Soil Morphology Research Articles

ENVIRONMENTAL FRAGILITY PROVIDED BY SOILS OF A PLATEAU EDGE OF SOUTH BRAZIL, ON ATLANTIC FOREST BIOME

Plateau areas have been considered with high land-use capacity in the Brazilian Meridional Plateau Edge of South Brazil. These areas belong Atlantic Forest biome, the second most extinction threatened ecoregion in the world, and weak knowledge about the environment leads to intensive use and degradation. We aimed to identify soil fragility and land-use capacity and limitation of the Brazilian Meridional Plateau Edge, in South Brazil, by the soil properties. Soil morphology, steady-state water infiltration, and physical and chemical properties at 0.00-0.10 and 0.10-0.20 m layers were evaluated at 57 sampling points in a grid of 20 x 20 m. Although under a small elevation slope, these areas have high soils and their properties variability, which implies high natural fragility. Unlike the soils and properties expected by farmers and scientists, naturally fragile soils (Leptosols, Regosols) with only patches of developed soils (Cambisols, Alisols, Planosols/Gleysols) predominate in these areas. The proper land-use and management of the soil and its landscapes depend on a detailed knowledge of the soil. Because, considering only the expected soil and environment capacity without the evaluation obtained with this study, the soils were intensively used and degraded.

Spatial distribution of soil morphology and physicochemical properties to assess land degradation under different NDVI and TRI in North Halmahera, Indonesia

Land degradation is currently a major environmental problem that can lead to decreasing biomass productivity. The causes of land degradation have been widely reported. However, the soil morphological characteristics and its detailed properties related to land degradation need to be investigated further. The research was conducted in North Halmahera Regency in March-April 2020. The study started with an overlay of basic maps such as rainfall, land use, topography, and soil types to map the degraded land units. Several land units classified from slightly damaged to severely damaged will be validated based on field observations and supported by laboratory measurements. Characterization of soil morphology and soil sampling was carried out according to USDA international standards. Sentinel 2A image and SRTM image from March to April 2020 were used to determine NDVI and TRI. The characteristics of the soils that have not been degraded tend to be found in volcanic landscapes, while those of the degraded soils tend to be found in structural and karst hills. The thickness of the degraded soil horizons tends to be shallower with an incomplete horizon arrangement, and many rock fragments are found in the soil surface layer. SOC gradually decreases in degraded soils, while the essential nutrients (N, P, and K) are relatively more varied across soil types. The improper land use without conservation on steep slopes causes the soils to be easily degraded. The soil degradation index has a linear relationship with NDVI and TRI. Thus, the revitalization of degraded lands needs to pay attention to the layout and types of vegetation with different slope levels according to the geomorphological zone.

Soil fertility status and land suitability evaluation for rice crops on former shrimp ponds

Undertaking suitable land, including former shrimp ponds for rice, is required to cope with future rice shortages. The purpose of this study was to identify the soil morphology and physicochemical properties, determine soil fertility status and assess irrigated rice suitability of ex-shrimp ponds. Soil morpho-physicochemical properties such as soil color, structure, texture, pH, organic-C, P2O5, K2O, base saturation, and cation exchange capacity were determined. The resulting data was then matched into the criteria for BSCR and SLAN/CCDS, five major soil fertility criteria, and ICALRRD land suitability. Soil physiographical, morphological, and physicochemical analysis suggested that the soil developed from the alluvial site of calcareous-marl parent material located at saturated backswamp, then permanently drained. ESP, SAR, and salinity values were detected relatively lower than saline, sodic, and saline-sodic soil. The entire cations fell below BCSR ideal ratios, whereas all exchangeable K were detected below the CCDS/SLAN thresholds. Actual suitability for land units of A, B, and C were S3-rc,na, S3-na and S3-rc,nr,na,eh, respectively. The improvement such as fertilization, amelioration, slope flattening/cut-filling, and irrigation management increases all land units to S1. This study pinpointed the importance of former shrimp pond soil to provide suitable land for rice crop cultivation. Also, encouraging further research to identify the origin of alluvial parent material from the soil at the study site

Afforestation With Different Tree Species Causes a Divergent Evolution of Soil Profiles and Properties

