黄土高原果园土壤有机质变化趋势分析——以陕西省为例

在典型果业生产区域的黄土高原选择5个采样区的45个果园5个对照常年作物农田,利用GIS定位仪共采集0-20 cm表土样品45份,对其土壤有机质含量进行了测定.果园划分为5～10 a、10～15 a和15 a以上3个园龄段,常年作物农田选择果园附近的普通农作物田块取样.利用单样本平均数t检验和单向分组资料方差分析,对果园与农田、园龄段分组与农田2个方面进行统计分析.结果表明:果园与农田相比土壤有机质含量有一定的提高,其中大部分有显著提高;苹果优质高产地区,随果园同龄增加,土壤有机质含量显著提高,同时表明果园种草能够显著提高果园土壤有机质含量.影响果园土壤有机质含量变化原因包括肥料投人数量与结构、种植方式、土壤类型、农产品市场行情和农业技术等方面.     

新疆农田土壤有机质含量及组成特征

目前新疆农田土壤有机质含量在5．3～24．21g／kg之间，平均14．65g／kg，与第2次土壤普查结果相比，新疆农田土壤有机质含量呈上升趋势；胡敏素碳（C)含量占到有机质C量的53％～70％，平均6l％，腐殖酸C量只占39％。     

北方典型区域果园表层土壤农药类POPs残留特征分析

在我国典型果业生产区域的黄土高原、胶东半岛和北京郊区选择11个采样区的99个果园,利用GPS定位仪共采集0~20cm表土样品99份,测定了DDT、六氯苯、七氯、氯丹、狄氏剂、异狄氏剂、灭蚁灵和艾氏剂等8种主要POPs残留量,对土壤POPs残留的环境安全性、土壤残留差异性以及区域分布特点进行了分析研究。结果表明：（1）果园表层土壤8种POPs残留浓度符合国家土壤环境质量标准,属于环境安全残留;（2）滴滴涕是果园土壤残留分布最广泛和残留量较高的POPs,其次是六氯苯、氯丹和七氯,再其次是狄氏剂、异狄氏剂、灭蚁灵和艾氏剂;（3）果园土壤POPs残留种类多、广泛残留与高残留量地区的共同特征是建园早、园龄长、自然条件好和农业经济较发达。     

植被恢复过程中土壤有机质和全氮的变化特征及区域差异

不同区域植被恢复对土壤化学性质变化的影响差异较大。本文通过收集前人在土壤化学性质方面的研究数据, 选取福建省长汀县、闽清县和陕西省陕北地区植被恢复过程中0~20 cm 表土层有机质和全氮含量,进行了两类区域土壤表层有机质和全氮在自然恢复和人为恢复过程中变化特征的比较分析。结果表明, 福建省长汀县和闽清县的植被恢复初期, 人为恢复对土壤有机质和全氮含量的影响较大, 后期自然恢复影响更大;陕北地区植被恢复初期自然恢复对土壤有机质和全氮含量的改善好于人为恢复, 之后二者差异不明显; 福建省长汀县和闽清县在整个植被自然恢复过程中土壤有机质和全氮累计增量和年平均增量都比陕北地区高。因此, 建议福建省长汀县和闽清县应先进行人为植被恢复, 然后进行自然恢复; 而陕北地区应先进行自然恢复,再人为恢复和自然恢复相结合, 这样可有效改善土壤有机质和全氮含量, 加快植被恢复。     

中国不同地区土壤有机质特征比较研究

土壤有机质是土壤的重要组成部分,既能为植物提供生长所需的各种营养成分,也能维持土壤生态系统的稳定。土壤有机质是陆地生态系统表层最大和最活跃的碳库,其微小波动会影响全球碳库的源汇效应。中国幅员辽阔,碳储量巨大,其在全球碳汇中具有举足轻重的地位。因此,在全球变化背景下研究我国土壤有机质的数量、组分和结构特征对于评价陆地生态系统碳循环有重要意义。本文对全国范围内具有代表性的东北、华北、西北、东南、西南和中部地区的土壤有机质数量、组分和结构特征进行了对比、分析、归纳和总结,阐述各个地区土壤有机质的特征,解析气候因素对土壤有机质地区间差异的影响,期望通过对我国主要地区土壤有机质特征论述,为未来各个地区的有机质研究和应对未来气候变化的策略提供参考资料。     

