Restoration Of Soil Properties Research Articles

Assessment of the Ecotoxicity of Platinum Oxide Based on the Biological Indicators of Ordinary Black Earth

The effect of contamination of ordinary black earth with platinum oxide (PtO2) on biological properties: root length and germination of radish, total number of bacteria, abundance of bacteria of the genus Azotobacter, activity of catalase and dehydrogenases have been studied. The concentrations studied were 0.01, 0.1, 1, 10 and 100 mg/kg in 10, 30 and 90 days after contamination. A stimulating effect (hormesis) of platinum oxide at a concentration of 0.01 mg/kg on the biological properties of ordinary black earth was recorded. It was found that in other cases, platinum oxide has a negative effect on the studied parameters, and exhibits the greatest toxicity after 30 days after contamination, followed by restoration of soil properties after 90 days. It was concluded that the most sensitive (highest degree of reduction) indicators to platinum oxide contamination were the total number of bacteria, germination and length of radish roots. Early diagnosis of the degree of soil contamination with platinum compounds is recommended in order to obtain a prompt assessment of the impact and prevent possible negative consequences.

Effect of composite organic amendment on Cd(II) ions stabilization and microbial activity under various ammonium sulfate levels

To attenuate the risk of Cadmium(Cd) contamination and the deterioration of soil quality caused by excessive nitrogen fertilizer application in greenhouse, a composite organic amendment (spend mushroom substrate and its biochar) was prepared to remedy Cd(II) ions contaminated soil (0.6 mg/kg) under different N fertilizer levels. The results showed that in the absence of a composite organic amendment, the soil pH decreased by 0.15 when the N level increased from 0.1 to 0.8 g N⋅kg−1. However, the pH increased by 0.86–0.91, the exchangeable Cd(II) ions content decreased by 26.0%–26.7%, the microbial biomass increased by 34.34%–164.46%, and the number of copies of the AOB gene increased by 13–20 times with the application of composite organic amendment and the increase of N level. Both Pearson correlation analysis and Mantel test demonstrated the reduction in Cd(II) ions availability, the restoration of soil properties and the increase in microbial biomass all contributed to the composite organic amendment, which is of importance for soil remediation under excessive N fertilizer.

Об экосистемных функциях гумусогенного слоя технозёмов в отдалённый период землевания отвалов угледобычи в Сибири

People strove for creating productive soils to increase the yield of cultivated crops since prehistoric times. Currently, restoration of soil properties is relevant for areas affected by mining. In Siberia, long-term coal mining has led to significant destruction of the soil cover, accumulation of overburden and host rocks on the daytime surface. This initiated the search for resource-saving technologies to compensate for soil losses, including methods of formation of artificial soil-like bodies with a deposited fertile layer for subsequent agricultural use. This article presents the results of a study of physicochemical and microbiological properties of the humus-accumulative layer after 40 years of man-made wasteland soiling in three natural zones (sub-taiga, forest-steppe, dry-steppe) in order to characterize the ecosystem functions that ensure fertility. It was established that the humus layer of perennial technogenic soils (technozems) has ecosystem functions of background soils, however, in the forest-steppe and dry-steppe zones it shows signs of decreased resistance to elevated pH, increased ecotoxicants, reduced organic carbon reserves and a pool of metabolic active nitrogen-fixing bacteria. In arid conditions, the greatest biogenic depletion of technozems is diagnosed, the manifestation of an inertial mutation of bacterial populations, ensuring their dissociation and preservation in extreme habitats. The information can be used to characterize ecosystem functions and ecosystem services of long-term technozems, in forecasts of the effectiveness of man-made wasteland management in different natural zones, and taken into account in the development of nature-like technologies.

