Relationships between soil respiration and soil moisture

The interaction of soil microbes with their physical environment affects their abilities to respire, grow and divide. One of these environmental factors is the amount of moisture in the soil. The work we published almost 25 years ago showed that microbial respiration was linearly related to soil-water content and log-linearly related to water potential. The paper arose out of collaboration between two young researchers from different areas of soil science, physics and microbiology. The project was driven by not only our curiosity but also the freedom to operate without the constraints common to the current system of science management. The citation history shows three peaks, 1989, 1999 and from 2002 to the present day. Interestingly, the annual citation rate is as high as it has ever been. The initial peak is due to the application of the work to studies on microbial processes. The second peak is associated with the rise of simulation modelling and the third with the relevance of the findings to climate change research. In this article, our paper is re-evaluated in the light of subsequent studies that allow the principle of separation of variables to be tested. This re-evaluation lends further credence to the linear relationship proposed between soil respiration and water content. A scaled relationship for respiration and water content is presented. Lastly, further research is suggested and more recent work on the physics of gas transport discussed briefly.     

面向土壤系统分类的土壤调查制图方法的初步研究

我国的土壤系统分类方案已经基本形成,但还没有相应的土壤调查方法技术研究。按照传统土壤调查的主要剖面、检查剖面、定界剖面的思想与办法,采用空间内插技术,在研究区的4条实验路线上共挖掘了64个剖面点,通过这些剖面点的诊断层和诊断特性确定了研究区的土壤类型并勾绘了土壤类型界线。再用1条检验路线对勾绘的土壤图进行检查,结果表明,在检验路线上设置的20个检查剖面点中,其中19个剖面点与实际情况相符,正确率95%,说明使用内插法进行面向土壤系统分类的土壤调查制图是可行的。再结合土壤景观可以辅助土壤调查工作者更高效地确定土壤类型、勾绘土壤界线。     

熏蒸处理对土壤微生物及硝化作用的影响

在田间条件下用溴甲烷(68.1g/m2)、威百亩(7.5mL/m2)进行土壤熏蒸,调查两种药剂对土壤微生物及硝化作用的影响。结果表明:两种熏蒸剂对土壤放线菌无抑制作用,对细菌总量影响较小,但亚硝酸细菌受到强烈抑制,土壤的硝化作用受到明显影响;同时,土壤中真菌的数量及种类变化显著。熏蒸后9周,处理区土壤中的微生物基本恢复正常。     

Effects of soil erosion on long-term soil productivity in the black soil region of northeastern China

China's northeastern Black Soil Region, one of the country's most important crop production areas, has been seriously affected by soil erosion. This study evaluated the effects of soil erosion on the long-term productivity of this region. We used a modified productivity index (MPI) model (MPI is a number between 0 and 1, with 1 indicating highest productivity) to assess the current effects of soil erosion on soil productivity, as well as to predict long-term change in productivity. Samples from 21 black soil profiles yielded varying MPI values, although most MPI values were indicative of moderate productivity. Organic matter content and available water capacity impact MPI values in the region, whereas soil clay content and pH were less important. Overall, organic matter content and available water capacity of soil profiles decreased consistently as depth of erosion increased. Modeling indicated that MPI in the region will decrease by 0.0052 for each centimeter of topsoil eroded; this rate represents 1% of the current average MPI for the study area. The model predicts a 9.6% productivity reduction over 100 years and a 48.3% reduction over 500 years.     

Effects of a vermicompost composted with beet vinasse on soil properties, soil losses and soil restoration

The use of organic rich wastes instead or as a complement of mineral fertilizers is considered a good environmental practice, provided that the organic wastes are not severely polluted (e.g. occurrence of heavy metals, organic pollutants and/or pathogens). However, the effect of a particular organic waste on soil properties, soil loss and soil restoration depends on its chemical composition. In particular, the application of fresh beet vinasse showed a detrimental impact on the soil's physical, chemical and biological properties, increasing soil loss and decreasing plant cover, probably because it contains high quantities of monovalent cations, such as Na⁺, which destabilize the soil structure. The main objective of this work was to study the effect of beet vinasse co-composted with a vermicompost (constituted by green forages) at rates of 5 and 10 t kg organic matter ha^− 1, on physical (structural stability and bulk density), chemical (exchangeable sodium percentage) and biological (soil microbial biomass-C, soil respiration and soil enzymatic activities) properties of soils and, consequently, how its application may contribute to soil loss and soil restoration. The experiment was carried out for three years on a Xerollic Calciorthid located near Seville (Guadalquivir Valley, Andalusia, Spain). The co-composting of beet vinasse and green waste vermicompost had a positive effect on the soil's physical, chemical and biological properties, leading to a decrease in soil loss (31.2% compared with unamended soil) and an increase in plant cover (68.7% compared with unamended soil). These results suggest that the co-composting of beet vinasse with vermicomposts protects the soil and contributes to its restoration, thus representing a good strategy for recovering semiarid areas.     

