Soil Physical Conditions Research Articles

Influence of soil properties and burial depth on Persian oak (Quercus brantii Lindl.) establishment in different microhabitats resulting from traditional forest practices

In seasonally dry environments such as the Zagros woodlands (Iran), severe drought stress and lack of appropriate management practices can cause failure of oak afforestation or reforestation. We investigated the effect of soil properties and burial depth on Persian oak (Quercus brantii Lindl.) establishment in different microhabitats resulting from traditional forest practices. Four microhabitats that were based on forest structure were considered for oak acorn seeding: (1) inside old sprout clumps (ISPC); (2) under the canopy of tall trees (UCTT); (3) outside the canopy of tall trees and sprout clumps; and (4) near recent stumps or sprout clumps. Acorns were seeded at two depths (2 and 5 cm), and seedling survival and growth variables were recorded for 4 years, together with soil chemical and biological attributes. Stepwise discriminant analysis showed that a combination of total soil nitrogen, cation exchange capacity, available phosphorus and potassium, litter depth, microbial quotient, metabolic coefficient, substrate-induced respiration and earthworm abundance was the best variables to characterise the microhabitats. With the exception of pH, bulk density and soil texture, these variables were higher in UCTT and ISPC than in the other microhabitats. Seedling emergence and survival were greater at a seed depth of 5 cm than at 2 cm. Seedling height and shoot, root and leaf biomasses were higher in the UCTT microhabitat compared to the other microhabitats and correlated positively with soil nutrients contents and most of the soil biological variables but negatively with soil bulk density. This study emphasised the role of microhabitats in creating a “canopy effect” producing favourable physical, chemical and biological soil conditions. In particular, large oak trees form islands of fertility and therefore are of key importance for successful seedling establishment in forests subjected to intense human activities.

Electromagnetic techniques in geoenvironmental engineering

The interaction of electromagnetic waves with matter is sensitive to various temporal and spatial scales. This allows probing the dynamics and structure of molecular processes at interfaces, macroscopic structural states of porous materials as well as altering of rock formations in the subsurface. Hence, high-frequency (radio to microwave) electromagnetic sensing techniques offer the possibility to monitor variations of soil physical state parameters, for example, the volume fraction of free pore water, with high spatial (from centimetre to kilometre) and temporal (from seconds to years) resolution. Against this background, these techniques become increasingly used in geotechnical and geoenvironmental engineering in order to quantitatively explore and examine soil both in laboratory and field investigations.

Effect of nitrogen and sulphur fertilizer levels on growth, yield and oil content of Linseed (Linum usitatissimum L.) in Sinana, South-Eastern Ethiopia

The experiment was conducted on research field of Sinana Agricultural Research Center (SARC), in the highlands of Bale, South-eastern Ethiopia during the main cropping season of 2013 to investigate the effect of nitrogen and sulphur on growth, yield and oil content of linseed. A factorial combination of four rates of N (0, 23, 46, 69 kg ha -1 ) with four rates of S (0, 20, 40 and 60 kg ha -1 ) was applied in randomized complete block in three replications. Analysis of variance revealed that the main effect of nitrogen significantly affected all tested parameters except for days to 50% emergence, number of seeds per capsule and stand count per meter square. In these study, most of yield and yield components of the crop lacked significant response to the application of sulphur. This might be due to the fact that sulphur content of the soil of the study site was medium. On the other hand, the interaction effect between nitrogen and sulphur was only significant for days to 50% emergence. Linseed crop grown without nitrogen application exhibited the highest seed oil content (40.7%). The economic analysis revealed that the highest net return of Birr 31980 ha -1 and the highest marginal rate of return 5045.21% were obtained from the treatment that received 23 kg N ha -1 . Therefore, for farmers cultivating linseed in Sinana and areas with the same soil chemical and physical conditions, application of 23 kg N ha -1 is sufficient for obtaining optimum seed and oil yield of the crop, with no need to apply sulphur as a fertilizer. However, to come up with a conclusive recommendation, the experiment should be repeated over seasons and locations.

