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We investigate the effects of bedrock and slope position on soil diversity in a semiarid, wooded, mountainous environment, and we use these results to examine differences between the current diagnostic criteria of the Soil Taxonomy System (STS) and World Reference Base (WRB) classification systems. To achieve these objectives, we characterize a total of ten pedons occurring across representative catenas on limestone and gypsum bedrocks. Differing parent material causes the most variation among diagnostic horizons of the soils. In soils overlying limestone catena, a mollic horizon can be consistently defined according to STS criteria. But according to WRB criteria, a mollic definition can receive different interpretations due to differing color values associated with high lime content and its bleaching action, as well as the introduction of the concept “finely divided lime”. In soil classification, it is proposed to consider the concept “equivalent calcium carbonate”. Under these assumptions, soils in limestone catena are classified as Lithic Haploxerolls/Rendzic-Epileptic Phaeozems at the top, which transition into Pachic Haploxerolls/Rendzic Phaeozem at the mid-slope. The foot slope of the limestone catena also includes occasional Pachic Calcixerolls/Calcic Chernozems, through the presence of calcic horizons. Topography causes variations in soil depth and water retention, which tend to increase from the top of the hillslope to its base, and for this reason, the estimated soil moisture regime changes from aridic, at the top, to xeric along both catenas. This feature strongly influences soil classification, especially in gypsum catena because the soil moisture regime is used at first taxonomic level in STS. The STS soil classification is therefore tentative, given uncertainties concerning the exact soil climate regime. The soils of uppermost areas of gypsum catena are classified as Leptic Torriorthent/Haplic Leptosol (gypsiric) according to the STS and WRB while soils from the middle and lower slope, with prominent pedogenic gypsum accumulations, are classified as Gypsic Haploxerept by STS. These soils would correspond to different units (Hypergypsic, Haplic or Salic Gypsisols) according to the WRB, a level of specificity contributed to in part by mineralogical class in the STS. Similarly to the equivalent calcium carbonate, the term “equivalent gypsum” should be used. At the base of gypsum catena, a salic horizon is defined according to the WRB but not according to the STS due to differences in its definition, which should be standardized. This study shows that the current versions of the STS and WRB include certain inconsistencies that require clarification and standardization in order to serve as a foundation for a universal classification system and to improve the systems themselves.

This work was initiated to study the concentration effects on phenanthrene and pyrene extraction during process of aging in phaeozem and burozem with or without freeze–thawing cycles. 1, 10, and 100 μg g − 1 phenanthrene and pyrene contaminated soils were extracted by 10,000 mg L − 1 surfactant SDBS at various times. The extraction amount decreased with increasing contact time. Aging process could be divided into two stages: an initially rapid and then a slow sorption period. The amount extraction of 1 μg g − 1 pyrene in phaeozem was higher at the initial sorption stage. The time for 100 μg g − 1 phenanthrene and pyrene extraction efficiency to reach equilibrium in both soils were shorter than 1 and 10 μg g − 1 . Changes in extraction efficiency rate caused by slow sorption were affected by contact time, physicochemical properties of soils and chemicals and the applied concentration of chemicals. For 1 and 10 μg g − 1 phenanthrene and pyrene contaminated soils, freeze–thawing cycle increased the extraction efficiency at the initial 1st and 8th days. The extraction efficiency with no freeze–thawing cycle was higher than that with freeze–thawing cycles at 30 and 120 days. A conceptual model was proposed to account for this process.

Heilongjiang Province is the main soybean-producing area in china. In this study, we analyzed the canopy structure, dynamic characteristics of light radiation and yield of Hefeng50 (the main variety of soybean in Heilongjiang Province) under six different cultivation patterns (ORP, TPCR, ORCP, BRHD, SRHD and FPHD). The results showed that SRHD and BRHD at different growth period (blossom period R1, podding R3 and grain filing period R5) produced an even distribution of the population leaf area, suitable mean foliage inclination angle (MFIA), low transparency coefficients for defuse penetration (TCDP) and transparency coefficients for radiation penetration (TCRP), high leaf area index (LAI), extinction light coefficient (K value), fraction of radiation intercepted (FRI) and light energy utilization rate. Grain number, dry matter weight per plant, and yield of SRHD and BRHD were significantly higher than those of other cultivation patterns. The yield of SRHD, BRHD, ORCP, FPHD and TPCR was increased by 136%, 112%, 79%, 50.1% and 14.7%, respectively, compared to that of ORP. These results suggest that SRHD and BRHD are the optimal cultivation pattern for the improvement of soybean yield in phaeozem region of northeastern China.

The main goal of the study was to determine the diversity of the potential nitrogen-fixing (PNF) bacteria inhabiting agricultural (A) soils versus wastelands serving as controls (C). The soils were classified into three groups based on the formation process: autogenic soils (Albic Luvisols, Brunic Arenosols, Haplic Phaeozem) formed on loess material, hydrogenic soils (Mollic Gleysols, Eutric Fluvisol, Eutric Histosol) formed under the effect of stagnant water and lithogenic soils (Rendzina Leptosols) formed on limestone. In order to determine the preferable conditions for PNF bacteria, the relationships between the soil chemical features and bacterial operational taxonomic units (OTUs) were tested. Additionally, the nitrogen content and fertilisation requirement of the lithogenic (LG), autogenic (AG) and hydrogenic (HG) soils were discussed. The composition of the bacterial communities was analysed with the next-generation sequencing (NGS) by the Ion Torrent™ technology. The sequences were clustered into OTU based on a 99 % similarity threshold. The arable soils tested were distinctly dominated by β-Proteobacteria representatives of PNF bacteria belonging to the genus Burkholderia. Bacteria from the α-Proteobacteria class and Devosia genus were subdominants. A free-living Cyanobacteria population dominated in A rather than in C soils. We have found that both soil agricultural management and soil formation processes are the most conducive factors for PNF bacteria, as a majority of these microorganisms inhabit the AG group of soils, whilst the LG soils with the lowest abundance of PNF bacteria revealed the need for additional mineral fertilisation. Our studies have also indicated that there are close relationships between soil classification with respect to soil formation processes and PNF bacteria preference for occupation of soil niches. Electronic supplementary material The online version of this article (doi:10.1007/s00248-016-0837-2) contains supplementary material, which is available to authorized users.

Soils may be contaminated by human or veterinary pharmaceuticals. Their behaviour in soil environment is largely controlled by sorption of different compounds in a soil solution onto soil constituents. Here we studied the sorption affinities of 4 pharmaceuticals (atenolol, trimethoprim, carbamazepine and sulfamethoxazole) applied in solute mixtures to soils taken from different horizons of 3 soil types (Greyic Phaeozem on loess, Haplic Luvisol on loess and Haplic Cambisol on gneiss). In the case of the carbamazepine (neutral form) and sulfamethoxazole (partly negatively charged and neutral), sorption affinity of compounds decreased with soil depth, i.e. decreased with soil organic matter content. On the other hand, in the case of atenolol (positively charged) and trimethoprim (partly positively charged and neutral) compound sorption affinity was not depth dependent. Compound sorption affinities in the four-solute systems were compared with those experimentally assessed in topsoils, and were estimated using the pedotransfer rules proposed in our previous study for single-solute systems. While sorption affinities of trimethoprim and carbamazepine in topsoils decreased slightly, sorption affinity of sulfamethoxazole increased. Decreases in sorption of the two compounds could be attributed to their competition between each other and competition with atenolol. Differences between carbamazepine and atenolol behaviour in the one- and four-solute systems could also be explained by the slightly different soil properties in this and our previous study. A great increase of sulfamethoxazole sorption in the Greyic Phaeozem and Haplic Luvisol was observed, which was attributed to elimination of repulsion between negatively charged molecules and particle surfaces due to cation sorption (atenolol and trimethoprim) on soil particles. Thus, our results proved not only an antagonistic but also a synergic affect of differently charged organic molecules on their sorption to soil constituents.

