Effects of foliar and soil insecticide applications on the collembolan community of an early set-aside arable field

Effects of foliar and soil insecticide applications on collembolan density and community structure were investigated in an early set-aside arable field. Insecticides were applied separately and in combination to the soil surface (chlorpyrifos) and vegetation (dimethoate). The treatments were established to investigate effects of above- and below-ground insects on plant succession. Starting in 1997, the insecticides were applied from April to November at 2-week (dimethoate) or monthly intervals (chlorpyrifos). Samples were taken in 2000 prior to and after insecticide application in March and June, respectively. Both insecticides are lethal to Collembola and insecticide applications resulted in a strong decline in the density of total Collembola. Application of chlorpyrifos reduced collembolan density to a greater extent than dimethoate; the effect of the combined application on total collembolan numbers was similar to that of chlorpyrifos only. Collembolan numbers recovered after the insecticide applications in 1999, but in the treated plots populations were still reduced in March 2000 before the re-application of insecticide treatments in that year. The insecticide applications changed the dominance structure of the collembolan community, but had no effects on species composition. The results may be of relevance for the interpretation of studies on plant–insect herbivore interactions using insecticides.     

侵蚀环境撂荒地植物群落恢复动态研究

以侵蚀环境不同退耕撂荒年限样地为研究对象,采用空间代替时间序列的方法调查植物群落特征,分析植物恢复过程。结果表明：植物群落覆盖度和地上生物量随退耕撂荒年限的增加,恢复演替的推进逐渐增大;群落物种多样性指数与撂荒年限呈正相关,而群落优势度指数与撂荒年限呈负相关;物种多样性指数能极好地反映群落物种丰富度,并能客观表达物种的动态变化,其演变呈升—降—升的趋势,退耕撂荒3、10和25 a左右时为物种多样性指数的高峰。植物群落结构稳定性与物种多样性、群落生物量、覆盖度和优势度关系密切,随着退耕撂荒地植被恢复演替的进展,植被结构稳定性呈阶梯式增强,从而为侵蚀环境生态恢复提供了基础保障。     

Effect of vegetation manipulation of abandoned arable land on soil microbial properties

 The effect of vegetation composition on various soil microbial properties in abandoned arable land was investigated 2 years after agricultural practice had terminated. Microbial numbers and processes were determined in five replicate plots of each of the following treatments: continued agricultural practice (monoculture of buckwheat in 1997), natural colonization by the pioneer community (arable weeds), and manipulated colonization from low (four species, three functional groups: grasses, forbs and legumes) or high diversity (15 species, three functional groups) seed mixtures from plant species that are characteristic of abandoned fields in later successional stages. The results indicated that differences in above-ground plant biomass, plant species composition and plant species diversity had no significant effect on soil microbial processes (net N mineralization, short-term nitrification, respiration and Arg ammonification), microbial biomass C and N (fumigation-incubation) or colony-forming units of the major microbial groups. Hence, there were no indications that soil microbial processes responded differently within 2 years of colonization of abandoned arable land by later successional plants as compared to that by plants from the natural pioneer weed community. Therefore, it seems that during the first few years after arable field abandonment, plants are more dependent on the prevailing soil microbiological conditions than vice versa. Received: 8 April 1999     

耕地土壤有机碳组分的季节变化

Carbon fractions in soils apparently vary not only in space, but also over time. A lack of knowledge on the seasonal variability of labile carbon fractions under arable land hampers the reliability and comparability of soil organic carbon(SOC) surveys from different studies. Therefore, we studied the seasonal variability of two SOC fractions, particulate organic matter(POM) and dissolved organic carbon(DOC), under maize cropping: POM was determined as the SOC content in particle-size fractions, and DOC was measured as the water-extractable SOC(WESOC) of air-dried soil. Ammonium, nitrate, and water-extractable nitrogen were measured as potential regulating factors of WESOC formation because carbon and nitrogen cycles in soils are strongly connected. There was a significant annual variation of WESOC(coefficient of variation(CV) = 30%). Temporal variations of SOC in particle-size fractions were smaller than those of WESOC. The stocks of SOC in particle-size fractions decreased with decreasing particle sizes, exhibiting a CV of 20%for the coarse sand-size fraction(250–2 000 μm), of 9% for the fine sand-size fraction(50–250 μm), and of 5% for the silt-size fraction(20–50 μm). The WESOC and SOC in particle-size fractions both peaked in March and reached the minimum in May/June and August, respectively. These results indicate the importance of the time of soil sampling during the course of a year, especially when investigating WESOC.     