To the question of conditions, factors and criteria of geodynamic risk in the boundaries of urban areas

Formulation of the problem Loess deposits are widespread. They are characterized by the singular difficult deformations, therefore, their structure collapses. We have shown in the previous researches that in a zone of influence of the city properties of rocks change over time. Physical condition and gradation of microaggregates change over time as well. As a result, complex changes of physical properties occur. The duration of moistening affects the type and magnitude of the changes. Microaggregates do not disintegrate when the duration of moisture is short. When the duration of moisture is long, disintegration of the microaggregates is accompanied by the re-packaging and increasing of the endurance.The purpose of the article. The forecast of relative subsidence values and endurance can be performed using statistical analysis and group accounting method arguments. In this paper, we show the possibilities of forecasting using the example of a concrete construction site.Methods. Statistical method and the method of inductive modeling by group accounting of arguments were used in prognostic researches. In calculation of subsidence in the zone influences and stability analyses we used standard methods.Results. The object of research is an elementary natural and technical system formed by a projected building. The house will be built in the zone of distribution of loess’s (the erosion basin Vstrechnaya, Dnipro). The groundwater level in erosion basin is at a depth of 0.5 to 14.0 m. The magnitude of the increase of Groundwater level is 1.55 m from the modeling results in the research area. According to the results of multi-year data statistical analysis, close correlation relations between the property indices, regression between indicators of the physical state was found. The forecast values of mechanical properties' indicators are established as the results of inductive modeling with the method of group accounting of arguments. The forecast values of humidity and other indicators of the physical state, the content of individual fractions were set as well. The values were calculated to characterize a moderate and intensive change in soil properties in comparison with the natural state. Deformation calculations in the ground base and stability analysis were performed by standard analytical methods.Scientific novelty and practical significance. The following variants of events were considered: long-term or short-term humidification, complete or selective change in indicators of the physical condition of soils and microaggregate structure. The loss of strength is most likely to happen in case of emergency soaking of soils when the physical state changes but dispersion do not change.

Soil Physical and Environmental Conditions Controlling Patterned-Ground Variability at a Continuous Permafrost Site, Svalbard

This study examines soil physical and environmental conditions controlling patterned-ground variability on an alluvial fan in a continuous permafrost landscape, at Adventdalen, Svalbard. On-site monitoring of ground temperature, soil moisture and snow depth, laboratory analyses of soil physical properties and principal component analysis indicate that the distribution of patterned ground depends primarily on soil texture, soil moisture and the winter ground thermal regime associated with snow cover. Mudboils and composite patterns (mudboils surrounded by small polygons) occupy well-drained areas composed of clay-rich aeolian sediments. Compared to mudboils, composite patterns show a sharper contrast in soil texture between barren centres and vegetated rims. Hummocks filled with organic materials develop on poorly drained lowlands associated with a shallow water table. Ice-wedge polygons are dominant on sandy loess-covered areas where the local wind regime minimises snow cover, enhancing ground cooling that promotes thermal contraction cracking. Copyright © 2016 John Wiley & Sons, Ltd.

Сезонна динаміка щільності складення чорнозему опідзоленого західного Лісостепу України за різного використання в агроценозах

Soil as multicomponent organized and complex ecosystem has a number of important ecosystem functions. Fertility is the most integrated of it, which is directly connected with all the functions and properties of the soil and is the result of effective cooperation. Thus, essential for optimal functioning of soil fertility is implementing its agrophysical properties that are the basis of the formation of high and stable crops yields. A special place to optimize the agrophysical properties takes soil structure density, which is the most objective and comprehensive summary measure. This statement came through the work of Y. B. Revuta, and his followers. These works had significant impact on the soil science development; thru bulk density peoples began to assess soil physical condition and its changes due to human impact. Soil compaction is the main reason of it productivity reducing. Plants feel strong anoxia when soil density index falls below 15%. Over compaction reduces soil biological activity, including nitrification, total number of cellulose destructors and actinomycetes. Soil density increase in 0.1 g/cm3 compared to an optimum – course crops yield reduction by 15-20%, and 0.2 g / cm3 - 50%. Soil structural condition, bulk density, water-physical properties, crop productivity are largely dependent on its tillage type, nutrient management in crop rotation. Tillage (especially deep plowing) and fertilization significantly change the natural structure of black soil. Thus, the result of years of plowing at the same depth a dense plow sole is formed. It affects many soil processes, especially in water, temperature and soil gas regime. V. D. Mukhas’ found that one of the main signs of land degradation indicators are bad soil structure and density structure of the soil during the growing season. Vladimir Medvedev says’ that mechanical tillage and soil structural changes caused by it are the main reason of water-physical properties degradation in arable land. Fedorovskyi D.V. notes’ that high soil density make soil water and nutrients unavailable for plants. Wheat roots do not penetrate into the layers of soil with a density of 1.65, roots of vegetables - 1.45 g / cm3. Apple trees are not durable if there is compaction layer under 1.55 in 2 meter layer of medium loamy soil, and more than 1.30 g/cm3 on clay soils. Kopytko P.G. indicates that density of soil with loamy texture (20-80 cm layer) in root zone under highly productive apple orchards is around 1.2-1.3 g/cm3. Therefore, these figures can be considered as an optimal for the functioning of the root system and fruit crops nutrition. In particular, it is known that manure as an organic improves soil physical, chemical, agrophysical properties and humus regime. Nowadays manure becomes irrelevant from economic point of view. Therefore against the backdrop of rising rates agrotehnogenesys in the literature there are more and more reports of adverse changes in the properties of soils under the influence of mineral fertilizers. Thus, G.V. Dobrovolsky indicates that fertilizer even in small doses lead to dispersion structure, reduced agrigates strength, reducing the visible poroznosti and increase bryluvatosti (Dobrovolski, 1983). That is why additional study of the effect of different soil tillage and nutrition plans on podzolic chernozem bulk density in different soil-climatic and farm specific conditions is needed.