The decomposer soil community maintains the arable soil ecosystem for the nutrient turnover. Here, we studied the dynamics of the soil fungal populations in a typical Phaeozem luvico in Argentina and related it to the management practices. Soil samples (at 0–10 cm depth) were collected from a field cultivated with wheat, at different sampling times: at post-harvest, before sowing, and at tillering. The relative abundance of individuals in the population on Nash Snyder and Oxgall agar media was assessed as colony forming units (CFU). The fungal population was classified by numerical taxonomy at the different sampling times. The highest values of CFU g−1 of soil were found at post-harvest under reduced tillage and differed significantly from those at conventional tillage. The genera Trichoderma, Fusarium, Aspergillus, Penicillium, and Fusarium oxysporum were present in the largest number of samples and discriminated the fungal community between times. This discrimination could be related to alterations in the availability of carbon sources during stubble degradation at post-harvest and before sowing and were of lesser importance at tillering., Centro de Investigaciones en Fitopatología

The enhancement of soil organic carbon (SOC) is important for sustainable agriculture, while changes in SOC depend on the balance between carbon (C) input and export. To investigate how chemical fertilizers contribute to C input (e.g. plant-derived C) and export (e.g. original SOC decomposition) in soil, a wheat (a C3 plant) pot experiment was conducted using a Phaeozem that had previously been used to cultivate maize (a C4 plant). The natural 13C abundance method was used to quantify wheat-derived SOC (WSC) and microbial respiration using the original SOC (Rmicrobial) during the wheat growing season. The wheat grain, WSC, wheat-derived C (WDC: including WSC, root and stubble biomass C) and Rmicrobial-derived CO2 emission (SCE) in fertilized treatments increased by 4.8–31.1%, 48.9–122.4%, 21.3–62.2% and 6.0–51.8%, respectively, when compared to unfertilized treatments. The total SOC in the post-experimental soil increased by 0.14–0.97% when compared to pre-experimental soil because the WSC input was larger than the SCE export, and it would be increased further if wheat root and stubble biomass C were included. Therefore, application of chemical fertilizer not only directly increases crop yield, but also indirectly contributes to C sequestration by favoring crop growth and crop-derived C input in soil.

The study was concerned with the physical properties of a soil which was under natural fallow for ten years (1996–2005). The experimental sites were situated on a Rendzic Phaeozem originating from cretaceous bedrock. Two adjoining arable plots (0.2 ha area of each) cultivated during the period were compared with the fallowed plot (0.1 ha area). The soil under study has been in use as arable land for over 100 years. The crops most frequently cultivated included cereals, sugar beet and potato. The primary soil tillage system applied was the conventional plough tillage system. An oat and barley mix was grown on this plot immediately before the fallowing started. The paper provides a presentation of results concerning the following physical properties of the soil: bulk density (BD), total porosity (TP), field air capacity (content of macropores Φ > 20 μm — FAC), field air permeability (FAP), moisture at the sampling moment (SM), field water capacity (FC), available water retention (AWC), unavailable water retention — wilting point (UWC), and the calculated ratio FC/TP. After the ten-year period of lying fallow the physical condition of the studied soil improved markedly. What should be noted as particularly valuable was the fact that after six years of exclusion from cultivation there was an improvement of soil compaction (BD) and an increase in total porosity (TP), field air permeability (FAP), field water capacity (FC) and available water retention (AWC). The ten-year (1996–2005) mean value of BD of the fallow soil was 1.11 Mg m − 3 , that of the soil from Field I — 1.17 Mg m − 3 , and from Field II — 1.15 Mg m − 3 ; TP: fallow — 0.550 m 3 m − 3 , Field I — 0.531 m 3 m − 3 , Field II — 0.543 m 3 m − 3 ; FAP: fallow — 104.1 × 10 − 8 m 2 Pa − 1 s − 1 , Field I — 47.9 × 10 − 8 m 2 Pa − 1 s − 1 , Field II — 66.9 × 10 − 8 m 2 Pa − 1 s − 1 ; FC: fallow — 0.374 kg kg − 1 , Field I — 0.353 kg kg − 1 , Field II — 0.354 kg kg − 1 ; AWC: fallow — 0.221 kg kg − 1 , Field — 0.202 kg kg − 1 , Field II — 0.201 kg kg − 1 . In view of the acquired data it should assumed that long-term fallow of arable fields is one of the methods leading to the physical regeneration of soil. Favourable changes in the physical structure of soil can be achieved through the application of reduced or no-till tillage systems.

Two sites with similar environmental parameters, except for the edaphic factor, were selected in the mountainous tropical forest of southern Mexico. Site 1 was established on an Alisol; site 2, on a Phaeozem. Representative soil profiles were examined on each of the sites, and topsoil was sampled on a regular grid pattern. The soil of site 2 was richer in organic matter and major nutrients and had a less acid reaction than the soil of site 1. The species diversity of the trees at site 2 (30 species) was higher than that at site 1 (17 species). The species compositions of the trees were different on the two soils: there were only six species in common for both sites. The coefficients of species similarity on the sites were low. We concluded that the presence of different soils within the same type of forest ecosystem increases its β-diversity. The examination of edaphic preferences of the species showed that Alstonia longifolia and Thouinidium decandrum preferred rich soils, Inga punctata and Ocotea sinuata preferred poor soils, and Cupania dentata and Hamelia patens did not display preferences in the studied range of soil properties. Thus, the spatial variability of the soil properties affect the spatial pattern of tree species in the studied tropical forest ecosystems.

Soil organic carbon (SOC) and total nitrogen (TN) stocks can be affected by soil erosion and this is of great significance in relation to global environmental concern about environmental change. This study investigated the spatial patterns of Cs-137, SOC and TN as well as their relationships for an agricultural catchment and presents a budget analysis of the redistributions of SOC and TN for the period 1954-2010. Cs-137, SOC and TN inventories were found to be significantly correlated, and the application of the(137)Cs technique proved to be useful for evaluating SOC and TN dynamics in the Luvic Phaeozem soil typical of the Chinese black soil region. Spatial patterns of soil, SOC and TN were greatly influenced by shelterbelts/windbreaks within the study catchment. Higher Cs-137, SOC and TN stocks were generally found upwind of the shelterbelts and at the study catchment outlet, whereas lower stocks of Cs-137, SOC and TN occurred behind the shelterbelts (i.e. in the lee). The total net losses of SOC and TN over the past 56 years were approximately 152 and 11 t respectively, with 47 and 38 per cent of the eroded SOC and TN in soils redeposited within the study catchment, respectively. Based on the relationships of soil, SOC and TN in the investigated catchment, erosion-induced SOC and TN losses per year are around 1.2 x 10(6) and 0.1 x 10(6) t for the typical black soil region of Northeast China. Copyright (C) 2012 John Wiley & Sons, Ltd.

Soybean ( Glycine max L.)–maize ( Zea mays L.) rotation has been recommended as a good cropping practice for soil quality improvement and crop productivity enhancement. However, its impacts on carbon sequestration in soil are not well documented. The main objective of this study was to learn whether soybean–maize rotation can promote soil organic carbon (SOC) sequestration. Based on a long-term field experiment (started in 1990) in Northeast China, we investigated the differences in soil organic carbon (SOC) and soil aggregate composition between cropping patterns. This experiment included four treatments: continuous maize cropping (CMC), maize–soybean rotation (MSR), continuous soybean cropping (CSC) and farmland fallow (FALL) in a Haplic Phaeozem soil. All treatments showed a sustained trend toward increasing SOC storage since 1990. The contents of SOC in the topsoil and in the profile to the 1 m depth were in the following order of CMC > MSR > CSC ≥ FALL, suggesting a greater potential of C sequestration under cropping with manure application than under the farmland fallow without any fertilizer application. In the 1 m soil profiles, SOC levels decreased with soil depth with a major part (around 60–71%) being distributed in the 0–40 cm layer, whereas different practices led to great differential of SOC distribution. The CMC had the highest SOC levels (47.3 Mg ha −1 ) in the topsoil (0–20 cm) among the four systems. Meanwhile, maize cropping system (e.g. CMC and MSR) promoted more SOC allocation in >40 cm soil layers. Moreover, cropping pattern also differently influenced the formation and transformation of soil aggregates and the distribution of SOC in the aggregates. Macro-sized aggregate and the associated C (18.6 Mg ha −1 ) dominated in the FALL, while the micro-sized fractions (44.0% and 52.5%, respectively) and corresponding associated C (14.8 Mg ha −1 and 19.2 Mg ha −1 , respectively) were maximized in the MSR and CSC. The CMC had the greatest silt + clay-sized aggregate fraction (42.0%) and associated C in the macro- (13.4 Mg ha −1 ) and silt + clay-sized aggregate (12.9 Mg ha −1 ) fractions when compared with the MSR and CSC. Thus, maize–soybean rotation may be not the best cropping practice for C sequestration in the rainfed farmland Mollisol (Cumulic Hapludoll) in Northeast China, and intensive cropping with manure application can sustain the soil fertility for a long-term with high crop yield.

