Fine earth soil bulk density at 0.2 m depth from Land Use and Coverage Area Frame Survey (LUCAS) soil 2018

Soil Bulk Density (BD) is an extremely important variable because it is an important site characterization parameter, and it is highly relevant for policy development because it is mandatory for calculating soil nutrient stocks. BD can influence soil chemical properties, land-use planning and agronomic management. The 2018 Land Use and Coverage Area Frame Survey (LUCAS) saw the unprecedented collection of BD core analysis in a subset of the locations in Europe and the United Kingdom where soil physical and chemical properties were analysed in the 2009 and the 2015 sampling campaigns. Here, we integrated the LUCAS 2018 BD sampling campaign with the mass fraction of coarse fragments previously determined in LUCAS 2009–2015 in order to provide a dataset of the volume fraction of coarse fragments and the BD of the fine earth and improve soil organic carbon (SOC) stock estimation accuracy for topsoil. BD data sampled at 0–10 and 10–20 cm were averaged to harmonize the BD with the mass fraction of coarse fragments measured in 2009, 2012 and 2015. Samples were from cropland, grassland and woodland soils, which accounted for 41%, 21% and 30%, respectively, of the total number of selected sites (n = 6059); ‘bareland’, and ‘shrubland’ accounted for 3% of the sites each, whereas ‘artificial land’ accounted for <1%. Only six samples were classified as ‘wetland’. The dataset was produced assuming the mass density of the coarse fraction to be constant across all LUCAS soil samples. We also estimated the SOC stocks associated with LUCAS 2018 BD and SOC content measurements and showed that correcting the BD by the coarse mass fraction instead of the coarse volume fraction generates SOC stock underestimation. We found the highest deviations in woodlands and shrublands. We showed that, when SOC stock is computed with coarse mass fraction, the error compared with the computation by volume may vary depending on the SOC and coarse mass fraction. This may imply a SOC stock underestimation for European soils. This dataset fits into the big framework of LUCAS soil properties monitoring and contributes both to soil awareness and soil research and assessments, which are two important objectives of the Soil Strategy and the European Soil Observatory (EUSO).     

黄土高原农地草地林地土壤团聚体稳定性沿降水梯度的变化特征

团聚体稳定性是表征土壤结构稳定性的重要指标,与坡面水文过程及侵蚀过程密切相关,为探明黄土高原团聚体稳定性(aggregatestability,MWD)沿降水梯度的变化特征及其影响因素。该论文在黄土高原沿降水梯度布设了7个采样点,测定每个采样点农地、草地和林地的MWD。结果表明,农地MWD沿降水梯度自南向北呈逐渐减小趋势;草地和林地MWD变化趋势比较相似且无显著差异(P=0.233),最南端宜君的MWD小于稍北富县的MWD,之后向北大体呈减小趋势。农地、草地和林地MWD空间变化特征除受土壤有机质、年均降水量和年均气温的影响以外,农地的MWD与土壤机械组成存在显著相关关系(P0.05),而草地和林地的MWD与根系质量密度存在显著相关关系(P=0.037)。非线性回归表明,农地MWD可以用土壤中值粒径和年均降水量模拟,而草地和林地MWD可用土壤有机质、根系质量密度和年均温模拟。研究成果对于理解黄土高原土壤团聚体稳定性空间变异及其影响因素、分析水文及侵蚀过程的区域变化规律具有理论意义。     

Soil nitrogen pools and turnover in native woodland and managed pasture soils

Dissolved organic nitrogen (DON) is a significant nitrogen (N) pool in most soils and is considered to be important for N cycling. The present study focused on paired sites of native remnant woodland and managed pasture at three locations in south-eastern Australia. Improved understanding of N cycling is important for assessing the impact of agriculture on soil processes and can guide conservation and restoration soil management strategies to maintain remnant native woodland systems, which currently exist as small pockets of woodland within extensive managed pasture landscapes. Organic and inorganic N pools were quantified, as well as the rates of amino acid and peptide mineralisation in the paired native woodland and managed pasture systems. Soil DON dominated the soil N pool in both land uses, and the proportion of DON to other N pools was greatest at the most N-limited site (up to ∼70% of extractable N). In both land uses soil ammonium and free amino acid concentrations were similar (∼20% of extractable N), and soil nitrate formed the smallest N pool (<∼5% of extractable N). Mineralisation of ¹⁴C-labelled amino acid and peptide substrates was rapid (<3 h), and more amino acid was respired than peptide in both the native woodland and managed pasture soils. Soil C:N ratio was important in separating site and land use differences, and contrasting relationships between soil physico-chemical properties and organic N uptake rates were identified across sites and land uses.     