Land-use change and specifically a change in the type of vegetation cover affects soil morphology, chemistry, biology, and nutrient regimes. Numerous studies have documented that in land-use conversions from agricultural land to forest, or from plantations to restored natural savanna most soil attributes and functions undergo changes. The purpose of the present study was to evaluate the changes brought about by afforestation of degraded croplands and to understand the impact of forest vegetation on soil evolution in a semiarid region where soils originally co-evolved with a savanna biotope. We used long-term experiments (>40 years) of five tree species: Pinus halepensis (PH), Pinus halepensis inoculated with ecto-mycorrhiza at planting (PM), Pinus pinea (PP), Eucalyptus spp. (E), and Gleditsia triacanthos (G) and compared these to an agricultural soil (A) at the same site near Santa Rosa, La Pampa in the semiarid center of Argentina. Soil profiles were described, and samples taken for chemical and physical analyses of soil properties [organic matter (OM), pH, cation exchange capacity (CEC) and exchangeable cations, particle size distribution (texture), aggregate stability (MWD), bulk density (BD), porosity (TP), and water holding capacity (WHC)]. We found a strong effect of tree species on soil profile morphology, even taxonomy, and on all studied variables. PM and G had highest OM, CEC, neutral pH, higher TP, WHC, while PH, PP, and E had acid pH, lower base saturation, OM, TP, and WHC. The effect of tree species on the soil profile was noticeable a depth of about 40 cm, comprising the A and AC, but not the C horizons. The results showed that to obtain reasonable results of OM sequestration under forest systems, tree species should be chosen to include legumes to improve C/N stoichiometry for C fixation, or inoculation with mycorrhiza to promote microbial transformation of forest litter.

Determination of Geotechnical Properties and Stability of Expansive Soil using Fly Ash

This study was conducted to have a detailed analysis of the geotechnical properties of expansive soil and fly ash from Sipat thermal power plant. It reported the findings of laboratory studies on certain common physical and geotechnical properties. The chemical properties and morphology of the black cotton soil (BCS) and fly ash is also determined using scanning electron microscopy and X-ray diffraction test. The geotechnical test includes determining specific gravity, particle size distribution, moisture content, standard proctor test, free swell index, and Atterberg’s limit. The different compositions of expansive soil with fly ash, yellow soil, moorum, and sand are studied. BCS was evaluated with fly ash, fly ash and sand, BCS with yellow soil, and moorum and fly ash. The study also analyzed the details and results of different tests conducted on soil samples. The results showed that strength and fly ash are inversely proportional; as fly ash increases, strength decreases, and vice versa. Fly ash was added from 20 to 80 % by replacing expansive soil by weight. The results indicated that expansive soil can be stabilized by the addition of fly ash to a limit of 10 to 20 %.
 HIGHLIGHTS
 
 The XRD And SEM results shows the mineral present in the FlyAsh and Expansive soil
 The geotechnical properties of Flyash and expansive soil is determined
 The OMC increases with decrease in densities
 The Particle size distribution curve shows the soil is GW soil
 
 GRAPHICAL ABSTRACT

Soil structure and soil moisture dynamics inferred from time-lapse electrical resistivity tomography

The semi-arid sagebrush steppe in the western United States faces pressures from the agriculture industry, recreation use, invasive grasses, and a changing climate. A key to facilitating the healthy management of this ecosystem is understanding the distribution and behavior of soil moisture in the vadose zone in both natural and agricultural settings. Within unsaturated environments, soil moisture is spatially and temporally heterogeneous, and changes in porosity and permeability within arid soils complicate characterization of soil hydrologic properties. Importantly, accumulations of ‘caliche’ or pedogenic calcium carbonate in arid soils can greatly limit permeability; however, observing the role that caliche plays in the hydrologic process is difficult because the installation of in situ instruments disturbs the soils and only provides information at a single point. To investigate vadose zone processes on a broad temporal and spatial scale, we installed a 7x8m2 electrical resistivity tomography (ERT) array at the Reynolds Creek Critical Zone Observatory in southwestern Idaho. Existing soil moisture observations show that infiltration is limited to depths less than 60 cm at this site, as compared to at least 90 cm at other sites in the watershed. To capture the seasonal wetting and drying of the soils, as well as the soils’ response to rainfall events, we monitored the site bi-weekly during the spring, summer, and fall of 2015 and 2016. A time-lapse ERT array was placed adjacent to coaxial impedance dielectric reflectometry (CIDR) probes so that the time-lapse ERT data could be referenced to precise measurements of volumetric water content. In addition to the measurements provided by the ERT array and CIDR probes, soil texture analysis and soil profile descriptions from a near-by soil pit show typical arid soil morphology, with accumulations of clays and calcium carbonate in the B horizon. The resulting ERT inversions show the following soil structure: (1) a high-resistivity top layer corresponding with minor amounts of pedogenic calcium carbonate; (2) a low-resistivity intermediate layer at depths corresponding with substantial accumulations (stage IV) of carbonate; and (3) a high-resistivity deep saprolite. The resistivity of the top layer varies seasonally with changes in precipitation, while the intermediate carbonate soil layer does not. This agrees well with the changes in soil moisture with depth measured by the CIDR probes and suggests that the top of the carbonate soil layer limits infiltration. However vertical structure and cracks within the carbonate soil layer create vertical preferential flow paths; resistivity within these flow paths responds to large precipitation events and seasonal changes in soil moisture. This implies that the preferential flow paths are a conduit for soil moisture flow that is not captured by the CIDR probes. From the combined interpretation of the ERT and CIDR we conclude that soil structure and the presence of calcic soil horizons inhibits soil moisture infiltration during both the summer dry months and the winter wet flux period; however, preferential flow paths provide an important vertical connection between the deep and shallow portions of the critical zone.

