绰墩遗址古今水稻土黏土矿物特征比较研究

在江苏绰墩山遗址考古发掘中,发现了在剖面不同深度埋藏的距今约6000年的史前水稻土层、距今约3 000年的商周史前的古水稻土层和现代水稻土层.本研究为了比较古今水稻土黏土矿物特征的差异,以土壤剖面P01(包含史前古水稻土、商周史古水稻土和现代水稻土)与P03(仅含商周时期古水稻土和现代水稻土)为对象,测定其各种形态铁锰...     

土壤粒度和磁化率特征对绰墩古水稻土成因的指示

本文研究了绰墩农业遗址P-02原状土剖面的粒度分布,定量分析了土壤黏粒的矿物组成,测定了土壤/沉积物及其各粒级组分(黏粒、粉砂粒、细砂粒和粗砂粒)的磁化率。结果表明：在0 ~ 30 cm和134 ~ 154 cm两层段,黏粒含量从下向上有降低的趋势,这可能预示着长期的水耕作业造成黏粒从表层向亚表层移动;在148 ~ 200 cm层段,土壤磁化率从下向上有降低的趋势,可能说明该处存在长期淹水的状况。总之,黏粒含量和质量磁化率数据说明长江下游地区的先民在马家浜文化时期已开始采用“水溽”方式进行水稻的栽培。     

河南仰韶村遗址原始农业活动研究

分析古土壤特征是获取古环境信息的重要手段,通过研究文化遗址区古土壤特征来推导不同时间尺度下原始农业信息日益成为国内外研究的热点。本文选取河南仰韶文化遗址区内的文化剖面和自然剖面为研究对象,通过对两者的孢粉、炭屑、有机碳同位素、植硅体等古土壤特征定量分析,推测当时的粮食作物等原始农业信息。结果表明:通过分析两者的孢粉、炭屑,发现当古人类活动开始增强后,对于生存、生活所需的植物,古人类有选择性地种植和采摘,导致禾本科含量增加明显,藜科含量也较高,而利用价值不大的植物则因居住、耕作需要而被砍伐、焚烧,导致木本、蕨类含量减少。通过有机碳同位素和植硅体分析,发现在古人类活动的影响下,以C_3植物为主的自然植被类型转变为以C_4植物为主的人工植被类型,其遗址区内农作物以粟、黍为主,并发现有水稻,推测该遗址在仰韶晚期处于"北粟南稻"交错地带。     

土壤黏粒和磁化率特征对绰墩古水稻土成因的指示

本文研究了绰墩农业遗址P-02原状土剖面的粒度分布,定量分析了土壤黏粒的矿物组成,测定了土壤/沉积物及其各粒级组分(黏粒、粉砂粒、细砂粒和粗砂粒)的磁化率。结果表明:在0～30 cm和134～154 cm两层段,黏粒含量从下向上有降低的趋势,这可能预示着长期的水耕作业造成黏粒从表层向亚表层移动;在148～200 cm层段,土壤磁化率从下向上有降低的趋势,可能说明该处存在长期淹水的状况。总之,黏粒含量和质量磁化率数据说明长江下游地区的先民在马家浜文化时期已开始采用"水溽"方式进行水稻的栽培。     

