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Soil is inevitably affected by highway construction, resulting in a large volume of bare soil exposed to degradation. As an increasingly important and demanding area, identifying and assessing soil...

The construction of highways in the subalpine mountains generates many cut slopes. Currently, the restoration of cut slope mainly focuses on the aboveground landscapes and slope stability. Yet, it remains elusive about the belowground ecosystem functions at the early stage of restoration. In this study, we evaluated the belowground ecosystem functions of cut slopes that had been restored approximately 3 years using soil enzymatic activities, microbial biomass, and stoichiometry as the proxies. The results indicated that the phenol oxidase activity was higher in cut slopes, while the activities of β-1,4-glucosidase, β-1,4-N-acetylglucosaminidase, leucine aminopeptidase, and acid phosphatase were lower in cut slope soils compared with natural soils. Soil nitrogen availabilities (total and/or ammonium nitrogen) showed high negative correlations with the phenol oxidase activity and positive correlations with the activities of almost all other enzymes. These results suggested that soil nitrogen was the key factor in driving the shifts of enzymatic activities across two types of soils. Moreover, we found the imbalance of soil nutrients in cut slope soils, especially the carbon vs. nitrogen and the nitrogen vs. phosphorus. By applying the vector analysis, we found that the vector A values were more than 45° in all samples, suggesting that microbial phosphorus limitation occurred in both cut slope and natural soils. These findings suggested that maintaining the balance of soil nutrient supplies is important to the recovery of the below-ground ecosystem functions at the early restoration stage of cut slopes. This study provided new insights into designing the ecological restoration strategies for cut slopes by considering the belowground ecosystem functions.

Aims Gut microbial alterations have great potential to predict the development of colorectal cancer (CRC); however, how gut microbes respond to the development of CRC in males and females at the community level is unknown. We aim to investigate the differences of gut microbiota between the male and female. Methods and results We reanalysed the dataset in a published project from a sex perspective at the community level by characterizing the gut microbiome in patients (including males and females) from three clinical groups representative of the stages of CRC development: healthy, adenoma, and carcinoma. The results indicated that the microbial α-diversity showed no significant difference in the male gut but had decreased significantly in the female gut with the development of CRC. In males, a significant difference in the microbial β-diversity was only observed between the healthy and carcinoma subgroups. However, significant community deviations were detected with the development of CRC in females. The microbial community assembly processes changed from deterministic to stochastic in males, whereas they became increasingly deterministic in females with the development of CRC. Moreover microbial co-occurrence associations tended to be more complicated in males; rare species were enriched in the co-occurrence network of the male gut, whereas key species loss was observed in the co-occurrence network of the female gut. Conclusions The microbial communities in the male gut were more stable than those in the female gut, and microbial community assembly in the gut was sex dependent with the development of CRC. Our study suggests that sexual dimorphism needs to be considered to better predict the risk of CRC based on microbial shifts. Significance and impact of the study To the best of our knowledge, this is the first report showing how gut microbes respond to the development of CRC in males and females at the community scale.

Cement is a critical building material used in the restorations of bare cut slopes. Yet, how cement affects ecosystem's functions and their undertakers remains elusive. Here, we revealed the dosage and temporal effects of cement on plant and soil traits, extracellular enzymes, greenhouse gas fluxes and microbiome using simulation experiments. The results showed that soil pH increased with the cement content at 1st day but relatively constant values around 7 to 7.5 were detected in the flowing days. The β-1,4-glucosidase, phenol oxidase, leucine aminopeptidase and acid phosphatase showed high activities under high cement content, and they generally increased with the cultivations except for acid phosphatase. CH

Cadmium (Cd) and lead (Pb) that accumulates in the surface soil of railway rock-cut slopes may migrate to nearby croplands. It is important to determine whether backfill soil type influences the transportation of Cd and Pb in the surface soil. Representative rock-cut slopes, backfill soil of 100% rock fragments, 100% agricultural soil, and 50% agricultural soil and 50% rock fragments (n = 2 for each type) were selected. The pollution and migration levels of Cd and Pb and the soil quality and erodibility were investigated. The soil concentrations of Cd and Pb on the rock-cut slopes were much higher than those of China soil quality standard. Soil erosion was the most important factor that influences the migration of Cd and Pb in the slopes. Increasing the percentage of agricultural soil in the backfill soil resulted in decreasing the diffusion of Cd and Pb by reducing soil erosion. The backfill soil affected the soil quality and erosion durability, which, in turn, affected the transportation of Cd and Pb in the runoff. The soil quality index (SQI) accurately reflects the soil quality and can serve as an indicator of the migration of Cd and Pb on the surface soil of the slopes. Therefore, agricultural soil was more appropriate to use as a backfill soil in slope revegetation practice than was the rock fragment, which was helpful for decreasing the environmental risk of Cd and Pb on the slopes.