Pedocomplex buried under the Cabin of Peter the Great in St. Petersburg (1703): Genesis, properties and paleoenvironmental inferences

A study was conducted on the buried soils identified at the base of the foundation of the Cabin of Peter the Great in Saint Petersburg, Russia, to help trace the Late Holocene landscape evolution in the lower reaches of the Neva River. The Cabin is a small wooden house, which was the first residence of Peter the Great in a newly emerged Saint-Petersburg. The house was built of pine logs on the Neva River's right bank. The time of its construction is now regarded as the city's founding date (1703). The pedocomplex with two buried soils has not been truncated and retains a record of the depositional environment, pedogenesis, vegetation history, and human activity before the construction of the city of Saint Petersburg. This pedocomplex was studied using various field and laboratory methods including soil morphology at macro-, meso-, and microlevels, and a full set of microbiomorphic analyses (diatoms, pollen, spores, phytoliths, plant detritus, and amorphous organic matter) supported by radiocarbon dating. The sediment sequence was formed in a contrasting depositional environment. The microbiomorphic studies indicated that the initial substrate was formed in aquatic environments. The analysis of diatoms suggested that these sediments were accumulated as a result of the River Neva breakthrough from Lake Ladoga to the Gulf of Finland ca 3500 yrs BP, which provided additional evidence for the River Neva formation. Soil analyses revealed two inundation events, with the earlier flood related to the termination of the Lake Ladoga transgression (LT) and the breakthrough of the Neva River, whereas the latter flood was likely to be connected with an increase of the fluvial activity. Those two inundation events were followed by two stages of pedogenesis. Both soils indicated the hiatus in sedimentation and were represented by Subquatic Umbric Gleysols that were the most widespread indigenous soils in the XVII century. The pollen data suggest that human impact started at ca 800 yrs BP and eventually resulted in the deforestation and the initial agricultural exploration of the study area. Saint Petersburg is the only large city in Russia that could be at risk from flooding if the sea level rises due to continuing global warming. Our research shows that the city's historical center was twice subjected to flooding in the Late Holocene, even without rises in the sea level. Therefore, the detailed analysis of the environmental dynamics within the Lower Neva area and the assessment of its possible consequences for the city are of great importance.

Influence of moisture and geofluids (GF) on the morphology of quarry fines treated lateritic soil

The influence of moisture migration in the form of GF on the morphology of lateritic soil has been studied with laboratory experiments. This was important due to the effect of adsorbed moisture during molding moisture addition in a stabilization protocol that gives rise to hydration. In addition, moisture adsorption and absorption play a very vital engineering role during the seasonal changes of wet and dry seasons when the water table rises and drops. This occurrence brings about alternate effects of wetting and drying of hydraulically bound structures like in pavement foundations. Therefore, it was pertinent to study how these changes affect soil microstructure to enable good design decisions. The soil used in this exercise was classified as highly plastic, poorly graded A-7-6 soil group according to AASHTO classification method. The soil was mixed with various proportions of quarry fines under different molding moisture conditions and the specimens were prepared for scanning electron microscopy (SEM) exposure. The results of the SEM exposure showed that GF applied here as molding moisture improve the agglomeration of treated soil particles to form flocs in a stabilization process. However, the microspores and crack propagation were observed more in the structure with less amount of quarry fine, i. e., at 2% QF than that at 4% QF. This showed the pozzolanic effect of QF on soil under the influence of GF. GF in all its forms should be studied for sustainable earthwork design and construction.

