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[Objectives]The paper aimed to explore the reasonable and effective application of different organic rotten materials combined with Pseudomonas fluorescein in reclaimed soil of mining area. [Methods]Maize was selected as the experimental crop to be performed in pot experiment, which was to study the effects of different organic rotten materials(sheep manure, cow manure, pig manure, chicken manure)combined with P. fluorescens on nitrogen form and enzyme activities of reclaimed soil. [Results]Based on the only application of organic rotten material, the combined application of different organic rotten material with P. fluorescens could effectively improve nitrogen content, microbial biomass carbon and nitrogen contents and enzyme activities of reclaimed soil. And the application of chicken manure combined with P. fluorescens showed the most significant improvement effect on nitrogen content, microbial biomass carbon and nitrogen contents and four soil enzyme activities, which significantly increased the content of ammonium nitrogen, microbial biomass carbon and protease activity by 13.12%, 20.21% and 16.11% respectively compared with the only application of chicken manure. [Conclusions]Combined application of rotten chicken manure with P. fluorescens showed the best effect, which could be used as a reasonable application method in reclaimed soil. [ABSTRACT FROM AUTHOR]

The microflora has been examined in a reclaimed arable land from area of Maritza – East. Agrochemical and physical analyzes have been made at eight different points of the site and the amount of basic groups of soil microorganisms – ammonifying and cellulolytic microorganisms, mineral nitrogen- utilizing bacteria, actinomycetes and microscopic fungi has been determined. It has been found that in the reclaimed arable area of Maritza – East, microbiological processes of varying intensity take place, depending on the point of sampling, agrochemical and physical parameters of the soil. Ammonifying microorganisms and mineral nitrogen-utilizing bacteria are in greatest quantity at sampling points with low mineral nitrogen content. Actinomycetes and microscopic fungi have better development at points with a lighter mechanical composition. Plant residues in the soil affect cellulose-decomposing microorganisms.Ammonifying microorganisms and mineral nitrogen-utilizing bacteria are in greatest quantity at sampling points with low mineral nitrogen content. Actinomycetes and microscopic fungi have better development at points with a lighter mechanical composition. Plant residues in the soil affect cellulose-decomposing microorganisms. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) and total nitrogen (TN) contents in different soil horizons are essential for vegetation growth and crucial indicators to evaluate soil quality in reclaimed mining areas. Compared with conventional wet chemistry methods, soil spectroscopy, including imaging spectroscopy, can be used as a cost and time-efficient soil analysis technique. However, there is a great challenge in combining laboratory point spectra and laboratory hyperspectral imagery for mapping vertical distribution of SOC and TN (0–100 cm) in reclaimed soils. This is primarily because mixing of spectral data from different sources and technologies to improve soil models is still in its infancy. The main objective of this study is to provide a generic workflow to efficiently evaluate and map reclaimed mine soils in different horizons using imaging spectroscopy and machine learning approaches. A total of 65 soil samples (0–100 cm) were collected from three reclaimed mining lands and one natural site in northern China. Both point soil spectral information and hyperspectral images (350–2500 nm) were obtained under laboratory condition. In order to enhance the relationship between soil quality indicators and spectral features, the stacked feature selection algorithms and three-bands spectral indices were proposed for further modelling. Three machine learning methods (partial least squares regression; PLSR, random forest; RF, and radial basis function model; RBF) based on the point spectra were applied to calibrate and map continuous vertical distribution of SOC and TN. According to the results, thirty spectral bands were identified as important spectral features for SOC and eighteen bands for TN. With feature spectral bands and optimized three-bands spectral indices, the RF model yielded the best predictions for both SOC (R2 = 0.97, RMSE = 7.5 g kg−1) and TN (R2 = 0.78, RMSE = 0.33 g kg−1). It was concluded that imaging spectroscopy can be used to quantify and map soil quality indicators for better monitoring ecological restoration process in reclaimed soil of mining site.

After the process of surface mining, stripping and covering, the vertical distribution of organic carbon (SOC) and total nitrogen (TN) in the reclaimed mine soil undergoes great changes, which directly determines the selection of vegetation species and the effectiveness of ecological restoration. Therefore, under the dual carbon target, monitoring and mapping SOC and TN in reclaimed soil profile (0−100 cm) are the important basis for evaluating ecological restoration and carbon sequestration in mining areas. Compared with traditional chemical methods, hyperspectral imaging is a rapid and non-destructive technique that can be used for the effective estimation of the important indicators of soil properties. Imaging spectroscopy technology has the advantage of spectral integration compared to point spectral measurement. Therefore, the reclaimed soil from arid and semi-arid grassland mining areas in northern China was selected as the research object, and soil profiles (0−100 cm) from different mining areas, modes and years were collected. The vertical distribution patterns and hyperspectral characteristics of SOC and TN in profiles were revealed under different cultivation years and patterns. And then, with the feature bands and spectral indices of SOC and TN, the interpretable machine learning models were constructed to achieve mapping SOC and TN contents in profiles. The results indicated that: ① The spectral reflectance of the soil samples decreased with the increase of SOC and TN contents. By combining stacked feature selection methods (Pearson correlation coefficient–successive projections algorithm, PCC-SPA), hyperspectral data were reduced in dimension. 30 bands of SOC and 18 bands of TN were clearly identified, and three-dimensional (3D) spectral indices were established; ② By comparing different machine learning algorithms (partial least squares regression; PLSR, random forest; RF, and radial basis function model; RBF), the prediction accuracy could be improved by filtering and transforming the selective bands of hyperspectral data. The RF with selective bands and optimal 3D spectral indices demonstrated the best results with R2=0.97, RMSE=7.5 g/kg, LCCC=0.84, bias=3.70 for SOC and R2=0.78, RMSE=0.33 g/kg, LCCC=0.74, bias=0.19 for TN; ③ Using SHAP value to explain the importance ranking of input features in machine learning models, it was found that the contribution of 3D spectral index to model prediction is greater than that of most feature bands; ④ With the optimization model, the SOC and TN content of each pixel in the hyperspectral image could be quickly predicted, and the mapping and visualization of the SOC and TN contents in the mine soil profile could be realized. Mapping profiles of reclaimed soil in open-pit coal mining areas based on imaging hyperspectral technology can help understand and reveal the formation and evolution process of reclaimed soil, clarify the driving forces of reclamation years and vegetation types in the succession process of the profile. It can also provide important data sources and technical support for dynamic monitoring of carbon sequestration potential of reclaimed soil in open-pit coal mining areas and evaluation of the benefits of soil carbon sequestration technology.