The processes of the organic matter (OM) mineralization in forest soils developed under temperate continental (Moscow oblast, Russia), Mediterranean (the central and western parts of Spain), and tropical monsoon (southern Vietnam) climates were studied under laboratory conditions. The potential and specific rates of the OM mineralization (PR min and PR min/Corg, respectively), the ecophysiological parameters of the microbial communities status (Cmic, qCO2, and Cmic/Corg), and the sensitivity of the rate of the OM mineralization to the rise in temperature were evaluated by the temperature coefficients (Q 10) determined in the humus horizons (0–10 cm, without forest litter). The average values of PR min for the climatic zones decreased in the following order: Mediterranean (57.1 ± 10.6 mg C/kg per day) > temperate continental (23.8 ± 7.1 mg C/kg per day) > tropical monsoon (10.4 ± 1.6 mg C/kg per day). The lowest resistance of the soil OM to mineralization as evaluated by the PR min/Corg values was found in the Albeluvisol and Phaeozem of the temperate continental climate and in the Acrisol of the Mediterranean climate. The highest Q 10 coefficients were attributed to the OM mineralization in the forest soils of the temperate continental climate. This allowed us to conclude that the observed and expected climate changes with an increase in the mean annual air temperature should lead to the maximum intensification of the OM mineralization processes in the forest soils of northern regions.

Summary Concern about combined pollution of agricultural ecosystems by chlorimuron-ethyl (CHL) and copper (Cu) has increased of late, particularly in northeastern China. Sorption and desorption of CHL and Cu on soils and their interactive effects strongly affect their mobility and bioavailability. Thus, the interaction between CHL and Cu(II) with regard to their sorption and desorption on brown earth (BE, luvisols) and black soils (BS, phaeozem), two typical soils in northeastern China, was investigated by using batch experiments. The results indicated that the presence of Cu(II) increased the sorption of CHL on the two soils, which can be attributed to decreased pH in the equilibrium solution and Cu-bridging. The formation of a Cu-CHL complex with stronger affinity to the soils than CHL itself may be another mechanism. Addition of Cu(II) also enhanced the hysteresis effect of CHL desorption from BS but decreased that from BE. CHL at small concentrations promoted Cu(II) slightly sorption on BE and BS by the bridging effect of CHL. In addition, CHL suppressed Cu(II) desorption from the two soils, decreasing the mobility and bioavailability of Cu(II).

It is difficult to analyse soil properties quantitatively with multispectral remote sensing data. An alternative solution is to determine the main spectral characteristic control points of soil hyperspectral reflectance curves by sensitivity analysis methods. Hyperspectral reflectance is simulated using the control points based on multispectral reflectance collected from satellites in this study. The laboratory hyperspectral reflectance and its continuum-removed curve of Phaeozem and the parent material (PM) of samples collected from Heilongjiang Province, China were analysed, and the spectral characteristic control points determined. Hyperspectral simulating linear and quadratic models based on laboratory reflectance were then built. Results show that montmorillonite and illite are the dominant minerals in Phaeozem PM. Organic matter content determines the spectral characteristics of Phaeozem and makes it suitable for reflectance simulation in the spectrum range of 1000 nm and less; the higher the organic matter content the greater the spectral absorption area. There are two absorption valleys at 500 and 660 nm, which determine the spectral characteristic control points of Phaeozem between 450 and 930 nm, namely 450, 500, 590, 660 and 930 nm. Both the linear and quadratic simulation models built with the characteristic control points accurately describe Phaeozem reflectance, which proves that the characteristic control points are selected reasonably and representatively. The hyperspectral simulation method based on multispectral reflectance closely represents the characteristics of Phaeozem hyperspectral reflectance, partly removes noise and improves the precision of predicting organic matter content. Therefore the method is feasible and useful for data compression of Phaeozem hyperspectral reflectance, soil and vegetation indices building, and quantitative remote sensing in the Phaeozem Zone, northeast China.

Understanding temporal variations in soil organic matter (SOM) is important because SOM improves soil, sustains soil productivity, and sequesters carbon. The Tibetan Plateau plays a critical role in climate change at both regional and global scales. Thus, the main objective of this study was to investigate temporal variations in SOM content in Tibetan soils as an important indicator of climate change. SOM content data were obtained from soil surveys conducted in the 1980s and resampled in the 2000s. In this study, SOM content data from the A horizon of the soil profile were compared over time, and a paired t-test was conducted to verify differences between the two datasets. The results reveal that SUM content in the A horizon decreased significantly. To determine the causes of SOM content decreases in the A horizon, soil samples were grouped into ten soil types, four land-use types, and seven physiogeographical units. SUM content in four soil types (felty soils, cambisols in the World Reference Base (WRB) for soil resources; cold calcic soils, cambisols in the WRB; bog soils, gleysols in the WRB; and meadow soils, umbric gleysols/haplic phaeozem in the WRB), pasture, and broad valleys and basins of the south Tibetan zone of montane shrubby steppe decreased significantly in the A horizon. Based on the analysis of some known realities, this change should be attributed to pasture degradation resulting from overgrazing and climate warming. (C) 2011 Elsevier B.V. All rights reserved.

The adsorption and desorption of carbendazim and cadmium (Cd) in soils (burozem and phaeozem) typically distributed in northeastern China were investigated at two different temperatures, 25 and 40 °C. The effects of interaction between carbendazim and Cd on their adsorption and desorption were also discussed. The results showed that the adsorption of carbendazim was exothermic with ΔH Θ values of − 5.3 kJ/mol for burozem and − 33.6 kJ/mol for phaeozem, while the adsorption of Cd was endothermic with ΔH Θ values of 43.2 and 37.4 kJ/mol, respectively. Increasing the temperature from 25 °C to 40 °C could promote the desorption hysteresis of carbendazim, but decreased the desorption hysteresis of Cd. The coexistence of carbendazim and Cd promoted the adsorption of carbendazim but suppressed the adsorption of Cd and the effect was amplified as the temperature increased to 40 °C. The adsorption amount of carbendazim at 25 °C increased 11% for burozem and 4% for phaeozem respectively when the concentration of Cd was 50 mg/L. This increased to 56% and 20% respectively when the temperature was increased to 40 °C. When the concentration of carbendazim was 30 mg/L, the amount of Cd adsorption decreased 13% for burozem and 5% for phaeozem at 25 °C, and 33% and 14% at 40 °C, respectively.

Common bean ( Phaseolus vulgaris L.) is one of the most important grain legumes in East Africa, but its yield has remained below the genetic potential. Declining soil fertility is among the primary constraints to bean production in most East African bean producing regions. Often existing recommendations are generic and inept to guide farm level decision making on nutrient replenishment. A greenhouse nutrient omission study was conducted to determine the limiting nutrients in three soils of Masaka District, commonly cropped to beans: “ Liddugavu ” a Phaeozem, “ Limyufumyufu ” a Cambisol and “ Luyinjayinga ” an Umbrisol soil. Nine treatments; (i) complete nutrient treatment, (ii) N omitted, (iii) P omitted, (iv) K omitted, (v) Mg omitted, (vi) S omitted, (vii) Ca omitted, (viii) Micronutrients omitted and (ix) control without nutrients. Each treatment was randomly assigned to the three soils and replicated three times using a completely randomised design. Nitrogen, phosphorus and potassium were limiting nutrients for bean production in Umbrisol (Luyinjayinja) while in Cambisol (‘ Limyufumyufu ), common bean production was most limited by soil acidity. The performance varied with soil types, with beans grown on the Phaeozem registering greater leaf number and growth, confirming both scientist’s and local farmer’s knowledge that this soil has greater potential than the other two soils. Key words: Cambisol, Phaeozem, Phaseolus vulgaris , Umbrisol