Morphological characteristics and classification of inceptisol in Mamuju regency, West Sulawesi

Soil morphology provide overview the evolution in the soil body through description and interpretation of soil profile properties as initial information in classifying soil. The research purpose is to determine the morphological characteristics and soil classification of Inceptisols in four study profiles: Kalonding, Batu Papan, Pepalang and Batu Ampat, in Mamuju regency, West Sulawesi. The research method used is descriptive qualitative exploration by survey in the field and soil analysis in the laboratory. The results showed that the dominant texture was clay in all soil profiles with a low silt/clay ratio. This was related to the high intensity of weathering due to high rainfall and easily weathered host rock and relatively high content of resistant minerals. Other chemical properties such as pH, N-total, cation exchange capacity, base saturation, exchangeable bases (Ca, Mg, K, Na) and P-available are generally low with a relatively constant distribution pattern with increasing depth. Soils are classified into the order of inceptisols in all soil profiles because they have a cambic sub-horizon resulting from physical alteration, chemical transformation or a combination of these processes. The hicks humidity regime so that the sub-order category is named udepts. The temperature regime includes Isohipthermic so that it is categorized into the Great Group Dystrudepts and the Typic Dystrudepts sub-group for the Study Profile of Batu Papan, Pepalang and Batu Ampat, while for the Profile of the Kalonding study is Lithic Dystrudepts.

Responses of Moringa oleifera to alteration in soil properties induced by calcium nanoparticles (CaNPs) on mineral absorption, physiological indices and photosynthetic indicators

BackgroundThe application of nanofertilisers in agriculture has been widely utilised due to their distinct characteristics and negative impacts of conventional chemical fertilisers. This study thus examined the influence of calcium nanoparticles (CaNPs) on soil composition vis-à-vis performance parameters in Moringa oleifera L exposed to water, 100 mg Ca(NO3)2kg−1 soil and 100, 75 and 50 mg CaNPs kg−1 soil. Soil morphology was determined with a scanning electron microscope coupled with energy dispersive x-ray (SEM-EDX) and elemental composition in both soils and M. oleifera roots determined with inductively coupled plasma-optical emission spectrometer (ICP-OES).ResultsThe CaNP-amended soils were more crystalline, more fertile and had reduced salinity. An increase in immobilisation percentage of heavy metals, improvement in physiological parameters (percentage germination, vigour indices, relative water contents, lengths of roots and shoots) and photosynthetic efficiency in M. oleifera were recorded.ConclusionThis study has demonstrated that CaNPs could improve soil composition for better plant performance and can act as nanofertilisers mobilising essential nutrients.Graphical abstract

MORFOLOGI DAN KLASIFIKASI TANAH PADA TOPOSEKUEN LERENG BARAT GUNUNG KELUD, KEDIRI, JAWA TIMUR

The research that was conducted from April to December 2020 in the Supiturung Micro-Watershed, located on the western slope of Mount Kelud, Kediri was aimed to study the morphological characteristics and soil classification using a topo-sequence approach. Four pedons were observed across the physiographic positions (upper, middle and lower slopes) on dry-land farming land use. The method used in this research included 8 stages, namely the preparation stage, pre-survey, map making, field observations, laboratory analysis, soil classification, data processing, and reporting. On the field, cross-sectional profiles were carried out on four selected pedons by testing the soil profile measuring 1 x 1 meter with a depth of 150-200 cm, followed by soil horizon, soil thickness, texture, structure, consistency, effective depth, type and number of pores, as well as other characteristics. Soil samples were collected from the genetic horizon of the pedons for being analyzed using standard procedures, then taken to the laboratory for soil physical and chemical analysis. Soil morphology with physicochemical properties was then classified based on the Keys Taxonomy of Soil to the Sub Group level. The results showed that each pedon has a different Sub Group. This condition can be caused by many factors, such as differences in epipedon thickness, base saturation values, organic C levels, and other morphological conditions at the time of direct observation. Four pedons have lithologic discontinuities, recognition of these types of lithologic changes is important because pedogenesis and pedogenic interpretations are greatly influenced by changes in the parent material.