Antimony (Sb) contamination has brought great environmental problems to the surrounding soils. However, few studies focused on the response of bacterial communities in earthworm gut to Sb. Eisenia fetida was cultured in four soils with Sb contents (5,25,50,100 mg•kg−1) to investigate the distribution of Sb species in earthworm gut and the response mechanism of bacterial communities to Sb contamination. The results showed that Sb accumulated in the gut and tissues of earthworms, and the mortality of earthworms showed a dose-response relationship with the increase of Sb content. Sb(III) and Sbexe were the major species in gut, whereas Sb(V) and Sbsrp were predominant in surrounding soil. There were significant differences in bacterial diversity between earthworm gut and soil, but there was no significant between the two with different Sb content. The network constructed by gut bacterial community of earthworm was less stable and more sensitive to Sb species than that in soil. Sb(III) had the greatest influence on the gut bacterial community of earthworm, which not only directly affected the community through Xanthomonadaceae, Rhodomicrobiaceae and Anaerolineaceae, but also indirectly influenced through Chthoniobacteraceae. This study fills a research gap on the effect of Sb contamination on the gut bacterial community of earthworm.

Outside soil spray seeding (OSSS), the technology of spraying an artificial soil mixture onto the surface of cut slopes for creating a bed for plant species to germinate and grow, has been widely used to restore cut slopes. The vegetation cover can effectively resist soil erosion, improve soil quality and facilitate the ecological restoration of cut slopes. However, researchers have different views on what kind of vegetation cover is best to improve artificial soil quality and enhance the structural stability of cut slopes. To evaluate the effect of different vegetation restoration types on the artificial soil of cut slopes restored with OSSS, various soil samples were obtained from four treatments [herbaceous-only vegetation restoration slopes (HS); mixed vegetation restoration type slope I, composed of herbs and shrubs (MSI); mixed vegetation restoration type slope II, composed of herbs, shrubs and trees (MSII); and natural slopes (NS)]. Three slopes were selected for HS, MSI, MSII and NS, respectively, for a total of twelve slopes. The soil properties measured included some fundamental parameters (physical, chemical and biological parameters) and structural characteristics (bias coefficients, peak convex coefficient, fractal dimension, structural failure rate and soil erodibility). Principal component analysis (PCA) and ascending and descending functions were used to determine an integrated soil quality index (SQI). The results showed that there are significant differences in fundamental parameters, structural characteristics and the SQI between HS and other treatments, while the same properties, except SQI, were not significantly different between MSI and MSII. These findings imply that the HS is not suitable for long-term restoration on cut slopes, whereas MSII is a better vegetation construction model for the ecological restoration of cut slopes. However, there is still a huge disparity in these soil properties between the cut slopes and NS; this difference is attributable to the NS having a soil optimization process with long-term no human interference. Therefore, more effective management measures should be implemented to promote the ecological restoration of cut slopes.

Large-scale railway construction has resulted in large areas of bare-cut-slope, and outside soil spray seeding (OSSS), a frequently used technique, has been adopted for slope restoration for many years. However, compared with natural slope soils, the quality of artificial soils on rock-cut slopes is low. Enzyme activity and microbial biomass are the main indices used for estimating soil quality; thus, our objective was to explore the influence of slope position, slope aspect, and season on two important factors that positively influence the plant growth capability in artificial soil. Further, we suggest modifications of the proportions of OSSS ingredients, not only to manage cut slopes more economically but also to provide a new framework for managing desertification. We chose a bare-cut-slope that had been restored five years ago near the Suiyu Railway (Chongqing-Suining), in Sichuan Province, China, as our study plot. Soil samples were collected at a depth of 10 cm. We conclude that natural slopes exhibited higher urease, sucrase, and catalase activity and higher microbial biomass than cut slopes. The protease and polyphenoloxidase enzyme activities and the microbial biomass were higher on the cut slopes in the months of October and January, with the highest protease activity in October, and the highest polyphenoloxidase activity in January. The enzyme activity and microbial biomass were always lower on lower slopes, with the exception of polyphenoloxidase activity. The slope aspect influenced soil enzyme activity, resulting in higher activity on north-facing slopes than on south-facing slopes. These results provided scientific support for artificial revegetation methods in an ecological context. (C) 2018 Elsevier Ltd. All rights reserved.

