Years Of Reclamation Research Articles

Changes in soil organic carbon and its fractions under grassland reclamation in alpine-cold soils, China

Grasslands are the main land use types in China, but their reclamation into croplands can influence the terrestrial carbon and, consequently, impact the global carbon balance. The long-term reclamation of alpine-cold grasslands to croplands are expected to decrease the soil organic carbon (SOC) and its fractions. Here, we conducted an in situ systematic study to measure the SOC and its fraction in soils sampled in an alpine-cold grassland with a gradient of cultivation history from 0 to 40 years. The SOC and its fractions significantly decreased after reclamation (P < 0.05), and the changes in the 0–20 cm soil layer were the greatest among the three sampling depths. After 40 years of reclamation, the SOC content and storage at 0–20 cm decreased by 74 and 60%, respectively. The decreases in the soil labile carbon fractions were more rapid and apparent than the SOC, especially the particular organic carbon (POC), which decreased by 82%. The soil humus carbon fractions also decreased, particularly the humic acid carbon (HAC), which decreased by 81%. The reduction rates of SOC and its fractions gradually decreased with an increase in the cultivation history. Besides, the ratios of the optical densities or absorbances of humic acid (HA) and fulvic acid (FA) solutions at 465 and 665 nm (E<sub>4</sub>/E<sub>6</sub> ratios) and the hue coefficient (Δlog K values), which is the logarithm disparity between the 400 and 600 nm absorbance of the HA (FA) substance, in the solution gradually decreased, indicating that the quality of the soil humus decreased. The reclamation significantly decreased the SOC and its fractions in the alpine-cold soils, which should not be underestimated in the impact on the terrestrial carbon cycles and balance in the long run.

Preliminary Research on Agricultural Cultivation Decreasing Amino Sugar Accumulation in Calcareous Soils in Subtropical Karst Region of China

Soil microbial residues play an important role in the formation and stabilization of soil organic matter and can be quantitatively characterized by amino sugars. However, the response of soil microbial residues to agricultural cultivation in karst areas remains unclear. In this study, we collected soil samples from natural reserved land as well as five plantation forests dominated by Citrus trees cultivated for 0, 1, 5, 15, 30 years to examine the effects of agricultural cultivation on the content of microbial residues (amino sugar analysis). Results showed that: (1) Soil Amino Sugars (ASs) contents were significantly reduced after agricultural cultivation along with the sharp decrease in soil organic carbon (SOC). After 30 years of cultivation, the contents of total ASs, glucosamine (GluN), galactosamine (GalN), and muramic acid (MurA) in cultivated soils decreased by 58.22%, 55.30%, 27.11%, respectively, compared with 0 yr.; (2) Microbial residual carbon contribution to SOC increased from 34.11% to 81.33% after 30 years of cultivation, including fungal residual carbon (FRC) (25.79% to 48.6%) and bacterial residual carbon (BRC) (8.32% to 32.72%); (3) Soil GluN/MurA values tended to decrease with increasing cultivation years. The results highlight the significant effect of cultivation years on amino sugar accumulation. It indicates that the years of reclamation in karst areas have different impacts on the organic fractions derived from various microbial communities in the soil organic matter pool, and the microbial residues indicated by amino sugar are of great significance for the interception of soil organic matter.

Influences of land reclamation on soil bacterial communities of abandoned salt pans in the Yellow River Delta

AbstractReclamation has been widely accepted as a means to restore abandoned lands. Most studies focused on the improvement of land reclamation explore soil nutrients and microbial activities. However, the effects of time since reclamation on bacterial communities of abandoned salt pans are still unclear. The object of our study are is to: (i) assess the successional change of soil physicochemical properties and bacterial communities in abandoned salt pans with different reclamation histories; and (ii) determine the main limiting factors on the improvement of soil quality in abandoned salt pans. The soils in farmland [reclamation time for blank (RTBL)] and six abandoned salt pans with 1 year (RT1), 2 years (RT2), 3 years (RT3), 4 years (RT4), 8 years (RT8), and 9 years (RT9) since reclamation were sampled to investigate the temporal variation of soil properties, heavy metal content, bacterial community composition, and diversity. Results showed that the soil bulk density (BD), total dissolved salt and median particle size (MMAD) decreased with the increase of time since reclamation, while soil nutrients (soil organic matter, total nitrogen, available phosphorus, available potassium) showed an opposite trend. The bacterial α‐diversity increased first, then decreased. Land reclamation enhanced the relative abundances of Acidobacteria, Chloroflexi, and Actinobacteria but reduced the relative abundances of Proteobacteria, Gemmatimonadetes, and Bacteroidetes. Compared with RTBL, the soil nutrients and bacterial community structure in RT1, RT2, RT3, and RT4 showed a significant difference. After 8‐9 years (RT8 and RT9) of reclamation, the soil nutrients and bacterial community structure in reclaimed abandoned salt pans showed RTBL. Therefore, time since reclamation is a vital driving force for restoring soil physicochemical properties and bacterial communities in abandoned salt pans.

