拟合效果更佳。此外,0~5和5~10 cm土层土壤温度变化与SOC含量无显著相关性,而日最高温度、日平均温度和日最低温度与POxC含量呈显著负相关。综上所述,不同夏闲期耕作下旱地麦田0~10 cm土层POxC含量季节变化与土壤质量含水量和温度变化密切相关,而SOC含量变化对土壤温度变化的敏感性较弱。本研究结果为旱地麦田碳库管理提供了理论依据。

有机无机肥配施对江苏滨海盐碱土农田生产力和碳库的影响

[目的]有机肥施用是江苏滨海轻度盐碱地主要的改土提质技术,本试验通过研究在有机替代模式下夏玉米种植系统农田生产力和土壤碳库的变化特征,探索在粉垄耕作模式下有机肥还田同氮肥减量的最佳比例。[方法]按照等氮量投入原则,以当地氮肥施用(CK)为对照,设置25%有机肥+75%氮肥(CT25)、50%有机肥+50%氮肥(CT50)、75%有机肥+25%氮肥(CT75)、有机肥全量替代氮肥(CT100)处理,开展粉垄耕作模式下不同比例有机肥替代氮肥玉米种植田间试验,对玉米农田生产力和土壤碳库指标进行测定。[结果]与氮肥全量施用相比,有机肥替代化肥比例在25%~50%时,玉米籽粒产量可增加8.74%~11.21%,其中CT25处理的玉米光合速率(P_(n))、气孔导度(G_(s))、蒸腾速率(T_(r))、胞间CO_(2)浓度(C_(i))显著增加,土壤全氮、全磷、全钾、碱解氮、速效磷、速效钾含量均较单施氮肥显著增加,有机替代比例超过50%以上时玉米产量和土壤养分较纯施氮肥无显著变化。相较于纯施氮肥,有机肥替代比例在25%~75%时土壤碳储量提升9.47%~14.61%,这主要依赖于土壤有机碳含量和容重的显著增加。土壤有机碳含量和玉米产量呈显著的正相关关系。[结论]粉垄耕作模式条件下,有机肥替代氮肥在25%~50%可以显著改善土壤理化性质,增加土壤碳储量,提升农田生产力,可作为江苏滨海旱作玉米种植推荐施肥技术。

有机和常规管理对茶园土壤固碳的影响——以林地为对照

为探究有机和常规管理方式对茶园土壤有机碳的影响,选择云南省普洱市思茅区常规管理茶园、有机管理茶园和附近自然林地3种典型土地利用类型,通过测定0~20 cm和20~40 cm土层的土壤有机碳(SOC)、易氧化有机碳(EOC)、非活性有机碳(NLOC)、颗粒态有机碳(POC)和矿物结合态有机碳(MOC)含量,计算土壤各组分有机碳的分配比例以及土壤碳库管理指数(CPMI),研究3种土地利用方式下土壤有机碳各组分含量和质量的变化特征。结果显示:1)常规管理茶园的SOC含量和储量分别比自然林地低48.67%~51.94%和27.25%~35.71%(P<0.05),而有机管理茶园的SOC含量和储量比常规管理茶园分别高52.09%~62.86%、15.54%~20.26%(P<0.05)。2)常规管理茶园的EOC、NLOC、POC和MOC含量均低于自然林地(P<0.05),而有机管理茶园的EOC、NLOC、POC和MOC含量比常规管理茶园分别高出46.39%~57.89%、54.24%~66.15%、80.87%~121.01%和40.07%~46.28%(P<0.05)。3)与自然林地相比,常规管理茶园的POC/SOC、NLOC/SOC较低,有机管理茶园的POC/SOC、NLOC/SOC则高于常规管理茶园。4)常规管理茶园具有较高的CPAI和较低的CPMI,常规管理茶园的CPMI比自然林地低24.53%~46.12%,有机管理茶园的CPMI比常规管理茶园高67.88%~100.33%,其差异均显著(P<0.05)。以上研究结果表明,与自然林地相比,常规管理的茶园土壤有机碳含量和土壤碳库质量下降,存在一定程度的土地退化,而有机管理是提高茶园土壤碳库质量的有效措施。

青藏高原高寒草地生态系统碳平衡对放牧强度的响应

青藏高原拥有世界上最广阔的高寒草地,以及长达数千年的悠久放牧历史。独特的高寒环境条件使这里对外界干扰更加敏感。尽管已经进行了很多青藏高原高寒草地生态系统碳平衡的相关研究,但放牧,尤其是放牧强度如何影响高寒草地碳平衡仍待进一步研究与明确。论文以围栏禁牧、轻度放牧、中度放牧、重度放牧4种放牧强度为基础,综述了青藏高原高寒草地生态系统碳平衡对不同放牧强度的响应。放牧强度变化通过干扰植物-土壤界面从而对碳输入和输出过程产生间接作用,最终影响高寒草地生态系统碳平衡。由于受到放牧历史、气候条件、草地类型等其他条件的干扰,高寒草地生态系统碳平衡对放牧强度的响应是复杂多样的,因此需要对放牧管理采取更加灵活、具体、有针对性的措施,这对于制定合理的草地管理决策、稳定青藏高原高寒草地生态系统碳平衡具有重要意义。