Whether production of winter wheat is stable without any fertilizer input on Greyic Phaeozem in the Czech Republic still remains unsolved. Phaeozems represent 3% of soils in Europe and they are particularly common in wet steppe regions. In this paper, the yield of winter wheat over 50 years of farmyard manure (FYM), N, P and K fertilizer application (12 treatments altogether) was analyzed in the Caslav Crop Rotation Experiment (CCRE), which was established in 1955 in a sugar beet growing area (mean annual precipitation and temperature 555 mm and 8.9 °C, respectively). In the unfertilized control treatment, low plant available P and suitable K concentrations were recorded after 50 years. The annual yield growth (AYG) of grain was positive, even in the control treatment without any fertilizer input. The mean AYG ranged from 24.9 kg ha −1 in the control treatment to 73.6 kg ha −1 following the application of 119 kg N ha −1 . In the first two decades of the experiment, there was no significant effect of treatment on grain yield. The increase in grain yield per 1 kg of applied N was 20.1 kg ha −1 in the last decade of the experiment. The mean grain yields of long-straw and short-straw varieties were 3.8 and 5.5 t ha −1 , respectively. In the control, the grain yields were 4.8, 4.1 and 3.3 t ha −1 after legumes, root crops and cereals, respectively. To summarize the 50 years of results of winter wheat production in the CCRE, grain yield was most influenced by variety, followed by mineral fertilizers, the preceding crop and only moderately by FYM application. The highest grain yields were recorded in treatments with the highest N application rate. The long-term stability of winter wheat production on Greyic Phaeozem can be expected under a crop rotation system with legumes and root crops, even without any fertilizer input.

The effects of soil type and organic material quality on the microbial biomass and functional diversity of cropland soils were studied in a transplant experiment in the same climate during a 1-year field experiment. Six organic materials (WS: wheat straw, CS: corn straw, WR: wheat root, CR: corn root, PM: pig manure, CM: cattle manure), and three contrasting soils (Ferralic Cambisol, Calcaric Cambisol and Luvic Phaeozem) were chosen. At two time points (at the end of the 1st and 12th months), soil microbial biomass carbon (C) and nitrogen (N) (MBC and MBN) and Biolog Ecoplate substrate use patterns were determined, and the average well color development and the microbial functional diversity indices (Shannon, Simpson and McIntosh indices) were calculated. Organic material quality explained 29.5-50.9% of the variance in MBC and MBN when compared with the minor role of soil type (1.4-9.3%) at the end of the 1st and 12th months, and C/N ratio and total N of organic material were the main parameters. Soil properties, e.g., organic C and clay content were the predominant influence on microbial functional diversity in particular at the end of the 12th month (61.8-82.8% of the variance explained). The treatments of WS and CS significantly improved the MBC and microbial functional diversity indices over the control in the three soils in both sampling periods (P < 0.05). These results suggest that the application of crop straw is a long-term effective measure to increase microbial biomass, and can further induce the changes of soil properties to regulate soil microbial community.

Long-term stationary fertilizer trials were performed at three different sites in order to study the subsequent effects of manure and full mineral fertilization. Dry matter yields of winter wheat grown after red clover were evaluated over the years 2003–2006. In the nil variant without any fertilization for the past 47–51 years, the basic grain yields were decreasing with the higher altitude. Three-year average yields varied from 3.39–8.09 t ha−1. The site productivity accounted for almost 80% in the Greyic Phaeozem and only about 53% in the Stagno-Gleyic Cambisol. The effect of mineral fertilization was the highest in the Stagno-Gleyic Cambisol, up to about 39%. The effect of weather conditions in individual years strongly differed in individual sites. The results have confirmed a complex of effects and interactions among various factors that affect winter wheat grain yields.

Soil C dynamics below the plow layer have been little studied, despite a suspected large C-stabilization potential of subsurface horizons. The objective of this study was to test two simple models (model A: single compartment for C 3 - and for C 4 -derived C; model B: division of C 3 and C 4 -derived C into active and passive compartments) in their ability to simulate the C dynamics in subsoil horizons of a Haplic Phaeozem after conversion from C 3 (rye) to C 4 cropping (maize). The models were calibrated on an unfertilized maize soil and then validated on a maize soil with NPK fertilization. Both models simulated well C 3 -C and C 4 -C dynamics in the investigated soil depths (20-40 cm and 40―60cm). In all cases, the model efficiency EF was > 0, which indicated that the simulated values described the trend in the measured data better than the mean of the observations. However, we observed some inconsistency in the obtained parameter set (e.g., a higher proportion of passive C for C 4 -derived than for C 3 -derived C or a very low decomposition rate constant for passive C 4 -C in 40-60 cm), which we assume to result from data restrictions on the investigated soils. More detailed data on SOC pools and turnover rates in subsoils which are generally not yet available for most experimental plots is vitally needed—especially for applying more sophisticated C-dynamics models.

Defoliation of grasses affects carbon (C) input from plants into the rhizosphere and so may affect C turnover in soil. We examined the effect of grassland's defoliation on root-derived CO2 efflux and microbial activity in Mediterranean Phaeozem. In situ partitioning of total CO2 efflux into root-derived and microbial-derived CO2 fluxes was performed by mesh-exclusion technique. Microbial basal respiration, N mineralization and the activity of enzymes involved in the cycling of C, N, P and S (also used to calculate microbial functional diversity) were measured in soils of defoliated and control plots. Cumulative CO2 efflux in defoliated plots was 18% lower in 2006 and equal to control plots in 2007. The contribution of microbial CO2 to total CO2 efflux from soil ranged from 71% to 86% without significant differences between defoliated and non-defoliated plots. The lack of correlation between root-derived CO2 and soil temperature after defoliation indicates that photoassimilate supply is the major determinant for root-derived CO2. Microbial-derived CO2 efflux was 20% lower in defoliated plots after accounting for temperature and humidity differences between the two treatments. Defoliation suppressed the activity of enzymes involved in the cycling of C, S and P and decreased basal respiration rates of soil microorganisms by 19%. In turn, defoliation stimulated activity of enzymes involved in the cycling of N, as indicated by the increase of potential nitrification rates and of leucine-aminopeptidase activity. Stimulation of N mineralization promotes a fast regeneration of defoliated plants. We confirm the presence of strong links between plant and microbial activity in a grassland community, as well as close coupling of aboveground photosynthetic activity with root-derived CO2.

Soil organic carbon (SOC) and its relationship with landscape attributes are important for evaluating current regional, continental, and global carbon stores. Data of SOC in surface soils (0–20 cm) of four main soils, Cambisol, Arenosol, Phaeozem, and Chernozem, were collected at 451 locations in Nongan County under maize monoculture in the Song-Nen Plain, Northeast China. The spatial characteristics of soil organic carbon were studied, using geographic information systems (GIS) and geostatistics. Effects of other soil physical and chemical properties, elevation, slope, and soil type on SOC were explored. SOC concentrations followed a normal distribution, with an arithmetic mean of 14.91 g kg −1 . The experimental variogram of SOC was fitted with a spherical model. There were significant correlations between soil organic carbon and bulk density ( r = −0.374**), pH ( r = 0.549**), total nitrogen ( r = 0.781**), extractable phosphorus ( r = −0.109*), exchangeable potassium ( r = 0.565**), and cation exchange capacity ( r = 0.313**). Generally, lower SOC concentrations were significantly associated with high elevation ( r = −0.429**). Soil organic carbon was significantly negatively correlated with slope gradient ( r = −0.195**). Samples of the Cambisol statistically had the highest SOC concentrations, and samples of the Arenosol had the lowest SOC value.

Findings of previous studies suggest that there are relations between thermal stability of soil organic matter (SOM), organo-mineral associations, and stability of SOM against microbial decay. We aimed to test whether thermal oxidation at various temperatures (200°C, 225°C, 275°C, 300°C, 400°C, or 500°C) is capable of isolating SOM fractions with increasing stability against microbial degradation. The investigation was carried out on soils (Phaeozem and Luvisol) under different land-use regimes (field, grassland, forest). The stability of the obtained soil organic carbon (SOC) fractions was determined using the natural-13C approach for continuously maize-cropped soils and radiocarbon dating. In the Luvisol, thermal oxidation with increasing temperatures did not yield residual SOC fractions of increasing microbial stability. Even the SOC fraction resistant to thermal oxidation at 300°C contained considerable amounts of young, maize-derived C. In the Phaeozem, the mean 14C age increased considerably (from 3473 y BP in the mineral-associated SOC fraction to 9116 y BP in the residual SOC fraction after thermal oxidation at 300°C). An increasing proportion of fossil C (calculated based on 14C data) in residual SOC fractions after thermal oxidation with increasing temperatures indicated that this was mainly due to the relative accumulation of thermally stable fossil C. We conclude that thermal oxidation with increasing temperature was not generally suitable to isolate mineral-associated SOC fractions of increasing microbial stability.