Characteristics and Assembly Process of Reclaimed Soil Microbial Communities in Eastern Plain Mining Areas

Understanding how soil microorganisms respond to land reclamation is essential to evaluating the success of ecological restoration actions in disturbed mine soil. However, the microbiological mechanism referred to as productivity reconstruction of the reclaimed soil is still unclear. To shed light on this mechanism, a total of 75 soil samples were collected for 16S rRNA amplicon high-throughput sequencing. The five sampling sites contained four reclamation plots (reclaimed 8 a, 11 a, 14 a, and 17 a) and 1 non-reclaimed plot, which served as the control sampling site. The microbial community composition, potential functions, and assembly mechanisms were also analyzed. The results showed that:①the richness of the microbial community increased with the reclamation time and was higher than that of the control site. However, the community diversity and evenness decreased with the increasing reclamation year (P<0.05). ②Acidobacteria, Chloroflexi, Proteobacteria, and Bacteroidetes dominated in the reclaimed soil, and the relative abundances of the first two phyla were significantly higher than that of the control (P<0.05), whereas the latter two presented the opposite trends (P<0.05). ③ Eight functions, including coenzyme transport and metabolism, translation, ribosomal structure, and biogenesis, showed a positive succession in the reclamation sites and enhanced with increasing reclamation years. ④ The molecular ecological networks of the microbial community in the plain mining area were well modular, whereas the key microbial groups belonged to the Acidobacteria and Bacteroidetes. The microbial communities were dominantly assembled with the deterministic process, and the homogeneous selection contributed the most, which might have been mainly controlled by the local special environment. The results presented herein will undoubtedly aid in the establishment of success indicators of ecological restoration activities in disturbed mining soil. These findings also provide the theoretical basis for improving the productivity and ecological services of reclaimed soil.

Are Iron Tailings Suitable for Constructing the Soil Profile Configuration of Reclaimed Farmland? A Soil Quality Evaluation Based on Chronosequences.

Iron tailings used as soil substitute materials to construct reclaimed farmland soil can effectively realize the large-scale resource utilization of iron tailings and reduce environmental risks. It is vital to understand the mechanisms affecting reclaimed soil quality and determine the appropriate pattern for reclamation with iron tailings. Thus, a soil quality index (SQI) was developed to evaluate the soil quality of reclaimed farmland with iron tailings in a semi-arid region. Soil samples were collected from two reclamation measures (20 cm subsoil + 20 cm iron tailings + 30 cm topsoil and 20 cm subsoil + 20 cm iron tailings + 50 cm topsoil) with reclamation years of 3 (R3), 5 (R5), and 10 (R10) at three soil depths (0–10, 10–20, and 20–30 cm) to measure 13 soil physicochemical properties in western Liaoning, China. Adjacent normal farmland (NF) acted as a reference. Results indicated that iron tailings were suitable for constructing the soil profile configuration of reclaimed farmland. SQI of reclaimed soil increased with the reclamation year, but it has not reached the NF level after 3 years, while it was better than NF after 5 years. The nutrient content of reclaimed soil increased with the reclamation year, but it still did not reach the NF level after 10 years. SQI of R10 (with 50 cm topsoil) was also better than NF but slightly lower than R5 (with 30 cm topsoil). For the semi-arid region with sticky soil texture, the topsoil thickness of reclamation was not the thicker the better, and 30 cm topsoil covered on iron tailings in western Liaoning could achieve a better reclamation effect than 50 cm.

Do the Reclaimed Fungal Communities Succeed Toward the Original Structure in Eco-Fragile Regions of Coal Mining Disturbances? A Case Study in North China Loess-Aeolian Sand Area.