Reasonable cropping systems and fertilizer management are vital for improving the quality of barren soil. The effectiveness of different crop rotation methods and fertilizers in soil improvement depends on various factors, including soil type, climate conditions, and crop type. In the present study, based on three rice-based cropping systems, the effects of organic fertilizers combined with slow-release fertilizers on rice yield and soil fertility in reclaimed soil were analyzed. The results showed that the rice grain yield was highest under the rice-fallow rotation system (RF) with the application of rapeseed meal fertilizer. Available nutrients such as AN, N_NH4+, TP, and AK showed a significant positive correlation with rice grain yield (p < 0.05). PCA and PERMANOVA analysis supported significant variation in CAZyme abundance among cropping systems (R2 = 0.60, p = 0.001) and significant differences between slow-release fertilizer treatments and organic fertilizer treatments (p < 0.05), but not among the three organic fertilizer treatments. Network analysis indicated positive stronger correlations among all functional enzymes in organic fertilizer treatments compared to chemical fertilizer treatments. RDA and correlation heat map results showed that C/N ratios and N_NH4+ were strongly related to CAZyme composition. PLS-PM analysis revealed that soil available nitrogen positively influenced several variables, while rice grain yield was negatively influenced by soil enzymes and TOC. These findings suggested that under appropriate cropping systems, partially substituting chemical fertilizers with organic fertilizers can effectively enhance the availability of nutrients in the soil, alter the activity of carbon-cycling microorganisms, and increase rice grain yield. [ABSTRACT FROM AUTHOR]

A field experiment was conducted to explore the effects of combined application of organic and chemical fertilizers (organic-chemical fertilizers) on reclaimed soil fertility and rice yield. The experiment involved five treatments: no nitrogen (N) fertilizer (CK1), 100% chemical fertilizer N (CK2), 40% chicken manure N + 60% chemical fertilizer N (T1), 40% vermicompost N + 60% chemical fertilizer N (T2), 40% rapeseed meal fertilizer N + 60% chemical fertilizer N (T3). Organic-chemical fertilizers maintained or increased rice yield. Rice yields of T2 and T3 increased by 6.7% and 8.9%, respectively, as compared with CK2. T1 showed similar value of rice yield with CK2. Organic-chemical fertilizers application increased contents of soil organic C (SOC), total N (TN), alkali-hydrolyzable N (AN), NH4+-N, NO3–N, available phosphorus (AP), available potassium (AK) as well as CEC by 10.5%~15.9%, 8.9%~39.3%, 16.9%~74.5%, 38.1%~77.2%, 18.3%~136.5%, 27.7%~75.0%, 16.1%~24.7% and 7.2 ~ 26.0%. T3 had highest soil TN, AN, NH4+-N, NO3–N, CEC as well as T2 showed the highest contents of soil AP and AK. Organic-chemical fertilizers application increased soil sucrase (S-SC), urease (S-UE) and catalase (S-CAT) activities. The highest soil S-SC activity was detected in T3, and the highest soil S-UE and soil alkaline phosphatase (S-AKP) activities were observed in T2. Rice yield was positively related to SOC, TN, AN, NH4+-N, NO3–N, AP and AK as well as S-SC, S-UE and S-AKP activities. In conclusion, 40% organic N + 60% chemical N application could improve soil fertility and rice yield in reclaimed soils, with rapeseed meal fertilizer the most effective organic N source, followed by vermicompost and chicken manure. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil nutrients of samples, from the reclaimed area and primary landform in the iron mining wasteland of 54 areas in 17 counties of Hebei province, were detected to clarify the soil nutrients status in the reclamation area. Soil organic matter contents from primary landforms and reclaimed areas were slightly deficient, deficient, or extremely deficient in most cities. In the primary landform, soil available nitrogen content was slightly deficient or much less, except for Qinhuangdao, Chengde, and Zhangjiakou. Soil available phosphorus contents were medium levels or slightly deficient levels. Soil available potassium contents were abundant or extremely deficient levels in different cities' samples. In the reclaimed area, soil available nitrogen contents were deficient levels and extremely deficient levels. Soil available phosphorus was slightly abundant and medium level. Soil available potassium was changed from a slight level to extremely deficient, except for Qinhuangdao. In a word, soil available nutrients in the reclaimed iron mining area, such as available nitrogen, available phosphorus, and available potassium, were low levels, which will provide a theoretical basis for soil fertility improvement during mining area reclamation in the future. [ABSTRACT FROM AUTHOR]

Abstract Exogenous humus can change the content and migration activity of cadmium (Cd) in soil. Humic acid (HA) is an important soluble humus component in soil. In order to explore the relationship between cadmium pollution mechanism and ecological environment of humic acid in reclaimed soil, the characteristics of humic acid adsorbing cadmium in alkaline conditions were studied. This study employed reclaimed soil from the Huainan mining area, China. The adsorption and desorption characteristics as well as influence mechanisms on the heavy metal cadmium (Cd) were explored under the influence of HA. The results show that: (1) When Cd concentration was low (0.2–10 mg/L), HA had little effect on Cd adsorption and desorption in reclaimed soil. When the Cd concentration was high (15–80 mg/L), HA had a great influence on the adsorption and desorption of Cd in reclaimed soil. The addition of HA can inhibit the adsorption of Cd by reclaimed soil and effectively improve the desorption capacity of Cd by reclaimed soil. (2) The kinetic curves of Cd adsorption and desorption of reclaimed soil with added HA show that both processes (adsorption and desorption) include two stages: rapid reaction and slow reaction. The adsorption of Cd by reclaimed soil under the influence of HA was 18.18% lower than that of normal reclaimed soil, and the increase of Cd desorption was 50.29%. (3) The factors affecting the adsorption and desorption of Cd in the soil were analyzed with gray theory, and their importance can be ordered as follows: Cd concentration > HA concentration > pH > temperature. Considering the influence of HA, a multi-factor coupling function model of adsorption and desorption of Cd in soil is established. This model provides theoretical guidance for the scientific prediction and evaluation of Cd environmental pollution risks in soil and will be useful for developing a new solution for engineering remediation of high concentration Cd contaminated soil.

Reasonable cropping systems and fertilizer management are vital for improving the quality of barren soil. The effectiveness of different crop rotation methods and fertilizers in soil improvement depends on various factors, including soil type, climate conditions, and crop type. In the present study, based on three rice-based cropping systems, the effects of organic fertilizers combined with slow-release fertilizers on rice yield and soil fertility in reclaimed soil were analyzed. The results showed that the rice grain yield was highest under the rice-fallow rotation system (RF) with the application of rapeseed meal fertilizer. Available nutrients such as AN, N_NH4+, TP, and AK showed a significant positive correlation with rice grain yield (p < 0.05). PCA and PERMANOVA analysis supported significant variation in CAZyme abundance among cropping systems (R2 = 0.60, p = 0.001) and significant differences between slow-release fertilizer treatments and organic fertilizer treatments (p < 0.05), but not among the three organic fertilizer treatments. Network analysis indicated positive stronger correlations among all functional enzymes in organic fertilizer treatments compared to chemical fertilizer treatments. RDA and correlation heat map results showed that C/N ratios and N_NH4+ were strongly related to CAZyme composition. PLS-PM analysis revealed that soil available nitrogen positively influenced several variables, while rice grain yield was negatively influenced by soil enzymes and TOC. These findings suggested that under appropriate cropping systems, partially substituting chemical fertilizers with organic fertilizers can effectively enhance the availability of nutrients in the soil, alter the activity of carbon-cycling microorganisms, and increase rice grain yield.