English

Brazilian semi-arid soils can be dystrophic and often occur in areas with high agricultural potential. Gypsum application improves chemical and physical soil conditions, favoring root system development of plants and can improve sugarcane production for energy production, as a strategy for sustainable development, avoiding native vegetation destruction in semi-arid regions. This study aimed to analyze the impact of gypsum application on the agro-energy potential of three sugarcane varieties, through MS production, moisture, neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, ash and gross calorific value (GCV). The experimental design consisted of 3 (varieties) x 2 (with and without gypsum) over two sugarcane growing periods in a completely randomized block design with four replications. The application of gypsum did not affect the tested agro-energy variables. GCV ranged around 17 MJ kg-1, confirming the suitability of the varieties for bioenergy use in semi-arid regions, but there were no significant differences between sugarcane varieties. Key words: Bioenergy, Saccharum spp, gross calorific value, oxisoils; soil amendments.

Artificial macropores attract crop roots and enhance plant productivity on compacted soils

The structure of compacted soils is characterised by decreased (macro-)porosity, which leads to increased mechanical impedance and decreased fluid transport rates, resulting in reduced root growth and crop productivity. Particularly in soils with high mechanical impedance, macropores can be used by roots as pathways of least resistance. This study investigated how different soil physical states relate to whole plant growth and whether roots grow towards spots with favourable soil physical conditions. Experiments were conducted under controlled and field conditions. Soybean (Glycine max L.), wheat (Triticum aestivum L.) and maize (Zea mays L.) were grown on uncompacted soil, compacted soil and compacted soil with artificial macropores. The interactions between roots and artificial macropores were quantified using X-ray computed tomography. Active growth of roots towards artificial macropores was observed for all three species. Roots grew either into macropores (predominantly in maize) or crossed them (predominantly in wheat). The presence of artificial macropores in compacted soil enabled all three species to compensate for decreased early vigour at later developmental stages. These results show that roots sense their physical environment, enabling them to grow towards spots with favourable soil conditions. The different kinds of root-macropore interaction indicated that macropores serve as a path of least resistance and a source of oxygen, both resulting in increased crop productivity on compacted soils.

Corn stover harvest and tillage impacts on near-surface soil physical quality

Excessive harvest of corn (Zea mays L.) stover for ethanol production has raised concerns regarding negative consequences on soil physical quality. Our objective was to quantify the impact of two tillage practices and three levels of corn stover harvest on near-surface soil physical quality through the Least Limiting Water Range (LLWR). We evaluated no harvest, moderate and high stover harvest treatments within no-tillage and chisel plow plots following seven years of continuous corn production. Forty undisturbed soil samples were taken from the 0–7.5cm deep layer within each treatment and used to determine water retention curves, soil resistance to penetration and bulk density values (Bd). No-tillage plots had higher average soil bulk density and resistance to penetration values, and were more affected by stover harvest than chisel plow plots. The results confirmed that soil resistance to penetration determined the lower limit of the LLWR regardless of tillage or stover treatment, whereas soil aeration controlled the upper limit only at Bd>1.45 and Bd>1.55Mgm−3 for chisel plow and no-tillage, respectively. The LLWR was smallest for no-tillage with moderate or high corn stover harvest, indicating poor soil physical condition for plant growth, while the largest LLWR occurred with moderate stover harvest and chisel plowing. The introduction of alfalfa (Medicago sativa L.) into an extended rotation with no-tillage improved the LLWR by reducing the potential crop growth restriction due to resistance to penetration. Although bulk density values were only occasionally higher than the critical level (Bd=1.60Mgm−3 for chisel plow and Bd=1.64Mgm−3 for no-tillage), lower soil structure quality was evident with no-tillage under moderate or high stover harvest and with chisel plowing under high stover removal. The LLWR was more sensitive than available soil water content for detecting tillage and stover harvest effects on soil structural degradation.