Mining activity has caused serious environmental damage, particularly for soil ecosystems. How the soil fungal community evolves in mine reclamation and what are the succession patterns of molecular ecological networks still needs to be studied in depth. We used high-throughput sequencing to explore the changes in soil fungal communities, molecular ecological networks, and interactions with soil environmental factors in five different ages (the including control group) during 14 years of reclamation in eco-fragile mines. The results showed that the abundance and diversity of soil fungi after 14 years of reclamation were close to, but still lower than, those in the undisturbed control area, but the dominant phylum was Ascomycota. Soil nitrate-N, C/N ratio, pH, and water content significantly affected the fungal community with increasing reclamation ages. Moreover, we found that Mortierellomycota, despite its high relative abundance, had little significant connectivity with other species in the molecular ecological network. Fungal molecular ecological networks evolve with increasing ages of reclamation, with larger modules, more positive connections, and tighter networks, forming large modules of more than 60 nodes by age 9. The large modules were composed mainly of Ascomycota and Basidiomycota, which can form mycorrhiza with plant roots, and are not only capable of degrading pollution but are also “encouraged” by most (more than 64%) physicochemical factors in the soil environment. The results can provide a basis for scientific mine ecological restoration, especially for eco-fragile regions.

Succession law and model of reconstructed soil quality in an open-pit coal mine dump of the loess area, China

Studying the change laws of reconstructed soil quality and constructing succession models are the main components and tools of reconstructed soil quality evaluation for the supervision and management of reconstructed soil. However, the evaluation and management system of reconstructed soil quality suitable for the loess area needs to be improved. This paper aimed to clarify the succession law of reconstructed soil in an open-pit coal dump in the loess area on the temporal scale and to construct a succession model of reconstructed soil quality to evaluate and manage reconstructed soil. The Pingshuo coal mine, a representative open-pit coal mine in the loess area, is the study area. Field investigation and sampling, time-space substitution, and the combination of qualitative and quantitative research methods were used. The reconstructed soil quality succession model was constructed based on the soil quality index method. Results: (1) As the reclamation period increased, the physical and chemical properties of reconstructed soil significantly improved, and reconstructed soil quality generally reached the quality of the original landform after approximately 15 years of reclamation. However, after long-term reclamation, soil physical properties still limited the improvement of reconstructed soil quality to a certain extent. (2) After long-term reclamation, the difference in reconstructed soil quality between layers gradually decreased, and the reconstructed soil condition of the 0–10 cm soil layer was obviously better than that of the other layers. (3) We quantitatively constructed and verified the reconstructed soil quality succession model that is suitable for the loess area, which can be used in conjunction with adaptive management for the evaluation and management of reconstructed soil in the loess area. In conclusion, this study is of great significance to meet the real needs of dynamic evaluation and management of reconstructed soil quality in the loess area and to enrich the soil evaluation and management system at home and abroad.

Influence of input litter quality and quantity on carbon storage in post-mining forest soil after 14 years of reclamation

Reclamation of post mining soils by planting trees is of great research interest due to its potential to stabilize mine soils and sequester atmospheric carbon (C). However there are knowledge gaps regarding the effect of different litter quality and biomass on the C sequestration vis-à-vis molecular characterization of soil organic carbon (SOC) in reclaimed mine soils. Hence, an experiment was conducted to determine the effect of litter quality, quantity, and leaf litter decomposition rate on the quality and quantity of carbon sequestered after 14 years of restoration by three representative plant species (Azadirachta indica, Dalbergia sissoo, and Gmelina arborea) which have been frequently used for revegetation of post-mining sites in India. Results indicate that significant amounts of carbon accumulated under different tree species (47.44, 42.34, and 20.17 Mg C ha−1 under A. indica, D. sissoo, and G. arborea plantations resepctively) as compared to recent dump. Decomposition rate constant had a significant relationship with C/N ratio and nitrogen (N) content and therefore tree species (A. indica) with high C/N, lignin/N ratios, and low N content had a significantly lower decomposition rate constant thereby sequestering more carbon, making it the tree species of choice. Among the three tree species studied, G. arborea witnessed the highest litterfall (4635 kg ha−1 yr−1) but had the lowest SOC stock due to the highest decomposition rate constant (0.00229), which established the fact that composition of leaf litter rather than total litterfall played a significant role in carbon sequestration. Furthermore, spectroscopic methods (UV–vis and FTIR) could clearly distinguish differences in functional groups and molecularity of the humic acids derived from plant species of different resource quality and hence can be effectively used in studying the quality of C sequestered.