How does forest restoration affect the recovery of soil quality? A global meta‐analysis for tropical and temperate regions

Restoring forest ecosystems to reverse soil degradation is critical to maintain environmental quality, forest and agricultural productivity, biodiversity conservation, and to provide valuable ecosystem services. Yet the impacts of forest restoration on soil quality remain under‐investigated. Here we aim to address a key knowledge gap: how does forest ecosystem restoration affect the recovery of soil quality in tropical and temperate regions? We conducted a global meta‐analysis to compare soil physical, chemical, and biological properties between restoring forests and reference old‐growth/less‐disturbed forests. We revealed for the first time that differences between restoring and reference forests are lower for physical (12–25%; based on median values of effect size) and chemical (10–74%) properties than for biological (32–90%) properties. More specifically, bulk density (12% of difference), pH (10%), and enzyme activity (32%) had mean values in restoring forests closer to those observed in reference forests. Overall, our results suggest that the restoration of soil properties was greater in tropical regions, after longer periods (>30 years), through passive restoration, and over pasturelands. Our global meta‐analysis helps to fill the soil information gap in forest restoration and increase our understanding of how to improve soil quality through forest restoration and soil monitoring processes in tropical and temperate regions.

Assessment of revegetation with waste coal on the reclaimed sites in the Kemerovo Region – Kuzbass

The paper presents the results of research and assessment of the revegetation degree in reclaimed areas using coal preparation waste in the Kemerovo region – Kuzbass. Reclamation of disturbed lands was carried out by backfilling the worked-out pits of the former coal mine with coal preparation waste and forming a root layer on the leveled surface of the waste using materials of the fertile soil layer (FSL) and potentially fertile rocks (PFR). During the field survey of reclamation sites, it was found that when sowing perennial grasses (Bromopsis inermis, Medicago sativa, etc.) or planting trees and shrubs (Hippophae rhamnoides, Pinus sylvestris, etc.) on the formed root layer from the PFR and / or FSL, favorable conditions are created for the formation of the primary phytocenosis in the reclaimed areas. The studies also showed that in reclaimed areas using a fertile soil layer for the formation of a root layer, a gradual restoration of soil properties is recorded in the surface covered layers, which in some parameters are close to natural soils common in the adjacent territories.

Efficiency of leaf litter mulch in the restoration of soil physiochemical properties and enzyme activities in temporary skid roads in mixed high forests

Various engineering measures, such as mulching, have been applied on decommissioned skid trails to suppress the adverse effects of overland flow and flood hazards. However, very little research has been done on the effects of such treatments on soil recovery. The aim of this study is to determine the effectiveness of different leaf litter levels on the restoration of soil properties and enzyme activity, when spread on decommissioned skid trails over a four-year period after soil compaction. In total, 90 soil samples in 18 runoff plots were measured under six treatments, including undisturbed (control) treatment, UND; untreated skid trail, U; and four levels of leaf litter, LML1, LML2, LML3, and LML4, with levels of 0.42, 0.81, 1.31, and 1.69 kg m−2, respectively. Soil bulk density and penetration resistance under the litter mulch treatments were lower than that under the U treatment, and at the lowest in the UND treatment. The total porosity, macroporosity, and aggregate stability were at the highest level in UND, followed by LML4 ≈ LML3 > LML2 ≈ LML1. Soil organic C, total N, C/N ratio, C and N sequestration, available nutrients (i.e., P, K, Ca, and Mg), and fulvic and humic acids were at the highest level in UND followed by LML4, and at the lowest level in U followed by LML1 ≈ LML2. The highest earthworm density and dry mass, fine root biomass, soil microbial respiration, microbial biomass carbon, NH4+, NO3−, nitrogen mineralization, and microbial biomass nitrogen were measured in UND, followed by LML4. Compared with U, all litter mulch treatments enhanced enzyme activity. Four years after mulch application, the values of soil biological and microbial properties and enzyme activity were significantly higher in LML4 ≈ LML3 followed by LML2 ≈ LML1, compared to U, but were still lower than the values of the UND treatment. We can conclude that the increased levels of leaf litter mulch moderately improved soil physio-chemical, biological, and microbial properties, as well as enzyme activity, after mechanized operations over a four year period, compared to the U treatment. However, the values of soil properties and enzyme activity were still lower than those in the UND treatment, indicating that four years is not long enough to restore the soil properties to pre-harvest levels in the study area. In conclusion, leaf litter level of LML3 with 1.31 kg m−2 can be applied as an optimal level for spreading leaf litter on skid trails to modify and enhance soil quality.