In order to analyze the influence of dredger fill initial mud (original mud) on the anti-liquefaction strength cyclic resistance ratio (CRR) value of different strata after dredger fill under earthquake. According to the theories of soil mechanics, fluid mechanics and particle sorting. The expression of the variation law of dredger fill liquefaction index CRR value in different strata under the influence of dredger fill initial mud FC value was derived. Firstly, based on the threshold FCth of dredger fill particle contact state, the influence of fine particle content FC on soil CRR value was classified and discussed, and combined with the theory of particle natural separation, the expression of the change law of dredger fills initial mud FC value affecting dredger fill liquefaction index CRR value was established. Finally, according to the field investigation data, the reliability of the theoretical model was analyzed. The results show that the calculation model of CRR value of initial slurry-sediment stratification can well describe the law of the influence of initial slurry of hydraulic filling on the CRR value of deposited strata. When FC≥FCth, silt takes part in the construction of the soil skeleton, and its CRR value shows a non-monotonic change law, and the properties of the soil also show the trend of the sand to silt. [ABSTRACT FROM AUTHOR]

Animal manures positively affect soil microbial activity and inorganic phosphorus (Pi) accumulation. However, how different types of manures affect microbial-driven Pi transformation at the aggregate scale is largely unclear. Here, we conducted a field experiment focused on maize cultivation in a reclamation site. Five fertilization treatments included no fertilizer (CK), chemical fertilizer (CF), chicken manure (CHM), pig manure (PM), and cow manure (CM). We examined microbial biomass, soil extracellular enzyme activities associated with carbon and phosphorus cycling, and Pi fractions (Labile-P, Moderately labile-P, and Stable-P) in three aggregate sizes (> 2 mm large macro-aggregates, 0.25–2 mm small macro-aggregates, and < 0.25 mm micro-aggregates), as well as grain yield. The results showed that manures addition significantly increased the proportion of large macro-aggregates and aggregate stability compared to chemical fertilizer. Stable-P constituted the largest proportion among the Pi fractions, accounting for 63 %–72 %. However, manures reduced Stable-P (5.4 %–10.7 %) and increased Labile-P (111 %–190 %) in Pi, especially in micro-aggregates. Both chemical fertilizer and manures increased microbial biomass and enzyme activities in aggregates, with manures causing a greater enhancement of soil microbial biomass carbon (SMBC) and C-cycling enzymes, especially under pig manure, and improving soil microbial biomass phosphorus (SMBP) and P-cycling enzymes, especially under chicken manure. Phytase, phosphatase and SMBP accounted for 81.4 %, 81.2 % and 87 % of the differences in large macro-aggregates, small macro-aggregates, and micro-aggregates, respectively. The structural equation model (SEM) demonstrated that manures facilitated the transformation of Stable-P to Labile-P by regulating aggregates and microbial activity, which consequently increased yield. In summary, manures addition, particularly chicken manure, can enhance inorganic phosphate (Pi) accumulation and transformation, thereby mitigating phosphorus (P) limitation in calcareous reclamation soils. • Manures (especially chicken manure) promoted Pi accumulation and transformation. • Phytase, phosphatase, and soil microbial biomass phosphorus were the main factors causing the differences in Pi. • Manures promote Stable-P to Labile-P via interactions with aggregates and microbes. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Organic acids are widespread in the environment and play an important role in the adsorption, desorption, and migration of soil cadmium (Cd). Under the effect of humic acid (HA) and citric acid, the properties and mechanism of Cd adsorption and desorption in reclaimed soil from the Panyi Mine in the Huainan mining area were investigated (CA). The addition of HA and CA inhibited the adsorption and enhanced the desorption of Cd in reclaimed soil, with HA having a stronger effect than CA. As the concentration of added HA or CA increased, the adsorption capacity of Cd in the reclaimed soil gradually decreased, while the desorption capacity gradually increased. That is, the adsorption inhibition/desorption promotion effect was stronger for higher concentrations of organic acid. Cd adsorption and desorption could be described as a logarithmic function of organic acid concentration. The kinetic curves of Cd adsorption and desorption in reclaimed soil under the influence of organic acids show that both adsorption and desorption involved two stages: a fast reaction stage followed by a slow reaction stage. [ABSTRACT FROM AUTHOR]

Exogenous humus can change the content and migration activity of cadmium (Cd) in soil. Humic acid (HA) is an important soluble humus component in soil. In order to explore the relationship between cadmium pollution mechanism and ecological environment of humic acid in reclaimed soil, the characteristics of humic acid adsorbing cadmium in alkaline conditions were studied. This study employed reclaimed soil from the Huainan mining area, China. The adsorption and desorption characteristics as well as influence mechanisms on the heavy metal cadmium (Cd) were explored under the influence of HA. The results show that: (1) When Cd concentration was low (0.2–10 mg/L), HA had little effect on Cd adsorption and desorption in reclaimed soil. When the Cd concentration was high (15–80 mg/L), HA had a great influence on the adsorption and desorption of Cd in reclaimed soil. The addition of HA can inhibit the adsorption of Cd by reclaimed soil and effectively improve the desorption capacity of Cd by reclaimed soil. (2) The kinetic curves of Cd adsorption and desorption of reclaimed soil with added HA show that both processes (adsorption and desorption) include two stages: rapid reaction and slow reaction. The adsorption of Cd by reclaimed soil under the influence of HA was 18.18% lower than that of normal reclaimed soil, and the increase of Cd desorption was 50.29%. (3) The factors affecting the adsorption and desorption of Cd in the soil were analyzed with gray theory, and their importance can be ordered as follows: Cd concentration > HA concentration > pH > temperature. Considering the influence of HA, a multi-factor coupling function model of adsorption and desorption of Cd in soil is established. This model provides theoretical guidance for the scientific prediction and evaluation of Cd environmental pollution risks in soil and will be useful for developing a new solution for engineering remediation of high concentration Cd contaminated soil. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Since the passage of legislation in 1977, Appalachian mineland reclamation is typically completed using non-native C3 grasses and forbs. Alternatively, reclamation with native prairie (C4) grasses and forbs offers a more ecologically friendly alternative that can contribute to native plant conservation and potentially improve soil properties more quickly than shallower rooted C3 cool-season grasses. We assessed the establishment of native prairie after reclamation, evaluating three treatments for six years after planting—traditional cool season planting, native prairie planted at light density, and native prairie planted at heavy density. All treatments reached the objectives of reclamation—percentage of ground covered by vegetation—within 2 years after planting. All treatments at all sites, except for one site by treatment combination near a forest, showed an increase in plant species richness and Shannon–Wiener diversity in the first four years of reclamation, a peak around 5 years, and subsequent decrease. Little difference in plant richness and Shannon–Wiener diversity among treatments was observed. However, the two native seed mixes quickly diverged from the traditional mix in terms of community structure and diverged further over time, with both native treatments heading towards a more desirable native prairie grassland state, while the traditional mix remained dominated by non-native cool season grasses. The native treatments also exhibited greater increase in microbial biomass and fungi:bacteria ratio over time compared to the traditional mix. Soil organic carbon increased over time regardless of seed mix treatment. Exchangeable base cations and phosphorus generally decreased over time, as expected, regardless of seed mix treatment, likely due to uptake from established plants. Native grassland species were able to establish despite inclusion of some traditional species in the native mix. Native plant establishment likely resulted in benefits including pollinator resources, bird and wildlife habitat, and increased soil health, and we recommend that native prairie mixes be used directly in reclamation moving forward, as they are able to meet reclamation goals while establishing a successful native prairie plant community. [ABSTRACT FROM AUTHOR]