Dissolved nitrogen in salt-affected soils reclaimed by planting rice: How is it influenced by soil physicochemical properties?

Planting rice is an effective way to reclaim salt-affected soils, but overapplying nitrogen fertilizer has resulted in a large loss in the amounts of soil dissolved nitrogen (SDN) from paddy fields. While the dynamic of SDN and its response to changes in soil physicochemical properties by planting rice are well-studied in non-salt-affected soils, little is known about the relationship between the SDN and soil physicochemical properties in reclaimed salt-affected soils. To fill this knowledge gap, soil samples were collected from bare salt-affected soils and three paddy fields with different reclaimed years (4, 9, 20) in six soil layers. Compared with bare salt-affected soils, soil salinity and sodicity exhibited trends of firstly increasing and then decreasing, whereas organic matter and total nitrogen tended to increase with the extension of the reclamation year. Soil dissolved organic carbon and total dissolved phosphorous showed decreasing trends. The sand content showed an increasing tendency, whereas the silt and clay contents tended to decrease. Ammonium nitrogen concentrations in reclaimed paddy fields were higher than those of bare salt-affected soils, and nitrate nitrogen concentrations in reclaimed paddy fields were smaller than those of bare salt-affected soils. However, the changing trends of dissolved organic nitrogen concentrations were not consistent among paddy fields with different reclamation years. Meanwhile, statistical analysis results revealed significant correlations between SDN and soil physicochemical properties. Moreover, dominant drivers influencing SDN were grouped using principal component analysis, identifying the following factors including soil sodicity, active nutrients, soil texture and water retention. Redundancy analysis also revealed that the soil physicochemical properties explained 69.65% of the variation in SDN and the influenced relationship between soil physicochemical properties and SDN nutrients. This study enhances our understanding of the mechanisms influencing SDN during planting rice and has implications for the management of the nutrient application of reclaimed salt-affected soils.

Changes in Reconstructed Soil Physicochemical Properties in an Opencast Mine Dump in the Loess Plateau Area of China.

Soil construction and revegetation are essential for ecological restoration in mining areas. The influence of vegetation on the horizontal and vertical distribution patterns of soil properties should be fully understood. However, most studies on reconstructed soils in mining areas only concentrate on the surface soil, without exploring the vertical variations in soil properties. Overall, this study aims to explore the potential mechanisms by which surface vegetation exerts some influence on the spatial distribution of soil physicochemical properties, and to provide some insight into revegetation and soil reclamation in mining areas. Descriptive statistics and one-way analysis of variance (one-way ANOVA) were employed to evaluate the differences in the soil physicochemical properties in horizontal and vertical directions under different land-use types in the south dump of Antaibao opencast mine in Pingshuo, Shanxi Province, China. The main results of this study are as follows: (1) In the horizontal direction, except for the strong variation (variation coefficient ≥ 100%) in soil organic matter (SOM) content at some depths, the degree of variation in other soil physicochemical properties at various depths was moderate or weak (variation coefficient < 100%). The soil physicochemical properties gradually remained constant after years of reclamation. In the vertical direction, the soil bulk density (SBD), soil porosity, SOM content, soil C/N ratio, soil total nitrogen (STN) content, soil available phosphorus (SAP) content, and soil available potassium (SAK) content showed significant variations (p < 0.05) between soil depths. In contrast, no significant difference was found for other physicochemical properties. (2) The SBD, STN, SAK, soil porosity, and soil clay content were significantly different (p < 0.05) under different vegetation cover types, but the influence of vegetation on other soil physicochemical properties seemed to be limited. The results reveal that trees have a stronger ability to reduce soil grain sizes and enhance SAP contents than shrubs or herbs; however, the beneficial effects of herbs on the physicochemical properties of shallow soil are more obvious than those of trees and shrubs. (3) This study indicates that more shrubs and trees should be planted in the areas with low vegetation coverage, and more measures should be taken to improve soil physicochemical properties in order to prevent the occurrence of large-scale degradation. The reconstruction of soil structure should be preferentially considered in the process of soil reconstruction and revegetation in areas under similar conditions. Herbs should first be planted in the early reclamation stage. At the same time, shrubs or trees can be adopted in the middle and late stages of vegetation reconstruction in order to achieve comprehensive revegetation.

