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。     

起源于暗棕壤和红壤的水稻土有机质特性研究

土壤有机质是土壤的重要组成部分,其不仅对土壤的理化性质、肥力水平具有深刻影响,而且所包含的有机碳库动态与全球气候变化关系密切。农业土壤受人类活动的高强度干扰,其持有的碳库是全球碳库中最活跃的部分,对于维持全球碳平衡具有不可忽视的贡献[1]。水稻土是我国重要的农业土壤资源,地域分布广泛,其有机质含量是我国耕作土类中最高的,且固碳潜力显著大于旱地土壤[2]。在不同土壤类型和有机碳库的背景下,引起农业土壤碳库变化的关键因素不同[3]。我国地域广阔,南北气候和稻田耕作制度差异很大,不同区域水稻土的起源土壤存在明显的地带性。不同区域水稻土既具有长期人为利用下形成的一系列共性,又由于不同生物气候、母土、耕     

水稻土胡敏酸中的氨基酸

对比研究了两种水分条件下的土壤胡敏酸以及新形成胡敏酸中的氨基酸组成及含量，结果表明：１．水分条件对胡敏酸的氨基酸组成无显著影响；２．胡敏酸酸解残渣中的氨基酸组成和第一次酸解液的有明显的不同３．胡敏酸中已检测出的各类氨基酸氮量占全氮量的一半以上。     

稻作制度对红壤性水稻土有机质特征的影响

采用长期定位试验,比较3种稻作制度对红壤性水稻土有机质总量、有机无机复合状况、腐殖质结合形态、腐殖质组成、胡敏酸光学性质和总酸度等的影响。结果表明:冬泡制度比水旱轮作有助于增加土壤有机质总量、重组有机质含量、胡敏酸含量和胡敏酸/富啡酸,而水旱轮作比冬泡制度有利于提高土壤松结合态腐殖质、松结合态腐殖质/紧结合态腐殖质、胡敏酸E4值和总酸度。由此说明,冬泡制度有利于土壤有机质总量和胡敏酸的累积,但不利于胡敏酸分子的增长,腐殖质品质较差。而水旱轮作条件下土壤有机质活性增加,胡敏酸分子结构趋于复杂,其氧化度和芳香度增加。因此,通过周期性的水旱轮作换茬,可使土壤有机质的腐殖化和矿质化过程比例协调,从而提高土壤有机质的质量。     

热辐射对水稻土有机质组成的影响

本文研究了受不同程度热辐射后的水稻土中有机质组分的变化情况,结果表明:随温度升高,土壤中水溶性有机碳(DOC)含量先增加后减少,200℃变化尤为显著,增加为CK的3.68 ～ 7.45倍,中性糖、糖醛酸与DOC的变化趋势一致.辐射温度不同,土壤中的胡敏酸、富里酸组成和含量亦发生不同程度的变化,300℃胡/富比值最大(1.79 ～ 5.04),土壤腐殖质聚合程度增加;200℃胡敏酸的E4/E6比值最大,反映此温度下土壤芳香缩合度低、具有较多的脂族结构物质、土壤腐殖化程度低.     

江西水稻土养分状况研究

为了解近年水稻土养分变化状况,于１９９７年采集原土壤普查点位的耕层土样１４２个,进行农化性状分析。结果表明：江西水稻土土壤有机质,全氮,碱解氮,速效磷含量呈上长这效钾含量稍有改善;ｐＨ值略有下降,并简略讨论了上述养分变化的主要原因。     

不同耕种年限红壤性水稻土理化性质的变化特征

以江西省余江县不同种植年限的红壤性水稻土为对象,研究了土壤有机质、pH、阳离子交换量(CEC)、游离氧化铁含量和氧化铁活化度随时间变化趋势;选择耕种7、22和80年的土壤剖面,研究了游离氧化铁和无定形氧化铁在剖面不同层次的分布。结果表明,耕层(0～20cm)土壤有机质含量随着水稻种植年限的增加而增加,淹水种稻导致土壤pH升高,但主要发生在种稻的前7年,7～80年间土壤pH变化不大。土壤CEC随着种植年限的增加而增加,在17年达到最大,然后随种稻时间的进一步增加而减小。土壤游离氧化铁含量随种稻时间呈下降趋势,但种稻后土壤氧化铁的活化度高于母土旱地红壤。对7年和80年水稻土,表层土壤游离氧化铁的含量低于底层土壤,说明铁在剖面中存在淋溶迁移。7年和22年水稻土表层土壤无定形氧化铁含量高于底层土壤,但对80年水稻土,土壤无定形氧化铁随采样深度的增加而增加。     