Background Gut microbial shifts have great potential to predict the risk of colorectal cancer, but how gut microbes respond to the development of colorectal cancer in males and females at the community scale is unknown. To address this question, we reanalyzed the dataset from a published project and grouped these data depending on sex into three groups, healthy, colorectal adenoma and carcinoma individuals, and community assembly and network patterns of gut microbes were evaluated by null model and co-occurrence network-based methods. Results The study showed that distinct changes in microbial α -diversities and community composition were observed between the male and female gut. Specifically, the microbial α -diversities did not significantly change in the male gut ( P > 0.05) but were lowered in the female gut ( P < 0.05), suggesting that permanent species loss might occur in the female gut during the development of colorectal cancer. These distinct changes in microbial α -diversities and community composition between the male and female gut might result from host immunity mechanisms and different microbial community assemblies in males and females. Indeed, we found that the microbial community tended to be primarily stochastic in males, whereas it became increasingly deterministic in females with the development of colorectal cancer. Moreover, microbial co-occurrence associations tended to be more complicated when communities were primarily driven by stochastic processes in males; rare species were enriched in the co-occurrence network of the male gut, whereas key species loss was observed in the co-occurrence network of the female gut. Conclusions Our findings indicate that microbial communities in the male gut are more stable than those in the female gut and that microbial community assembly in the gut is sex-dependent with the development of colorectal cancer. Our study suggests that sexual dimorphism needs to be taken into account to better predict the risk of colorectal cancer based on microbial shifts.

The stability of soil aggregates is regarded as the key factor for soil erosion resistance on cut slopes of engineering works in serious debris flow disaster areas. Information on the stability of soil aggregates and related physicochemical properties on cut slopes is helpful to maintain the soil quality and slope stability. Therefore, in order to evaluate the stability of artificial soil aggregates for cut slope restoration, soil samples from three positions of a cut slope restored with artificial soil (upper slope, URS; middle slope, MRS; lower slope, LRS) and a nearby natural slope (NS) were analyzed. The results showed that the stability of soil aggregates (MWD, mean weight diameter; GMD, geometric mean diameter) of artificial soil on the cut slope (URS, MRS, LRS) was significantly lower than that of NS based upon fast wetting (FW) test and wet sieving. The values of MWD and GMD for slow wetting (SW) and mechanical breakdown (WS) tests in the four slopes had no significant difference. Among the three positions of cut slope, URS had the highest MWD and GMD, whereas MRS had the lowest corresponding value. Furthermore, >2 mm soil aggregates accounted for a major percentage of the total weight determined in all the tests for each slope. MWD for fast wetting increased with the increase in content of soil organic matter (SOM). Slaking was the main disruptive force leading to the breakdown of artificial soil aggregates, and FW was the best method to measure the stability of soil aggregates in these conditions. These results demonstrate that the SOM and the stability of soil aggregates on cut slope should be given more attention while conducting engineering works in serious debris flow disaster areas.

Roadway rock-cut slopes have a strong effect on soil organic carbon (SOC), its fractions and overall soil health. However, it is still unknown how SOC fraction properties are influenced under different aspect conditions. We quantified differences in artificial SOC fractions, soil nutrients, and enzyme activities across eight types of roadway rock-cut slopes in Songpan, China. On slopes in landslide areas, four aspects (S, W, N, E) were selected for study, and four equivalent aspects on slopes not affected by a landslide were selected as a reference. SOC, easily oxidizable organic carbon (EOC), particulate organic carbon (POC), urease, sucrase, total nitrogen (TN), and carbon pool management index (CPMI) significantly differed among non-landslide aspects, however, except for POC and urease, did not differ with aspect on landslide-affected slopes. In contrast, dissolved organic carbon (DOC), nitrate nitrogen (NO3–-N), and ammonia nitrogen (NH4+-N) significantly differed among aspects on landslide-affected slopes, while they did not significantly differ on aspects of non-landslide slopes. However, higher SOC, EOC, POC, TN, urease, sucrase, and CPMI occurred on non-landslide slopes than landslide-affected slopes of the same aspect, suggesting that landslide slopes may face serious degradation. Our findings indicate that slope aspect and the occurrence of landslides have an influence on SOC pools, and consequently on CPMI.

The research of soil bacterial community biodiversity in special habitats is important for ecological restoration. In this paper, distribution patterns and drivers of artificial soil bacterial community on cut-slopes at different altitudes (2950 m, 3300 m, 3650 m and 4000 m) in alpine region were studied. The results demonstrated that the artificial soil bacteria genera on cut-slopes showed single-peak patterns along with altitude. Soil bacteria communities conformed to abundance distributions for a large number of rare species and a small number of common species, and there was a long tail for very rare species. The distribution patterns of plant communities along with altitude was basically the same as that of bacteria, and plant communities were mainly influenced by soil types and light-temperature conditions. The distribution pattern of bacterial communities was influenced by individual number of plants, the contents of available potassium (AK), organic matter (OM), total nitrogen (TN), alkali-hydrolyzed nitrogen (AN), moisture content (MC) and available phosphorus (AP). Complicated relationships of soil bacteria community, plant communities and soil nutrients in alpine regions are conducive to the stability of the community structure, which is beneficial to ecological restoration of cut-slopes.