山西平朔露天矿区不同年限复垦地植被重建特征对比分析

PDF HTML阅读 XML下载 导出引用 引用提醒 山西平朔露天矿区不同年限复垦地植被重建特征对比分析 DOI: 10.5846/stxb202102270548 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（U1810107，41701607）；中央高校基本科研业务费项目（2-9-2018-025，2-9-2019-307） Comparative analysis of vegetation reconstruction characteristics of different years in the reclaimed land of the Pingshuo opencast mining area, Shanxi Province Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:平朔矿区是中国首个露井联采的亿t级矿区，剧烈的采煤活动导致矿区局部植被彻底损毁，植被重建是矿区生态系统恢复重建的保障，目前针对长期复垦序列下矿区复垦地植被重建特征与演替规律的研究较少。以复垦年限分别为6 a、7 a、25 a和27 a的复垦排土场和原地貌样地为研究对象，采用时空替代法和描述性统计分析法分析了不同复垦年限下复垦地的植被重建特征，并与原地貌进行了对比分析。研究结果表明：（1）植被重建工作显著提高了复垦地的物种丰富度，各复垦地乔灌植株的物种丰富度明显高于原地貌。但在重建植被演替过程中，并非随复垦年限增加，物种丰富度越来越高；复垦地Shannon-Wiener指数随复垦年限增加呈先增后减的变化趋势，该值在R-25a样地达到峰值（0.62），其与复垦地的植物物种组成及其自身生长习性、土壤条件、降水等自然条件和人为干扰等息息相关。（2）从乔木植株的生长状况来看，刺槐作为先锋树种，是植被重建时可优先选择的乔木树种。从复垦地草本植株组成来看，草本植物以多年生为主，占比77.78%；从草本植株的重要值来看，草本优势种以禾本科（Gramineae）、菊科（Compositae）和豆科（Leguminosae）为主，硬质早熟禾（Poa sphondylodes）、拂子茅（Calamagrostis epigeios）、披碱草（Elymus dahuricus）、紫苜蓿（Medicago sativa）和鹅观草（Roegneria kamoji）为明显优势种，其为复垦时优先考虑的草本物种。（3）复垦地的总地上生物量89%以上取决于乔灌地上生物量，其随复垦年限增加呈现先增后减再增的变化趋势，并且逐渐接近于原地貌。R-6a、R-7a、R-25a和R-27a样地的地上生物量分别为原地貌（OL）样地的27.55%、52.44%、36.55%和68.84%，在R-27a样地达到最大值（5.9710 kg/m2），其在一定程度上表明随复垦年限增加复垦地的植被生长状况和复垦效果逐渐变好。因此开展不同年限复垦地植被重建特征及其演替规律的研究，能够在一定程度上表征土地复垦效果，其可为该矿区或类似矿区未来进行植被重建工作时应如何选择适宜的植物物种和制定合理的植被配置模式提供一定参考，进而提升复垦地植被恢复的速度与效果。 Abstract:As the first open-pit combined mining area with 100 million ton reserves, Pingshuo mining area has suffered from severe vegetation damage due to the intensive coal mining activities. Although vegetation reconstruction is the guarantee for the restoration and reconstruction of the ecosystem in mining areas, few studies have been carried out to explore the vegetation reconstruction characteristics and succession rules of reclaimed land in mining areas under long-term reclamation sequences. The time-space substitution method and descriptive statistical analysis method were employed to analyze the vegetation reconstruction characteristics of the reclaimed land under different reclamation years (i.e. 6, 7, 25 and 27 years), the results of which were further compared with those of the original landform. The results showed that:(1) the species richness of the reclaimed land was significantly improved relative to the the original landform during vegetation reconstruction processes, the evidence of which was that the species richness of arbors and shrubs in each reclaimed land was significantly higher than that of the original landform. However, instead of a monotonous increasing tendency, the species richness tended to increase and then decrease in the process of the vegetation succession. The Shannon-Wiener index of the reclaimed land reached the peak at the R-25 a plot (0.62), which was closely associated with the composition and growth habits of plant species, natural conditions (e.g. soil conditions and precipitation) and human interference. (2) Based on the growth status of arbors, Robinia pseudoacacia was the pioneer tree species and should be preferentially adopted for vegetation reconstruction. Most of herbs (77.78%) were perennial and the evidence from herbal importance value indicated that the herbaceous species mainly comprised Gramineae, Compositae and Leguminosae were the dominant families while Poa sphondylodes, Calamagrostis epigeios, Elymus dahuricus, Medicago sativa, and Roegneria kamoj were the obviously dominant species and preferentially considered herbs in land reclamation. (3) More than 89% of the total aboveground biomass of the reclaimed land was derived from the aboveground biomass of trees and shrubs, which tended to increase, then decrease and finally increase again, and gradually approached that of the original landform with the increase of reclamation years. The aboveground biomass of R-6a, R-7a, R-25a, and R-27a accounted for 27.55%, 52.44%, 36.55%, and 68.84% of the original landform (OL) plots, and the maximum value occurred at the R-27a plot (5.9710 kg/m2), which indicated that the vegetation growth status and reclamation effect were gradually getting better after the land reclamation practice. Therefore, the study on the vegetation reconstruction characteristics and succession rules of reclaimed land in different reclamation years can reflect the effect of land reclamation to a certain extent. It can also provide a reference for how to select suitable plant species and formulate a optimal vegetation configuration model when similar mining areas need vegetation reconstruction, which can improve the speed and effect of vegetation restoration on reclaimed land. 参考文献 相似文献 引证文献