红壤典型区土壤中有机质的分解、积累与分布特征研究进展

土壤有机质分解转化是红壤生态系统碳循环的重要环节。自中国科学院红壤生态实验站建站以来,本课题组围绕土壤有机质分解转化的关键科学问题,重点开展了有机物料在土壤中的分解与影响因素、土壤有机质的矿化过程动态、土壤有机质的积累过程特征、以及红壤水稻土团聚体中有机碳的分布规律等方面的研究。本文回顾了过去所开展的主要研究内容的进展情况,并对今后的研究工作做出了初步展望。     

黑土典型区土壤有机质遥感反演

土壤有机质（SOM）含量时空变异规律研究对于土壤肥力评价、土壤碳库估算、土壤资源利用与保护具有重要意义,而地貌、成土母质、土壤类型等差异、高光谱卫星影像较少等因素制约了区域尺度的SOM含量遥感反演方法研究的开展。该文以黑龙江省黑土带典型区为例,采集区域土壤样本,获取Landsat TM遥感影像,基于有机质含量与土壤反射率的定量关系,建立区域SOM遥感预测模型。结果表明：黑土区SOM含量高,一般大于2%,决定了有机质对土壤反射光谱特性的主要作用,而且该区SOM空间变异性显著,且耕作方式、气候等因素决定了裸土时间长,因而该区适于SOM含量遥感反演;有机质与TM各波段反射率均显著相关,最大相关系数在第3波段（0.63～0.69 μm）,为-0.710,其次为4波段（0.76～0.90 μm）,与实验室基于高光谱反射率数据分析的结果一致;基于TM影像2、3、4波段的SOM指数模型最优,预测精度高、稳定性好,可以用于揭示黑土典型区SOM含量的空间分布特征。该研究将为改进土壤理化参数遥感反演、土地质量评价、土壤碳库估算等工作方法提供理论与技术支持。     

典型黑土区坡耕地土壤碱性磷酸酶和有机质空间分布研究

以东北黑土侵蚀严重区宾州河流域为研究区,通过采集流域上游、中游和下游6个典型坡面及各坡面不同坡位的土壤样品,分析坡耕地土壤碱性磷酸酶和土壤有机质在流域和坡面尺度的空间分布特征及其与土壤侵蚀的关系。结果表明,在流域尺度上,坡耕地土壤碱性磷酸酶活性和土壤有机质含量均表现为下游 > 中游 > 上游,坡面尺度上总体表现为坡面上部 < 坡面中部 < 坡面下部的趋势,且坡位对土壤有机质分布的影响较其对土壤碱性磷酸酶活性的影响更为明显。土壤碱性磷酸酶活性与土壤有机质间存在极显著的正相关关系。流域土壤碱性磷酸酶活性和有机质空间分布与土壤侵蚀空间分布相对应,反映出土壤侵蚀是影响该区耕层土壤碱性磷酸酶活性和土壤有机质含量的主要因素。     

黄土塬面果园土壤养分特征及演变

为了探明黄土高原沟壑区长期种植果树对果园土壤肥力的影响,应用空间代时间的方法,对不同种植年限果园的土壤肥力状况进行多元统计分析。结果表明,果园土壤全磷、速效磷和速效钾含量丰富,有机质、全氮、碱解氮含量属中等偏下水平。不同果园中各养分变异较大的是土壤速效磷、速效钾,土壤有机质和全氮的变异系数最小。与当地农田土壤养分相比,果园土壤养分除有机质含量差异不显著,全氮含量显著低于农田外,其余养分含量均显著高于农田。总体上看,不同种植年限间果园土壤养分含量差异显著。果园土壤肥力综合指数与种植年限二者之间有显著的相关性,其变化趋势符合y=-0.0011x2+0.0419x+0.2078模型。在黄土高原沟壑区种植果树能够提高土壤肥力,但当果树种植年限超过19年时果园土壤肥力开始衰退,果园生态系统质量下降。     