This study assesses environmental receptors impacted by alluvial gold mining at Kibi Goldfields Limited in the Eastern region of Ghana to establish trace metals contamination risk. Specific objectives are to determine concentrations of (1) As, Cr, Ni and Pb in soils, drainage and food crops, using X-ray fluorescence, (2) Cl- in drainage using standard methods. Mean concentrations of As, Cr and Ni in soils are higher at impacted sites than control sites; while Pb and As concentrations in drainage exceeds the maximum contamination guideline values in drinking water. Using Cl- as a conservative tracer, As and Pb are adsorbing from water, while Cr and Ni are desorbing into water. In the food crops, bioaccumulation factors of As and Ni are profound at the impacted site than control sites; Except Cr in cocoyam at impacted sites, translocation factors are negligible in the food crops. Cr bioaccumulates in in cocoyam and plantain at the control site, while Ni bioaccumulates in only plantain at the impacted sites. Overall, the metal contamination is of concern in the receptors, except Pd in plants. Results from this study can be used for trace metals risk assessment in the environment.

An accurate determination of the soil organic matter (SOM) levels present in reclaimed mine soil is necessary to evaluate the success of the ecological reclamation of mines. Visible and near-infrared diffuse spectroscopy is a fast and efficient method for collecting data for soil management during the reclamation of soil removed from mines. In this work, we used spectroscopy to characterize and estimate the SOM of lands from different reclamation years after coal mining in semi-arid grasslands of North China. Our goals were: (1) to explore the SOM characteristics and the spectra of reclaimed mine soil with different reclamation ages, and (2) to establish a reliable and accurate SOM prediction model by comparing support vector machine (SVM), partial least-squares regression (PLSR), and random forest (RF) modeling methods by determining the optimal preprocessing method and input spectral region. The results showed that spectral characteristics are useful indicators for understanding progressive SOM changes in the topsoil at different reclamation ages. RF is a more appropriate method for assessing the performance of a selected spectral region and provides more accurate results with a root mean square error (RMSE) of 4.34 g·kg−1 between predicted and observed SOM values. This study provides an alternative method that uses spectroscopy to estimate reclaimed soil conditions for the environmental monitoring of mining sites. [ABSTRACT FROM AUTHOR]

Over the last few decades, much of the desert‐oasis ecotone in northwestern China has been reclaimed for cotton cultivation. However, we still know little about the composition of the soil bacterial community relative to soil chemical properties in reclaimed soil after long‐term monocultural cotton production in arid and extremely arid areas. Here, we collected soil samples from two farms where cotton has been continuously planted for more than 20 years. We found that the composition of the soil bacterial communities was significantly different between these two farms, variance in which could be explained by available K, N, and P, total N, and soil pH. The relative abundance of Verrucomicrobia was significantly higher at the Xinhu farm, while Bacteroidetes and Nitrospirae predominated at the Tenth farm. Across sites, the abundance of Bacteroidetes was positively correlated with available N and P, while the abundance of Verrucomicrobia was positively correlated with total N and available K. Moreover, bacterial community diversity, as quantified via phylogenetic diversity, Shannon diversity, and operational taxonomic unit richness, was higher at the Tenth farm. These soil bacterial diversities were all positively correlated with available N, but negatively correlated with available K in arid and extremely arid areas. Our results suggest that available K, N, and P, total N, and pH are all key factors in shaping soil bacterial communities. The influence of available N and K on bacterial community diversity should therefore be considered for cotton cultivation in reclaimed soil. [ABSTRACT FROM AUTHOR]

• The vertical distribution (0–100 cm) of SOC and TN were mapped in reclaimed coal mine soils. • Vertical distribution maps were conducted using a transfer model approach (from point spectra to imaging spectra). • The calibration models were enhanced and simplified through the use of 5 three-dimensional optimal indices. • Vertical distribution maps can be used to evaluate the different dumping techniques. Soil organic carbon (SOC) and total nitrogen (TN) contents in different soil horizons are essential for vegetation growth and crucial indicators to evaluate soil quality in reclaimed mining areas. Compared with conventional wet chemistry methods, soil spectroscopy, including imaging spectroscopy, can be used as a cost and time-efficient soil analysis technique. However, there is a great challenge in combining laboratory point spectra and laboratory hyperspectral imagery for mapping vertical distribution of SOC and TN (0–100 cm) in reclaimed soils. This is primarily because mixing of spectral data from different sources and technologies to improve soil models is still in its infancy. The main objective of this study is to provide a generic workflow to efficiently evaluate and map reclaimed mine soils in different horizons using imaging spectroscopy and machine learning approaches. A total of 65 soil samples (0–100 cm) were collected from three reclaimed mining lands and one natural site in northern China. Both point soil spectral information and hyperspectral images (350–2500 nm) were obtained under laboratory condition. In order to enhance the relationship between soil quality indicators and spectral features, the stacked feature selection algorithms and three-bands spectral indices were proposed for further modelling. Three machine learning methods (partial least squares regression; PLSR, random forest; RF, and radial basis function model; RBF) based on the point spectra were applied to calibrate and map continuous vertical distribution of SOC and TN. According to the results, thirty spectral bands were identified as important spectral features for SOC and eighteen bands for TN. With feature spectral bands and optimized three-bands spectral indices, the RF model yielded the best predictions for both SOC (R2 = 0.97, RMSE = 7.5 g kg−1) and TN (R2 = 0.78, RMSE = 0.33 g kg−1). It was concluded that imaging spectroscopy can be used to quantify and map soil quality indicators for better monitoring ecological restoration process in reclaimed soil of mining site. [ABSTRACT FROM AUTHOR]