Биогеохимическая характеристика корнеобитаемого слоя травянистых растений на рекультивированных участках техногенных отходов

The introduction of the work substantiates the relevance of studying the biogeochemistry of the root layer of herbaceous plants growing on man-made waste from coal mining and iron ore enrichment after 40 years of reclamation. The main part of the report is devoted to the results of determining the gross content of heavy metals and metalloids, Sorg., residual toxicity, occurrence and growth characteristics of the bacterium Azotobacter chroococcum in embryos and background soil under similar plants. It is shown that during the long-term development of embryosems on waste of different origin, a high pool of heavy metals and metals is preserved in them, and Sorghum accumulates. In the area of coal mining around the roots of the clover, the maximum concentrations of Pb are detected, while cereals - Br. On the forested tails of the iron ore agglomeration, the trend is different: Ca, Ni, Cu, Mn, Zn are concentrated around the roots of cereals, and As is near the roots of the clover. However, the residual toxicity is manifested only on the tailings of the iron ore agglomeration. It has been established that the occurrence of azotobacter in the root layer of different plants is ubiquitous, but in the embryos of the forested tailings pond, the bacterial populations are heterogeneous, they contain donkey strains showing luminescence, rhizoid growth type and antagonism. Around the roots of the clover, conditions were formed that were less favorable for reproduction than under cereals. The data obtained expand knowledge about the role of phytobiomes in the migration of chemical elements at man-made facilities, can be taken into account when developing toxicity neutralization and in predicting the effectiveness of biological reclamation.

The effect of an extended agricultural reclamation on changes in physical properties of technosols in post-lignite-mining areas: A case study from central Europe

Opencast mining destroys soils that have formed over many thousands of years. Their place is taken by post-mining areas such as external and internal dumps with materials whose physical and chemical properties are unfavorable from the point of view of plant growth and development. In order to minimize the negative effects of opencast mining, reclamation is necessary. In this work, we examined the impact of 42-year agricultural reclamation, in which three variants of mineral fertilization (0NPK, 1NPK, and 2NPK) were applied in the cultivation of alfalfa with the addition of orchard grass on changes in physical properties of Technosols. After forty-two years of agricultural reclamation, there has clearly been a differentiation of post-mining material into genetic horizons that differ in physical properties. The surface part of Technosols was converted to a humus-enriched surface horizon (Ap), which consisted of two subhorizons: Ap1 and Ap2, differing in structure, color, and consistency. In the 1978–2020 period in Ap1 of fertilized soils, there was a decrease in bulk density (BD, 9.0–10.9%) and particle density (PD, 1.5%), but an increase in structural stability index (SI, 243–337%), soil porosity (SP, 15.5–19.2%), air-filled porosity (AFP, 10.8–11.7%), field capacity (FC, 49–21.6%), plant available water capacity (PAWC, 46.4–48.0%) and S-index (46.9–50%). In the Ap2 subhorizon, there was a similar trend of changes; however, BD (for 2NPK), FC (for 1NPK), and PAWC (for 1NPK and 2NPK) were not significant. BD (5.4–14.3%) increased in most horizons of parent material (Cd) between 1978 and 2020, and SP (10.9–29%), AFP (16. 2–73.9%), and S-index values (9.4–34.4%) decreased. On the other hand, PD, SI, FC, and PAWC values did not change significantly.Cultivation o alfalfa with orchard grass in the 1978–2020 period significantly affected the profile variation in physical properties of Technosols, which was not observed when the field experiment was set up (1978). In the Ap horizon, DB and PD had significantly lower values, while SI, SP, AFP, FC, PAWC, and S had significantly higher values compared to parent materials (Cd). This is related to the indirect effect of soil organic carbon (SOC), which was beneficial to improving the surface horizon properties of developing Technosols. The diversity of physical properties of the 42-years old post-mining Technosols in the Ap was dependent on fertilization, especially in the Ap1 subhorizon. In fertilized Technosols, the BD and PD values were lower, and SP, DP, AFP, FC, PAWC, and S values were higher compared to unfertilized Technosols. Parent material (Cd) horizons after 42 years of reclamation had similar physical properties regardless of fertilization.