用土壤温度估算表层土壤导温率与热通量的研究

对比研究了6种用土壤湿度计算表层土壤导温率的方法结果表明，振幅法、相位法、反正切法、对数法虽需较少观测值，计算简单，但结果却不太稳定；谐波法计算过程虽较复杂，但导温度的估算值较稳定，是最可靠的方法之一。利用计算的土壤导温率估算近地表土壤热通量，结果与由温度积分法决定的土壤热通量值非常一致。     

中国土壤系统分类土族和土系划分标准

中国土壤系统分类建立了亚类以上高级单元分类标准和检索,但在基层分类标准方面尚待系统建立和完善.本文主要介绍了中国土壤系统分类土族与土系划分的标准,从标准建立的背景、原则与特点到标准本身进行了较为详尽的描述,并用实例演示了土族土系标准在具体土壤上的应用.     

A new definition of soil to promote soil awareness,sustainability, security and governance

In these last decades, the awareness that soil is a very important resource for humans has noticeably increased. Many actions and initiatives to promote soil governance, aiming at sustainable soil management and soil security have been undertaken by several national and international institutions and in many countries. Analysis of the changes of soil perception over the centuries allows highlighting a perfect harmony between the evolution of soil awareness and the level of knowledge and technology achieved by humans during their history and evolution. Notwithstanding these many achievements, soils continue to be scarcely considered in politics and society. We suggest some thoughts and reflections that could lead to an up-to-date and effective definition of soil that directly focuses the public attention on its economic value. In our opinion, soil economic value could be the only aspect that truly attracts the attention of politicians and administrators, which could increase soil awareness and encourage soil sustainability, security and Sustainable Development Goals and finally promote soil governance.     

荒漠草原土壤酶与土壤养分的动态研究

研究了内蒙古荒漠草原不同利用强度单元内土壤养分以及5种酶活性,并对土壤酶活性与土壤养分含量之间的相关性进行了分析。结果表明,草原的利用强度直接影响着草地的土壤养分状况和酶活性,轻度利用有利于土壤中5种酶活性的增加,重度利用则导致土壤转化酶和蛋白酶活性显著降低。轻度利用增加了土壤中有机质、全氮和全磷的含量,重度利用则导致土壤有机质、全磷、全氮和全钾含量降低。脲酶和多酚氧化酶的活性在年季内变化幅度较大。相关性分析表明,蛋白酶与各养分之间的相关性最大。     

红壤丘陵区农田土壤酸化的时空变化研究

通过GPS技术,采集38个农田土壤样品,研究了红壤丘陵区农田土壤pH的时空间变化特征。结果表明:20年来,江西省兴国县农田土壤pH平均下降0.94个单位。pH下降的面积为645.9 km2,降幅在1.0～2.0个单位,主要分布在千枚岩、花岗岩和红砂岩发育的土壤地区,面积分别为296.1 km2、136.2 km2和42.2km2;pH增加的面积有24.1 km2,主要分布在紫色页岩发育的土壤地区,面积为11.3 km2。从土壤类型看,pH值下降的土壤主要为潴育型水稻土;从海拔上看,pH增加的土壤主要分布在海拔300 m以下的地区,pH降幅最大的土壤主要分布在海拔300 m以下及300～500 m的地区。相关分析显示土壤pH变化量与初始pH呈负相关关系,与海拔、有机质含量、黏粒含量呈正相关关系,通过线性回归模型可以预测pH的变化量。     