3D DEM simulation of initial anisotropy in dredger fill soft soil

The initial anisotropy has a significant effect on the mechanical properties of the soft soil. Based on the initial anisotropy of the particles, the mechanical characteristics are analysed from a microscopic view, and the micro-macro relationship of the soil is established. According to the particle morphology of soft soil, the discrete element method is used to construct the flaky particle clusters, and seven sets of samples with different initial deposition angles are established for consolidation and undrained triaxial simulation tests. The results show that the strength of the sample decreases first and then increases with the increase of the deposition angle. When the deposition angle is 0°, the flaky particles mostly appear in a nearly horizontal suspension, and the sample has the largest shear strength. The distribution of the contact force chain formed by the particles in the shearing process is also related to the deposition angle. Different deposition angles form displacement fields of different shapes. When the deposition angles are 45° and 60°, there are obvious deformation displacement bands. At the same time, the initial deposition angle affects the particle coordination number. The higher the sample strength corresponding to the lowest average coordination number of particles. The contact normal anisotropy coefficient is related to the strain hardening and strain softening characteristics in the shearing process. The increase in the contact normal anisotropy coefficient shows the characteristics of hardening, and the smaller the contact normal anisotropy coefficient shows the characteristics of softening.

Toposequent Effect on Soil Morphology and Classification of Ultisol Soil in the Ayer Hitam Forest Reserve, Peninsular Malaysia

Morphology in forest soils has developed over a long time due to the non-intensive management of forest soils. Damage to forest soil occurs when there is logging activity, fire, or land use change. Some forest was used as productive land for example agroforestry and forest production. As with landuse in agriculture, intensive management of forests can also reduce soil productivity. Inaccuracy forest land use would cause environmental or economic damage, so basic soil management data in forest areas is needed. However, the soil morphology of the Ayer Hitam Forest Reserve (AHFR) in Malaysiahas never been observed. The objective of this study is to assess the soil characteristic and soil morphological properties of theAHFR. Studying the characteristics of soil morphology in toposequent conditions is necessary to find out the differences in soil from different heights and the effects of erosion, transportation, and deposition on the soil. This study was conducted in the AHFR, Puchong, Selangor Darul Ehsan, Peninsular Malaysia. Mapping of the area under investigation was carried out by conventional soil survey techniques with a physiographic approach using maps with a scale of 1:30,000. The results showed that AHFRhas some different soil morphological characteristics and classification in subgroupamong five different slope positions with similar soil order, which is a Ultisol soil. The soil in the AHFRis formed from highly weathered soil due to high rainfall in this location.The results of this study are important for soil development, identification management, and land use priority such as erosion control on steep-slope forest areas, regeneration and reforestation, and it can also be used for forest education, practice, research, and training activities.Keywords: Ayer Hitam Forest Reserve, forest soil, soil morphology, toposequent, Ultisol soil

The variability of soils and vegetation of hydrothermal fields in the Valley of Geysers at Kamchatka Peninsula

The picturesque and high conservation value thermal landscapes of the Valley of Geysers feature endothermal (heated by endogenous fluids) soils which support endangered and unique species. However, such soils have not been distinguished as a separate taxon within most classification systems. In this study, we described the soil morphology at macro-, meso- and micro-scales, chemistry, mineralogy and vegetation of these landscapes as they are affected by the steam-heated acid-sulfate waters. The studied catenary sequence from exothermal (non-heated) to endothermal soils was characterized by decreasing contents of soil organic carbon, sand fraction, essential nutrients (Ca, K, Mg, Mn and Si), increasing soil acidity, amounts of fine particle-size fractions and contents of trace elements (Al, As, Co, Cr, Cu, Fe, Pb, Ti and V) as well as the development of sodium-sulfate salinity, kaolinization and ferrugination. In phytocenoses supported by endothermal soils, species of order Rosales and Asparagales were overrepresented among obligate and facultative thermophytes respectively, and species of order Poales were underrepresented among facultative thermophytes in relation to the flora of the Valley of Geysers. Phytocenoses on the non-heated Andosols were enriched in Polypodiopsida species. The results of our comparative analysis of the thermally-induced variability in the soils and vegetation contribute to the general understanding of mineralogical, bio-abiotic and biological systems affected by steam-heated acid-sulfate waters. We hope that our findings will provide a basis for future transdisciplinary studies of the influence of steam-heated waters of a hot spring on the thermal landscapes.