The diversity and distribution patterns of soil nematode communities in phaeozem agroecosystems of Northeast China were assessed to evaluate nematode taxonomic diversity and functional diversity in relation to climatic condition and soil characteristics in human modified landscape. Along the latitudinal gradient, soil samples were collected from north (Hailun) to south (Gongzhuling) down to a depth of 100 cm with intervals of 0–20, 20–40, 40–60, 60–80, and 80–100 cm. The nematode abundance and taxonomic diversity (generic richness) were lower at Hailun than at other sites, and higher values of evenness were observed at Hailun and Harbin than at Dehui and Gongzhuling. Nematode faunal analysis revealed that soil food web at Hailun was successionally more mature or structured, and the environment little disturbed, while at Harbin and Gongzhuling, the soil food web was degraded with stressed environment. The environmental variables relevant in explaining the patterns of nematode distribution and diversity in phaeozem agroecosystems, using canonical correspondence analysis (CCA), were the mean annual temperature, total nitrogen, electrical conductivity, mean annual precipitation, and other soil properties. Among these variables, the mean annual temperature was a relatively important factor, which could explain 29.05% of the variations in nematode composition.

The effects of soil freezing and thawing on the extractability by dichloromethane of pyrene from two Chinese soils are investigated. The soils were collected from the Northeast region of China where heavy pollution of soils by Polycyclic Aromatic Hydrocarbons (PAH) is common. Two soils were considered: a burozem obtained from the Shenfu irrigated region in Liaoning province and a phaeozem collected from the Hailun area in Haerbin province. The soils were collected from areas free from PAH pollution. Pyrene was aged in sterilized soil, and autoclaved deionized water was then added to adjust the soil to different moisture levels. The combined dichloromethane extractions of pyrene in soils at various periods showed that the quantity of pyrene extracted with dichloromethane could be divided into two stages: the initially rapid period and a longer, slower period. The frequency of freeze-thawing cycles had different and contradictory effects on pyrene extractability between the two soil types. Soil moisture also was found to have different and opposite effects on pyrene extractability. Freeze-thawing cycles had great influence on pyrene extractability both in aged and unaged soils. The changes in unaged soil were more significant than those in 1-year aged soil and attributed to changes in the soil organic matter. Our research shows that the effect of freezing and thawing on pyrene extraction is complicated due to the differences in physical and chemical properties of soils as well as the aging process.

The analysis of pharmaceuticals and potential endocrine disruptors in the environment has rightly concentrated on their presence in wastewaters and possible contamination of receiving bodies, such as groundwaters. However, wastewater is increasingly being reused for irrigation and in order to fully understand the environmental fate of these compounds, reliable methods for their analysis in soil are required, of which there are relatively few available. This article reports a method for a range of acidic pharmaceuticals, carbamazepine, and endocrine disrupting compounds in soils with final analysis by gas chromatography-mass spectrometry. Two soil types (Phaeozom and Leptosol) and three fortification levels were used to validate the method. Recoveries of acidic pharmaceuticals varied between 62 and 102%, carbamazepine from 75 to 118%, and potential endocrine disruptors between 54 and 109%; most recoveries were between 75 and 95% and relative standard deviations were generally less than 10%. Detection limits were between 0.25 and 2.5 ng/g except for phthalates and 4-nonylphenols (25 ng/g). The method was used to analyze soils where untreated wastewaters have been used to irrigate crops for approximately 90 years. Concentrations of acidic pharmaceuticals in the soil were1 ng/g and potential endocrine disruptors varied from below the limit of detection (estrone, 17beta-estradiol, and 17alpha-ethinylestradiol) to 2079 ng/L (bis-diethylhexyl phthalate). This data indicated that despite the continuous application of the contaminants over many years, concentrations were generally lower than those expected to be contributed by a single irrigation event. Only carbamazepine, at concentrations of 6.48 ng/g (in Phaeozem) and 5.14 ng/g (in Leptosol), showed any evidence of persistence in the soils analyzed.

Soil structure stability was studied in every diagnostic horizons of six soil types (Haplic Chernozem, Greyic Phaeozem, two Haplic Luvisols, Haplic Cambisol, Dystric Cambisol) using different techniques investigating various destruction mechanisms of soil aggregates. Soil aggregate stability, assessed by the index of water stable aggregates (WSA), varied depending on the organic matter content, clay content and pHKCl. The presence of clay and organic matter coatings and fillings, and presence of iron oxides in some soils increased stability of soil aggregates. On the other hand periodical tillage apparently decreased aggregate stability in the Ap horizons. Coefficients of aggregate vulnerability resulting from fast wetting (KV1) and slow wetting (KV2) tests showed similar trends of the soil aggregate stability as the WSA index, when studied for soils developed on the similar parent material. There was found close correlation between the WSA index and the KV1 value, which depended also on the organic matter content, clay content and pHKCl. Less significant correlation was obtained between the WSA index and the KV2 value, which depended on the organic matter content and clay content. Coefficients of vulnerability resulting from the shaking after pre-wetting test (KV3) showed considerably different trends in comparison to the other tests due to the different factors affecting aggregate stability against the mechanical destruction. The KV3 value depended mostly on cation exchange capacity, pHKCl and organic matter content.

The impact of chromium(III) and (VI) forms on soil catalase activity was presented. The Orthic Podzol, Haplic Phaeozem and Mollic Gleysol from different depths were used in the experiment. The soil samples were amended with solution of Cr(III) using CrCl3, and with Cr(VI) using K2Cr2O7 in the concentration range from 0 to 20 mg/kg, whereas the samples without the addition of chromium served as control. Catalase activity was assayed by one of the commonly used spectrophotometric methods. As it was demonstrated in the experiment, both Cr(III) and Cr(VI) have an ability to reduce soil catalase activity. A chromium dosage of 20 mg/kg caused the inhibition of catalase activity and the corresponding contamination levels ranged from 75% to 92% for Cr(III) and 68% to 76% for Cr(VI), with relation to the control. Catalase activity reached maximum in the soil material from surface layers (0-25 cm), typically characterized by the highest content of organic matter creating favorable conditions for microorganisms.

Acute laboratory toxicity tests were carried out to assess the individual and combined toxic effects of metals including cadmium (Cd), lead (Pb) and the metalloid arsenic (As) in Phaeozem on the seed germination and seedling growth of soybean, Glycine max. Seeds were exposed to varied concentrations of Cd, Pb and As individually and in mixtures including Cd + Pb, Cd + As, Pb + As and Cd + Pb + As. The sum of toxic units (TU) for medium effective concentration of the mixture (EC 50mix ) was calculated based on the dose (TU-based)-response relationship using the Trimmed Spearman-Karber method. Binary metal combinations of Cd + Pb, Cd + As and Pb + As produced additive, synergistic and antagonistic effects, respectively, on shoot growth and synergistic, synergistic and antagonistic effects on root growth. Ternary combination of Cd + Pb + As had a synergistic effect on shoot growth and an additive effect on root growth. Bioaccumulation of metals was observed in soybean and inhibited or enhanced bioaccumulations of individual metals were found in mixtures due to different combinations of metals.

A pot experiment was conducted to investigate the effects of different cadmium (Cd) concentrations of phaeozem on growth and uptake of Cd and mineral nutrient copper (Cu) and zinc (Zn) by three maize genotypes in the mature stage. The results showed that the dry‐matter accumulation of shoots was inhibited by added Cd for Jidan209 and Jitian6, but this did not influence Chunyou30. The root biomasses decreased significantly for Jitian6 and stimulated Jidan209 and Chunyou30. Yields of three genotypes of maize were decreased by increasing soil Cd concentrations. Among them, Chunyou30 had a high tolerance and Jitian6 was most sensitive to Cd. The accumulation order of Cd in different parts of plants was root > leaf > stem > grain. The percentage of absorbed Cd by roots was 70–85% of total absorbed amount. Cadmium uptake by maize in the mature stage had a significant genetic variation: Jitian6 > Jidan209 > Chunyou30 for root, stem and leaf, and Jidan209 > Jitian6 > Chunyou30 for grain, respectively. In...