Managing soil organic matter – implications for soil structure on organic farms

Abstract. This paper reviews current understanding of soil structure, the role of soil organic matter (SOM) in soil structure and evidence for or against better soil physical condition under organic farming. It also includes new data from farm case studies in the UK. Young SOM is especially important for soil structural development, improving ephemeral stability through fungal hyphae, extracellular polysaccharides, etc. Thus, to achieve aggregate stability and the advantages that this conveys, frequent input of fresh organic matter is required. Practices that add organic material are routinely a feature of organically farmed soils and the literature generally shows that, comparing like with like, organic farms had at least as good and sometimes better soil structure than conventionally managed farms. Our case studies confirmed this. In the reviewed papers, SOM was generally larger on the biodynamic/organic farms because of the organic additions and/or leys in the rotation. We can therefore hypothesize that, because it is especially the light fraction of SOM that is involved in soil structural development, soil structure will improve in a soil to which fresh organic residues are added regularly. Thus, we argue it is not the farming system per se that is important in promoting better physical condition, but the amount and quality of organic matter returned to a soil.     

Invertebrate control of soil organic matter stability

 The control of soil organic matter (SOM) stability by soil invertebrates is evaluated in terms of their impact on the inherent recalcitrance, accessibility to microorganisms, and interaction with stabilizing substances of organic compounds. Present knowledge on internal (ingestion and associated transformations) and external (defecation, constructions) control mechanisms of soil invertebrates is also reviewed. Soil animals contribute to the stabilization and destabilization of SOM by simultaneously affecting chemical, physical, and microbial processes over several orders of magnitude. A very important aspect of this is that invertebrates at higher trophic levels create feedback mechanisms that modify the spatio-temporal framework in which the micro-food web affects SOM stability. Quantification of non-trophic and indirect effects is thus essential in order to understand the long-term effects of soil biota on SOM turnover. It is hypothesized that the activities of invertebrates which lead to an increase in SOM stability partly evolved as an adaptation to the need for increasing the suitability of their soil habitat. Several gaps in knowledge are identified: food selection and associated changes in C pools, differential effects on SOM turnover, specific associations with microorganisms, effects on dissolution and desorption reactions, humus-forming and humus-degrading processes in gut and faeces, and the modification of invertebrate effects by environmental variables. Future studies must not be confined merely to a mechanistic analysis of invertebrate control of SOM stability, but also pay considerable attention to the functional and evolutionary aspects of animal diversity in soil. This alone will allow an integration of biological expertise in order to develop new strategies of soil management which can be applied under a variety of environmental conditions. Received: 6 April 1999     

大别山区江子河流域土壤有机质的空间变异

土壤有机质(Soil organic matter,SOM)是土壤的重要组成部分,是反映土壤肥力的重要指标,是全球碳循环的重要源和汇,目前已成为土壤学和环境学的研究热点之一[1]。土壤空间异质性是系统的某种属性在空间上的复杂性和变异性,是土壤重     

Predicting soil N mineralization: Relevance of organic matter fractions and soil properties

Distinct extractable organic matter (EOM) fractions have been used to assess the capacity of soils to supply nitrogen (N). However, substantial uncertainty exists on their role in the N cycle and their functional dependency on soil properties. We therefore examined the variation in mineralizable N and its relationship with EOM fractions, soil physical and chemical properties across 98 agricultural soils with contrasting inherent properties and management histories. Mineralizable N was determined by aerobic incubation at 20 °C and optimum moisture content for 20 weeks. We used multivariate statistical modelling to account for multi-collinearity, an issue generally overlooked in studies evaluating the predictive value of EOM fractions. Mineralization of N was primarily related to the size of OM pools and fractions present; they explained 78% of the variation in mineralizable N whereas other soil variables could explain maximally 8%. Both total and extractable OM expressed the same soil characteristic from a mineralization perspective; they were positively related to mineralizable N and explained a similar percentage of the variation in mineralizable N. Inclusion of mineralizable N in fertilizer recommendation systems should be based on at least one OM variable. The most appropriate EOM fraction can only be identified when the underlying mechanisms are known; regression techniques are not suitable for this purpose. Combination of single EOM fractions is not likely to improve the prediction of mineralizable N due to high multi-collinearity. Inclusion of texture-related soil variables or variables reflecting soil organic matter quality may be neglected due to their limited power to improve the prediction of mineralizable N.     