Managing land application of coal seam water: A field study of land amendment irrigation using saline-sodic and alkaline water on a Red Vertisol

Coal seam (CS) gas operations coproduce water with gas from confined CS aquifers. This CS water represents a potential agricultural resource if the water is able to be chemically amended to comply with management guidelines. Stoichiometric quantities of sulphur and gypsum amendments can be used to neutralise the alkalinity and reduce the sodicity of CS water respectively. These amendments can either be mixed in-line at a water treatment plant or applied directly to land prior to the application of CS water (a practice termed land amendment irrigation - LAI). This study compared the efficacy of LAI with in-line chemical amendment of CS water and irrigation with non-saline, non-sodic and non-alkaline (good quality) water under field conditions in southern Queensland. Soil chemical properties, soluble Ca, Mg, K, Na, electrical conductivity (EC), pH, chloride and alkalinity, as well as saturated hydraulic conductivity were measured to determine the impact of the irrigation treatments on soil chemical and physical conditions. Irrigation of lucerne pasture using solid-set sprinklers applied a total of 6.7 ML/ha of each treatment irrigation water to the experimental plots over a 10-month period. Alkalinity was neutralised using LAI, with no increase in soil alkalinity observed. Soil sodicity did not exceed threshold electrolyte concentration values under either CS water irrigation treatment. Soil chemical and physical properties were comparable for both LAI and in-line chemical amendment of CS water. Soil saturated hydraulic conductivity was maintained under all irrigation treatments. Results showed that the constrained capacity of the irrigation system was unable to meet crop evapotranspiration demand. This resulted in accumulation of salt within the root-zone under the CS water treatments compared to the good quality water treatment. LAI successfully chemically amended Bowen Basin CS water facilitating its beneficial use for agricultural irrigation.

Does the harvest of logging residues and wood ash application affect the mobilization and bioavailability of trace metals?

Residue biomass from conventional forestry, such as slash (i.e., tree tops and branches) and stumps, are used at an increasing rate for energy purposes in Sweden. This review examined current knowledge on how extraction of forest biomass for large-scale energy production, including the practice of ash application for nutrient recycling, influences the mobility and stocks of trace metals in the forest environment at different time scales. The study focussed on Swedish energy production systems and contemporary forest management practices, as well as the heavy metals lead (Pb), cadmium (Cd) and mercury (Hg). The historic accumulation of these elements in forest soils has mainly originated from diffuse, long-term atmospheric deposition.There is little conclusive evidence that slash harvest generally increases the risk for mobilization of trace metals from soils during the regeneration phase, compared with stem-only harvesting. However, microbial transformation of mercury into the highly toxic methyl mercury (MeHg) species is facilitated in suboxic soil conditions that may increase during the regeneration phase. Therefore it has been hypothesized that stump harvest could result in increased mercury methylation and transport to surface waters, owing to stump harvest effects on soil physical conditions and hydrological pathways. The few studies available on the stump harvest effects of Hg showed no consistent difference in runoff from clear-felled and stump harvested catchments compared to clear-felled and soil-scarified catchments in terms of concentrations or fluxes of MeHg.Assuming that the highest trace metal concentrations in wood ash recommended by the Swedish Forest Authority are not exceeded, wood ash application does not currently increase metal loads at the national scale, because trace metal export in harvested biomass is much larger than that returned in wood ash. The net load of Pb, Cd, and Cu will not increase at the local scale if ash doses do not greatly exceed the compensation for nutrients exported in harvested biomass. Biomass harvest and ash application have negligible effects on the load of mercury to forest soils.A large number of studies have examined the effects of wood ash on trace metal content in soil, water and biota. Most studies showed no effect of wood ash application. When increased concentrations were found (Cd, Cr, Cu, Zn), this was in soils where concentrations remained well below harmful levels. Relatively fewer reports of increased concentrations are reported for soil water and plants, and no effects were reported for edible berries or fungi.