The impact of varying soil micromorphology on soil hydraulic properƟ es and, consequently, on water fl ow and herbicide transport observed in the fi eld is demonstrated on three soil types. The micromorphological image of a humic horizon of Haplic Luvisol showed higher-order aggregates. The majority of detectable pores corresponding to the pressure head interval between −2 and −70 cm were highly connected, separaƟ ng higher-order peds with small intrapores that possibly formed zones with immobile water. Herbicide was regularly distributed in this soil. The majority of detectable large capillary pores in a humic horizon of Greyic Phaeozem were separated and aff ected by clay coaƟ ngs and fi llings. The herbicide transport in this soil was highly aff ected by preferenƟ al fl ow. Macropores corresponding to pressure heads higher than −2 cm were detected in a humic horizon of Haplic Cambisol. However, preferenƟ al fl ow only slightly infl uenced the herbicide transport in this soil. Single-porosity and either dual-porosity or dual-permeability fl ow and transport models in HYDRUS-1D were used to esƟ mate the soil hydraulic parameters from laboratory mulƟ step ouƞ low and ponded infi ltraƟ on experiments via numerical inversion and to simulate the herbicide transport experimentally studied in the fi eld. Appropriate models were selected on the basis of the soil micromorphological study.

Quantitative information about the amount and stability of organic carbon (OC) in different soil organic-matter (OM) fractions and in specific organic compounds and compound-classes is needed to improve our understanding of organic-matter sequestration in soils. In the present paper, we summarize and integrate results performed on two different arable soils with continuous maize cropping (a) Stagnic Luvisol with maize cropping for 24 y, b) Luvic Phaeozem with maize cropping for 39 y) to identify (1) the storage of OC in different soil organic-matter fractions, (2) the function of these fractions with respect to soil-OC stabilization, (3) the importance and partitioning of fossil-C deposits, and (4) the rates of soil-OC stabilization as assessed by compound-specific isotope analyses. The fractionation procedures included particle-size fractionation, density fractionation, aggregate fractionation, acid hydrolysis, different oxidation procedures, isolation of extractable lipids and phospholipid fatty acids, pyrolysis, and the determination of black C. Stability of OC was determined by 13C and 14C analyses. The main inputs of OC were plant litter (both sites) and deposition of fossil C likely from coal combustion and lignite dust (only Phaeozem). Total soil OC stocks down to a depth of 65 cm (7.83 kg m–2 in the Luvisol and 9.66 kg m–2 in the Phaeozem) consisted mainly of mineral-bound OC (87% of total SOC in the Luvisol and 69% in the Phaeozem). In the Luvisol, free light particulate OM, OM associated with sand and coarse silt, and particulate OM occluded in macro-aggregates represented SOM fractions with mean turnover times shorter than that of the bulk soil OC (54 y). Additionally, the turnover of all individual compounds or compound classes (except for black carbon) was faster than that of bulk soil OC. These OM fractions that were less stable than the bulk soil OM made up 13% to 20% of the total OC. Organic matter in fine and medium silt and clay fractions, particulate OM occluded in micro-aggregates (53–250 lm) and OM resistant to acid hydrolysis had intermediate turnover times of about 50–100 y. These fractions with intermediate turnover times contributed 70%–80% to total soil OC. Passive OM with turnover times >200 y was isolated from the mineral-bound OM by different oxidation procedures (H 2 O 2 ,N a 2 S 2 O 8 ) and made up ≤10% of the total OC. The isotopic signature of PLFAs suggests an efficient recycling of OC derived from C3 substrate. In the Phaeozem, partitioning of maize-derived C exhibited a pattern similar to the Luvisol, but turnover rates of vegetation-derived soil OC were lower, probably because of the considerably smaller input of plant residues. Fossil C contributed approx. 50% to the total OC and accumulated preferentially in the particulate OM occluded in aggregates and in the fine-sand and

Aggregate size distribution and pore structure affect many soil functions and root growth. The aggregate structure is associated with soil genesis and management practices applied. In this study the effects of various size ranges of aggregates (

Soils contain the largest inventory of organic carbon on the Earth’s surface. Therefore, it is important to understand how soil organic carbon (SOC) is distributed in soils. This study directly measured SOC distributions within soil microaggregates and its associations with major soil elements from three soil groups (Phaeozem, Cambisol, and Ultisol), using scanning transmission X-ray microscopy (STXM) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at a spatial resolution of 30 nm. Unlike previous studies, small intact soil microaggregates were examined directly in order to avoid preparatory procedures that might alter C speciation. We found that SOC exists as distinct particles (10s to 100s of nm) and as ubiquitous thin coatings on clay minerals and iron-oxides coatings. The distinct SOC particles have higher fractions of aromatic C than the coatings. NEXAFS spectra of the C coatings within individual microaggregates were relatively similar. In the Phaeozem soil, the pervasive spectral features were those of phenolic and carboxylic C, while in the Cambisol soil the most common spectral feature was the carboxyl peak. The Ultisol soil displayed a diffuse distribution of aromatic, phenolic, and carboxylic C peaks over all surfaces. In general, a wide range of C functional groups coexist within individual microaggregates. In this work we were able to, for the first time, directly quantify the major mineral elemental (Si, Al, Ca, Fe, K, Ti) compositions simultaneously with C distribution and speciation at the nm to μm scale. These direct microscale measurements will help improve understanding on SOC–mineral associations in soil environments.

The community of culturable cellulolytic bacteria was analyzed in two long-term experimental field sites on Albic Luvisol (silty sand) and Haplic Phaeozem (loam), with and without farmyard manure treatment. Against the backdrop of significant differences in soil properties, the bacterial community structure differed clearly between sites and was affected by manure application as analyzed by T-RFLP of 16S rDNA. The population densities of cellulolytic bacteria were significantly increased by manure application in Phaeozem. Cellulose decomposing potentials of 537 isolates were tested on soluble, colloidal, and crystalline cellulose. The results showed some evidence of a greater proportion of isolates with high decomposition activity in Luvisol, but no impact from manure application could be observed in both soils. Restriction analysis and sequencing of 16S rDNA of isolates revealed a rather simple community composition that was dominated by Streptomyces (67%). The composition of the RFLP groups was affected by manure application, which was most evident in Luvisol, whereas an effect of the soil type could not be found. Although abundant RFLP groups were assigned to phylogenetically different bacterial classes (Actinobacteria, Betaproteobacteria, and Gammaproteobacteria), cellulolytic activity could not consistently be differentiated. All in all, cellulolytic capabilities of the isolates were highly variable and did not map to phylogenetic affiliation.

A sequence of serpentine soils (soils with ultramafic parent materials) on four Quaternary terraces was characterized in southwestern Oregon. The soils are Mollisols (Phaeozems), Inceptisols (Cambisols), and Alfisols (Luvisols and Acrisols) that range from thousands to hundreds of thousands of years old. Weathering has practically eliminated olivine from the oldest soil and greatly diminished serpentine from both sand and clay fractions. Citrate-dithionite-extractable Fe increased from 21 g kg -1 in the Bw horizon of the youngest soil to 166 g kg -1 in the fine earth (soil 0.4 to about 0.1 mmol + /g of clay. Base saturation decreased from 75% in the slightly acid Bw horizon of the youngest to 17% in the moderately acid Bt2 horizon of the oldest soil. Nevertheless, the oldest soil is an Alfisol (or Acrisol), because the base saturation is 44% at 125 cm below the top of a kandic horizon. Tree growth, as gauged by timber site index, increases slightly as the estimated available-water capacity in the soils increases from 6 cm in the 100-cm depth on the youngest terrace to 10 cm on the penultimate terrace, and then tree growth increases greatly from the penultimate to the ultimate (oldest) terrace as excess Mg is leached from the soil. The timber site index indicates that the expected (from site curves) conifer height on the oldest terrace is 26 m in 50 years, or 55 m in 300 years.