Stabilization technique is regarded effective to control heavy metal pollution in soil. Traditional stabilizers have raised concerns about soil acidification/alkalization, or the stable effectiveness in a long-term. To stabilize vanadium (V) in calcareous purple soil in an environmentally friendly way, Na-bentonite (Na–B) modified by tea polyphenol (TP-B), by FeSO4 (Fe–B), and by TP and FeSO4 (TP-Fe-B) were prepared, characterized and assayed. The tea polyphenol modification loaded –CH2 on TP-B and TP-Fe-B, and ferrous modification introduced rozenite to Fe–B and TP-Fe-B, which supplied reaction sites to V. The effects of stabilizer dosage, soil moisture, and initial V concentration in soil were considered to ascertain the optimum stabilization conditions. Applying 5 wt% Fe–B into the 696.63 mg V/kg soil at 60% field water capacity soil yielded stabilization rates of 19.1%, 37.7% and 20.5% for water-extractable V, bioavailable V, and pentavalent V, respectively. Further study was conducted to assess the stable period of the passivation effect and the stability of the passivation effect under acid rain. The stabilization effect remained functional for at least 4 weeks after TP-B, Fe–B, and TP-Fe-B application. Notably, adding Fe–B could reduce the risk of V transfer from soil into the aquatic environment under acid rain. However, Fe–B resulted in a decrease in soil organic matter and alkali-hydrolyzed nitrogen, thus fertilization should be considered. These results proved that Fe–B was a potential stabilizer for V contaminated soil even under acid rainfall.

In the subalpine mountainous region of southwest China, the artificial soil properties of restored cut slopes along the altitude gradient were studied, including available nitrogen (AN), available phosphorus (AP), available potassium (AK), urease (UR), sucrase (SC), protease (PR), catalase (CAT), texture, and aggregate stability of soil. Soil aggregatet stability by mean weight diameter (MWD), geometric mean diameter (GMD), structure failure rate (P), index of unstable aggregates (IUA) and area difference of dry and wet sieve cumulative distribution curve (ΔS) were measured and analyzed. It was found that available soil nutrients, UR, and CAT activities increased initially and then decreased, but the texture of soil was finer, and aggregate structure tended to be more stable along with an increase in the altitude gradient. The soil aggregate stability index that MWD, GMD, P, IUA, and ΔS indicated that the higher the altitude, the stability of soil aggregates was better. Principal component analysis (PCA) was used to determine the soil quality index (SQI). The obtained results from this study showed that the artificial soil quality of the cut slopes was better at a higher altitude compared to a lower altitude. These results provide a reference for the improvement of artificial soil properties of cut slopes and their quality in the future. It is necessary to pay attention to the soil quality management at a low-altitude area and reform the soil nutrients, enzyme activities, and soil structure for the restored cut slopes in the mountainous subalpine highway of southwest China.

External-soil spray seeding (ESSS), a technique of spraying artificial soil materials onto bare slopes for vegetation cover construction, has been widely used to restore rock-cut slopes. However, studies on the effect of the practical application of this technique on different topographic aspects have been rarely performed. In this study, two topographic aspects, namely, north-facing versus south-facing, were investigated under two railway lines, and two local natural slopes (north-facing versus south-facing) were selected as references. Vegetation and soil conditions, which are paramount aspects of ecological restoration assessment, were characterized in terms of the richness and diversity indices, vegetation canopy cover, basic soil physico-chemical properties, and structural characteristics of these slopes. Results showed that (1) the topographic aspect significantly affected the vegetation restoration and artificial soil quality of rock-cut slopes restored by ESSS; (2) the ecological restoration effect of north-facing slopes were better than that of south-facing slopes; and (3) the vegetation and soil conditions of natural slopes were better than those of rock-cut slopes. Therefore, additional scientific management measures should be implemented to promote the ecological restoration of rock-cut slopes, especially for south-facing slopes.

Outside soil spray seeding (OSSS) is used widely for road cut revegetation, and the artificial soil used in OSSS can improve slope soil conditions and nutrients, and help promote plant growth and succession. Three different slopes was investigated to evaluate the effectiveness of OSSS for restoration, including a natural slope (NS), a cut slope without any artificial recovery treatment (CSW) and a cut slope treated with OSSS (CSO). The recovery of cut slopes was determined by evaluating a number of factors, including indices associated with plants on the slopes, soil enzyme activities (urease and sucrase), and soil nutrient content (soil organic matter (SOM), total phosphorous (TP), total potassium (TK), available nitrogen (AN), available phosphorous (AP), available potassium (AK), potassium (K+), calcium (Ca2+), magnesium (Mg2+), and sulphate (SO42−)). The results indicated that the vegetation and soil conditions differed between the three slopes. The Shannon-Wiener index (H), the Simpson index (D), and the Margalef index (R) values from the CSO and NS were lower than those of the CSW, whilst the Pielou index (E) value and vegetation canopy cover were higher for the CSO and NS than for the CSW. The content of SOM and AN in soil from the CSO was lower than in soil from the NS and CSW, and content of many nutrients were higher in soil from the CSO than in soil from the NS and CSW. This suggests that the restoration of vegetation and soil nutrients on the CSO was relatively successful. Our results indicated that the use of OSSS to restore cut slopes is effective in plateau areas. However, despite improvements in soil nutrient levels, there were still nutritional imbalances. Therefore, more attention should be paid to balancing nutrients in the later stage of OSSS implementation for the recovery of cut slopes at high altitudes.