土壤碱溶有机质的测定研究与应用

本文研究了一种土壤供氮能力快速测定方法-土壤碱溶有机质的测定,以及碱溶有机质与常规土壤有机质的相关性、碱溶有机质与植株氮素吸收的相关性及其在测土推荐施肥中的初步应用。选择我国有代表性的潮土、黑土、红壤土样各50个,研究土壤碱溶有机质与常规方法-丘林法测定的土壤有机质的相关性,结果显示二者呈极显著相关（p>0.01）,相关系数R = 0.9345,相关直线回归方程为：土壤有机质（gkg-1） = 3.3265碱溶有机质（gkg-1）+ 6.9389。选择代表我国主要土壤类型的28个土样进行盆栽试验,研究土壤供氮能力测定方法与植株氮素吸收的相关性,结果表明,土壤碱溶有机质与不施氮处理植株吸氮量相关性极显著（相关系数为0.628,p>0.01）,且其相关系数高于土壤有机质和土壤全氮与植株吸氮量的相关系数。虽然土壤碱溶有机质与植株氮素吸收的相关性低于生物培养方法即好气培养2周后土壤矿质氮（硝态氮+铵态氮）与植株氮素吸收的相关性,但土壤碱溶有机质更适合测土推荐施肥实验室高效快速测定的需要,可见碱溶有机质是可浸提的土壤腐殖质,可用比色法快速测定并能较好估测土壤的供氮能力,值得推荐在测土配方施肥实验室应用。     

Temperature response of soil organic matter mineralisation in arctic soil profiles

Soil organic matter (SOM) in arctic and boreal soils is the largest terrestrial reservoir of carbon. Increased SOM mineralisation under increased temperature has the potential to induce a massive release of CO₂. Precise parameterisation of the response of arctic soils to increased temperatures is therefore crucial for correctly simulating our future climate. Here, we investigated the temperature response of SOM mineralisation in eight arctic soil profiles of Norway, Svalbard and Russia. Samples were collected at two depths from both mineral and organic soils, which were affected or not by permafrost and were incubated for 91 days at 4, 8, 12, and 16 °C. Temperature response was investigated through two parameters derived from a simple exponential model: the intensity of mineralisation, α, and the temperature sensitivity, Q10. For each sample, SOM quality was investigated by ¹³C-NMR, whereas bacterial and fungal community structure was characterised by T-RFLP and ARISA fingerprints, respectively. When estimated from the whole incubation period, α proved to be higher in deep permafrost samples than in shallow active layer ones due to the presence transient flushes of mineralisation in deep permafrost affected soils. At the end of the incubation period, after mineralization flushes had passed, neither α nor Q10 (averaging 1.28 ± 0.07) seemed to be affected by soil type (organic vs mineral soil), site, depth or permafrost. SOM composition and microbial community structure on the contrary where affected by site and soil type. Our results suggest that deep samples of permafrost affected soil contain a small pool of fast cycling carbon, which is quickly depleted after thawing. Once the mineralization flush had passed, the temperature response of permafrost affected soil proved to be relatively homogenous among sample types, suggesting that the use of a single temperature sensitivity parameter in land surface models for SOM decomposition in permafrost-affected soils is justified.     

土壤碱溶有机质的测定研究与应用

研究了一种土壤供氮能力快速测定方法-土壤碱溶有机质的测定,以及碱溶有机质与常规土壤有机质的相关性、碱溶有机质与植株氮素吸收的相关性及其在测土推荐施肥中的初步应用。选择我国有代表性的潮土、黑土、红壤土样各50个,研究土壤碱溶有机质与常规方法-丘林法测定的土壤有机质的相关性,结果显示二者呈极显著相关(p>0.01),相关系数r=0.9345,相关直线回归方程为:土壤有机质(g kg-1)=3.3265μ碱溶有机质(g kg-1)+6.9389。选择代表我国主要土壤类型的28个土样进行盆栽试验,研究土壤供氮能力测定方法与植株氮素吸收的相关性,结果表明,土壤碱溶有机质与不施氮处理植株吸氮量相关性极显著(相关系数为0.628,p>0.01),且其相关系数高于土壤有机质和土壤全氮与植株吸氮量的相关系数。虽然土壤碱溶有机质与植株氮素吸收的相关性低于生物培养方法即好气培养2周后土壤矿质氮(硝态氮+铵态氮)与植株氮素吸收的相关性,但土壤碱溶有机质更适合测土推荐施肥实验室高效快速测定的需要,可见碱溶有机质是可浸提的土壤腐殖质,可用比色法快速测定并能较好估测土壤的供氮能力,值得推荐在测土配方施肥实验室应用。     