河岸带耕地降雨径流产流特征分析

在孟津黄河漫滩的河岸带上开展了野外定位观测,研究了自然降雨情况下,河岸林地转变成农耕地前后降雨地表径流产流的污染特征。结果表明,河岸滩区具有较强的土壤人渗能力,径流产流的次降雨量临界值为20mm;滩区径流系数相对偏小：耕地平均3．5％,林地平均2．0％;在耕地开垦初期,由于雨滴的直接溅蚀,表土存在“板结”现象,径流系数增加较为明显。河岸滩区的降雨径流呈弱碱性（pH=8．0—9．5）,且盐分含量偏高;耕地径流和林地径流水质的差异表现在耕地径流具有较低的高锰酸盐指数和总氮含量;由于耕地的径流产生量明显大于林地,耕地径流的污染物（土壤颗粒物、有机物、总氮和总磷）产生总量约是林地径流的1．5-3．0倍。土壤翻动后的首次降雨通常会引起耕地较平时5—10倍的土壤颗粒物和总磷流失。林改耕后,径流颗粒物和总磷含量较参照耕地平均增加3倍,成为滨河漫滩农田开垦初期的应首要控制的污染物。河岸滩区在河岸缓冲、屏障和面源污染物削减方面具有重要的水文生态功能,因此在河岸滩区的开发进程中,应注重加强对原生河岸带的生态保护与管理。     

沙地土壤水分特征及水分时空动态分析

通过对宁夏盐池沙地不同立地类型土壤水分连续两年的定位观测,探讨了固定沙丘不同部位、不同立地的沙柳林地和柠条林地的土壤水分特征和时空动态变化。结果表明:柠条林地的土壤容重最小,而保水能力最好。各样地土壤水分垂直分布总体表现出明显的分层特征,可划分为3层:土壤水分低值层、土壤水分活跃层、土壤水分相对稳定层,每一层的厚度因不同的立地类型而不同。     

Replacement of soil and soil-forming materials by loose tipping in reclamation to woodland

Abstract. Four experiments studying ground preparation for the restoration of disturbed land to a woodland cover are described. They provide consistent evidence to suggest that methods of soil replacement which minimize compaction are preferable to conventional methods followed by deep ripping to relieve compaction induced in the placement operation. In addition, soil loosening using an excavator is more effective than that achieved by ripping. The research supports modern guidance which advocates 'loose tipping' as the best method of ground preparation for a woodland or forestry after-use on sites reclaimed after dereliction or mineral extraction.     

Multi-site validation of a soil organic matter model for arable fields based on generally available input data

The paper describes a simplified carbon balance model, derived from the CANDY model, which works in annual time steps requiring only clay content, soil type of the German classification system “Reichsbodenschätzung”, average air temperature and rainfall as site characteristics, a value for organic carbon content as the initial value as well as crop yield and organic matter amendments as management data.The Candy Carbon Balance (CCB) model has been validated using a dataset from 40 long-term experiments situated in Central Europe including 391 treatments with a total number of 4794 C_org observations. Statistical measures to prove model validity were mean error (ME = − 0.001) and root mean square error (RMSE = 0.119). In addition a number of tests were performed to make sure that the model has no systematic error for different types of site conditions and management activities. After this successful validation the CCB model is considered applicable for advisory service for arable fields on a wide range of site conditions. Due to the poor representation of clay soils in this study some more model tests on these soils would be recommendable.     

南方红壤区侵蚀退化马尾松林地生态恢复研究

我国南方红壤区严重侵蚀退化马尾松林地土壤极度贫瘠,加之退化面积广等因素,导致其恢复的难度加大,如何恢复侵蚀退化马尾松林地成为当前面临的一个艰巨而又迫切的任务,因此加快相关方面的研究和治理,探讨其退化机理,解决生态恢复关键技术,对于推动红壤区的生态建设具有重要意义。该文从土壤退化、人为因素、马尾松的生物学特性等方面阐述了马尾松林地的退化机理,总结了退化马尾松林地生态恢复的途径和模式及其产生的生态环境效应,并提出了马尾松侵蚀退化林地进一步研究的展望,以期为退化马尾松林地生态修复的后续研究作一参考。     

Assessment and monitoring of soil quality using near-infrared reflectance spectroscopy (NIRS)