Condição física e desenvolvimento radicular de gramíneas em solo construído após mineração de carvão

Resumo O objetivo deste trabalho foi avaliar a condição física e a potencialidade de uso agrícola de um solo construído após mineração com carvão, além do desenvolvimento radicular de gramíneas tropicais nesse solo, tendo-se considerado diferentes períodos de revegetação. O solo foi construído no início de 2003, e o experimento instalado em novembro/dezembro de 2007. A condição física do solo construído foi avaliada nas parcelas ocupadas por gramíneas perenes, como Urochloa humidicola, Panicum maximum e U. brizantha. Em julho de 2012, foram coletadas amostras de solo com estrutura preservada e não preservada para a determinação dos atributos físico-químicos, nas camadas de 0,00-0,10, 0,10-0,20 e 0,20-0,30 m. Monólitos de solo foram coletados para caracterização do sistema radicular das diferentes gramíneas. Após 58 meses de revegetação, a condição física do solo construído ainda é inadequada ao uso agrícola que envolva práticas mais intensivas de manejo de solo. Entre as camadas avaliadas, somente a de 0,00-0,10 m fornece condições para que o solo cumpra suas funções no ecossistema. Urochloa brizantha mostra-se mais promissora para a recuperação da estrutura do solo na camada de 0,00-0,10 m, e a densidade radicular foi o atributo mais sensível para a diferenciação do desenvolvimento potencial das diferentes espécies nesta camada.

Estimation of soil structure and physical state in the seedbed under different tillage and environmental conditions

Estimation of soil structure and physical state in the seedbed under different tillage and environmental conditions

Adopting soil organic carbon management practices in soils of varying quality: Implications and perspectives in Europe

Soil organic carbon (SOC) content can greatly affect soil quality by determining and maintaining important soil physical conditions, properties and soil functions. Management practices that maintain or enhance SOC affect soil quality and may favour the capacity of soils to sequester further organic carbon. Nevertheless, the effectiveness of these measures depends upon both the soil characteristics and the current SOC content.This study defines an indicator of soil potential stability (n-potential) allowing the most effective practices in terms of soil stability and capacity to store organic carbon to be selected. By relating the clay content to SOC content, the n-potential indicates the “potential” presence of non-complexed clay (NCC) in soils, enabling the soil stability and its capacity to store carbon (C) to be inferred. In this work, we classify soils of European regions based on five n-potential categories (i.e. >20; 15–20; 10–15; 5–10; <5). By relating the information provided by the n-potential to the specific texture of the analysed soils, priority actions (i.e. protecting the existing soil stability or promoting soil aggregate formation) that should be adopted are identified. Our findings show that the selection of the appropriate SOC management practices can greatly contribute improving soils of European regions in terms of quality and capacity to store organic carbon.The n-potential contributes to the understanding of the physical consequences on soils arising from implementation of SOC management practices. This can guide the development of policies promoting the application of such practices, and can help farmers to select the practices that are most effective in maintaining or increasing of SOC content and soil stability.

Bicultures of oat (Avena sativa L.) and grazing vetch (Vicia dasycarpa L.) cover crops increase contents of carbon pools and activities of selected enzymes in a loam soil under warm temperate conditions

ABSTRACTThis study evaluated effects of oats (Avena sativa L.) and grazing vetch (Vicia dasycarpa L.), bicultures, in rotation with summer maize (Zea mays), on soil organic matter fractions and activities of selected enzymes. The trial was initiated in April 2009. The treatments were 100% oat, 100% vetch, 90% oat + 10% vetch, 70% oat + 30% vetch, 50% oat + 50% vetch, and weedy fallow, in a randomized complete block design (RCBD) with three replications. Soil samples were collected in October 2011, from the 0–5 and 5–20 cm depths, and analyzed for total carbon (C), particulate organic matter (POM), water-soluble carbon (WSC), microbial biomass carbon (MBC) and activities of selected enzymes. Total C was higher in bicultures, particularly the 70% oat + 30% vetch, and 100% vetch than in 100% oats and the control. The greatest MBC, WSC, dehydrogenase, aryl-sulphatase and phosphomonoesterase activities were in the 70% oat + 30% vetch biculture, and declined where the proportion of oats or vetch was higher. Increasing proportions of vetch resulted in increases in urease and β-glucosidase activity and decrease in POM. The findings suggested that, in addition to increased maize yields, bicultures of oats and vetch also have synergistic effects on soil carbon pools and enzyme activities, with potential benefits of improved soil physical condition and nutrient cycling compared with the individual crops, under warm temperate conditions.