不同比例化肥减量配施有机肥对植烟土壤有机碳固存的影响

为探究不同比例化肥减量配施有机肥影响植烟土壤有机碳固存的长期效应,基于连续9年的田间定位试验,设置不施肥(CK)、100%化肥(CF-1,当地常规推荐施肥)、80%化肥(CF-2)、80%化肥配施有机肥(OF-1)、60%化肥配施有机肥(OF-2)、70%化肥配施有机肥+生物有机肥(BOF)处理,对植烟土壤有机碳储量盈亏、固碳速率、有机碳组分含量、有机碳敏感指数、土壤碳库活度和土壤碳库管理指数进行对比,探讨不同比例化肥减量配施有机肥对植烟土壤有机碳固存的长期效应。与CF-1处理相比,连续不施肥(CK)处理植烟土壤有机碳组分、储量和土壤碳固存速率显著下降。不同比例化肥减量配施有机肥的OF-1、OF-2和BOF处理,植烟土壤有机碳含量分别增加9.6%、20.9%和13.9%,土壤活性有机碳含量分别增加43.4%、68.0%和41.7%,土壤可溶性有机碳含量分别增加14.8%、19.1%和25.4%,土壤微生物量碳含量分别增加22.8%、37.2%和36.4%,土壤有机碳储量分别增加15.3%、30.2%和31.2%,年平均固碳速率分别提高191.3%、382.6%和391.3%,碳库管理指数分别提高100.8%、159.8%和79.6%。不同比例化肥减量配施有机肥显著提升土壤活性有机碳敏感指数。与CF-1相比,OF-1、OF-2和BOF处理的烟叶产量分别提高10.3%、33.5%和35.3%,中上等烟叶比例分别提高14.6%、22.0%和18.0%。连续9年化肥减量配施有机肥显著提高植烟土壤有机碳组分含量和土壤有机碳固存速率,促进烟叶产质量提升,是烟叶绿色优质生产、农田土壤固碳增效的有效途径,以OF-2和BOF效应更好。

生物炭对毛竹林土壤有机碳组分及碳库管理指数的影响

为探究不同生物炭施用量对毛竹林土壤有机碳组分及碳库管理指数的影响,本研究以广西桂林漓江上游毛竹林土壤为研究对象,以毛竹废弃物高温热解制备的生物炭为供试材料,通过一年野外施用试验,探究不同生物炭施用量下(0(CK)、10 t·hm^(-2)(BC1)、20 t·hm^(-2)(BC2)、40 t·hm^(-2)(BC4))毛竹林土壤有机碳活性组分和土壤碳库管理指数变化特征,分析环境因素对其影响。结果表明:与对照(CK)相比,高添加量生物炭(BC4)后土壤pH值、速效磷、速效钾、铵态氮、可溶性有机氮、微生物量氮等含量显著提高,但土壤全磷含量显著降低(P<0.05)。生物炭对总有机碳、易氧化有机碳、颗粒有机碳及碳库管理指数等有显著的促进作用,均在生物炭施用量为40 t·hm^(-2)时达到最大值。相关分析表明,土壤碳库管理指数与pH、NH_(4)^(+)-N、EOC、POC均呈极显著正相关关系(P<0.01)。路径分析模型表明在生物炭添加下,土壤性质和可利用性养分直接影响活性碳组分,进而影响土壤碳库管理指数。综上所述,毛竹林中施用生物炭是提高土壤质量、促进土壤碳固存及合理利用竹林废弃物的有效手段,其中生物炭添加量为40 t·hm^(-2)的处理效果最优。

陇中温性荒漠4种草地型土壤有机碳组分及碳库活度变化特征

为明确陇中温性荒漠不同草地型土壤有机碳(Soil organic carbon,SOC)各组分分布状况,本研究以陇中温性荒漠为对象,分析了4种草地型(盐爪爪型,红砂型,珍珠猪毛菜型,合头藜型)SOC、易氧化有机碳(Readily oxidisable organic carbon,ROC)、可溶性有机碳(Dissolved organic carbon,DOC)、颗粒有机碳(Particulate organic carbon,POC)、矿物结合态有机碳(Mineral-bound organic carbon,MOC)、惰性有机碳(Non-labile carbon,NLC)的含量和分配比例及碳库活度(Carbon pool activity,CA)的差异性变化。结果表明:SOC,ROC,POC,MOC,NLC,CA和ROC分配比例盐爪爪型草地显著高于其他草地型;在SOC及其组分中,POC可作为评估陇中温性荒漠草地型变化对SOC库影响的良好指标;SOC组分和CA与有效磷和速效钾含量呈正相关关系。盐爪爪型草地可作为提高陇中温性荒漠SOC及组分含量的优选类型,今后应加强对盐爪爪型草地的保护,改善土壤质量,稳定土壤碳库。

长期连作茭白增加水田深层土壤有机碳的积累

为了解长期连作茭白后水稻土有机碳库及其组分的变化,选择了连续种植茭白时间分别为0(对照)、2~5、5~10、10~20、20~30、30~35 a等6组种植茭白前土壤类型相同的18块农田,通过挖掘标准土壤剖面采集0~20、20~40、40~60、60~80 cm分层土样,分析了土壤有机碳、不同稳定性有机碳组分和微生物生物量碳。结果表明:随着茭白种植时间的增加,土壤容重由上层至下逐渐下降;各土层中有机碳总量、高活性有机碳、中活性有机碳、低活性有机碳和惰性有机碳及微生物生物量碳均逐渐增加,增幅以20~40、40~60 cm等2个土层最为明显。同时,深层土壤中高活性有机碳比例呈现显著的增加,20~80 cm土层中有机碳总量及其各形态有机碳贮量占0~80 cm土层有机碳总量的比例逐渐增加,呈现有机碳向深层土壤积累的特点。分析认为,深耕、长期浸水及茭白生产过程田间人为频繁踩踏,导致土壤犁底层逐渐消失、软糊层形成是造成茭白田深层土壤有机碳快速积累、有机碳活性增加的主要原因。