Artificial soil on railway rock-cut slopes may be considerably contaminated with cadmium (Cd) and lead (Pb), which may migrate to nearby croplands and pose substantial risks to human and animal health. We investigate the influence of three types of revegetation modes - herbs (HS); herbs and shrubs (HSS); and herbs, shrubs, and trees (HSTS) - on the transportation of these heavy metals in soils. Six representative rock-cut slopes were chosen, and the vegetation, pollutant concentration, phytostabilization, and simulated rainfall were investigated. The results indicated that Cd posed a considerable ecological risk, while Pb posed a low ecological risk in the artificial soil. The erosion of artificial soil on the slopes played a primary role in the migration of Cd and Pb, because 87-91% of Cd and 85-89% of Pb was lost in sediments. Revegetation modes significantly affected the transportation of Cd and Pb. HSTS controlled a lot of Cd in their dominant plants among the three revegetation modes. HSTS not only decreased enrichment factor (EF) and ecological risk (Er) values of Cd in the soils, but also decreased runoff, sediment and cumulative migrated Cd and Pb. The relationships among multi-factors were analyzed by stepwise mediation effect test and the results indicated that root weight density, aboveground biomass and immobilization of dominant plants for Cd and Pb were important direct factors which influenced the transportation of Cd and Pb. Overall, HSTS has proven to be beneficial in controlling the migration of Cd and Pb to croplands near the slopes and reducing their environmental risk. These results can offer a tested and implementable solution for mitigating the risks posed by these pollutants around the quickly expanding railways in the study region.

Large-scale railway/highway construction in hilly areas in China has created a number of bare rock cut slopes. Artificial soil is often sprayed onto those slopes to promote revegetation. The artificial soil used is a mixture of backfill soil, humus, straws, soluble chemical fertilizer, composite material and plant seeds. The backfill soil is the most important component of the artificial soil. Knowledge of the changes in the artificial soil quality induced by backfill soil is important for the management of the revegetation of rock cut slopes. This study was conducted to assess the effects of different backfill soils on soil quality parameters and slope restoration parameters, including the particle size distribution, water-stable aggregates, soil organic carbon (SOC), organic carbon fractions, soil water characteristics (SWC), plant coverage, Margalef index and Shannon-Wiener diversity index. In experiment one, the treatments included slopes backfilled with rock fragment (RF), slopes backfilled with agricultural soil (AS) and a natural slope (NS). In experiment two, the treatments were experiment plots with different proportions of agricultural soil to rock fragments. Soils were sampled from the surface layer (0-5 cm) of the slopes. The results indicated that the backfill soil significantly affected the soil structure. RF increased the percentage of large particles (>0.25 mm) and decreased that of microparticles (

Background: Transport infrastructure has severe impacts on ecosystems and results in large numbers of cut slopes, which are difficult to revegetate. To increase successful revegetation, it is crucial to understand the relationships of soil properties and vegetation during spontaneous vegetation recovery on cut slopes.Aims: To assess the effects of different slope positions on soil properties and vegetation on a cut slope and to determine the key factor(s) affecting vegetation distribution on a cut slope in a semi-tropical environment.Methods: Soil samples were collected in three slope positions: upper slope (US), middle slope (MS) and foot slope (FS). Soil pH, moisture and bulk density and concentrations of soil organic carbon (C), total nitrogen (NT), available nitrogen (NA), total phosphorus (PT), available phosphorus (PA), total potassium (KT) and available potassium (KA) were determined. Vegetation composition and cover were recorded along the slope. One-way analysis of variance (ANOVA), indicator spe...