The Development and Utilization of Saline–Alkali Land in Western Jilin Province Promoted the Sequestration of Organic Carbon Fractions in Soil Aggregates

Soil samples from T (0~20 cm) and S (20~40 cm) layers of four saline–alkali rice fields (R5, R15, R20, and R35) with different reclamation years were selected to study the distribution of soil aggregates and the contents of readily oxidizable organic carbon (ROC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), potentially mineralizable carbon (PMC), and soil organic carbon (SOC). The effects of large macroaggregate (&gt;2 mm, LMA), small macroaggregate (0.25 to 2 mm, SMA), and microaggregate (&lt;0.25 mm, MA) particle size, soil layer, and soil physicochemical properties on SOC fractions were also analyzed. The results showed that the LMA size in saline–alkali paddy fields were easily decomposed and was unstable due to the influence of the external environment. With the increase in reclamation years, the proportion of LMA in the S layer decreased gradually. The ROC, DOC, MBC and TOC contents of aggregates in the T and S layers gradually increased with the increase in reclamation years, and SOC fractions contents of aggregates in different grain sizes were SMA &gt; LMA &gt; MA. An effective way to increase carbon sink and improve the ecological environment in western Jilin Province is to change the soil environment by planting rice in saline–alkali land.

Effects of wetland reclamation on amino sugar accumulation in soils of the Sanjiang Plain

Microbial residues play important roles in the formation and stabilization of soil organic matter. The responses of soil microbial residues to wetland reclamation, however, remain unclear. In this study, we collected soil samples from a native wetland dominated by Calamagrostis angustifolia as well as three agricultural lands cultivated for 5, 15, and 25 years to examine the effects of wetland reclamation on the content of microbial residues (amino sugar analysis). Results showed that soil amino sugar contents were significantly reduced after wetland reclamation, with a positive relationship between the reduction and the duration of reclamation. After 25 years of reclamation, the content of glucosamine, galactosamine, and muramic acid in agricultural soils decreased by 38.0%, 38.1%, and 35.9%, respectively, compared to the natural wetland. The reduction of muramic acid (25.8%) was stronger than glucosamine (14.9%) after 5 years of reclamation, indicating that bacterial-derived microbial residues were more sensitive to wetland reclamation than fungal-derived counterparts in the short term. Total amino sugars were decreased by 21.1%, 34.0%, and 38.0% after 5, 15, and 25 years of wetland reclamation, respectively. The proportion of total amino sugars in soil organic matter was significantly decreased from 4.8% in natural wetland to 4.4% after 25 years of reclamation, indicating that long-term wetland reclamation accelerated the depletion of microbial-derived organic components, and thus changed the composition of soil organic matter. Such changes may affect long-term stabilization of soil organic matter and ecosystem functioning.

Effects of Seven-Year Fertilization Reclamation on Bacterial Community in a Coal Mining Subsidence Area in Shanxi, China.