Soil degradation processes have dramatically increased in their extent and intensity over the last decades. Progressively, actions have been taken in order to evaluate and reduce the major threats that have already wreaked havoc on soil conditions. Efficient and standardized monitoring of soil conditions is thus required but soil quality research is facing an important technological challenge because of the number of properties involved in soil quality. The objective of the present review is to examine critically the suitability of near-infrared reflectance spectroscopy (NIRS) as a tool for soil quality assessment. We first detail the soil quality-related parameters (chemical, physical and biological) that can be predicted with NIRS through laboratory measurements. The ability of imaging NIRS (airborne or satellite) for mapping a minimum data set of soil quality is also discussed. Then we review the most recent research using soil reflectance spectra as an integrated measure of soil quality, from global site classification to the prediction of specific soil quality indices. We conclude that imaging NIRS enables the direct mapping of some soil properties and soil threats, but that further developments to solve several technological limitations identified are needed before it can be used for soil quality assessment. The robustness of laboratory NIRS for soil quality assessment allows its implementation in soil monitoring networks. However, its routine use requires the development of international soil spectral libraries that should become a priority for soil quality research.     

A survey of vehicular lead deposition in a woodland ecosystem

The changing levels of Pb in the soil and vegetation of a small woodland bounded on its southern side by the major London orbital motorway, the M 25, have been investigated over a period of 6 mo. The pattern of Pb deposition, as measured by soil Pb burdens, shows that concentrations decrease with increasing distance from the road. For vegetation sited close to the motorway results indicate that different tree species have different propensities for the capture and retention of Pb. The pattern of Pb deposition throughout the woodland as revealed by bryophyte analysis is also reported. Results suggest that Pb levels are high close to the motorway, as anticipated. However enhanced levels are also to be found on the woodland edges over half a kilometer away.     

Importance of cryptic growth,yield factors and maintenance energy in models of microbial growth in soil

A simple model is described which predicts microbial growth rates in soil. The recycling of dead microorganisms and maintenance energy requirements are taken into account. Appropriate values for the maximum yield factor and the specific maintenance rate are discussed. The effect of changing these parameters as well as substrate input and biomass levels on the mean generation time in soil are considered with particular reference to a deciduous woodland.     

不同地理尺度下综合施肥模型的建模与验证

在新疆北疆采用包含正交设计的方案进行了多点肥料试验,建立了不同地理尺度下的综合施肥模型和肥料效应函数方程,通过校验试验对综合施肥模型与肥料效应函数方程施肥推荐施肥效果进行了比较研究。试验采用相同的试验设计在2000-2002年间进行,每年试验点数为31个。研究结果表明,通过趋势系数可以建立包括地点变量的综合肥料效应方程,回归方程各参数有明确的肥料学意义。不同地理尺度下建立的综合施肥模型都可以有效地进行施肥推荐。和传统的肥料效应函数方程相比,综合施肥模型的氮素推荐量与土壤碱解氮或有机质含量呈显著负相关,表明方程可以根据土壤供氮能力调节施氮量,在小尺度下尤其如此。综合施肥模型磷肥推荐量显著低于肥料效应函数方程推荐量,其推荐质量高于肥料效应函数方程。小尺度下综合施肥模型的推荐量比大尺度下综合施肥模型精确度更高,但两种施肥模型都优于肥料效应函数方程。     

南方红壤丘陵区马尾松林下水土流失现状、成因及防治

马尾松林下水土流失已经成为南方红壤丘陵区水土流失治理一个亟待解决的问题。在分析南方红壤丘陵区马尾松林下水土流失现状及特点的基础上,从马尾松林下植被状况、人为干扰、地形、降雨侵蚀力、土壤性状等方面综合探讨了马尾松林下水土流失的成因。认为:林下植被匮乏是造成马尾松林下水土流失最主要和最直接的原因;掠夺性人为干扰是造成马尾松林下水土流失的根本原因;破碎的地形、较高的降雨侵蚀力和土壤可蚀性则为林下水土流失的发生提供了有利条件。同时总结了诸如微地形改造、林下补植、封禁保护等马尾松林下水土流失治理的成功经验,以期为今后马尾松林下水土流失治理提供参考。     