秸秆深还不同年限对黑土腐殖质组成和胡敏酸结构特征的影响

秸秆深还(Corn stover deep incorporation,CSDI)指将作物秸秆深埋于土壤亚表层20~40 cm深处,用以解决秸秆焚烧和土壤肥力退化的可持续利用模式。本文以吉林农业大学玉米连作耕地试验田未施用秸秆和秸秆深还不同年限的土壤为研究对象,设置CK、CSDI(2014)、CSDI(2013)和CSDI(2012)共4种处理,分别代表未施入秸秆、2014年秸秆深还(深还第1年)、2013年秸秆深还(深还第2年)、2012年秸秆深还(深还第3年),研究秸秆深还不同年限对黑土腐殖质组成和胡敏酸结构特征的影响。通过腐殖质组成修改法提取富里酸(Fulvic acid,FA)、胡敏酸(Humic acid,HA)和胡敏素(Humin,HM),国际腐殖质协会(International Humic Substances Society,IHSS)推荐的方法提取HA样品,通过元素组成、红外光谱和差热分析测定HA结构。结果表明:与CK相比,秸秆深还1年后显著提高了土壤和腐殖质各组分有机碳含量,亚表层累积效果更明显,其土壤有机碳(SOC)、HA、FA和HM有机碳含量分别增加了23.7%、30.5%、27.3%和46.1%,但PQ值(HA在可提取腐殖物质的比例)没有显著变化;HA氧化度和缩合度降低明显,表层和亚表层(O+S)/C比值分别降低14.31%和14.68%,H/C比值分别增加27.74%和28.86%,脂族链烃和芳香碳含量增加,热稳定性降低,HA结构趋于简单化。随着年限增加,深还3年后SOC、FA和HM有机碳含量呈下降趋势,HA有机碳含量呈上升趋势,PQ值变化显著,HA缩合度、氧化度呈上升趋势,脂族性减弱,芳香性增强,HA结构趋于复杂化。说明随着年限增加,秸秆不断矿化分解,秸秆深还对土壤腐殖质组成和结构特征的影响效果减弱。     

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。     

五十年来宁波平原水稻土有机质变化及其调控措施

2008年对宁波平原水稻土的有机质进行了研究.结果表明:50年来宁波平原水稻上有机质含量有了很大变化,从1958年第一次土壤普查时的27.8 g/kg,上升到1980年第二次土壤普查时的55.3 g/kg,增加了98.g%.但到2008年下降到48.37g/kg.下降了12.5%,达显著水平.本文探讨了近28年来宁波平...     

Impact of organic matter addition on pH change of paddy soils

Purpose

The objective of the present study was to explore the effect of initial pH on the decomposition rate of plant residues and the effect of residue type on soil pH change in three different paddy soils.

Materials and methods

Two variable charge paddy soils (Psammaquent soil and Plinthudult soil) and one constant charge paddy soil (Paleudalfs soil) were used to be incubated at 45 % of field capacity for 105 days at 25 °C in the dark after three plant residues (Chinese milk vetch, wheat straw, and rice straw) were separately added at a level of 12 g?kg^?1 soil. Soil pH, CO₂ escaped, DOC, DON, MBC, MBN, NH ₄ ⁺ , and NO ₃ ^? during the incubation period were dynamically determined.

Results and discussion

Addition of the residues increased soil pH by 0.1–0.8 U, and pH reached a maximum in the Psammaquent and Plinthudult soils with low initial pH at day 105 but at day 3 in the Paleudalfs soil with high initial pH. Incorporation of Chinese milk vetch which had higher concentration of alkalinity (excess cations) and nitrogen increased soil pH more as compared with incorporation of rice and wheat straws. Microbial activity was the highest in Chinese milk vetch treatment, which resulted in the highest increase of soil pH as compared with addition of rice and wheat straws. However, nitrification seemed to be inhibited in the variable charge soils of Psammaquent and Plinthudult but not in the constant charge soil of Paleudalfs.