The effect of exclosures on restoration of soil properties in Ethiopian lowland conditions

Land degradation is one of the environmental challenges in the semi-arid areas of Africa such as Ethiopia. To tackle this problem, exclosures have been established on degraded open grazing lands. However, there was paucity of research regarding their ecological merits, especially in the lowlands of Tigray, Northern Ethiopia. Hence, this study was conducted to explore the effect of conversion of grazing lands to an exclosure on soil chemical properties and soil organic carbon stock (SOC stock) in Tselemti district, which was taken as testing site to represent the lowlands of Tigray. A total of 36 plots (18 from grazing land and 18 from exclosure), measuring 20 m × 20 m, were established along 6 transects for soil sampling. From each plot, 1 composite soil sample for analyses of total nitrogen (TN), available phosphorus (avP), cation exchange capacity (CEC), electrical conductivity (EC), available potassium (avK), soil pH and soil organic carbon content (SOC) and 1 undisturbed soil sample for soil bulk density (BD) determination was collected from a depth of 0–30 cm. Hence, a total of 72 soil samples (36 for nutrients and 36 for bulk density analysis) were analyzed in the laboratory. Paired samples t test statistics at 5% level of significance using SPSS version 20 was used to compare the land uses. Pearson correlation test was also used to analyze the relationship among the different soil properties. The study showed that the conversion of open grazing land to an exclosure enhanced most of the soil properties except soil pH, avP and EC. The results revealed that the exclosure had significantly (p < 0.05) higher SOC (1.89 ± 0.1 and 1.29 ± 0.06) and SOC stock (73.61 ± 4.9 and 45.64 ± 2.57 Mg ha−1), indicating an improvement by 46.5 and 61.3% as compared to the grazing land. Similarly, it enhanced CEC, TN and avK level significantly (p < 0.05) by 16.8, 45.5 and 34%, respectively. It can be concluded that conversion of open grazing lands to exclosures is a viable option to restore degraded soils. For this reason, additional exclosures have to be established on previously degraded open grazing lands in the area and areas with similar biophysical setup.

Spatial variability of soil properties in relation to land use and topography in a typical small watershed of the black soil region, northeastern China

Soil degradation resulted from unreasonable land use and erosion has been a serious problem in the black soil region of northeastern China. This paper seeks to understand the relationships between topsoil properties and topography and land use for land management targeting at improving soil quality in this region. A total of 292 soil samples and 81 volumetric rings were taken from a typical small watershed of the region in June 2005 for examining total carbon (TC), total nitrogen (TN), soil texture (clas- sified into gravel, sand, silt, and clay), and bulk density (qb), respectively. Spatial variability of these soil proper- ties was evaluated with classical statistics and geostatistics methods. The results of classical statistics indicated that TC, TN, sand, silt, clay content, and qb were moderate variables while gravel had great variability. Soil properties were mainly correlated to slope position, elevation and land types. Geostatistical analyses showed that the spatial autocorrelation for TC, TN, and silt was weak, strong for clay and moderate for and qb sand, respectively. The spa- tial variations of soil properties are affected comprehen- sively by topographic factors, land use, erosion, and erosion control in this watershed. Past erosion, however, is the most important component to induce change of soil properties. In this small watershed, current soil and water conservation measures play an important role in controlling soil loss. But the restoration of soil properties was unsat- isfactory. Comparing with untilled soil of this region, TC, TN, silt content are excessively low; whereas qb, sand and clay content are excessively high; gravel appears at most sampling locations. It is necessary for improving soil properties to protect forest and grassland and change cul- tivation system of farmlands.