Long-term field experiments have been carried out in the Chernobyl exclusion zone in order to determine the parameters governing radiochlorine (36Cl) transfer to plants from four types of soil, namely, Podzoluvisol, Greyzem, Phaeozem and Chernozem. Radiochlorine concentration ratios (CR = concentration of 36Cl in the fresh plant material divided by its concentration in the dried soil in the upper 20 cm layer) were obtained in green peas (2.6 ± 0.4), onions (1.5 ± 0.5), potatoes (8 ± 1), clover (90 ± 26) and ryegrass (158 ± 88) hay, oat seeds (36 ± 23) and straw (305 ± 159), wheat seeds (35 ± 10) and straw (222 ± 82). These values correlate with the stable chlorine values for the same plants. It was shown that 36Cl plant/soil CR in radish roots (CR = 9.7 ± 1.4) does not depend on the stable chlorine content in the soil (up to 150 mg kg-1), soil type and thus, that stable chlorine CR values (9.4 ± 1.2) can also be used for 36Cl. Injection of additional quantities of stable chlorine into the soil (100 mg kg-1 of dry soil) with fertilizer does not change the soil-to-plant transfer of 36Cl. The results from a batch experiment showed that chlorine is retained in the investigated soils only by live biota and transfers quickly (in just a few hours) into the soil solution from dry vegetation even without decomposition of dead plants and is integrated in the migration processes in soil. © 2007 Elsevier Ltd. All rights reserved.

Burning of crop residues in the fields is a routine post-harvest practice and results in accumulation of ashes in soils. Recent studies have shown that the ashes may significantly contribute to the herbicide sorption in soils. This study was conducted to evaluate the potential role of wheat ash in immobilization of anionic herbicide MCPA in soils. The results showed that wheat ash is highly effective sorbent for herbicide MCPA. Amendment of Fluvi-Gleyic Phaeozem and Eutric Regosol with 1% wheat ash caused a 8-fold and 16-fold increase in MCPA sorption, respectively. Desorption of MCPA was also influenced by wheat ash in soils. The addition of wheat ash to both soils increased the resistant fraction to desorption up to 80%. Generally, the field burning of crop residues appears to increase the sorption of pesticides in agricultural soils and decrease their leaching.

The aim of the present study was the influence of various methods of long-term soil utilisation on the content of polycyclic aromatic hydrocarbons (PAH) in selected silty soils. Four soils were selected for the present studies, i.e.: Eutric Fluvisol originating from silty formations, Haplic Phaeozem developed from loess, Haplic Luvisol (non-uniform) developed from silt, Haplic Luvisol developed from loess. Five study sites were chosen, i.e.: apple orchards, hop gardens, fields, grasslands and natural woodland ecosystems. Samples were collected from the depth of 0–10 cm. In the samples the content of 16 PAHs was determined by means of the HPLC-UV method. The total PAHs content was at a low level. Depending on the soil and object type, the total PAHs content ranged from 72.5 to 764.0 μg·kg−1. The pollutant level determined together with composition of individual PAHs suggested a limited anthropogenic influence relating mainly to pyrolytic processes. The total PAH content as well as the content of individual PAHs depended on agricultural land use and management. It has been shown that PAH level was influenced by environmental conditions specific for a given type of land use. In the soils in which organic carbon content differed only slightly among locations, a higher influence of the soil utilisation method on the content of individual PAHs was observed.

There is evidence of black carbon (BC) contributing to stable humus in the soil environment but its quantity and fate are poorly examined. We used benzene polycarboxylic acids (BPCAs) as markers to assess the contents and distribution of BC in soils and soil fractions of the long-term field experiments in Halle (Haplic Phaeozem), Bad Lauchstadt (Haplic Chernozem), Rotthalmunster (Haplic Luvisol) and an additional site near Bad Lauchstadt (Haplic Phaeozem), Germany. Black carbon comprised 11.9–13.2% of organic C in the top soils (0–10 cm) of the black soils located around Halle and Bad Lauchstadt while it explained only 2.7% of organic carbon in the Haplic Luvisol of Rotthalmunster. The BPCA pattern at Bad Lauchstadt and Halle suggested that two thirds of BC were of fossil origin. In general, BC contents (in g kg− 1 soil) decreased with increasing soil depth. The C-normalized BC concentrations, however, increased and reached 35 ± 7% of organic carbon at a depth of 87–114 cm. With increasing depth BC was increasingly localized in the coarse silt and sand fractions and the heavy mineral fraction. This indicated that BC was connected to the minerals of this size and preserved there. Inorganic fertilization for > 30 years did not affect BC contents.

Plants have an important impact on soil microbial communities and their functions. However, how plants determine the microbial composition and network interactions is still poorly understood. During a four-year field experiment, we investigated the functional gene composition of three types of soils (Phaeozem, Cambisols and Acrisol) under maize planting and bare fallow regimes located in cold temperate, warm temperate and subtropical regions, respectively. The core genes were identified using high-throughput functional gene microarray (GeoChip 3.0) and functional molecular ecological networks (fMENs) were subsequently developed with the random matrix theory (RMT)-based conceptual framework. Our results demonstrated that planting significantly (P

In Hungary, 0.5 million m3 of thermal water is exploited every day for diverse purposes. After utilization, this enormous amount of thermal water becomes sewage water with a high concentration of salts, heavy metals, ammonia, nitrate, an unfavorable ion composition and high temperature. A common treatment is to dispose of waste water into a surface recipient through uninsulated channels surrounded by arable land. By infiltration, sewage water can cause potential salinization/sodification/alkalinization and contamination of soil and groundwater. This work investigates the manifestation of these problems in different soil types, Chernozem, Phaeozem and Arenosol, representing case studies regarding the environmental risks of used thermal water. The results conclude that seeping thermal water has a high Na+-concentration and salt content, which represents risk of soil sodification/salinization, while leaching facilitates a rise in the salty groundwater table, and a change in the chemical type (Na+dominance) surrounding the channel. Together, these factors lead to soil degradation in the investigated Chernozem and Phaeozem profiles. In Arenosol, the aforementioned processes were not observed, but infiltrating thermal water reached groundwater adjacent to the channel and enhanced its total salt content and Na+-rate. Referring to the Chernozem and Phaeozem soils, statistical analyses were carried out to determine the significant variation in soil properties between profiles located at different distances from the channel. Via principal component analysis combined with discriminant analysis, Mg2+-mobilization and salinization processes were identified near the channel. On the basis of the computed discriminant function, sample groups of two localities (control and thermal water affected) can be unambiguously distinguished.

Fungal diversity seems to be a good indicator of ecosystem disturbance and functioning. The purpose of this work was to quantify the fungal population as a sensitive indicator of the changes caused by stubble placement in two tillage systems: reduced tillage (RT) and conventional tillage (CT) with and without cropping. To this end, we determined the effect of soil disturbances such as N fertilization, tillage practice, and cropped area on the soil fungal communities of a Phaeozem luvico of the El Salado river basin (Argentina). Soil samples (at 0-10 cm depth) were collected from a field cultivated with wheat at post-harvest, before sowing and at tillering. The relative abundance of individuals of the fungal population was studied on Nash Snyder and Oxgall agar media after different treatments and assessed as colony forming units (CFU/g of soil). The diversity of the fungal population was studied by Shannon´s index (H). The tillage system showed a marked effect only at post-harvest and the number of propagules was highest under RT for both culture media. The largest values of H were found only at post-harvest when Oxgall agar was used. A significant decrease in the values of H was observed when CT and high fertilization was applied in the wheat cropped area. The relative abundance of individuals of the fungal population was different in soils under the different tillage practices., Centro de Investigaciones en Fitopatología