Since the passage of legislation in 1977, Appalachian mineland reclamation is typically completed using non-native C3 grasses and forbs. Alternatively, reclamation with native prairie (C4) grasses and forbs offers a more ecologically friendly alternative that can contribute to native plant conservation and potentially improve soil properties more quickly than shallower rooted C3 cool-season grasses. We assessed the establishment of native prairie after reclamation, evaluating three treatments for six years after planting—traditional cool season planting, native prairie planted at light density, and native prairie planted at heavy density. All treatments reached the objectives of reclamation—percentage of ground covered by vegetation—within 2 years after planting. All treatments at all sites, except for one site by treatment combination near a forest, showed an increase in plant species richness and Shannon–Wiener diversity in the first four years of reclamation, a peak around 5 years, and subsequent decrease. Little difference in plant richness and Shannon–Wiener diversity among treatments was observed. However, the two native seed mixes quickly diverged from the traditional mix in terms of community structure and diverged further over time, with both native treatments heading towards a more desirable native prairie grassland state, while the traditional mix remained dominated by non-native cool season grasses. The native treatments also exhibited greater increase in microbial biomass and fungi:bacteria ratio over time compared to the traditional mix. Soil organic carbon increased over time regardless of seed mix treatment. Exchangeable base cations and phosphorus generally decreased over time, as expected, regardless of seed mix treatment, likely due to uptake from established plants. Native grassland species were able to establish despite inclusion of some traditional species in the native mix. Native plant establishment likely resulted in benefits including pollinator resources, bird and wildlife habitat, and increased soil health, and we recommend that native prairie mixes be used directly in reclamation moving forward, as they are able to meet reclamation goals while establishing a successful native prairie plant community.

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

How to restore the soil fertility and productivity in a damaged and then reclaimed area with extremely low fertility is a big concern worldwide. To explore the method of soil restoration in the coal mining subsidence area, the effects of biochar application coupled with organic fertilizer (animal manures) on the process of organic nitrogen (N) mineralization were studied in a 149 days leaching experiment. Biochar were applied (wt/wt) at the rates of 0%, 1%, and 3%. Two organic fertilizers with different C/N ratio (chicken and sheep manures) were applied at the rate of 200 mg N·kg−1 soil. A vegetable soil with high-fertility was used as the comparison. The results showed that when treated with chicken manure, the reclaimed soil had 11.13% lower mineralization potential and 20.00% lower inorganic nitrogen production from mineralization than the vegetable soil. Compared with the non-biochar treatment, biochar at both application rates decreased N leaching in chicken manure-treated reclaimed soil, i.e., by 21.49% (1% biochar) and 28.31% (3% biochar), respectively, whereas only high rate of biochar application decreased N leaching in chicken manure-treated vegetable soil by 8.10%. However, N leaching in sheep manure-treated reclaimed soil was unaffected by the biochar application. Thus, the effect of the biochar on the organic nitrogen mineralization was affected by both soil and organic fertilizer type. [ABSTRACT FROM AUTHOR]

Biochar amendment of soil is well known to improve soil fertility and microbial function. However, little is known about the effect of biochar addition to reclaimed soil in coal mining subsidence area on microbial community. A plant soil cultivation experiment was conducted with wheat grown and four treatments were included: P and K fertilizer (CK); NPK inorganic fertilizer (NPK); NPK inorganic fertilizer and straw (NPKS); and NPK inorganic fertilizer and biochar (NPKB). The results indicated that biochar amendment significantly increased the concentrations of NH4+-N, total N, and available P and K compared with the NPK. Biochar addition also significantly increased the grain yield and total biomass of wheat. Furthermore, biochar amendment treatment increased the absolute abundance and altered the community structure of soil bacteria and fungi in the reclaimed soil. Illumina MiSeq sequencing showed that the addition of biochar increased α-diversity of bacteria and relative abundances of Proteobacteria, Actinobacteria, and Bacteroidetes, whereas the relative abundance of Firmicutes were decreased by 61%. However, biochar addition did not change the relative abundance of dominant fungal phyla. Redundancy analysis (RDA) suggested that total N, available P, and K contents were the key factors correlated with changes in microbial community structure. Overall, our results suggest that biochar amendment in reclaimed soil in coal mine subsidence area could increase wheat yield and abundance and alter microbial community compositions. [ABSTRACT FROM AUTHOR]

Phosphate solubilizing bacteria (PSB) can convert insoluble forms of phosphorus (P) to accessible forms. Five highly efficient PSB strains, H22, Y11, Y14, Y34, and S32, were screened and isolated from an alfalfa rhizosphere in heavy metal-contaminated reclamation area in Shanxi Province, China. Based on morphological observations, 16S rRNA sequencing, cellular fatty acid composition analysis, and the BIOLOG test, H22, Y11, and Y34 were identified as Pseudomonas sp., while Y14 and S32 were identified as Pantoea sp. Among them, S32 showed the highest P-solubilizing efficiency in culture medium containing Ca3(PO4)2, lecithin, and powered phosphate rock. The culture medium conditions to obtain the highest P-solubilization efficiency were optimized as follows: the culture temperature was 30°C; the incubation time was 5 days; the initial pH was 7.0; and glucose served as the carbon source. Furthermore, the P-solubilization efficiency of S32 in media containing CaHPO4, lecithin, phosphate rock (PR), FePO4, or AlPO4 was determined to be 18.38, 3.07, 0.16, 0.51, or 2.62%, respectively. In addition, the acid and alkali phosphatase activities of S32 were tested as 6.94 U/100 mL and 4.12 U/100 mL, respectively. The soil inoculation experiment indicated that inoculation with S32 resulted in an obvious improvement in the available P of both the experimental and reclaimed soil. The rice seedling growth experiment also suggested that the application of S32 significantly increased the plant height, biomass, root growth, and P uptake of rice in both experimental and reclaimed soil. Taken together, the isolated S32 strain showed high P-solubilization capacity for both Pi and Po, and its ameliorative effect on reclaimed soil recovery provides the theoretical basis for crop development in the reclaimed soil of mine field.