半干旱黄土区土壤水分垂直分布规律的研究——以甘肃省兰州市孙家岔流域为例

以甘肃省兰州市孙家岔流域为研究对象,使用1982~1983年、2011年实测土壤水分资料,利用地统计法分析了该流域土壤水分的垂向变异特征。结果表明,球状模型对丰水年不同土地利用（梯田、荒坡、坡耕地、乔木林地）土壤水分的垂向分布拟合为极显著。在平水年球状模型仅对梯田、乔木林地的实验变异函数拟合较好,而对坡面地区的坡耕地和荒坡的拟合并不显著。枯水年梯田和林地的空间变异对模型仍然有一定的吻合,而坡耕地和荒坡土壤水分空间分布变异中有较大的随机性,即使在雨季时空间自相关也很弱。不同水文年下不同土地利用的土壤水分垂向变化表现出明显的季节变化趋势,变程为1.687～3.404 m,在该自相似范围内测得土壤特性的变异程度基本一致。     

半干旱黄土区土壤水分垂直分布规律的研究——以甘肃省兰州市孙家岔流域为例

以甘肃省兰州市孙家岔流域为研究对象,使用1981-1983年、2011年实测土壤水分资料,利用地统计法分析了该流域土壤水分的垂向变异特征.结果表明,球状模型对丰水年不同土地利用(梯田、荒坡、坡耕地、乔木林地)土壤水分的垂向分布拟合为极显著.在平水年球状模型仅对梯田、乔木林地的实验变异函数拟合较好,而对坡面地区的坡耕地和荒坡的拟合并不显著.枯水年梯田和林地的空间变异对模型仍然有一定的吻合,而坡耕地和荒坡土壤水分空间分布变异中有较大的随机性,即使在雨季时空间自相关也很弱.不同水文年下不同土地利用的土壤水分垂向变化表现出明显的季节变化趋势,变程为1.687 ～3.404 m,在该自相似范围内测得土壤特性的变异程度基本一致.     

淮北地区5种不同植物群落土壤呼吸研究

选取河南西平杨树人工林生态系统中5种不同植物群落土地为研究对象,利用Licor-8100土壤呼吸测定系统对其土壤呼吸进行了连续观测,分析、比较5种不同植物群落土壤呼吸的差异及其影响因素。研究结果表明:（1）5种植物群落下土壤呼吸有所差异,但其日变化及年内变化趋势大致相同,均与土壤温度变化趋势一致,呈单峰曲线,其土壤呼吸大小顺序为:8 m行宽林间小藜—牛筋草地 > 2 m行宽林间苍耳地 > 8 m行宽林间水蓼—灰灰菜地 > 8 m行宽林间苍耳地 > 2 m行宽林间裸地;（2）采用土壤温度和湿度单因素模型（R_s=ae^bT_s或R_s=aW+b）进行分析:土壤温度和土壤含水量分别解释了不同植物群落土壤呼吸季节变化的41%~79%和2.3%~21%;而采用双因素模型分析（R_s=ae^bT_sW^c）,土壤温湿度共同解释了土壤呼吸速率季节变化的49.1%~86.7%,表明不同植物群落的土壤呼吸均受土壤温度和土壤含水量的共同影响;（3）运用Q₁₀=e^10b模型分析,Q₁₀值大小顺序为:8 m行宽林间小藜—牛筋草地（2.47） > 2 m行宽林间苍耳地（2.3） > 2 m行宽林间裸地（2.7） > 8 m行宽林间水蓼—灰灰菜地（2.59） > 8 m行宽林间苍耳地（2.22）,且5种不同植物群落下土壤呼吸Q₁₀值均表现为春季 > 冬季 > 秋季 > 夏季,即土壤呼吸温度敏感性随着温度的升高呈现出降低的趋势。     

阴山北麓不同用地土壤有机质含量对抗风蚀的作用研究

随着人类对土地利用的强度不断增大,改变了自然土壤表层原有的性质,并对风产生不同的抗蚀效果。不同的土地利用方式下,土壤的有机质含量是不同的。土壤有机质影响土粒间微结构的胶结力和土壤结构体间的抵抗离散力,从而影响土壤的抵抗风蚀能力。通过对阴山北麓不同土地利用方式下的土地进行野外调查取样和室内理化分析,分析了土壤有机质含量变化过程,研究了土壤有机质含量对抗风蚀的影响。结果表明：土壤有机质含量与土壤抗风蚀强度成正相关关系,也就是随着土壤有机质含量的增加,土壤的抗风蚀强度增强,凡是有机质含量较高的土地利用类型,其土壤的抗风蚀强度较强,例如：人造林地的土壤有机质含量为3.904%,其土壤风蚀相对强弱指数是1.726;未成林林地的土壤有机质含量为2.775%,其土壤风蚀相对强弱指数是23.409;人造林地的土壤有机质含量高于未成林林地,而人造林地的土壤风蚀相对强弱指数小于未成林林地,也就是人造林地的抗风蚀强度大于未成林林地。因此,应当针对阴山北麓处于西北风主风向地带、风速大、土壤风蚀易发生的实际情况,合理保护和利用有限的土地资源,使土壤资源得以保护。     