野生型水稻及其低硅突变体中植硅体和植硅体碳的含量与分布特征

【目的】水稻是典型的富硅植物,植硅体沉积在水稻体内可封存有机碳。本文分析不同吸硅能力基因型水稻植硅体含量、形态、分布及其固碳特征,探究水稻植硅体固碳机理。【方法】盆栽试验在浙江大学玻璃房内进行。供试材料为水稻低硅突变体Lsi1和Lsi2及其野生型,所有施肥和管理措施一致。于成熟期,取水稻地上部茎、叶、鞘样品,常规方法测定硅、植硅体、植硅体碳含量。【结果】1)不同基因型水稻体内硅含量、植硅体含量、生物量干物质植硅体碳含量存在显著差异,均表现为突变体显著低于其野生型,大小依次为Lsi1野生型> Lsi2野生型> Lsi2突变体> Lsi1突变体,Lsi1和Lsi2突变体水稻植硅体碳含量显著高于其野生型,大小依次为Lsi1突变体> Lsi2突变体> Lsi2野生型> Lsi1野生型。2)野生型水稻硅与植硅体含量为鞘>叶>茎,而突变体水稻硅与植硅体含量为叶>鞘>茎,水稻叶片中的植硅体碳与生物量干物质植硅体碳含量最高,植硅体碳含量整体分布趋势为叶>茎>鞘,生物量干物质植硅体碳含量整体变化趋势为叶>鞘>茎。3)水稻植硅体含量与硅含量之间呈极显著正相关(P <0.01),高吸硅的水稻植硅体含量高,且形成的植硅体比表面积小,表明植硅体含量及其形态受其遗传特性的影响。植硅体含量与生物量干物质植硅体碳含量之间呈极显著正相关(P <0.01),植硅体碳含量与生物量干物质植硅体碳含量之间呈极显著负相关(P <0.01),表明生物量干物质植硅体碳含量除了受植硅体含量影响,还受植硅体所包裹的有机碳浓度影响。4) Lsi1及Lsi2野生型水稻生物量、植硅体储量、植硅体碳储量显著高于其突变体。【结论】具有高吸硅能力的野生型水稻与其突变体相比,生物量、硅、植硅体、生物量干物质植硅体碳含量增加,分布不同,虽然植硅体碳含量降低,但植硅体碳储量增加。Lsi1及Lsi2野生型水稻比低硅突变体水稻具有更高的固碳潜力。     

绰墩山遗址古水稻土的一些微生物学特性研究

在江苏绰墩山遗址考古发掘中,发现了在剖面不同深度埋藏的距今约6 500 a的史前古水稻田土层(100~200 cm)和距今约3 320 a的商周时期的古水稻田土层(42~100 cm)。本研究为了解古水稻土的生物学性状及其与现代水稻土的差别,以土壤剖面P-01(包含史前古水稻土和商周时期古水稻土)与P-03(仅含商周时期古水稻土)为对象,利用土壤厌氧培养、Biolog分析和广古生菌界16S rDNA的V3区的PCR-DGGE分析,初步研究了不同土层厌氧微生物多样性、产甲烷潜势以及产甲烷古菌群落多样性的变化。结果表明,史前古水稻土仍有较多厌氧微生物存活,可达7.0×105cfu g-1干土,并且其单一碳源利用能力和多样性也显著高于其湖相沉积母质和相同时期的非水稻土(黄土母质)。与现代水稻土相比,古水稻土仅存留了很微弱的产甲烷潜势。但史前古水稻土比同期非水稻土和商周时期古水稻土的产甲烷潜势较高。PCR-DGGE结果显示,水稻土层都有其区别于非水稻土层的产甲烷古菌群落结构,而现代水稻土、商周时期古水稻土和史前古水稻土也各有不同的优势产甲烷古菌种群,不同时期的水稻耕作方式是造成这种差异的可能的重要原因之一。     

绰墩遗址新石器时期水稻田、古水稻土剖面、植硅体和炭化稻形态特征的研究

绰墩遗址第六次发掘的300 m2范围内出土22块古田块,通过对其田埂、灌排系统(水口、水沟、水井)等结构特征的观察研究,对古田块和水沟中出土的灌溉用具——陶罐和陶盆碎片的鉴定是属于马家滨文化时期的器物;从田块表土层中淘洗出大量的炭化稻粒,每克土壤中检测到有上万至十余万颗水稻植硅体,这些结果证明所发现的田块是马家滨时期的灌溉稻田。对出土的炭化稻粒和土壤有机质的14C定年结果表明其年龄分别为5 907 a BP和6 280 a BP,是新石器即晚马家滨文化时期的水稻文明。对在遗址挖掘的两个整段剖面(P-01和P-03)的研究发现,P-01剖面上42~103 cm层位埋藏有马桥文化-商朝初期(3 320 a BP)和在103~200 cm层位埋藏有马家滨时期(6 280 a BP)的两个古水稻土剖面,这一结果佐证了前人关于8 000年来长江三角洲地区曾有过几次大的洪水泛滥而使人类耕作活动中断的气候变化事件的结论。然而距P-01仅15 m的P-03整段剖面上仅出现了马桥-商朝初期的古水稻土剖面(40~100 cm),未发现马家滨时期古水稻土剖面(100~200 cm),说明当时的生产力非常低下,仅能利用低洼平坦的地方种稻,稍高一点的居住点附近的坡地就无法改成梯田种植水稻了。这两个埋藏的古水稻土剖面均已经发育了水稻土的明显特征。对出土炭化稻粒的形态学研究表明,外型多为椭圆形,长宽比的变异较大,稃面有方格凹陷结构、周边有稃毛,顶端残留有稻芒的基部,基部有护颖而没有小梗,"钝形"的双峰乳突、浅平的凹陷乳沟等均显示其为人工栽培的粳型水稻。结果与丁颖20世纪50年代在黄河流域发现的汉代的炭化稻粒的特征是吻合的,从而支持了关于"我国长江流域与黄河流域古代最早栽培的水稻都是粳稻品种"的论点。     