Phosphate solubilizing bacteria (PSB) can convert insoluble forms of phosphorus (P) to accessible forms. Five highly efficient PSB strains, H22, Y11, Y14, Y34, and S32, were screened and isolated from an alfalfa rhizosphere in heavy metal-contaminated reclamation area in Shanxi Province, China. Based on morphological observations, 16S rRNA sequencing, cellular fatty acid composition analysis, and the BIOLOG test, H22, Y11, and Y34 were identified as Pseudomonas sp., while Y14 and S32 were identified as Pantoea sp. Among them, S32 showed the highest P-solubilizing efficiency in culture medium containing Ca3(PO4)2, lecithin, and powered phosphate rock. The culture medium conditions to obtain the highest P-solubilization efficiency were optimized as follows: the culture temperature was 30°C; the incubation time was 5 days; the initial pH was 7.0; and glucose served as the carbon source. Furthermore, the P-solubilization efficiency of S32 in media containing CaHPO4, lecithin, phosphate rock (PR), FePO4, or AlPO4 was determined to be 18.38, 3.07, 0.16, 0.51, or 2.62%, respectively. In addition, the acid and alkali phosphatase activities of S32 were tested as 6.94 U/100 mL and 4.12 U/100 mL, respectively. The soil inoculation experiment indicated that inoculation with S32 resulted in an obvious improvement in the available P of both the experimental and reclaimed soil. The rice seedling growth experiment also suggested that the application of S32 significantly increased the plant height, biomass, root growth, and P uptake of rice in both experimental and reclaimed soil. Taken together, the isolated S32 strain showed high P-solubilization capacity for both Pi and Po, and its ameliorative effect on reclaimed soil recovery provides the theoretical basis for crop development in the reclaimed soil of mine field. [ABSTRACT FROM AUTHOR]

Soil properties in reclaimed land altered inevitably due to human activities. To realize sustainable land use and management in mining area, the long-term dynamic monitoring of reclaimed soil properties is required. Traditional dense sampling network is time consuming and expensive. Therefore, it is necessary to devise a scientific sampling design that maximizing the accuracy of results while minimizing the costs. In this study, we developed an improved simulated annealing method considering the spatial correlation to optimize the sampling design for soil properties, to enhance the efficiency of sampling plans for the prediction of space variables. A separate optimization for each soil property and a sampling optimization integrating various soil properties were conducted by combining simulated annealing and artificial neural networks. The number of sampling points from present improved simulated annealing method was markedly reduced, the spatial correlation was increased and the sampling points obtained showed more accurate predictions for soil properties. The sampling points for each soil property were mostly distributed in the marginal areas and appropriately added in the middle of the dumps. There were more sampling points distribution in these areas with large changes in topography for each soil property after improved simulated annealing optimization and more sampling points were needed to reflect soil information in southern dump in Antaibao opencast coal mine. When operating optimization integrating all the properties, some sampling points of various properties were added to the sampling pattern, showing a uniform distribution of sampling points. This study provides a theoretical basis for optimal design for soil property monitoring and sustainable land management. [ABSTRACT FROM AUTHOR]

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The paper show a preliminary study on biological parameters of salty recently reclaimed soils in Italy (Valle di Mezzano, Comacchio and Ostellato – Ferrara). The soils were characterized and classified. Biological parameters were measured and calculated: Basal Respiration Carbon (Cbas) (mg C-CO2/kg soil); Cumulative Respiration Carbon (Ccum) (mg C-CO2/kg soil); Microbial Carbon (Cmic) (mg C/kg soil); Metabolic Quotient (qCO2) ((10-2) h-1); Mineralization Quotient (qM) (%). The combination of these biological parameters was used to create an index of soil fertility (Benedetti and Mocali 2008) and the same index is on the way of being evaluated for these soils as well. The objectives of the work are: (a) give insights on the dynamics of the salinization processes, (b) better understand biogeochemical cycles of soils affected by high electrical conductivity and fertility loss, and (c) propose land management strategies.

Reclaiming the subsidence area that results from coal-mining could alleviate the shortage of arable land in China. This study examined the effects of fertilization and reclamation age on soil nutrients and other properties in the 0-100 cm profile at an underground coal mine site on the Loess Plateau of China. Soil samples were collected representing three successive reclamation ages (1, 3 and 7 years) and an undisturbed reference farmland soil. Treatments included chemical fertilizers only (CF), organic fertilizers only (OF), a combination of 50% chemical fertilizers and 50% organic fertilizers (COF) and a no-fertilizer control (CK). The study showed that Soil pH and electrical conductivity ranged from 8.03 to 8.43 and 0.11 to 0.25 dS/m, respectively, and no significant differences were found due to any soil depths, fertilizer treatments, reclamation ages. Nutrient contents tended to increase over time as a whole. Additionally, applying manure had a better effect on increasing, available phosphorus and potassium, organic matter and cation exchange capacity in the 0-20 cm soil layer (topsoil) than did applying only chemical fertilizer or a combination of chemical and organic fertilizer; however, no obvious change was found in the properties of the 20-100 cm soil layers for any treatments. Given the above, it is feasible for coal-mining subsidence areas to be reclaimed and returned to farmland on the Loess Plateau of China. [ABSTRACT FROM AUTHOR]

As a new soil amendment, biochar has become an environmentally friendly material. The application of biochar is one of the most promising management practice to improve soil quality. Using a reclaimed soil from a coal mine subsidence area, the plat soil cultivation experiment in this study investigated the effects of biochar application at varying rates on soil properties, the abundance and composition of soil denitrifier communities. Biochar application significantly increased the crop yield which might be associated with the increased level of cation exchange capacity (CEC), total nitrogen (N), ammonium-N, available phosphorus (P) and potassium (K) in soil. In combination with N fertilizer, the abundance of both nirK and nirS genes significantly increased only at biochar application rate of 4% compared with the nil-biochar treatment. Biochar application significantly increased the community diversity of nirK gene, while not for nirS gene. Redundancy analysis showed that the level of nitrate-N (NO 3 − -N), available P, and pH in soil significantly affected community structure of nirK gene, while the nirS community composition was only affected by soil NO 3 − -N level. Our results indicate that biochar application to the reclaimed soil in coal mine subsidence area could influence the abundance and diversity of soil denitrifiers and improve soil nutrients thus crop yield. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Agronomy is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mine soils are often polluted and degraded. The objectives of this study were to assess the effects of soil properties and vegetation on soil solute transport in reclaimed soil at an opencast coal mine site on the Loess Plateau. Four reclaimed areas with different vegetation types were selected for the analysis of physical and chemical properties. The miscible displacement technique was used to obtain the breakthrough curves (BTCs) of NO 3 − ion transport in undisturbed soil columns, which were taken from the soil profiles of the different sites. The chemical properties, such as total N, P, K and SOM, exhibited low contents, and the soil physicochemical properties showed high heterogeneity between different depths and different reclaimed areas. The structural stability index was less than 5%. The initial and entire penetration times were longer in the deeper layers than in the top layer. The BTCs of NO 3 − were fitted well by the deterministic equilibrium convection dispersion equation (CDE) model. Preferential flow and transport were found in the soil columns. The reclaimed soil had poor structure, and planting vegetation improved the physiochemical properties of the soil. The soil solute transport parameters exhibited high heterogeneity between different samples and were significantly correlated with soil bulk density and soil texture, which were highly influenced by vegetation and human activities. In the process of land reclamation, increasing the bulk density and selecting fine-textured soils could reduce the average soil pore water velocity and the dispersivity coefficient, thereby extending the solute penetration time. [ABSTRACT FROM AUTHOR]