Organic compounds with high Ni content: Effects on soil and strawberry production

ABSTRACT The use of organic residues can improve soil chemical and physical conditions and plant growth. However, these residues often contain heavy metals that can interfere with growth. Here, a pot experiment was performed to compare the effects of organic compound (OC) containing a high nickel (Ni) load with those of a mineral Ni source (NiCl2, a soluble salt) on the production, quality and nutritional status of strawberry and on soil chemistry. Six dosages of Ni (0, 9, 18, 36, 72 and 144 mg kg-1) were added to the soil using both OC and NiCl2. The use of high-Ni OC resulted in increased productivity and fruit weight, whereas the soluble NiCl2 salt caused reduction in fruit weight. Application of NiCl2 at concentrations &gt;18 mg kg-1 also caused internerval chlorosis on leaves, suggesting that strawberry is highly sensitive to Ni. The mineral Ni source was almost 15-fold more effective than the organic source at increasing leaf Ni content. Application of OC caused an increase of organic matter, Ca, sum of bases, cation exchange capacity, base saturation, Zn, Mn, and Cu, but reduced the levels of Mg in soil.

Simulated annual changes in plant functional types and their responses to climate change on the northern Tibetan Plateau

Abstract. Changes in plant functional types (PFTs) have important implications for both climate and water resources. Still, little is known about whether and how PFTs have changed over the past decades on the northern Tibetan Plateau (NTP) where several of the top largest rivers in the world are originated. Also, the relative importance of atmospheric conditions vs. soil physical conditions in affecting PFTs is unknown on the NTP. In this study, we used the improved Lund–Potsdam–Jena Dynamic Global Vegetation Model to investigate PFT changes through examining the changes in foliar projective coverages (FPCs) during 1957–2009 and their responses to changes in root zone soil temperature, soil moisture, air temperature, precipitation and CO2 concentrations. The results show spatially heterogeneous changes in FPCs across the NTP during 1957–2009, with 34 % (13 %) of the region showing increasing (decreasing) trends. Dominant drivers responsible for the observed FPC changes vary with regions and vegetation types, but overall, precipitation is the major factor in determining FPC changes on the NTP with positive impacts. Soil temperature increase exhibits small but negative impacts on FPCs. Different responses of individual FPCs to regionally varying climate change result in spatially heterogeneous patterns of vegetation changes on the NTP. The implication of the study is that fresh water resources in one of the world's largest and most important headwater basins and the onset and intensity of Asian monsoon circulations could be affected because of the changes in FPCs on the NTP.

Soil aggregation and root growth of perennial grasses in a constructed clay minesoil

Studying constructed soils (anthropogenic) in mined areas provides an opportunity to expand the existing knowledge about the formation and stabilization of aggregates, due to the magnitude of ecosystem disruption, that creates a “zero time” scenario. The aim of this study was to evaluate the relationship between the aggregation and the root growth of perennial grasses 103 months after the reconstruction of a constructed minesoil, in a coal mining area located in Candiota/Rio Grande do Sul State, Brazil. The evaluated plant species were Hemarthria altissima, Paspalum notatum cv. Pensacola, Cynodon dactylon cv. Tifton, and Urochloa brizantha. The grass roots promoted the recovery of the soil physical condition in the 0.00–0.10m layer, with a decrease in dry bulk density and an increase in soil macroporosity related to the formation of new aggregates. The decrease in root development of all species below 0.10m depth is the result of the restrictive soil physical conditions, with high bulk density and low macroporosity related to aggregates formed originally by compression. The results of root and soil attributes found in this study suggest a different soil-aggregation hierarchy in compacted constructed minesoils, where first a disintegration occurs of large cohesive aggregates formed by compression followed by a re-aggregation process, with sequential re-formation and stabilization of aggregates. The Urochloa brizantha showed a greater root density, volume, length and area, thus presenting a greater potential to recover the physical attributes of the degraded areas, especially those in the compacted layer below 0.10m depth. The recommendation of this and other species in the reclamation of constructed soils after coal mining should take into account the thickness of the topsoil layer because the roots of these species can grow into the overburden layers and thus accelerate the sulfurization process. The recovery of physical attributes of the constructed minesoil, especially below the 0.00–0.10m layer, is a slow process, possibly due to the low accumulation rates of organic carbon in this layer.