Soil chronosequences, soil development, and soil evolution: a critical review

Soils chronosequences are valuable tools for investigating rates and directions of soil and landscape evolution. Post-incisive chronosequences are the most common type of chronosequence. They are found in many landscapes, including sand dunes, glacial moraines, landslide scars, old pasture, burnt landscape patches, old mining areas, lava flows, alluvial fans, floodplains, river terraces, and marine terraces. They register pedogenic change over time-scales ranging from years to millions of years. Soil chronosequences help in testing rival theories of pedogenesis. Traditional soil formation theory sees a soil developing progressively under the influence of the environmental state factors until it is in equilibrium with prevailing environmental conditions. This developmental view of pedogenesis is supported by the classic soil chronosequence studies. A new evolutionary view of pedogenesis, which was prompted by the omnipresent inconstancy of environmental conditions and the notions of multidirectional changes and multiple steady states (as predicted by non-linear dynamics), proposes that environmental inconstancy and non-linear behaviour in soil-landscapes lead to soil evolution, rather than to soil development. Soils ‘evolve' through continual creation and destruction at all scales, and may progress, stay the same, or retrogress, depending on the environmental circumstances. Some recent soil and vegetation chronosequence investigations support an evolutionary view of pedogenesis. It is concluded that soil chronosequences are still potent instruments for pedological investigations and that they have a starring role to play in the testing of pedological theories.     

An overview of soil loss tolerance

As the criterion for judging whether a soil has potential risks of erosion, productivity loss and whether a river has downstream over-sedimentation as well as the ultimate criterion for erosion control for the preservation of soil productivity and environmental security in the long term, the level of soil loss tolerance (T value) must be determined in a scientific manner. This overview summarized the development of T value. The factors influencing T value were then discussed, and the calculation methods for T value were also presented and evaluated. Finally, it was proposed that the evaluation of T value should be based on three criteria (referred to as T₁, T₂ and T₃, respectively) with respective definitions and research fields involved. Two key issues, which can prevent the damage by soil erosion, i.e. tolerance for agrochemicals and self-restoration capacity of ecological environments should be addressed in the near future.     

Effects of two beet vinasse forms on soil physical properties and soil loss

Two beet vinasse forms (fresh (BV) and composted with a cotton gin crushed compost (CV)) have been applied for 4 years on a Typic Xerofluvent under dryland conditions near to Sevilla city (Guadalquivir River Valley, Andalusia, Spain) and their effect on soil physical, chemical and biological properties and their repercussion on soil loss was studied. BV and CV were applied at rates of 5000, 7500, and 10,000 kg ha^− 1 organic matter ha^− 1, respectively. The application of CV to the soil resulted in improved some soil properties and soil loss decreased. However, when BV was applied soil physical properties deteriorated and soil loss increased. We think that the high amounts of monovalent cations, particularly Na⁺, and of fulvic acids in BV destabilized soil structure. These results show that the addition of soil organic matter not always prevents soil loss, and they suggest the preferential use of composted beet vinasse versus fresh vinasse under dryland conditions.     

城市化过程对土壤资源影响研究进展

世界范围内的快速城市化过程对土壤资源的质与量都产生了深刻影响.作为一种不可再生性自然资源,土壤在我国快速城市化过程中的强烈人为活动影响下发生功能上的转化、弱化甚至消失.城市及其周边地区的土壤景观、各种土壤过程都明显异于传统的土壤质量演变规律.与农业生态系统相比,城市生态系统更加复杂,城市化过程中土壤演变研究的挑战性也更大.深入开展城市化过程中土壤质、量响应及其生态环境效应的系统研究意义重大.     

Strip-tillage effect on seedbed soil temperature and other soil physical properties

The no-tillage system is perceived as having lower soil temperatures, wetter soil conditions, and greater surface penetration resistance compared with conventional and other conservation tillage systems. Concerns associated with the effect of the no-tillage system on certain soil physical properties (i.e. soil temperature, moisture, and compaction) prompted this study to evaluate the effect of an alternative tillage system, strip-tillage, on these physical properties, compared with chisel plow and no-tillage systems. The study was conducted on two Iowa State University research and demonstration farms in 2001 and 2002. One site was at the Marsden Farm near Ames, where the soils were Nicollet loam (Aquic Hapludolls) and Webster silty clay loam (Typic Haplaquolls). The second site was at the Northeast Research and Demonstration Farm near Nashua, where the soils were Kenyon loam (Typic Hapludolls) and Floyd loam (Aquic Hapludolls).Soil temperature increased in the top 5 cm under strip-tillage (1.2–1.4 °C) over no-tillage and it remained close to the chisel plow soil temperature. This increase in soil temperature contributed to an improvement in plant emergence rate index (ERI) under strip-tillage compared with no-tillage. The results show no significant differences in soil moisture status between the three tillage systems, although the strip-tillage soil profile has slightly greater moisture content than chisel plow. Moisture content through the soil profile particularly at the lower depths under all tillage treatments was greater than the plant available water (PAW). However, the changes in soil moisture storage were much greater with strip-tillage and chisel plow than no-tillage from post-emergence to preharvest at 0–30 and 0–120 cm. It was observed also that most change in soil moisture storage occurred between post-emergence and tasseling. Penetration resistance was similar for both strip-tillage and no-tillage, but commonly greater than chisel plow. In general, the findings show that strip-tillage can contribute effectively to improve plant emergence, similar to chisel plowing and conserve soil moisture effectively compared with no-tillage.     