Railway transportation is an important transportation mode. However, railway transportation causes heavy metal pollution in surrounding soils. Heavy metal pollution has a serious negative impact on the natural environment, including a decrease of enzyme activities in soil and degradation of sensitive ecosystems. Some studies investigated the heavy metal pollution at railway stations or certain transportation hubs. However, the pollution accumulated in artificial cut slope soil all along the rails is still questioned. The interest on non-point source pollution from railways is increasing in an effort to protect the soil quality along the line. In this study, we studied spatial distributions of heavy metals and five enzyme activities, i.e., urease (UA), saccharase (SAC), protease (PRO), catalase (CAT), and polyphenol oxidase (POA) in the soil, and the correlation among them beside three different railways in Sichuan Province, China, as well. Soil samples were respectively collected from 5, 10, 25, 50, 100, and 150 m away from the rails (depth of 0–8 cm). Results showed that Mn, Cd, Cu, and Zn were influenced by railway transportation in different degrees while Pb was not. Heavy metal pollution was due to the abrasion of the gravel bed as well as the tracks and freight transportation which caused more heavy metal pollution than passenger transportation. Enzymatic activities were significantly negatively correlated with heavy metals in soils, especially Zn and Cu. Finally, it is proposed that combined use of PRO and POA activities could be an indicator of the heavy metal pollution in cut slope soils. The protective measures aimed at heavy metal pollution caused by railway transportation in cut slope soils are urgent.

Outside soil spray seeding (OSSS) is widely used to restore cut slopes in southwest of China, and artificial soil is often sprayed onto cut slopes to establish a soil layer for revegetation. The stability of artificial soil layer and its supply of water and nutrients for plants is crucial for successful restoration. To evaluate the long-term effectiveness of OSSS, the texture, structure and nutrient availability of artificial soil were studied, various soil samples were obtained from three cut slopes with different restoration time (restored with OSSS in 1996, 2003 and 2007 respectively) and one natural developed slope (NS). The properties measured including soil particle size distribution (PSD), texture, fractal dimension of PSD (Dm), the bias (CS) and peak convex (CE) coefficients of aggregate size distribution, structure failure rate, bulk density, moisture, pH, soil organic carbon (SOC), calcium carbonate content, Available nitrogen (NA), Available phosphorus (PA), and Available potassium (KA). The results showed that different restoration time resulted in significant differences in soil PSD, Dm, CS, CE, structure failure rate, bulk density, moisture, pH, NA, and KA. And these properties improved with increasing restoration age. However, there is still a huge disparity in soil texture, structure, and the availability of nutrients and moisture between the cut slopes and NS over a restoration period of up to 17 years, and this is caused by the little fine particles and the lack of slow release fertilizers and organic fertilizers in the artificial soil, resulting in poorer soil structure stability, retention and availability of moisture and nutrients on the cut slopes. Overall, the OSSS technique shows a long-term effectiveness in southwest of China, but there is still room for improvement.

Organic materials in soils mainly consist of alkanes, esters, aromatic compounds and plant secondary metabolites, but they are different from one another in material type and quantity, depending on the types of slopes. This paper conducts a comparitive study on soils from slopes along the Suining-Chongqing Railway. Preparing soil samples from the rocky slope, the cultivated and uncultivated slopes by using ultrasonic methods, we measured the organic materials with a chromatograph mass spectrometer (QP2100). The results show that the number and types of organic materials decrease from the cultivated slopes to uncultivated slopes and then to rocky slopes. No contaminant appears in artificial soils on rocky slopes, but it is found in natural soils. Hence, it can be concluded that the reconstruction of soils on engineering slopes is beneficial not only for ecological restoration, but also for the prevention of pollution.

Cut slopes are frequently generated by construction work in hilly areas, and artificial soil is often sprayed onto them to promote ecological rehabilitation. The artificial soil properties are very important for effective management of the slopes. This paper uses fractal and moment methods to characterize soil particle size distribution (PSD) and aggregates composition. The fractal dimension (D) showed linear relationships between clay, silt, and sand contents, with coefficients of determination from 0.843 to 0.875, suggesting that using of D to evaluate the PSD of artificial soils is reasonable. The bias (CS) and peak convex (CE) coefficients showed significant correlations with structure failure rate, moisture content, and total porosity, which validated the moment method to quantitatively describe soil structure. Railway slope (RS) soil has lower organic carbon and soil moisture, and higher pH than natural slope soil. Overall, RS exhibited poor soil structure and physicochemical properties, increasing the risk of soil erosion. Hence, more effective management measures should be adopted to promote the restoration of cut slopes.