Soil physical properties of agriculturally reclaimed area after lignite mine: A case study from central Poland

For the assessment of the extent of post-mine land degradation, arranging management practices for sustainable land use, and evaluation of reclamation success research on soil physical properties plays a significant role. The aim of this study was to quantify and interpret the effects of varied agricultural reclamation methods in order to assess which of the treatments yielded higher soil quality with respect to its physical state. Basic physical and chemical parameters (texture, particle and bulk density, total porosity, total organic carbon and pH), soil water characteristic curves, water and air permeability, structure of the soil damaged by mining in the area of internal dumping ground PĿtnów (Central Poland) were therefore measured. The soil samples were taken from the following 5 different variants of over 30-year-long reclamation: black fallow (BF), monoculture of winter wheat (WW), monoculture of winter wheat with a single application in 1992 of lignite dust (WW+L), monoculture of alfalfa with orchard grass in the proportion of 90/10% (A+G), and spontaneous succession (SS). We collected from each treatment: 12 soil cores for soil water and air properties; 6-kg composite bulk samples for basic physical and chemical properties of soil; 1 undisturbed soil block for structure analysis. The reclamation methods applied on the post-mining grounds influenced in a diverse manner the physical state of the 0⿿10cm layer of the developed technogenic soil. Bulk density values generally decreased with the increase of number of factors potentially loosening the soil structure. The studied plots had sandy loam or loamy sand texture which determined their overall air and water properties. The soils were characterized by high macroporosity and favourable content of water available for plants. Less beneficial conditions of the soil were associated with air and water permeability. The present studies indicated that spontaneous succession, with the highest typological diversity of vegetation, contributed to the most preferred soil physical state. Remaining variants of reclamation (including black fallow without vegetation) also provided sufficient air and water relations in the soils. However, it should be emphasised that plants play an important role in TOC accumulation and ensuring relative stability of soil structure. Therefore rehabilitation of post-mining grounds involving vegetation is recommended.

Impact of flue gas desulfurization gypsum and lignite humic acid application on soil organic matter and physical properties of a saline-sodic farmland soil in Eastern China

Appropriate land management is important for improving the soil quality and productivity of the saline-sodic farmland. A recent study has revealed that flue gas desulfurization (FGD) gypsum and lignite humic acid application enhanced the salt leaching and crop production. The purpose of this study was to investigate the effects of applied FGD gypsum and lignite humic acid (powder) on the soil organic matter (SOM) content and physical properties. This study was based on a field experiment of five consecutive rapeseed-maize rotations in a saline-sodic farmland soil (Aquic Halaquepts) at coastal area of North Jiangsu Province, China. The soil is sandy clay loam texture with pH of 8.43 and clay content of 185 g kg−1. Six treatments included three FGD gypsum rates (0, 1.6, and 3.2 Mg ha−1) and two lignite humic acid rates (0 and 1.5 Mg ha−1). The amendments were incorporated into 0–20 cm soil depth manually every year. Soil samples were collected from each treatment and analyzed for soil organic matter, water-stable aggregates (wet sieving method), bulk density (clod method), water retention capacity (pressure plate apparatus), total porosity (calculated from bulk density and particle density), and microporosity (calculated from water content at 0.01 MPa). After 5 years, the SOM and soil physical properties were significantly (P < 0.05) affected by the application of FGD gypsum and lignite humic acid, especially at the 0–20 cm soil depth. The highest amount of SOM with best soil physical condition was observed in the field which was treated with FGD gypsum at 3.2 Mg ha−1 with lignite humic acid, and the SOM, total porosity (TP), microporosity (MP), mean weight diameter (MWD), water-stable macroaggregate (WSMA), and available water content (AWC) were increased by 22.8, 6.34, 23.2, 48.1, 55.5, and 15.8 %, respectively, while the bulk density (BD) was decreased by 5.9 % compared to no amendments applied. The generalized linear regression analysis showed that the SOM explained 42.9, 55.0, 48.5, and 54.2 % of the variability for BD, MWD, WSMA, and MP, respectively. This study illustrates the benefits of applying FGD gypsum and lignite humic acid for increasing the soil organic matter content and improving the soil physical properties and suggests a great potential for ameliorating saline-sodic farmland soil (Aquic Halaquepts) by using combined amendment of FGD gypsum with lignite humic acid.