土壤团聚体中有机碳研究进展

增加土壤有机碳有助于农业可持续发展, 同时对缓解温室气体增加造成的全球气候变暖等具有重要意义。土壤团聚体是土壤的重要组成部分, 影响土壤的各种物理化学性质。土壤团聚体和有机碳是不可分割的, 前者是后者存在的场所, 后者是前者存在的胶结物质。本文在综合各方面研究的基础上, 阐述了土壤团聚体和有机碳的依存关系, 影响团聚体固碳的几大因素, 团聚体对有机碳的物理保护机制以及目前应用比较广泛的团聚体内有机碳的研究方法, 为以后的研究提供理论和方法上的支持。     

EM堆肥对土壤生物影响的研究

长期定点施用EM堆肥试验结果表明:EM有机堆肥能提高土壤细菌、真菌、放线菌数量;相同有机物料投入水平下,EM堆肥处理的微生物总量最高;随着有机物料投入水平的降低,土壤微生物数量下降;施用EM能提高土壤微生物活性,增加微生物的分布密度。施用EM堆肥土壤蚯蚓数量均显著高于其他施肥处理。EM堆肥各处理平均土壤螨虫数量高,但在相同的有机物料投入水平下,差异不显著。在大部分作物生长期,施EM 15t/hm2处理与化肥处理和对照处理土壤生物总量差异显著。     

Using plot soil loss distribution for soil conservation design

Soil conservation design is generally based on the estimation of average annual soil loss but it should be developed taking into account storms of a given return period. However, use of frequency analysis in soil erosion studies is relatively limited. In this paper, an investigation on statistical distribution of soil loss measurements was firstly carried out using a relatively high number of simultaneously operating plots of different lengths, λ (11, 22, 33 and 44 m) at the experimental station of Sparacia (southern Italy). Using a simple normalization technique, the analysis showed that the probability distribution of the normalized soil loss is independent of both the scale length λ and the temporal scale, which are completely represented by the mean soil loss calculated for a given event using all replicated data collected in plots having the same length. Then, a comparison between the frequency distribution of soil loss and rainfall erosivity index of the USLE was carried out. An estimating criterion of the annual soil loss of a given return period was also developed. By this criterion, the frequency distribution of the rainfall erosivity factor can be used to design soil conservation practices.     

不同土壤改良剂处理对连作西洋参根际微生物数量、土壤酶活性及产量的影响

以北京地区连作西洋参为研究对象, 通过3种土壤改良剂(熟石灰、EM菌剂、沼液)随机区组试验对其土壤理化性状、酶活性、根际微生物区系及产量进行了系统研究。结果表明: 低浓度熟石灰、中浓度EM菌剂及高浓度沼液处理最有利于提高西洋参产量; 施加熟石灰处理后, 土壤微生物主要类群数量显著减少, 土壤pH显著升高, 并对土壤脲酶活性有明显抑制作用; 施加沼液和EM菌剂处理后, 土壤有效微生物菌群显著增加(P<0.05), 土壤有机质和营养物质含量也显著增加(P<0.05), 并对土壤脲酶和多酚氧化酶活性有一定的促进作用。相关性分析发现, 土壤微生物主要类群的数量与蔗糖酶、脲酶、多酚氧化酶活性均有一定的相关性, 其中, 土壤细菌数量与蔗糖酶、多酚氧化酶活性呈极显著正相关(r分别为0.895^**和0.808^**), 土壤真菌和放线菌数量与蔗糖酶、脲酶、多酚氧化酶活性呈极显著正相关(r分别为0.932^**、0.769^**、0.840^**和0.837^**、0.891^**、0.797^**)。另外, 土壤细菌数量与有机质含量呈极显著正相关(r=0.863^**)。表明连作西洋参根际微生物区系及土壤酶活性与土壤理化性状之间紧密联系, 通过施加不同土壤改良剂, 可以为耐连作种植西洋参提供适宜的土壤环境。