Conclusions

The effectiveness of increasing soil pH after incorporation of the plant materials would be longer in low initial pH soils of Psammaquent and Plinthudult than in high initial pH soil of Paleudalfs. In order to achieve the same degree of pH improvement, higher amounts of plant residues should be applied in constant charge soils than in variable charge soils.     

紫色水稻土轻组有机质的季节动态研究

以位于重庆市北碚区西南大学试验农场(30°26′N,106°26′E)的紫色水稻土为研究对象,利用重液(NaI,密度1.8 g·cm-3)对土壤中轻组组分进行提取,对土壤中轻组有机质在整个油菜生长季的季节变化情况进行分析与讨论。结果表明:表层(0~30 cm)土壤轻组物质(LF)的含量为2.95%~5.51%,平均值为4.38%;土壤轻组有机碳含量(LFOC)和轻组氮含量(LFN)的变化范围分别为1.44~3.72 g·kg-1和0.08~0.17 g·kg-1,其平均值分别为2.79 g·kg-1和0.14 g·kg-1。LFOC具有明显的季节变化(P<0.05),其含量在油菜生长中期最高,其次是生长后期,而在生长初期最低;LFN的季节变化趋势与LFOC一致,但季节差异性不显著(P>0.05)。轻组有机碳分配比例(LFOC/SOC)的变化范围为9.21%~24.47%,具有明显的季节变化(P<0.05),其变化趋势与LFOC的季节变化一致;而轻组氮的分配比例(LFN/TN)变化范围为4.55%~12.58%,无明显的季节变化。轻组C/N比值季节变化范围为18.52~25.04,平均值为20.66,全土C/N比值的变化范围为9.04~14.36,平均值为11.66,说明轻组有机质的生物可利用性较土壤总有机质高。相关分析表明,轻组有机碳、氮含量分别与根系生物量、根系碳含量、根系氮含量呈极显著(P<0.01)或显著(P<0.05)正相关;回归分析表明,土壤轻组有机碳、氮含量变化的40%~60%可由根系生物量、根系碳氮含量决定,说明根系是调控紫色水稻土轻组有机碳、氮季节变化的主要生态因子。     

南方典型母质发育水稻土剖面酸化特征研究

明确我国南方典型母质发育水稻土的剖面酸化特征及其影响因素,为稻田土壤酸化有效防控及治理提供理论依据.选取湖南长株潭区域不同母质(板页岩、第四纪红土、花岗岩、河流冲积物、砂岩、石灰岩及紫色砂页岩)发育的潴育性水稻土剖面,分别测定耕作层(A)、犁底层(P)、潴育层(W)及母质层(C)各层次的土壤pH,利用A与C层间pH的变...     

泰国水稻土Fe还原细菌对盐分和有机物改良的响应

In paddy soils of Thailand,the addition of organic matter (OM) is used to efficiently limit the effect of salinity on rice culture and production.OM used as an amendment and fertilizer promotes the reduced condition and increases iron solubilization without provoking ferrous toxicity.In this study,the intricate biogeochemical role of iron-reducing bacteria (IRB) involved in the quality of water and soil of paddy fields,particularly when the paddy fields were subject to salinity and organic matter addition,were studied in paddy fields of Thailand.The results demonstrated that the addition of OM increased the proliferation of cultivable IRB and their specific activity.Cultivable IRB communities decreased in the presence of salt.The presence of salt modified the structure of the bacterial populations by favoring the development of alkaline and moderately halophilic bacteria (Virgibacillus spp.,Oceanobacillus spp.,and Paenibacillus spp.).The paddy soils studied contained very diversified (halosensitive,halotolerant,and halophilic) IRB populations that could be adapted to a variety of salinity conditions (0-90 g L 1 NaCl) using different organic substrates (glucose,acetate,and soil organic matter) to maintain significant activities under extreme conditions of salinity.The rhizosphere of rice stimulated IRB community growth without organic matter,whereas organic matter addition limited the rhizosphere effect on IRB cultivable number in saline condition.The interactive action of salinity and organic amendment had a negative impact on the rhizosphere effect.The presence of specific iron-reducing populations (fermentative,iron-respiring,anaerobic,and facultative anaerobic),having different behaviors under salt and redox stresses,appeared to be a key factor that contributed to the control or enhancement of the quality of water and soil in paddy fields.     