Swell-shrink behaviour of an expansive soil stabilised by CCR-fly ash (FA) columns and CCR-FA blends

ABSTRACT This paper presents the results of laboratory-scale swell-shrink tests performed in an oedometer on an expansive soil stabilised by calcium carbide residue-fly ash (CCR-FA) columns. The expansive soil used in this study had a swell potential of 11.56%. The CCR-FA columns (3 mm in diameter) were seven in number diametrically arranged in the oedometer. In another series of tests, the expansive soil was directly mixed with the CCR-FA blends. The 3-D volumetric shrinkage of the samples was measured using digital image analysis in five swell-shrink cycles. The results were compared with the shrinkage measured manually. The impact of this treatment on soil morphology was interpreted using SEM. A significant reduction of 62% was observed in swell potential when CCR-FA columns were used at the CCR:FA ratio of 20:80. Uneven swelling patterns for some of the cycles indicate partial loss of cementation. The results of the 3-D volumetric shrinkage indicated only partial success of the treatment in preventing shrinkage. The digital image analysis estimated slightly higher 3-D volumetric shrinkage than that observed through manual measurement. SEM demonstrated the observed changes in soil morphology due to swell-shrink cycles. Further studies would be required to conclude on prevention of shrinkage.

Effects of Mixed Application of Wood Vinegar and Biochar on Cadmium Absorption of Pakchoi under Different Concentrations of Cadmium Stress

Because of its characteristics, wood vinegar is widely used in agricultural production processes. Wood vinegar can be used as a strong antioxidant, anti-bacteria, plant growth agent, an insecticide, and currently shows superiority in the treatment of heavy metals. Wood vinegar contains organic acids, organic compounds, and phenol, which can effectively adsorb heavy metals. A large number of studies have been conducted on the adsorption of heavy metals by biochar, but few studies have analyzed the effects of biochar and wood vinegar fertilization on the growth of cadmium soil genus plants and changes in soil heavy metal forms. This article analyzed the effects of wood vinegar and biochar mixed fertilizer on the growth and plant efficacy of pakchoi from the properties of wood vinegar, and confirmed that 0.75% wood vinegar liquid treatment is the most effective concentration. By analyzing the effectiveness of 0.75% wood vinegar and biochar mixture and single fertilization, the combined application of biochar + wood vinegar reduced the absorption rate of cadmium by pakchoi leaves and roots by 12.8% and 13.1% compared with the single treatment group. The yield of crops increased by 111.9~150.1%. The results of evaluating the enrichment coefficient and single-factor index are 0.17~0.67%, 0.005-0.008, and the ranking is D> E> C> B> A> CK. When observing the changes in soil morphology, the content of residual cadmium, carbonate-bound cadmium, and iron-manganese oxide-bound cadmium increased by 0.3~233.7 times, and the exchangeable cadmium content and the content of organic and sulfide-bound cadmium were reduced to 1.0~6.6 times. It can be seen that under different cadmium stress conditions, the mixed fertilization of wood vinegar and biochar will reduce the growth of pakchoi and the plant availability of cadmium, and it has a higher mitigation effect on cadmium soil pollution.

CHANGES IN SOIL MORPHOLOGY AND PROPERTIES UNDER LONG－TERM SOIL MANAGEMENT IN HUMID TROPICAL REGIONS OF LAMPUNG, INDONESIA

A humid tropical climate is characterized by high amounts of rainfall and high temperatures throughout most of the year. It results in elevated rates of soil weathering, soil loss, the leaching of cations, and the oxidation of the organic matter in the soil. The aim of this research was to observe the changes in soil morphology and soil properties due to the differences in soil management over a period of 20 years. Three types of soil management methods were applied, namely, intensive tillage (IT), minimum tillage (MT), and no tillage (NT). Basically, minimum tillage and no tillage are types of conservation tillage (CT). The results showed that, with IT management, the lower content of organic matter in the upper layer of the soil caused the soil to become lighter in color, which was characterized by higher chroma. The soil structure on the top layer of the soil changed from crumbs toward angular blocky. The topsoil was seen to be more friable than when the other two management methods were applied, while the lower layer was denser or more compact. Generally, the chemical properties of the soil with the CT management methods were better than those with the IT method, and those with the NT method were slightly better than those with the MT method.

Intercropping of Peanut-Tea Enhances Soil Enzymatic Activity and Soil Nutrient Status at Different Soil Profiles in Subtropical Southern China.