A computerized soil information system for arable land in Japan

A computerized soil information system was compared to manual punch card methods for storage and retrieval of Japanese soil survey data. In spite of the high cost, a soil information system using computers is the most appropriate system for the future, because by this method more than three factors can be analyzed simultaneously, various kinds of soil map data can be stored, retrieved and updated and many kinds of interpretative maps can be constructed automatically. There are large amounts of valuable soil survey data available in Japan which previously were used only for drawing soil maps. These should be utilized to develop a computerized soil information system. At the end of this report, essential processes and the possible structure of a Japanese Soil Information System were discussed.     

Mycorrhizal colonization of plants in set-aside agricultural land

Agricultural overproduction has led the European Union to encourage long-term abandonment of agricultural land and the adoption of management practices which enhance transition to semi-natural grassland or forest. This paper reports the results of a field study conducted in newly abandoned agricultural land where the development of the mycorrhizal community was investigated in response to manipulation of the above-ground vegetation. The field site consisted of plots where the plant diversity was managed by (1) sowing 15 plant species, (2) sowing four plant species, and (3) allowing plots to be naturally colonized by plants. The plant mixture contained grasses, legumes and forbs that were all expected to occur on the site following succession. Each of the low diversity replicates contained a different subset of the high diversity mixture, in order to avoid confounding diversity effects with sampling effects. A subset of these plots was inoculated with soil cores from a later successional stage and the experiment was arranged in a randomized block design. The catch plants, Fagus sylvatica, Picea abies and Plantago lanceolata, were planted in the experimental plots and the presence of ecto- or arbuscular mycorrhizal (AM) fungi on their roots was determined. The level of AM colonization of P. lanceolata and the ectomycorrhizal colonization of F. sylvatica was lower in the sown treatments with high and low plant diversity compared to areas that were naturally colonized by plants. The survival of catch plants of the tree species was also higher in the naturally colonized plots. Soil inoculations had no effect on either of the mycorrhizal types or the survival of catch plants. The establishment of non-introduced woody plant species was more successful in the naturally colonized treatments.     

Soil Oribatida and Collembola communities across a land depression in an arable field

A small-scale field study of oribatid and collembolan communities was conducted in the floodplain area of the Ondava River in the East-Slovak Lowland, to assess the role of temporary water pools in microdepressions with heavy soils for microarthropod distribution in an agricultural landscape. Soil samples were taken from five sites across a microdepression without water outflow located in a cultivated field. For comparison, willow field margin was included into the study. Results from ordination analysis showed specific communities at the pool-shore, clearly different from those of the arable field and willow margin sites. Pool-shore communities were mainly affected by soil pH (positive correlation) and dominated by oribatid mites Subiasella quadrimaculata and Microppia minus, together with Collembola Folsomia quadrioculata and Lepidocyrtus cyaneus. The soil surrounding freshwater pools is assumed to be a temporary microhabitat for several microarthropod species that contribute to the biodiversity of the agricultural landscape.     

科尔沁沙地土地利用变化对大型土壤节肢动物群落影响

土地利用类型是地球表层系统最突出的景观标志,不仅可以客观地展示地球表面特征空间格局的活动,还反映着地球表面景观的时空动态过程[1-2].由于土地利用变化与人类活动和全球气候变化密切相关,对生物多样性消长、生态环境演变、生态安全水平以及人类可持续性发展有着重要影响,因而其研究已成为当今全球变化研究的前沿和热点课题[1,3].     

Alphaproteobacteria communities depend more on soil types than land managements

Soil properties and agricultural practices take a joint effect on the communities of soil bacteria. The aim of the present study was to survey Alphaproteobacterial communities as possible indicators of soil quality considering clay, loamy and sandy soils under conventional and organic farming. Alphaproteobacteria community composition were analysed by 16S rRNA gene with nested-PCR (polymerase chain reaction) and denaturing gradient gelelectrophoresis (DGGE). Sequencing of partial 16S rRNA gene from the DGGE bands were performed. Conventional and organic farming resulted in significant differences in chemical properties of soils. According to the results community fingerprints were separated into groups depending on soil types and farming systems. This separation can be attributed mostly to soil pH, AL-P₂O₅,-K₂O. The analysed sequences were identified as soil bacteria which could play the main role in nitrogen fixing, mineralisation and denitrification. The highest diversity index was revealed from the organic farming at sandy texture site, where mainly Mesorhizobium sp. and Rhizobium sp. were detected. The soil type and actual crop could have a stronger impact on the soil bacterial composition than the management.     