土壤植硅体碳积累潜力影响因素分析

土壤植硅体封存有机碳(phytolith-occluded organic carbon,PhytOC)是植物在地质历史时期固碳的重要形式之一,不同植物、不同器官、不同组织、不同生长时期的植硅体形态、含量、大小、分布、组合有所不同。土壤中植硅体碳积累潜力主要受气候变化、植物生产力、植硅体固碳效率、植硅体碳稳定性、土地利用方式、农艺措施、国家宏观政策等因素的影响。本文对各因素进行了较深入的分析。同时指出,固碳机理、植硅体固碳高效品种选育、人为干扰下农林生态系统植硅体碳循环过程为今后植硅体碳汇研究的重点。     

河南仰韶村文化遗址的土壤指示特征研究

人类作为生物因素的重要组成部分,其对土壤的影响越来越受到关注。在古人类遗址土壤研究中,通过分析土壤理化性质以及包含物特征,可还原古人类活动类型以及强度。在河南仰韶村文化遗址内,分别选取一个受到古人类活动干扰的土壤剖面(简称文化剖面)和没有受到古人类活动干扰的土壤剖面(简称自然剖面),通过观察和分析,比较两个剖面在遗物遗迹、土壤理化性质以及植物遗存方面的差别,从而获取该遗址的土壤指示特征。研究结果显示文化剖面中出现陶片、石器、灰坑、灰烬层和文化层;通体粒度组成偏砂,在灰烬层砂粒含量达到最大;低频磁化率(χlf)高于自然剖面,且出现异常高值,频率磁化率(χfd)略低于自然剖面;色度参数红度(a*)、黄度(b*)、亮度(L*)值低于自然剖面,均在灰烬层出现最小值;容重小于自然剖面,在文化层出现最小值;全磷含量高于自然剖面,在灰烬层和文化层出现极大值和最大值;禾本科(Gramineae)和藜科(Artemisia)含量高于自然剖面,存在驯化的粟、黍、水稻植硅体;有机碳同位素(δ13C)值较自然剖面偏正,指示剖面植物类型以C4为主;炭屑含量大约为自然剖面的4倍。土壤在古人类活动影响下,宏观上,土体中的侵入体和剖面形态特征与自然剖面具有明显的差别;微观上,粒度组成、磁化率、色度、全磷、容重、孢粉、植硅体、炭屑和有机碳同位素也与自然剖面有明显的差别。     

中国不同生态系统土壤硅的研究进展

硅是土壤和岩石的一种基本成分,具有促进植物的生长、增强植物抗性、参与生物地球化学循环过程、调节全球碳循环和缓解全球气候变暖趋势等方面的作用.本文在全面介绍土壤硅的形态、有效性及生物循环特征基础上,分析了我国不同生态系统中土壤硅及植硅体含量状况,阐明了影响土壤有效硅及植硅体的因素,重点阐述了近年来有关稻田土壤有效硅与水稻...     

长江三角洲绰墩遗址古水稻土孢粉和植硅体分析

A number of paddy fields pertaining to the Majiabang Cultures （5500-3800 years BC） were discovered during the archaeological excavations that were carried out since 1998 at the Chuodun site in the Yangtze River Delta. The pollen and phytolith analyses of two soil profiles from the northeastern part of this site were carried out to trace the agricultural practices of the Neolithic period. The phytolith results showed that rice domestication in the Yangtze River Delta could be traced back to as early as the Majiabang Culture. The pollen assemblage also revealed low levels of aquatic species, similar to that in modern paddy fields. This finding suggested that humans might have removed weeds for rice cultivation during the Neolithic period. Thus, pollen analysis in association with phytolith analysis was a promising method for identifying ancient paddy fields.     

Effects of rice cropping intensity on soil nitrogen mineralization rate and potential in buried ancient paddy soils from the Neolithic Age in China’s Yangtze River Delta

Purpose

Rice cropping density, rice cropping duration, and fertilization can affect soil nitrogen (N) supply, but rice cropping intensity (RCI) on soil N fertility is not fully understood, particularly for ancient paddy soils without N fertilization.