Intercropping is one of the most widely used agroforestry techniques, reducing the harmful impacts of external inputs such as fertilizers. It also controls soil erosion, increases soil nutrients availability, and reduces weed growth. In this study, the intercropping of peanut (Arachishypogaea L.) was done with tea plants (Camellia oleifera), and it was compared with the mono-cropping of tea and peanut. Soil health and fertility were examined by analyzing the variability in soil enzymatic activity and soil nutrients availability at different soil depths (0–10 cm, 10–20 cm, 20–30 cm, and 30–40 cm). Results showed that the peanut–tea intercropping considerably impacted the soil organic carbon (SOC), soil nutrient availability, and soil enzymatic responses at different soil depths. The activity of protease, sucrase, and acid phosphatase was higher in intercropping, while the activity of urease and catalase was higher in peanut monoculture. In intercropping, total phosphorus (TP) was 14.2%, 34.2%, 77.7%, 61.9%; total potassium (TK) was 13.4%, 20%, 27.4%, 20%; available phosphorus (AP) was 52.9%, 26.56%, 61.1%; 146.15% and available potassium (AK) was 11.1%, 43.06%, 46.79% higher than the mono-cropping of tea in respective soil layers. Additionally, available nitrogen (AN) was 51.78%, 5.92%, and 15.32% lower in the 10–20 cm, 20–30 cm, and 30–40 cm layers of the intercropping system than in the mono-cropping system of peanut. Moreover, the soil enzymatic activity was significantly correlated with SOC and total nitrogen (TN) content across all soil depths and cropping systems. The depth and path analysis effect revealed that SOC directly affected sucrase, protease, urease, and catalase enzymes in an intercropping system. It was concluded that an increase in the soil enzymatic activity in the intercropping pattern improved the reaction rate at which organic matter decomposed and released nutrients into the soil environment. Enzyme activity in the decomposition process plays a vital role in forest soil morphology and function. For efficient land use in the cropping system, it is necessary to develop coherent agroforestry practices. The results in this study revealed that intercropping certainly enhance soil nutrients status and positively impacts soil conservation.

Morphology and Physicochemical Properties of Alluvial Soils in Riparian Forests after River Regulation

The elimination of flooding and lowering of the groundwater table after large-scale river regulation allow deep penetration of soils by plant roots, soil fauna, and microorganisms, thus creating favorable conditions for advanced pedogenesis. Although the changes of the morphology and properties of agriculturally used drained alluvial soils in Central Europe have been well characterized, studies in riparian forests remain insufficient. An analysis of 21 profiles of forest soils located on the Holocene river terrace (a floodplain before river regulation and embankment) in SW Poland confirmed a noticeable pedogenic transformation of soil morphology and properties resulting from river regulation. Gleyic properties were in most profiles replaced with stagnic properties, testifying to a transition from dominant groundwater supply to precipitation-water supply. The development of a diagnostic mollic and cambic horizons, correlated with the shift in soil classification from Fluvisols to Phaeozems, and in the majority, to Cambisols, demonstrated a substantial change in habitat conditions. The transformation of alluvial soils may result in an inevitable modification of forest management in the river valley, including quantitative alteration in species composition of primarily riparian forests.

Comprehensive microstructural characterization of saline–alkali soils in the Yellow River Delta, China

ABSTRACT Soil salinization in the Yellow River Delta, China, is a matter of concern from agricultural and environmental perspectives. This study characterizes the relationship between the permeability and microstructure of saline–alkali soil. Soil microstructure, including mineral composition, pore distribution, and particle morphology of soils at different depths, was analyzed using X-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy. Results indicated that the soil mean saturated hydraulic conductivity and porosity, excluding the surface soil, were only 6.0 × 10−5 cm/s and 33.0%, respectively, and the mean proportion of clay minerals (illite, chlorite and kaolinite) was 6.1%. The pore distribution results showed that small pores (2 ≤ d< 10 μm) and micropores (0.1 ≤ d< 2 μm) constituted the majority of the soil pores. We attributed the deterioration of the soil permeability to low soil porosity, which, in turn, was associated with soil pore size distribution and a closely inlaid ‘brick wall’-type particle arrangement. Quantitative analysis of the scanning electron microscopy images showed that the fractal dimension of pores and roundness of particles increased with depth, whereas the fractal dimension of particles and roundness of pores decreased with depth. However, the azimuth, perimeter, Fred diameter, and orientation of saline–alkali soil did not significantly change with the increase in depth. This study revealed that the microstructure of saline–alkali soil exhibits a good correlation with its permeability.