Modelling soil organic carbon concentration of mineral soils in arable land using legacy soil data

Soil organic carbon (SOC) concentration is an essential factor in biomass production and soil functioning. SOC concentration values are often obtained by prediction but the prediction accuracy depends much on the method used. Currently, there is a lack of evidence in the soil science literature as to the advantages and shortcomings of the different commonly used prediction methods. Therefore, we compared and evaluated the merits of the median approach, analysis of covariance, mixed models and random forests in the context of prediction of SOC concentrations of mineral soils under arable management in the A‐horizon. Three soil properties were used in all of the developed models: soil type, physical clay content (particle size <0.01 mm) and A‐horizon thickness. We found that the mixed model predicted SOC concentrations with the smallest mean squared error (0.05%²), suggesting that a mixed‐model approach is appropriate if the study design has a hierarchical structure as in our scenario. We used the Estonian National Soil Monitoring data on arable lands to predict SOC concentrations of mineral soils. Subsequently, the model with the best prediction accuracy was applied to the Estonian digital soil map for the case study area of Tartu County where the SOC predictions ranged from 0.6 to 4.8%. Our study indicates that predictions using legacy soil maps can be used in national inventories and for up‐scaling estimates of carbon concentrations from county to country scales.     

The long‐term soil phosphorus balance across Chinese arable land

Quantifying temporal and spatial variation of soil phosphorus (P) input, output and balance across Chinese arable land is necessary for better P management strategies. Here, we address this challenge using a soil P budget to analyse the soil P balance in arable land across the whole of China, for the period 1980–2012. Results indicated that the total P input to soil increased from 22.5 kg P/ha in 1980 to 79.1 kg P/ha in 2012. However, the total P output from soil only increased from 17.9 kg P/ha in 1980 to 36.9 kg P/ha in 2012. Therefore, the average net soil P surplus in China increased from 4.6 kg P/ha in 1980 to 42.1 kg P/ha in 2012. Our research found great variation in soil P balances across different regions. Soil P balance varied between regions with the order of southeast (SE) > north central (NC) and the middle and lower reaches of Yangtze River (MLYR) > southwest (SW) > northwest (NW) > northeast (NE). Phosphorus that has accumulated in agricultural soil across China could theoretically meet crop P demands for approximately 4.8–12.0 yrs, depending on the bioavailability of P stored in soils. Increasing the return rates of manure and straw could substantially reduce the demand for fertilizer‐P. This paper represents a basis for more targeted, regionally informed P fertilizer recommendations in Chinese soils.     

农村居民点土地整理及其对耕地的影响

为明晰农村居民点土地整理的目的与效果及其对耕地数量的影响,根据目前农村居民点土地整理的研究进展,从土地整理潜力、土地整理模式及土地整理政策建议三方面对该领域研究成果进行梳理,分析了目前农村居民点土地整理研究中存在的问题,阐明了农村居民点土地整理对于保障中国粮食安全的重要意义,提出了理论与实际相结合为主导的农村居民点土地整理及进一步明确大力开展农村居民点土地整理以便增加耕地数量的建议。     

Effect of desert plant ecophysiological adaptation on soil nematode communities

Nutrient source limitation in desert ecosystems enhances competition among plant communities, leading to creation of microhabitats beneath the shrubs that can determine composition and abundance of soil organisms. The aim of the study was to determine the effect of plant ecophysiological adaptation on soil nematode communities in the rhizosphere of tightly interweaving shrubby communities. Soil samples were collected monthly under the canopies of three perennial desert shrubs: Artemesia herba-alba, possessing the allelopathic ability to dominate in relationships with other plants; Reaumuria negevensis, a salt-resistant plant; and Noea mucronata, a typical dry desert shrub. An inter-plant area was used as a control. The results demonstrated that soil water content (SWC) and total organic carbon (C_org) were significantly different under different plants and inter-plant areas, with the highest values found under R. negevensis (SWC) and N. mucronata and R. negevensis (C_org). Plant parasite and omnivore-predator nematodes were more sensitive to the ecophysiological individual features of observed plants versus the total number of nematodes and bacteria- and fungi-feeding nematodes. Generally accepted ecological indices such as Wasilewska (WI), trophic diversity (T), maturity (MI, MMI), basal (BI), enrichment (EI), structure (SI), and channel (CI), pointed to specific ecological conditions under canopies of the observed plants.     