In past decades, coastal tidal flats in China have experienced rapid and extensive agricultural reclamation due to the increasing pressure of population growth. With more coastal land likely reclaimed in the future, an increase in the understanding of the effects of the reclamation history and changes in land use on soil properties is essential. In this study, a total of 746 surface soil/sediment samples were collected from three study areas with different reclamation durations and land use patterns on the coasts of Dafeng, Rudong and Cixi in eastern China, covering a total area of 1926 km 2 . The results showed that mean soil organic carbon (SOC) and soil total nitrogen (STN) in the three study areas differed slightly and ranged from 7.24 to 7.69 g kg −1 and from 0.71 to 0.76 g kg −1 , respectively. SOC and STN increased significantly with an increase in reclamation duration in all of the study areas, except for the early stage of land conversion in Cixi and the late stage of conversion in Dafeng, which highlighted that the accumulation of SOC and STN was positively correlated with reclamation duration. In Dafeng and Rudong, land dominated by human uses had much higher levels of SOC and STN than those in the tidal flats. For the same duration of reclamation, paddy land had higher levels of SOC and STN than those in the upland, with the exception of the 10-year-old land in Cixi. Our results also indicated that reclaimed coastal soils can sequester considerable amount of OC through improved land management. The differences in the sequestration potential for OC and the dynamics of SOC and STN among the three chronosequences were attributed to specific land use patterns in each study area. [ABSTRACT FROM AUTHOR]

The study area was divided into four kinds of sampling plots as A (>100 cm),B (60-100 cm), C(40-60 cm), and D (20-40 cm) according to different topsoil thicknesses. The soil or coal gangue samples from different depths of reconstruction soil profile were collected to determine their water content (WC), pH value, bulk density (BD), organic carbon (SOC), microbial biomass carbon (MBC), and dissolved organic carbon (DOC). Thus the authors studied the effect of topsoil thickness on active organic carbon (AOC) distribution. The results show that the SOC content of soil layer 0-20 cm increases 0.48 g/kg in the test field after 5 a, while DOC and MBC average content is respectively 46.86 mg/kg,46.09 mg/kg. The recovery progress of organic carbon stock from the reclaimed soil in the experimental field is slower compared with other areas, which it is mainly subject to the nature of the reclamation soil and land utilization pattern. The SOC content of the same soil layer in the test zone is in relation to A>B>C>D, namely, the SOC content of the reclaimed soil filled with coal gangue also increases with the topsoil thickness increases. The MBC content of soil layer 0-20 cm in the sampling plots B and C is relatively higher, that too thick or thin for topsoil thickness are not conducive to the MBC accumulation of surface soil. The DOC content of coal gangue layer in plot D is as high as 97.90 mg/kg, and that of surface soil also reaches 64.80 mg/kg, which is higher than that of other sampling plots. The DOC of the topsoil may be affected by coal gangue layer when the topsoil thickness is thinner. The Soil qMBC value of coal gangue layer can not accurately reflect the reconstruction soil fertility quality, but the topsoil fertility quality and SOC can be represented with its MBC content.MBC and pH value, BD show a significant negative correlation (p<0.01), while it and WC have a significant positively correlation (p<0.05). The relationship of above mentioned soil physico-chemical properties and SOC, DOC is on the contrary to MBC. [ABSTRACT FROM AUTHOR]

A rod shaped, Gram-stain positive, non-motile, facultative anaerobic and gelatin hydrolysing bacterium, strain PG1, was isolated from reclaimed land soil in Kyehwa-do, Republic of Korea. Strain PG1 showed highest 16S rRNA gene sequence similarity (97.4 and 96.5 %, respectively) to Paenibacillus shenyangensis A9 and Paenibacillus hunanensis FeL05, and clustered closely with the members of the family Paenibacillaceae. DNA-DNA hybridization studies revealed a genomic relatedness of 47 ± 9 % with P. shenyangensis A9. The predominant fatty acids of strain PG1 were identified to be anteiso-C (46.7 %) and C (22.7 %). Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid were found to be the major polar lipids. The genomic DNA G+C content was found to be 47.7 mol%. This polyphasic characterisation of the newly isolated strain PG1 justifies its description as representative of a novel species in the genus Paenibacillus, for which the name Paenibacillus gelatinilyticus sp. nov., (type strain = PG1 = KCTC 33642 = JCM 30624) is proposed. [ABSTRACT FROM AUTHOR]

Mine soils are often polluted and degraded. The objectives of this study were to assess the effects of soil properties and vegetation on soil solute transport in reclaimed soil at an opencast coal mine site on the Loess Plateau. Four reclaimed areas with different vegetation types were selected for the analysis of physical and chemical properties. The miscible displacement technique was used to obtain the breakthrough curves (BTCs) of NO 3 − ion transport in undisturbed soil columns, which were taken from the soil profiles of the different sites. The chemical properties, such as total N, P, K and SOM, exhibited low contents, and the soil physicochemical properties showed high heterogeneity between different depths and different reclaimed areas. The structural stability index was less than 5%. The initial and entire penetration times were longer in the deeper layers than in the top layer. The BTCs of NO 3 − were fitted well by the deterministic equilibrium convection dispersion equation (CDE) model. Preferential flow and transport were found in the soil columns. The reclaimed soil had poor structure, and planting vegetation improved the physiochemical properties of the soil. The soil solute transport parameters exhibited high heterogeneity between different samples and were significantly correlated with soil bulk density and soil texture, which were highly influenced by vegetation and human activities. In the process of land reclamation, increasing the bulk density and selecting fine-textured soils could reduce the average soil pore water velocity and the dispersivity coefficient, thereby extending the solute penetration time. [ABSTRACT FROM AUTHOR]

Chloride ion transport in reclaimed soil solutions filled with fly ash (FA) was investigated by measuring the hydraulic parameters (i.e. water retention curves and hydraulic conductivity) of three substrates, namely GSL, GFA, and CFA. Similar simulations were carried out under certain weather conditions. The different boundary conditions of chloride transport were also discussed from FA texture, cover soil thickness, groundwater table level, and initial chloride concentration. Furthermore, the sensitivities of chloride ions to these effect factors were analyzed. The results show that the different top soil thickness and initial chloride concentration have no effect on salinity of topsoil solution in the monitoring points, but they can clearly change the chloride concentration of FA layers. The sensibilities from top soil thickness and initial chloride content are exceedingly weak to the salinity balance based on two dimensions of the time and concentration. While the different FA texture and groundwater table not only affect the salinity equilibrium process of the whole reclaimed soil profile, but also change its balance state. Generally, coarse FA particles and high groundwater table can defer the salinity balance process of the reclaimed soil solution, and they also increase the chloride concentration of FA layer solutions, and even topsoil ones. [ABSTRACT FROM AUTHOR]