The restoration of soil fertility and microbial communities is the key to the soil reclamation and ecological reconstruction in coal mine subsidence areas. However, the response of soil bacterial communities to reclamation is still not well understood. Here, we studied the bacterial communities in fertilizer-reclaimed soil (CK, without fertilizer; CF, chemical fertilizer; M, manure) in the Lu’an reclamation mining region and compared them with those in adjacent subsidence soil (SU) and farmland soil (FA). We found that the compositions of dominant phyla in the reclaimed soil differed greatly from those in the subsidence soil and farmland soil (p < 0.05). The related sequences of Acidobacteria, Chloroflexi, and Nitrospirae were mainly from the subsided soil, whereas those of Alphaproteobacteria, Planctomycetes, and Deltaproteobacteria were mainly derived from the farmland soil. Fertilization affected the bacterial community composition in the reclaimed soil, and bacteria richness and diversity increased significantly with the accumulation of soil nutrients after 7 years of reclamation (p < 0.05). Moreover, soil properties, especially SOM and pH, were found to play a key role in the restoration of the bacterial community in the reclaimed soil. The results are helpful to the study of soil fertility improvement and ecological restoration in mining areas.

Diversity Is Not Everything

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.

Soil salinity and sodicity changes after a one‐time application of flue gas desulphurization gypsum to paddy fields

AbstractSodic soil is more likely to deteriorate in paddy fields than in other fields. Flue gas desulfurization (FGD) gypsum can reclaim sodic soils, but how long a one‐time application of FGD gypsum provides benefits in paddy fields is poorly understood. In this study, soil salinity, sodicity, and soluble and exchangeable cation concentrations were evaluated over a 7‐year period to investigate the reclamation of sodic soil in a paddy field by FGD gypsum. After 7 years, compared with those in the initial soil, the pH, sodium adsorption ratio, and exchangeable sodium percentage of the topsoil (0–20 cm) decreased by at least 2 units, 72.2% and 80.9%, respectively. In the process of FGD gypsum reclamation, substantial changes in topsoil salinity and sodicity occurred mainly between the 4th and 5th years of reclamation, representing the boundary of the FGD gypsum dissolution stage, which was followed by the soil reclamation maintenance stage. In the FGD gypsum dissolution stage, soil salinity was dominated by Ca2+ that accumulated in the 0–10 cm soil layer. Over time, the exchangeable Ca2+ concentration decreased with soil depth to 40 cm. In the reclamation maintenance stage, FGD gypsum was basically depleted, but the sodicity still showed a significant decrease compared with that in the initial soil. These results indicate that FGD gypsum can significantly and effectively reclaim sodic soil in paddy fields for at least 7 years. Though the FGD gypsum was exhausted 5 years after its application, reclamation continued to be maintained due to the presence of exchangeable Ca2+.

Microbial community variation and its relationship with soil carbon accumulation during long-term oasis formation

The conversion of desert to farmland may change not only surface soils but also deeper soils due to massive irrigation and fertilization. However, limited information exists on the response of microorganisms throughout the soil profile to long-term crop development in desert regions. The shifts in the microbial community were investigated in relation to soil depth (0–2 m) and years of reclamation, as well as their relationship to soil organic carbon (SOC) dynamics in an irrigated arid area of northwest China. Oasis farmlands cultivated for 3, 5, 10, 20, 50, and > 100 years were compared with adjacent deserts. Total phospholipid fatty acids (PLFAs), bacterial PLFAs, and microbial biomass and activity within the whole profile increased from the beginning of farming and peaked at 20 years post-reclamation. Fungal and actinomycete PLFAs decreased in the beginning of reclamation but increased after 10 years and peaked at 20 years. Microbial community composition was dynamic within the first 10 years of reclamation and tended to become stable thereafter. During oasis formation, the carbon to nitrogen ratio of microbial biomass decreased from 9.0–10.5 to 7.2–8.0; the fungi to bacteria ratio decreased from 0.3–0.5 to 0.2–0.3, and the gram-positive to gram-negative bacteria ratio (GP:GN) increased from 0.3–0.4 to 0.4–0.6. Increases in microbial abundance and shifts in community structure were positively correlated with SOC accumulation. Redundancy analysis indicated that microbial changes were closely associated with increased soil moisture and nutrients and decreased salinity and pH. We believe the predominant factor driving microbial community shifts and soil carbon accumulation is the increased input of plant residue due to enhanced water and nitrogen availability after desert reclamation. This study emphasizes the significance of the microbial changes and the close association between increased GP:GN and SOC accumulation during oasis formation, especially in deeper soils (0.6–2.0 m).

The Changes in Physicochemical Properties in Soils Subjected to Many Years of Reclamation

The Changes in Physicochemical Properties in Soils Subjected to Many Years of Reclamation