Interrelation between soil physical properties and Enchytraeidae abundances following a single soil compaction in arable land

In spring 1995 a silty clay soil was compacted dynamically by wheeling with graded wheel loads up to 6 times. The reaction towards wheeling was recorded immediately. In the following 3 years some soil physical parameters as well as the Enchytraeidae abundances were recorded regularly. To the first wheeling, the soil reacted plastically in vertical direction. The reaction became elastically after the 4th wheeling. After the 6th passage with a 5‒tonnes wheel load soil structure collapsed totally, which can be concluded from the stress ratios. After the wheeling event, abundances of Enchytraeidae decreased obviously compared to uncompacted plots. The increase in air permeability, air capacity, and the decrease of soil bulk density depend on primary tillage events. The recovery of Enchytraeidae abundances developed in parallel. Abundances seem to be regenerated in the 3rd year after the wheeling event. Primary tillage can help to induce biological and macroscopic structural regeneration of the top soil after a compaction event.     

Effect of applying paper mill sludge to arable land on soil fertility and crop yields

Abstract. Two field trials were established in 1991 to determine the effects on crop yield, N uptake, soil moisture content and heavy metal concentration of applying de-inked paper mill sludge (DPMS) over the period 1991 to 1993. In the first year, during decomposition of the DPMS, N immobilization occurred resulting in loss of cereal yield ( P < 0.05) at low rates of N fertilizer. Approximately 40 kg extra N fertilizer/ha was required per 100t DPMS/ha to compensate for this N immobilization. Soil volumetric moisture content was increased ( P < 0.001) by c. 20% at both sites by 200 and 300t DPMS/ha. DPMS did not significantly increase ( P > 0.05) soil concentrations of total Zn, Cu and Pb. Soil nitrate concentrations after harvest were reduced ( P < 0.01) by c. 17 mg N/kg per 100t DPMS/ha with increasing rates of DPMS up to 200 t/ha. In the second year following the DPMS application, there were no significant effects on grain yield indicating that very little or no N was immobilized. By the third year, the soil N supply was 7 kg N/ha higher where a single dressing of 100t DPMS/ha had been applied compared to the control. This resulted in an overall yield increase of 7% ( P < 0.10). Soil N supply was lower (N.S.) but crop yields were similar ( P > 0.05) to the control where single dressings of 200 and 300t DPMS/ha had been applied.     

Succession of plant and soil microbial communities with restoration of abandoned land in the Loess Plateau, China

Purpose

There have been a number of studies on the succession of vegetation; however, the succession of soil microbes and the collaborative relationships between microbes and vegetation during land restoration remain poorly understood. The objectives of this study were to characterize soil microbial succession and to explore the collaborative mechanisms between microbes and vegetation during the restoration of abandoned land through quantitative ecology methods.

Materials and methods

The present research was carried out in the succession of a 5-year abandoned land and its conversion to Hippophae rhamnoides shrubs, Larix principis-rupprechtii plantation, and a naturally regenerated forest (mixed forest). Soil bacterial, archaeal and fungal characteristics were tested by real-time quantitative PCR assays and terminal restriction fragment length polymorphism. The richness, diversity, and evenness indices were employed to analyze plant and microbial communities’ structure. The stability of plant and microbial communities was tested using Spearman’s rank correlation. The relationships between the regeneration scenarios and environmental factors were determined through canonical correspondence analysis.

Results and discussion

The aboveground biomass was significantly different among the sites. Soil bacterial, archaeal, and fungal rRNA gene abundances did not increase significantly with increasing soil organic carbon content. There were higher correlation coefficients between plant and total microbial communities on the richness, diversity, and evenness indices and ratios of positive to negative association compared to ones between plant and individual bacteria, archaea, and fungi. Soil bulk density, clay, pH, and litter were the primary significant environmental factors affecting the structure of plant and microbial communities. The positive relationships between plant and soil bacteria, fungi, and total microbe communities, as well as the negative relationships between plant and archaea, were demonstrated.

Conclusions

The results suggested that plants promote the growth of soil bacteria and fungi during the process of community succession on a small scale; however, plants inhibit the growth of soil archaea.     