Manure is a source of plant nutrients and can make a valuable contribution to soil organic matter (SOM). Two experimental sites were studied on a Halpic Phaeozem soil near Bad Lauchstadt in Germany. The first experiment, called the static experiment, commenced in 1902. The impact of fresh farmyard manure (FYM) (0, 20 and 30 t ha −1 2 year −1 ) combined with P, K and N fertiliser application on total organic C (C T ), labile C (C L ), non-labile C (C NL ), total N (N T ), mean weight diameter (MWD) and unsaturated hydraulic conductivity ( K unsat ) was investigated. The second experiment commenced in 1984 and investigated the effect of extreme rates of fresh FYM applications (0, 50, 100 and 200 t ha −1 year −1 ) and cropping, or a continuous tilled fallow on the same soil properties. At both sites a nearby grassland site served as a reference. On the static experiment, FYM application increased all C fractions, particularly C L , where application of 30 t ha −1 2 year −1 increased C L by 70% compared with no FYM application. Fertiliser additions to the static experiment had a positive influence on C fractions while N T increased from both FYM and fertiliser application. MWD increased as a result of FYM application, but did not reach that of the grassland site. Both fertiliser and FYM application increased K unsat (10 mm tension) on the static experiment. In the second experiment application of 200 t ha −1 year −1 of FYM increased concentrations of C L by 173% and of C NL by 80%, compared with no FYM application to make them equivalent to, or greater than the grassland site. A continuously tilled fallow resulted in significant decreases in all C fractions, N T and MWD compared with the cropped site, while K unsat (10 mm tension) was increased on the 0 and 50 t ha −1 year −1 treatments as a result of a recent tillage. There was no difference in K unsat between the cropped and the continuous tilled fallow at FYM applications of 100 and 200 t ha −1 year −1 . There were similar significant positive correlations of all C fractions and N T with MWD on both experimental sites but the relationships were much stronger on the extreme FYM experiment. Weaker relationships of C fractions and N T with K unsat (10 mm tension) occurred for the static experimental site but these were not significant for the extreme FYM experimental site. The strongest relationship between C fractions and K unsat was with C L . This research has shown that applications of FYM can increase SOM and improve soil physical fertility. However, the potential risk of very high rates of FYM on the environment need to be taken into consideration, especially since the application of organic materials to soils is likely to increase in the future.

The Teotihuacan Valley, Mexico has been the object of considerable interest because of its importance in the context of human history in America. Although, archeological research has been extensively conducted to understand causes of the decline of Teotihuacan culture, no sufficient scientific evidence has been provided. This paper is focused on paleopedological evidence, especially properties that constitute ‘‘soil memory,’’ in order to reconstruct the spatial distribution of environment variability during the Late Pleistocene and Holocene. Three profiles that include modern soils and buried paleosols were studied in different geomorphic positions: uplands (Cerro Gordo site, CG), lower talus slope/transition to valley bottom (Maseca, MA), and the mouth of the Valley, at the ancient border of the former Texcoco lake. This last site is near Tepexpan (TE) where some of the oldest human remains in Mexico were recovered. The oldest paleosol is at CG at 3000 m a.s.l. It is dated at 22,000 yr BP and exhibits a truncated profile with a very well developed Bt horizon, dominated by kaolinite, with phytoliths of C3 plants. All of its features are related to a humid, probably warm environment. It was classified as a Luvisol. This paleosol is buried by another Luvisol, dated at 13,000 yr BP, with morphological characteristics similar to the previous soil, although clay mineralogy consists mostly of halloysite and a higher percentage of C4-plant phytoliths is apparent. In MA the oldest paleosol was not recognized. It is probable that the two paleosols found in CG merge into one at MA, which shows strong redoximorphic features, but high percentages of C4-plant phytoliths and halloysitic clays. At the TE site paleosols are less developed Fluvisols. Modern soil cover also varies in relation to its geomorphic position. In CG it is a Phaeozem, while in MA and TE present day soils have carbonate accumulation. We interpret prevailing conditions during the Last Glacial Maximum in the Teotihuacan valley to be humid, with a tendency towards drying at the end of Pleistocene. Dry conditions prevail in the valley today.

The combined effects of cadmium (Cd, 10 mg/kg of soil) and butachlor (5, 10 and 50 mg/kg of soil) on enzyme activities and microbial community structure were assessed in phaeozem soil. The result showed that phosphatase activities were decreased in soils with Cd (10 mg/kg of soil) alone whereas urease acitivities were unaffected by Cd. Urease and phosphatase activities were significantly reduced by high butachlor concentration (50 mg/kg of soil). When Cd and butachlor concentrations in soils were added at milligram ratio of 2:1 or 1:2, urease and phosphatase activities were decreased, while enzyme activities were greatly improved at the ratio of 1:5. This study indicates that the combined effects of Cd and butachlor on soil urease and phosphatase activities depend largely on the addition concentration ratios to soils. The random amplified polymorphic DNA (RAPD) analysis showed that the changes occurring in RAPD profiles of different treated samples included variation in loss of normal bands and appearance of new bands compared with the control soil. The RAPD fingerprints showed substantial differences between the control and treated soil samples, with apparent changes in the number and size of amplified DNA fragments. The results showed that the addition of high concentration butachlor and the combined applied Cd and butachlor significantly affected the diversity of microbial community. The present results suggest that RAPD analysis in conjunction with other biomarkers such as soil enzyme parameter etc. would prove a powerful ecotoxicological tool.

Black Mollisols are typically rich in charred organic matter, however, little is known about the zonal distribution of black C (BC) in steppe soils. In this study, we used benzene polycarboxylic acids (BPCA) as specific markers for BC in particle-size fractions of depth profiles in several zonal soils (Greyzem, Phaeozem, Chernozem, Kastanozem) of the Russian steppe. In addition, liquid-state 13 C-NMR spectra were obtained on the alkaline-soluble soil organic matter (SOM). The results showed that both the content and depth distribution of BC varies in the different soil types; the concentration of BC in the bulk top soils being closely related to the aromaticity of the SOM (r 2 = 0.98 for the native topsoils, 0.83 for top- and subsurface soils). Especially the Chernozems were rich in aromatic SOM, which partly contained more than 17% BC of total C, most of which being allocated in the mineral fractions. Long-term arable cropping did not reduce the BC contents of the surface soil, though it did promote the enrichment of BC in the silt fractions. The same shift was detected as soil depth increased. We conclude that BC is not fully inert in these soils, but apparently can be preserved in the silt as decomposition of SOM increased, i.e., it accumulates exactly in that fraction, which has been formerly assigned to contain old, aromatic C.

Although soil lipids are an important class of soil organic substances, which is involved in numerous soil processes, their origin and fate in soils is insufficiently known. Therefore, this study aimed at investigating the free lipid fraction in crop residues and farmyard manure (FYM), and soils which received these materials for long time. We sampled rye and maize stubble and roots, FYM, and Ap horizon soils from the ‘Unfertilized’ and ‘FYM’ plots of ‘Eternal Rye Cultivation’ experiment at Halle, Saxony-Anhalt, Germany. Free lipids were extracted by dichloromethane/acetone and analyzed by gas chromatography/mass spectrometry. Aliphatics were most abundant in all extracts, accounting for 61 to 77% of the total extractable lipids. By comparing the lipid composition of the added organic materials with that of the corresponding treated soil, the long-chain members of n-alkanols, n-alkanes, α,ω-alkanedioic acids, and unsaturated alkanoic acids from C16 to C19 did not disappear in soil whereas ω-hydroxyalkanoic acids and long-chain branched alkanoic acids were not extracted from soil probably because they were bound to nonextractable forms. It is suggested that the methodological approach can give information on decomposition and retention of free extractable lipids in soil. More information is needed to trace the fate of all lipids in the plant–soil system by the determination of bound molecules, which are nonextractable by organic solvents.

Surface and profile Phaeozem soil samples from 31 locations affected by various anthropogenic activities such as mining, chemical manufacturing, traffic emission and pesticide application were collected in Heilongjiang Province and Jilin Province, northeast China. The range of total concentrations of four heavy metals Cd, Pb, Cu and Zn in the soil was 0.011-3.137, 10.31-62.34, 9.74-51.21 and 39.54-247.59 mg kg(-1), respectively, determined using the acidic digestion procedure. Four methods including single contamination evaluation, background concentration comparison, surface/subsurface concentration comparison and exchangeable fraction evaluation were used to evaluate the extent of metal contamination in Phaeozem. The results indicated that different activities increased the concentrations of the heavy metals in surface soils, where high concentrations of cadmium and lead were found close to chemical plants and in the suburbs of the investigated cities. The four methods showed a general trend of increased soil contamination with heavy metals. Cadmium was of the most concern compared with the other contaminated elements in the study area, due to the long-term phosphatic fertilizer utilization and industrial activities. The proper evaluation method for cadmium contamination was the background concentration comparison, while for zinc and copper was the single contaminative index evaluation. Cadmium and lead could be the potential environmental risk in the Phaeozem area based on the different evaluations.