Materials and methods

Eight buried ancient paddy soils from the Neolithic Age in China’s Yangtze River Delta, and its parent material, and seven present paddy soils in the same fields were used to investigate the effects of RCI on soil nitrogen mineralization rate and potential. In the present study, concentration of phytolith of rice in soils was used to indicate the RCI.

Results and discussion

Soil N content was obviously greater in the buried Neolithic paddy soils than in the parent material. Total soil N increased with increasing phytolith from 5,200 to 60,000 pellets g^?1, but tended to decrease with increasing phytolith from 60,000 to 105,000 pellets g^?1. A possible reason for RCI-induced increase of soil N was due to biological N₂ fixation in the rice field because there was a significant negative relationship between total N and δ¹⁵N in the buried Neolithic soils. The mineralization rate constant (k) ranged from 0.0126 to 0.0485 d^?1 with an average of 0.0276 d^?1, which was similar to that of the parent material, but lower than those in the present paddy soils. The k value increased with increasing RCI in the Neolithic paddy soils. There was a significant positive relation between RCI and the percentage of cumulative mineralizable N in the 14 d of that within 103 d incubation.

Conclusions

Soil N content tended to increase with the increasing intensity of rice cropping and then decreased under the high intensity of rice cropping; the excessive high intensification of rice cropping could facilitate fast N mineralization (labile N) fraction in the cumulated mineralized N. The unfertilized paddy field could only meet soil N supply under the low intensification of cropping rice in the Neolithic Age. The N fertilization is necessary in order to improve soil fertility for sustaining the present high-yield rice production.     

中国史前灌溉稻田和古水稻土研究进展

通过连续4 a多的研究,科学地证明了位于江苏昆山绰墩遗址的稻田群是迄今发现的地球上最早的灌溉稻田群(6 280 a BP),提出了一套诊断古水稻田和古水稻土的技术指标;获得了新石器时期"火耕水溽"——原始灌溉稻作技术的科学证据。阐明了史前水稻土和现代水稻土表层有机质、全氮和全钾含量接近,而全磷、有效磷则是前者大大高于后者的事实,是先民长期以动物残余物肥田的结果。古、今水稻土有机质含量均高于同时期旱地土,揭示了稻田生态系统和水稻土固持大气二氧化碳的巨大潜力。新石器时期水稻土也含有较高的多环芳烃(PAHs)等有机污染物,是源于田间秸秆的焚烧。微生物学的研究表明,史前水稻土产甲烷潜势很低,硝化功能完全丢失。提出了今后应进一步研究的问题。     

开垦年限对稻田土壤腐殖质组成和胡敏酸结构特征的影响

以吉林省磐石市朝阳山镇青山村开垦年限分别为5 a、20 a和50 a的稻田土壤为研究对象,研究了0~15 cm和15~30 cm土层的土壤有机碳含量(SOC)、水溶性物质(WSS)、富里酸(FA)、胡敏酸(HA)和胡敏素(Hu)组成和HA结构特征及土壤养分含量的变化。结果表明:随稻田开垦年限增加(5~50 a),表层(0~15 cm)与亚表层(15~30 cm)土壤变化如下:(1)电导率分别增加74.8%和113.7%,p H均基本稳定。土壤速效氮、有效磷和速效钾含量分别增加0.24%、15.8%、29.7%和1.33%、6.92%、14.7%。(2)有机碳总量分别增加42.1%和47.9%,WSS、HA和Hu含量分别增加28.4%、51.9%、76.2%和87.7%、84.9%、70.1%,而FA含量分别下降了9.2%和1.74%。说明稻田耕作年限越长越有利于土壤有机碳的积累。(3)胡敏酸占腐殖质的比例(PQ)值均增大,土壤腐殖化程度加深。(4)HA的氢碳元素物质的量之比(H/C)、色调系数(?lg K)、半定量分析得红外光谱在2 920和1 720峰处吸收强度之比(E2 920/1 720)与在2 920和1 620峰处吸收强度之比(E2 920/1 620)均减小,HA分子芳化度增强,缩合度上升,结构变得复杂。     

Land use affects soil organic carbon of paddy soils: empirical evidence from 6280 years BP to present

Purpose

Submerged rice cultivation has been practiced in China for 7000 years. Empirical evidence on changes of soil organic carbon (SOC) contents in paddy soils over this historical time period is scarce. Therefore, a field study was conducted to investigate the effect of submerged rice cultivation on the accumulation and preservation of SOC in paddies.