Discriminating the effects of agricultural land management practices on soil fungal communities

The structure of fungal communities was examined in soil subjected to 5 years of different agricultural land management and tomato production practices. Length heterogeneity polymerase chain reaction (LH-PCR) of fungal rDNA internal transcribed spacer-1 (ITS-1) regions was used to create genomic fingerprints of the soil fungal communities. Three years after initiation of land management practices, univariate analysis of genetic diversity failed to detect differences among soil fungal communities in plots managed organically, conventionally or maintained free of vegetation by continuous tillage (disk fallow). Genetic diversity was significantly higher in plots maintained as a perennial pasture grass (Paspalum notatum var Argentine bahiagrass) or as an undisturbed weed fallow. The composition of soil fungal communities within organic, pasture grass or disk fallow plots were separated into unique clusters by non-parametric multivariate analysis of their Bray-Curtis similarity matrices, computed from the relative abundance of ITS-1 amplicons, while the composition of communities within disk fallow and conventional plots could not be distinguished from each other. Diversity of soil fungal communities was significantly reduced following the cultivation of tomato in year four when compared to the diversity in plots where tomato was not cultivated. Divergence in the composition of soil fungal communities was observed following the cultivation of tomato under all land management regimes except organic, where communities continued to remained clustered based upon similarities among their ITS-1 amplicons. Divergence in the composition of fungal communities became more pronounced following two major hurricanes (Francis and Jeanne, September 2004) except for communities in the organic and pasture grass plots. Following the completion of a second tomato crop in year 5, genetic diversity and richness was similar under all land management regimes except the pasture grass, where it remained significantly higher. By contrast, following two consecutive years of tomato production, unique but mutually similar compositions of fungal communities were detected only in plots subjected to the organic land management regime. This was supported by observations that fungal communities were dominated by a 341 bp rDNA amplicon fragment in all land management regimes except the organic. Cloning and sequencing indicated that the 341 bp fragment generated by LH-PCR had a sequencing size of 343 bp, which was most closely related to Fusarium oxysporum. Thus, land management practices that disturb or disrupt soil fungal communities will significantly reduce their diversity. However, the composition of soil fungal communities is more strongly influenced by land management practices and communities within an organically management system were more resistant to anthropogenic and meteorological disturbances.     

Evaluating the efficiency of sampling methods in assessing soil macrofauna communities in arable systems

The soil fauna is often a neglected group in many large-scale studies of farmland biodiversity due to difficulties in extracting organisms efficiently from the soil. This study assesses the relative efficiency of the simple and cheap sampling method of handsorting against Berlese–Tullgren funnel and Winkler apparatus extraction. Soil cores were taken from grassy arable field margins and wheat fields in Cambridgeshire, UK, and the efficiencies of the three methods in assessing the abundances and species densities of soil macroinvertebrates were compared. Handsorting in most cases was as efficient at extracting the majority of the soil macrofauna as the Berlese–Tullgren funnel and Winkler bag methods, although it underestimated the species densities of the woodlice and adult beetles. There were no obvious biases among the three methods for the particular vegetation types sampled and no significant differences in the size distributions of the earthworms and beetles. Proportionally fewer damaged earthworms were recorded in larger (25 × 25 cm) soil cores when compared with smaller ones (15 × 15 cm). Handsorting has many benefits, including targeted extraction, minimum disturbance to the habitat and shorter sampling periods and may be the most appropriate method for studies of farmland biodiversity when a high number of soil cores need to be sampled.     

基于农用地分等的区域耕地整理规划

耕地整理类型区与整理区优先度划分是土地整理规划的基础。该文以北京大兴区为例,充分利用农用地分等成果,从耕地整理的基本目标出发,分析选取了土地整理类型区划分的因子,并运用模糊聚类方法划分整理类型区;提出了基于土地整理效益与评价单元对新增耕地和提高耕地综合生产能力的迫切性需求的双重目标的土地整理优先度评价指标体系和方法。结果表明,研究区内耕地最主要的限制性因素是土壤肥力偏低,亟需培肥地力的区域耕地面积为27 603.8 hm2,占总耕地面积的64.9%;其次是耕地地块的坡度、规模和景观指数等因素导致的耕地生产条件差,而需要实施整理工程的耕地占总耕地面积的17.86%;近期整理区分布与新增耕地相关的整理类型相一致,占区域总耕地面积的15.82%;中期整理区集中连片分布在该区的北部地区,占区域总耕地面积的46.18%;远期整理区在较长时间内以实施培肥地力工程为主,将来主要通过居民点和闲散用地整理增加耕地面积。研究结果可为区域土地整理规划编制和土地整理实践提供科学依据。