Ai, Y., Chen, Z., Guo, P., Zeng, L., Liu, H., Da, Z. and Li, W. 2012. Fractal characteristics of synthetic soil for cut slope revegetation in the Purple soil area of China. Can. J. Soil Sci. 92: 277–284. Revegetation of the cut slopes formed during railroad construction can reduce potential hazards, improve the quality of the environment, and beautify the landscape along the railways. Artificial backfill soil is required to anchor the plant roots and satisfy the plant's moisture and nutritional demands on the bare rock face. The soil particle size distribution (PSD), fertility and stability of the reconstructed topsoils are affected by the soil type used as a backfill. In this study, a fractal method was used to characterize the PSD. The relationships between the fractal dimension of the PSD and selected soil properties, including soil moisture, bulk density, and organic carbon are discussed. Various soil samples were obtained from four different land-use environments in the purple soil area in southwest, China: a cut slope reconstructed from rock fragments (RF), a cut slope reconstructed with agricultural soil (AS), a naturally developed slope (NS), and a cropland used for growing Vicia faba (CL). Analysis of the soil samples revealed that: (1) from CL to RF, the sand content increased from 59.6 to 83.9%; (2) the fractal dimension of PSD ranged from 2.605 for RF to 2.725 for CL, being the greater the sand content and the lower the fractal dimension; (3) there existed marked linear relationships between the fractal dimensions and selected physicochemical properties of the soils. Therefore, the fractal dimension of PSD can be a useful parameter with which to monitor the structural deterioration and nutrient loss of the synthetic soils used for the revegetation of a cut slope.

Through unflooded mulching in field plots and 15nitrogen microplot tracer experiments, nitrogen (N) uptake of rice and N utilization have been studied compared with normal irrigation cultivation. The results showed that N uptake of unflooded rice and N derived from fertilizer (NDFF) of root, stem, and grain under mulching cultivation were lower than that under cultivation without mulching. However, the NDFF of rice under unflooded cultivation was higher than that under normal irrigation cultivation. The N utilization has been greatly enhanced under unflooded cultivation without mulching and unflooded plastic film cultivation with mulching as compared with normal irrigation. At the same time, there was no significant difference on the N uptake of unflooded rice among different ways of mulching cultivations. During the growth period of rice, no prominent differences were found in the soil residue, recovery, and N losses of fertilizer except the N uptake of rice between unflooded mulching and normal...

Taking the slope of Suiyu Railway to study, the research separately studied soil resistivity, soil electrochemistry (corrosion potential, oxidization reduction potential, electric potential gradient and pH), soil anions (total soluble salt, Cl−, SO42− and "Equation missing") and soil nutrition (moisture content, organic matter, total nitrogen, alkali-hydrolysable nitrogen, available phosphorus and available potassium) at different slope levels and conducted corrosion grade evaluation on artificial soil according to its single index and comprehensive indexes. Compared with other factors, water has the biggest impact on the corrosion of slope protection net, followed by anion content. Total soluble salt has the moderate impact on the corrosion of slope protection net and stray current has the moderate impact on the corrosion of mid-slope protection net. Comprehensive evaluation on the corrosive degree of soil samples indicates that the corrosion of upper slope is moderate and the corrosion of mid-slope and lower slope is strong. Organic matter in soil is remarkably relevant to electric potential gradient. Available nitrogen, available potassium and available phosphorus are remarkably relevant to anions. The distribution of soil nutrient is indirectly relevant to slope type.

Non-flooded mulching cultivation (NFMC) for lowland rice, as a novel water-saving technique, has been practiced in many areas of China since the 1990s. However, the information on NFMC effects on crop production, nitrogen and water use in rice–wheat rotations is still limited. A field experiment using 15N-labeled urea was conducted to evaluate the impacts of NFMC on crop yield, fertilizer N recovery and water use efficiency in rice–wheat rotations. Plastic film mulching (PM), and wheat straw and plastic film double mulching (SPM) resulted in the same rice grain yield (7.2 t ha−1) while wheat straw mulching (SM) and no mulching (NM) led to 5 and 10% yield reduction, compared with rice under traditional flooding (TF). In the rice–wheat rotation, crop productivity in PM, SM or SPM was comparable to that in TF but greater than in NM. Weed growth and its competition with rice for nitrogen were considered the main reason that led to yield decline in NM. Compared with TF, NFMC treatments did not obviously affect fertilizer N recoveries in plant and soil in both rice and wheat seasons. The total fertilizer N recoveries in crop, weed and soil in all treatments were only 39–44% in R–W rotations, suggesting that large N losses occurred following one basal N application for each growing season. Water use efficiency, however, was 56–75% greater in NFMC treatments than in TF treatment in the R–W rotation. The results revealed that NFMC (except NM) can produce comparable rice and wheat yields and obtain similar fertilizer N recovery as TF with much less water consumption.

The title compound, C19H11N7O2S2, was synthesized as a potential new plant elicitor, by reaction of 2-amino-4-methyl­pyrimidine with 1,2,3-benzothia­diazole-7-carbonyl chloride. There are two crystallographically independent mol­ecules in the asymmetric unit. In the crystal structure, the mol­ecules are linked by a weak C—H⋯N hydrogen-bonding inter­action.