有机质对典型铜锌污染土壤自然修复过程的影响

为阐明土壤有机质含量对外源铜（Cu）、锌（Zn）自然修复过程的影响,选取红壤、潮土和黑土长期试验中不同有机质含量的土样,分别加入400 mg/kg Cu或500 mg/kg Zn,采用室内培养法研究Cu、Zn污染物的自然修复过程。结果表明：各种土壤有效态Cu、Zn浓度在培养开始的10～20 d内迅速下降,随后变化减缓,培养30～60 d后基本达到平衡。外源Cu、Zn自然修复过程符合二级动力学方程。自然修复90 d后,在红壤和潮土低有机质含量的处理中有效Cu浓度比高有机质含量的处理高24.2%～57.1%;而在黑土和潮土高有机质含量的处理中有效态Zn浓度是有机质含量低的处理的3.44～6.33倍。这说明在3种土壤上增加有机质含量对Cu、Zn的作用效果不同,在红壤上抑制了Cu的有效性,在潮土上抑制有效Cu促进有效Zn,在黑土上则促进Cu、Zn有效性。在3种土壤中,碱性潮土外源Cu、Zn修复速率较快,且有效态Cu、Zn平衡浓度较小,其对Cu、Zn的固定能力最强,酸性红壤则最弱。采用各种措施提高土壤有机质含量可作为修复红壤和潮土重金属Cu污染的有效措施之一,但增加了黑土及潮土Zn的环境风险。     

Redox control on carbon mineralization and dissolved organic matter along a chronosequence of paddy soils

Paddy soils are subjected to periodically changing redox conditions. In order to understand better the redox control on long‐term carbon turnover, we assessed carbon mineralization and dissolved organic carbon (DOC) of paddy topsoils sampled along a chronosequence spanning 2000 years of rice cultivation. Non‐paddy soils were used as references. We exposed soils to alternating redox conditions for 12 weeks in incubation experiments. Carbon mineralization of paddy soils was independent of redox conditions. Anoxic conditions caused increasing DOC concentrations for paddy soils, probably because of desorption induced by increasing pH. We assume desorption released older, previously stabilized carbon, which then was respired by a microbial community well adapted to anoxic conditions. This assumption is supported by the ¹⁴C signatures of respired CO₂, indicating larger mineralization of older carbon under anoxic than under oxic conditions. The increasing DOC concentrations under anoxic conditions did not result in an equivalent increase in carbon mineralization, possibly because of little reducible iron oxide. Therefore, net DOC and CO₂ production were not positively related under anoxic conditions. The overall 20–75% smaller carbon mineralization of paddy soils than of non‐paddy soils resulted from less respiration under oxic conditions. We conclude that carbon accumulation in paddy as well as in other wetland soils results from a microbial community well adapted to anoxic conditions, but less efficient in mineralizing carbon during transient oxic periods. Carbon accumulation might be even larger when mineralization under anoxic conditions is restricted by a lack of alternative electron acceptors.     

Effects of organic matter application on microbial biomass and available nutrients in various types of paddy soils

Abstract

The effect of the addition of bromacil (pesticide) or/and a sewage sludge on the urease, phosphatase and dehydrogenase activities of soil was studied. Urease and phosphatase activities increased initially with the addition of bromacil. This effect disappeared after 28 d of soil incubation. The increase in the urease and phosphatase activities caused by the addition of sewage sludge was more pronounced than that of bromacil. The combined addition of sewage sludge and bromacil also led to an increase in the activity of both hydrolases. Dehydrogenase activity was affected negatively by the addition of bromacil and positively by the sewage sludge addition. When sewage sludge and bromacil were added simultaneously, dehydrogenase activity was higher than when sewage sludge alone was added.