Materials and methods

Two buried ancient paddy profiles (6280 years BP, named P-01 and P-03) in the Yangtze Delta of eastern China were excavated to illustrate the development of SOC contents in soils during the evolution of paddies under anthropogenic land use and environmental changes from the prehistoric period to the present time. Trends in SOC concentrations, total nitrogen concentrations, and stable carbon isotope ratio were identified for different points in time.

Results and discussion

Accumulation of organic carbon was found in the paddy soil layers of P-01 at 100–174 cm depth. This site was taken under submerged rice cultivation in about 6280 years BP. The average SOC concentration in the prehistoric paddy topsoil in 100–130 cm depth was 1.27 %, which is seven times higher than that in the adjacent uncultivated land at 103–130 cm depth of P-03. This implies that the paddy soil has experienced substantial CO₂ sequestration under submerged management during that time. By about 3320 years BP, organic carbon contents were halved, potentially due to marine inundation by sea level rise. Up to the year 2003, the SOC contents in all horizons in the present time paddy soil have increased, especially in the surface layer, indicative of continuous rice cultivation. However, due to rapid urbanization and industrialization, the cultivation of paddies in eastern China has gradually been discontinued leading to the loss of SOC stocks of approximately 10 % in a 6-year interval (from 2003 to 2009). A significant relationship between SOC and rice phytolith contents was found in the paddy soil horizons of P-01 (r?=?0.71, p?<?0.01) and P-03 (r?=?0.72, p?<?0.01), suggesting that phytolith-occluded organic carbon could be used as a biomarker to ascertain the development of SOC in the evolution of rice paddies over the past 6000 years.

Conclusions

Submerged rice cultivation led to a noticeable accumulation of SOC in paddies. Phytolith-occluded organic carbon could be used as a biomarker to monitor changes of OC contents in paddy soils.

     

Characterization and implication of phytolith-associated potassium in rice straw and paddy soils

Rice straw contains up to 2.3% K in dry matter, including potassium (K) subcompartmented in phytoliths, complex siliceous structures formed in plant tissue via precipitation of Si. Rice straw is usually returned to the soil as a conventional practice to sustain soil nutrients, and therefore, the K pool accompanied with rice straw phytoliths is also cycled. Based on phytoliths obtained by ashing of rice straw at 400 °C and dissolution experiments using batch extraction in combination with physical separation of phytoliths by heavy liquid, this study evaluated the phytolith K(phytK) pool in rice straw and aged phytoliths in paddy soils. Entrapped organic matter containing K within phytolith silica cells was visualized by X-ray tomographic microscopy, and releases of this phytK pool accompanying phytolith dissolution were quantified. A 1% Na₂CO₃ solution, which has been commonly used to extract amorphous Si and to quantify soil phytoliths, showed obvious responses for K derived from phytolith dissolution, indicating that the Na₂CO₃ method can be developed for measurement of phytK. In 13 soil samples, Na₂CO₃-dissolvable K content assignable to phytK was 0.55 ± 0.39 g kg^?1 in the puddled horizon, suggesting the phytK pool is of high significance for the management of K in paddy soils.     

耕作模式对冷浸田水稻产量和土壤特性的影响

为探明不同耕作模式对冷浸田的影响机制,挖掘冷浸田的生产潜力,以冷浸田为研究对象,通过田间试验,以常规平作模式为对照,研究了垄作和稻鱼共作模式对冷浸田水稻产量以及土壤团聚体、温度、pH及有机质和还原性物质含量以及酶活性的影响。结果表明:相比对照(CK),垄作模式(T1)能显著降低土壤微团聚体(0.25 mm)含量,促进大团聚体的形成,提高土壤温度,增加土壤有机质含量,提高土壤pH,抑制水稻分蘖期后土壤亚铁含量的上升,降低土壤亚锰含量,减轻其对水稻根系的毒害作用,提高土壤酶活性,增加土壤速效养分含量。稻鱼共作模式(T2)对冷浸田土壤理化性状影响不显著,但能显著增加土壤速效养分含量,土壤速效钾含量在水稻孕穗期和成熟期分别较对照(CK)增加18.2%和69.2%,从而为水稻生长提供良好的土壤环境和营养,促进水稻生长发育,提高水稻产量。研究表明T1和T2模式能显著提高冷浸田水稻产量,增产范围为8.8%~25.8%,T1模式增产效果最显著,实际产量达到7 623 kg·hm-2。综上所述,垄作模式可以有效地改善冷浸田土壤特性,提高水稻产量,而稻鱼共作模式增产效果主要体现在增加冷浸田水体和土壤的速效养分。     