Artificial soil is often sprayed onto cut slopes alongside railroad tracks to promote revegetation. This study evaluated the heavy metal content and the distribution of heavy metal chemical fractions in the soil, as well as the uptake of heavy metals by plants. The soil at four sites was determined to be considerably contaminated with Cd and Pb. The concentrations of Cd and Pb increased with the length of time the railway had been in use and decreased further away from the railway tracks. Pb primarily existed in reducible form but as residual fractions, whereas Cd was predominantly in exchangeable form. A correlation analysis indicated that pH, organic matter, and total phosphorus levels were important factors affecting the distribution of the heavy metal chemical fractions. The amounts of exchangeable Pb and Cd in the soil were highly correlated with their amounts in the plants sampled, indicating that the exchangeable fraction is a better indication of heavy metal phytoavailability than the total amount of heavy metals in the soil. Bioaccumulation and translocation factors indicated that Indigofera amblyantha had moderate tolerance and bioaccumulation capability for Pb, as did Leucaena leucocephala for Cd. These two plant species can serve as ideal slope remediation plants.

Heavy metal concentration in soil was investigated at three sites with different topography (cut slope, flat and embankment) within the vicinity of Chengdu-Kunming railway in Sichuan, China. Surface soil was sampled at certain distances from the track at each site and was analyzed for Cu, Mn, Pb, Zn, Cd by atomic absorption spectrometry. Cu, Cd and Zn concentrations in some soil exceeded the thresholds for non-polluted soil following the soil quality standard set by the State Environmental Protection Agency of China. Compared to local background values, the highest enrichment factor values of Cu, Mn, Zn and Cd were 2.7, 3.4, 3.7 and 7.7, respectively, indicating a moderate or significant enrichment of these metals in soil closest to the railway. Pb showed little accumulation with the EF values generally nearer 1 at the chosen sites. Topography profile was found to influence metal levels and distribution in soil alongside railway. At the cut slope site, Mn, Zn, Cd showed the highest concentrations and the smallest dispersion distance of 2 m, while Cu showed further dispersion distance of 25 m due to a main Cu emission source, the head-over traction cable, being located higher than any other metal emission source (wheels and tracks). Heavy metal concentrations decreased conversely as compared to distance from the track, peak values occurring at locations closest to the tracks, whilst embankment site soil Cd concentrations peaked at distances of 25 m. Significant correlation was found amongst Mn, Cu, Zn and Cd, which indicates that these metals have the same anthropogenic origin there. Organic matter content had no significant correlation to the elements Mn, Cu and Zn, which implies relatively high mobility to those metals.

A field experiment on a sandy loam was conducted to evaluate the effects of non-flooded mulching cultivation on the productivity, nutrient uptake and nutrient balance in rice–wheat (R–W) cropping systems in Chengdu flood plain, southwest China over a 3-year period. Plastic film mulching (PM) resulted in 12% higher average yield of rice while wheat straw mulching (SM) led to 14% lower average yield of rice compared with lowland rice under traditional flooding (TF). Biomass accumulation and nutrient uptake followed similar trends to grain yield. Changes in soil temperature in relation to root growth and nutrient uptake were likely to be the major factor responsible for the changes in rice yields under non-flooded mulching cultivation. Compared with TF, PM of preceding rice did not affect the grain yield of wheat, whereas SM of preceding rice resulted in comparable grain yields of wheat at a lower N rate (60 kg N ha−1) in the wheat season. The system productivity (total yield of rice+wheat) in PM was similar to that of TF and higher than that of SM. The yield decline in rice, however, could be partly compensated by the yield increase in wheat following rice, particularly at lower N rates. Apparent nutrient budgets showed positive nitrogen (N) and phosphorus (P) balances but negative potassium (K) balance in the TF and non-flooded mulching R–W systems. Compared with TF, PM led to lower NPK balance due to more nutrient removal by crops while SM led to greater NPK balance due to more nutrient inputs from straw but less nutrient removal by crops. After 3 years soil organic carbon (OC) and total nitrogen (TN) were not significantly altered by PM and SM but soil Olsen-P (AP) and exchangeable K (EK) were significantly increased by SM compared with TF. The changes in soil properties under non-flooded mulching cultivation initially reflected the nutrient balances in R–W systems. In conclusion, non-flooded mulching cultivation as PM and SM could be applied to R–W systems in southwest China but nutrient (especially N) management should be optimized in the two systems.

In the title compound, C13H14N4OS, which was synthesized as a candidate plant activator by the reaction of 1-amino-1-methyl-1-propyl­acetonitrile and 1,2,3-benzothia­diazole-7-carbonyl chloride, the benzothia­diazole moiety is essentially planar, forming a dihedral angle of 14.5 (4)° with the amide group. In the crystal structure, mol­ecules are linked by inter­molecular N—H⋯O hydrogen bonds [H⋯O = 2.20 (4) A] to form extended chains in the a-axis direction.