Dissolved organic matter enhances the sorption of atrazine by soil

The influence of dissolved organic matter (DOM) on the sorption of atrazine (2-chloro-4-ethylamino-6-isopylamino-1,3,5-triazine) by ten soils was investigated. Batch sorption isotherm techniques were used to evaluate the important physiochemical properties of soil determining the sorption of atrazine in the presence of DOM. The sorption of atrazine as a representative of nonionic organic contaminants (NOCs) by soil with and without DOM could be well described by the Linear and Freundlich models. The n values of the Freundlich model were generally near to 1, indicating that linear partitioning was the major mechanism of atrazine sorption by soil samples. The apparent distribution coefficient, value, for atrazine sorption in the presence of DOM initially increased and decreased thereafter as the DOM concentration increased in the equilibrium solution. DOM at relatively lower concentrations significantly enhanced the sorption of atrazine by soil, while it inhibited the atrazine sorption at higher concentrations. For all the soil samples, the maximum of was 1.1~3.1 times higher than its corresponding K _d value for the control (without DOM). The maximum enhancement of the distribution coefficient () in the presence of DOM was negatively correlated with the content of soil organic carbon (SOC) and positively correlated with the clay content. The critical concentration of DOM, below which DOM would enhance atrazine sorption, was negatively correlated with SOC. The influence of DOM on atrazine sorption could be approximately considered as the net effect of the cumulative sorption and association of atrazine with DOM in solution. Results of this study provide an insight into the retention and mobility of a NOC in the soil environment.     

Carbon and nitrogen in operationally defined soil organic matter pools

Humic substances [humic acid (HA), fulvic acid (FA), and insoluble humin], particulate organic matter (POM), and glomalin comprise the majority (ca 75%) of operationally defined extractable soil organic matter (SOM). The purpose of this work was to compare amounts of carbon (C) and nitrogen (N) in HA, FA, POM, and glomalin pools in six undisturbed soils. POM, glomalin, HA, and FA in POM, and glomalin, HA, and FA in POM-free soil were extracted in the following sequence: (1) POM fraction separation from the soil, (2) glomalin extraction from the POM fraction and POM-free soil, and (3) co-extraction of HA and FA from the POM fraction and POM-free soil. Only trace amounts of HA and FA were present in the POM fraction, while POM-associated glomalin (POM-glomalin) and POM alone contributed 2 and 12%, respectively, of the total C in the soil. Mean combined weights for chemically extracted pools from POM and from POM-free soil were 9.92 g glomalin, 1.12 g HA, and 0.88 g FA kg⁻¹ soil. Total protein and C, N, and H concentrations showed that glomalin and HA were, for the most part, separate pools, although protein was detected in HA extracts. Even though percentage carbon was higher in HA than in glomalin, glomalin was a larger (almost nine times) operationally defined pool of soil organic C. Glomalin was also the largest pool of soil N of all the pools isolated, but all pools combined only contained 31% of the total N in the soil.     

Use of organic carbon and loss-on-ignition to estimate soil organic matter in different soil types and horizons

Summary Loss-on-ignition (LOI) and the organic C content have been used to estimate soil organic matter. Organic matter is often estimated from organic C by applying a factor of 1.724. Several authors have examined the relationship between LOI, used as an estimate of organic matter, and C by simple linear regressions. In the present study, this approach was examined in relation to two sets of data. LOI overestimates organic matter in soils with significant proportions of clay minerals because of bound water, and correcting for bound water gives some LOI: C ratios of less than 1. It is concluded that differences in the nature of the organic matter in different soils and horizons make the simple regression approach unsuitable. More attention needs to be paid to studies of the nature of the organic matter.