中国东北松嫩平原农田-林地景观土壤无机氮界面的季节变化

To study the seasonal variability of soil inorganic nitrogen (N) across borders at the woodland-farmland ecotone and potential mechanisms, contents of soil inorganic N were measured during the dry season (May 20 and June 30) and the rainy season (August 10 and September 20) of 2006 in the Songnen Plain of Northeast China. The borders between farmland and woodland were determined by a border-and-ecotone detection analysis (BEDA). The ecotone limits, often referred to as the depth-of-edge influence (DEI), are critical for determining the scale at which edge effect operates. The results showed that the soil inorganic N border between the woodland and farmland was located further toward the woodland interior during the rainy season (DEI = 53.4 ± 8.7 m, August 10) than during the dry season (DEI = 35.0 ± 12.6 m, May 20). The seasonal variability in the soil inorganic N border was found to be associated with seasonal changes of deposition flux of N (the correlation coefficients between them for the dry season and rainy season were 0.61 and 0.67, respectively), which resulted from foliation patterns of trees and crops. Accordingly, the leaf area index at woodland edges was lower than that in the woodland interior, so woodland edges captured large amounts of atmosphere nitrogen deposition. The average DEI was 44.1 m, which was in accordance with the values of other temperate forest boundaries in literatures; therefore, BEDA was an appropriate method to estimate the borders of ecotones.     

Reducing the dimensionality of soil microinvertebrate community datasets using Indicator Species Analysis: Implications for ecosystem monitoring and soil management

Soil microinvertebrates are closely associated with soil decomposition and nutrient cycles and may be particularly responsive indicators for soil management practices. However, identification of appropriate bioindicator species for many systems has been severely limited by a lack of information on species taxonomy, distribution, and functional role. We evaluated Indicator Species Analysis (ISA) as an objective method for assessing the indicator potential of different taxa without regard to their ecological role or expected management response. Restricting ordination and site classification to significant indicator morphotaxa reduced the dimensionality of the community data matrix by 69% while only slightly decreasing the efficiency of unsupervised classification (from 87.2 to 84.4%); the percentage of total variability explained by first two PCA axes increased following ISA. When these same indicator morphotaxa were used to classify an independent set of samples, the percentage of total variability explained by the first two PCA axes increased from 55.3 to 65.2%; cluster analysis of the test dataset correctly classified 47 out of 50 plots by cover type (94% accuracy). However, restriction of analysis to indicator morphotaxa alone reduced detection of differences between sampling dates relative to the complete dataset. Although care needs to be taken to ensure that the dataset used for indicator selection is fully representative of underlying temporal and spatial variability, ISA appears to overcome many of the limitations associated with parametric and multivariate approaches for identifying indicator morphotaxa and has the potential to greatly reduce the taxonomic expertise and labor costs associated with sorting and identification of soil microarthropods.     

A practical two‐step approach for mixed model‐based kriging,with an application to the prediction of soil organic carbon concentration

Soil scientists often use prediction models to obtain values at unsampled locations. The spatial variation in the soil is best captured by using the empirical best linear unbiased predictor (EBLUP) based on a restricted maximum likelihood (REML) approach that efficiently exploits available data on both mean trends and correlation structures. We proposed a practical two‐step implementation of the REML approach for model‐based kriging, exemplified by predicting soil organic carbon (SOC) concentrations in mineral soils in Estonia from the large‐scale digital soil map information and a previously established prediction model. The prediction model was a linear mixed model with soil type, physical clay content (particle size < 0.01 mm) and A‐horizon thickness as fixed effects and site, transect, plot, year, year‐transect random intercepts and site‐specific random slopes for clay content. We used only the site‐specific intercept EBLUPs for estimating spatial correlation parameters as they described most of the variation in the random effects (86.8%). Fitting an exponential correlation model to these EBLUPs resulted in an estimated range of 10.5 km and the estimated proportion of the variance from the nugget effect was 0.23. The results of a simulation study showed a downwards bias that decreased with sample size. The results were validated through an external dataset, resulting in root mean square errors (RMSE) of 1.06 and 1.07% for the two‐step approach for kriging and the model with only fixed effects (no kriging), respectively. These results indicate that using the two‐step approach for kriging may improve prediction.