Soil purple phototrophic bacterial diversity under double cropping (rice‐wheat) with free‐air CO2 enrichment (FACE)

Soil purple phototrophic bacterial (PPB) communities and their responses to elevated atmospheric carbon dioxide (CO₂) concentration and nitrogen (N) fertilizer were investigated under a rotation of paddy rice (Oryza sativa L.) and winter wheat (Triticum aestivum L. cv. Yangmai 14) cultivation in a FACE (free‐air CO₂ enrichment) system. Community structures and abundances of PPB were determined by denaturing gradient gel electrophoresis (DGGE) and real‐time quantitative PCR respectively, targeting the pufM gene, which encodes a protein in the light reaction centre of PPB. Soil PPB communities were more diverse and larger under rice than under wheat cultivation, which may be attributed to the flooding of the paddy field and soil moisture changes. Elevated atmospheric CO₂ concentration significantly increased the abundance and biodiversity of PPB in soils under rice cultivation, while N fertilizer application rate had less effect on the abundance and diversity. Phylogenetic analysis showed that two common dominant DGGE bands belonged to Bradyrhizobium‐ and Rhodopseudomonas palustris‐like PPB in both rice and wheat soils. The results demonstrated a significant shift in soil PPB communities during the rice‐wheat rotation, and a strong positive response of PPB communities to an elevated atmospheric CO₂ concentration. Our results also indicated that a diverse and abundant soil PPB community could occur in upland crop fields as well as in aquatic environments and paddy‐rice fields. These findings extend our understanding of the ecological significance of PPB in terrestrial soil environments and their responses to future climate change.     

长期垄作免耕对稻田土壤有机碳剖面分布的影响

以稻田免耕长期定位试验为平台,研究长期垄作免耕对稻田土壤有机碳剖面分布的影响。结果表明,垄作免耕(中稻)、垄作免耕(稻油)、常规平作(中稻)和水旱轮作(稻油)4种耕作处理实施20年后,稻田0-60cm土体中各土层有机碳含量最高值和最低值分别出现在垄作免耕(稻油)和水旱轮作(稻油)中,且水旱轮作(稻油)中各土层有机碳含量均显著低于其他耕作处理;垄作免耕(稻油)中0-10cm和40-60cm土层有机碳含量与垄作免耕(中稻)、常规平作(中稻)之间差异不显著,但20-40cm土层有机碳含量则显著高于其他耕作处理(P<0.05),可见同传统耕作相比,长期垄作免耕(稻油)稻田的增碳优势主要体现在20-40cm土层。不同耕作处理连续实施20年后,稻田0-60cm土体有机碳密度的高低顺序为垄作免耕(稻油)>垄作免耕(中稻)>常规平作(中稻)>水旱轮作(稻油),且处理间差异显著(P<0.05)。垄作免耕15～20年期间,稻田0-10cm表层土壤有机碳储量基本稳定,但20-40cm土层有机碳储量仍有增加,其中垄作免耕(稻油)增加最为明显,表明20-40cm土层碳累积是长期垄作免耕下稻田发挥增碳功能的重要机制。     

澧阳平原古水稻土有机质红外光谱特征

澧阳平原杉龙岗古水稻土遗址剖面中不同耕作年限、不同环境条件、不同深埋的有机质的积累与迁移变化明显。以澧阳平原杉龙岗古水稻土遗址为研究对象,采用溴化钾压片法对剖面中古水稻土和现代耕作水稻土进行红外光谱测定,分析土壤中有机质的官能基团以及各基团的结构特征。结果表明,古水稻土官能基团的振动主要集中在卤素化合物和无机化合物,有机质对古水稻土官能团影响很大,其中,古水稻土中波数1 882 cm-1(烯烃碳)在去有机质后吸收峰弱化;古水稻土中波数为1 631~470 cm-1段,逐渐形成苯环、烯烃化合物且芳构化程度增加,卤素和无机化合物的结合力增强。由一阶导数可知,古水稻土与现代耕作水稻土相差不大,在去有机质后,波峰均被弱化且FD值峰值均小于去有机质前FD值。