In order to study the effects of soil compaction, and soil physical and chemical characteristics after land reclamation, selected lands that were reclaimed after 1, 2, 3, 4, and 5 a, respectively, in the Majiata Mine of the Shendong Open Pit; tested the effects of soil compaction; and collected soil samples from 5 different depths, which are 0∼7.62, 7.62∼15.24, 15.24∼22.86, 22.86∼30.48, and 30.48∼38.10 cm, respectively. The results show that: ➀ Land reclamation leads to soil compaction. The lowest effect of soil compaction is in the top layer and the highest one at the depth of 20∼30 cm; ➁ The bulk density of reclaimed soil is higher than that of undisturbed soil; this declines with the reclamation and nearly reaches the level of undisturbed soil after 5-year reclamation; ➂The content of reclaimed soil nutrients is lower than that of undisturbed soil. The lowest one is in the soil dumping site, which reaches the level of undisturbed soil after 5-year reclamation; ➃ The pH value of reclaimed soil is lower than that of undisturbed soil. The highest one is in the soil dumping site; this declines with the reclamation. [ABSTRACT FROM AUTHOR]

The present investigation was carried out to study the effect of planting and harvesting time on yield and quality of sugar beet cultivars under North Sinai conditions. Two field experiments were conducted in a newly reclaimed sandy soil in a private farm at North Sinai region to study the effect of three sowing dates (1st Aug., 1st Sep. and 1st Oct.) and three harvesting dates (170, 190 and 210 days after planting) on yield and quality of six sugar beet cultivars, viz.,Pamela, Hipoly2, Pleno, Monte Bianco, Oscar poly and Gloria. The results obtained from this study showed that sowing dates had significant effects on sucrose and purity per cent, as well as, root and sugar yields/fed in both seasons. The highest root and sugar yield were obtained from the 1st Sept. sowing. Harvesting after 210 days from sowing recorded the highest root weight, sucrose and purity per cent as well as root and sugar yields/fed. Oscar poly variety recorded the highest root yield but, Monte Bianco cultivar surpassed all cultivars in sugar yield. The interaction between each two factors under study was insignificant. The response equation of root yield/fed to delaying harvest showed diminishing returns. The results revealed that a higher predicted root yield than that retained herein, could have been obtained if harvest was delayed beyond 210 days after sowing. [ABSTRACT FROM AUTHOR]

Ground penetrating radar (GPR) is a geophysical method that incorporates a microwave technique, which can gather a great deal of information about the near-surface in a non-destructive penetration way. The aim of this study is to investigate the application of GPR under the constrained conditions of reclaimed soil. There is a large difference between the result of volumetric moisture content (VMC) detected by GPR and the one measured by the oven drying method (ODM). However, the two methods give similar results when VMC reaches about 40%, beyond this moisture level, the difference in the results obtained using the two methods increases with the increase of moisture content. The VMC of reclaimed soil detected by GPR shows a close correlation with soil electrical conductivity and soil porosity. Consequently, a mathematical model of VMC for reclaimed soil has been developed. This correlation provides a real-time soil moisture data on a field scale, and solves the problem posed by the use of the kernel technique for efficient irrigation management. [ABSTRACT FROM AUTHOR]

Two well-documented case histories on liquefaction of reclaimed fills during the 1995 Kobe earthquake are discussed in this paper. The two sites, Vertical Array site (VA-site) and Packing House site (PH-site) are in proximity to each other and have practically identical stratification with an 18 m thick fill layer overlying an alluvial clay layer. At the VA-site, no ground improvement had been implemented and the reclaimed deposit of gravelly sand is loose with a low SPT blow count of about 5 to 10. The fill layer at the PH-site, on the other hand, had been densified prior to the earthquake by means of the rod compaction technique resulting in an increase in the SPT resistance to approximately 20 to 30 blow counts. To investigate the effects of ground treatment and evaluate the difference in the ground response between the densified fills and undensified loose fills during the Kobe earthquake, detailed studies were conducted for the two sites including field investigations, laboratory tests and effective stress analyses. It was found that both the extent of liquefaction and ground deformation were significantly different at the two sites. The undensified loose fills at the VA-site completely liquefied below the water table resulting in maximum shear strains of about 4% and settlement of the ground of about 25–30 cm. On the other hand, the analyses reveal that only the deep part of the densified fills at the PH-site liquefied where the maximum shear strains are estimated to have reached 2% and settlement of the ground was about 8 cm. Thus, the densification of the fills was found to be effective in preventing liquefaction from developing at shallow depths of the deposit and in limiting the overall deformation and settlement of the ground. [ABSTRACT FROM AUTHOR]

The hydraulic placement of sand fill is one of the most important methods of land reclamation. During the reclamation process, losses of fines in sand are induced by the transportation of soil which affects the dynamic properties of the soil materials. In this study, the reclaimed soil in the Yunlin area of Taiwan is adopted as the test material. Different fines contents, different relative densities, and initial stress ratio were taken as test conditions. Resonant column tests were performed to evaluate the shear modulus and damping ratio of the reclaimed soil under initial shear stress. The results show that the maximum shear modulus decreases as the fines content increases. The influences of initial shear stress are discussed. A prediction method for maximum shear modulus under different fines content and initial shear stress is proposed based on empirical equations obtained. The results can be helpful for land reclamation design and assessment.Key words: reclaimed soil, fines content, initial shear stress, dynamic properties.Le remblayage hydraulique du sable est une des plus importantes méthodes de réhabilitation des terrains. Au cours du processus, la perte de particules fines dans le sable se produit au cours du transport du sol. Ceci va influencer les propriétés dynamiques des sols. Dans cette étude, on a utilisé le sol réhabilité de la région de Yunlin de Taiwan comme échantillons d'essais. Différentes teneurs en particules fines, différentes densités relatives et différents rapports de contraintes initiales ont été utilisés comme conditions d'essai. Des essais à la colonne résonnante ont été réalisés pour évaluer le module de cisaillement et le rapport d'amortissement du sol réhabilité sous la contrainte initiale de cisaillement. Comme le montrent les résultats, le module maximum de cisaillement décroît avec l'augmentation de particules fines. On discute également l'influence de la contrainte initiale de cisaillement. On propose une méthode de prédiction du module maximum de cisaillement avec différentes teneurs en particules fines et différentes contraintes initiales de cisaillement sur la base des équations empiriques obtenues. Les résultats peuvent être utiles pour la conception et l'évaluation de la réhabilitation de terrains. Mots clés : sol réhabilité, teneur en particules fines, contrainte de cisaillement initiale, propriétés dynamiques.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]