Soil Chemistry Research Articles

The Impact of Ecological Restoration on Soil Quality in Humid Region Forest Habitats: A Systematic Review

Ecological restoration is widely recognized as an essential technique for addressing soil degradation, biomass decline, and biodiversity loss. Improving and maintaining soil quality is critical to ensuring environmental sustainability and successful forest recovery. This systematic review aimed to assess the impact of ecological forest restoration efforts on soil quality in humid regions, as well as to compare the effectiveness of various ecological restoration strategies on soil quality indicators. Subsequently, a systematic search on various databases (e.g., Scopus and Google Scholar) yielded 696 records, of which 28 primary studies met the inclusion criteria. The results emphasized that chemical and physical soil properties are the key indicators for assessing ecosystem performance during forest restoration. The most commonly measured parameters were soil carbon, nitrogen, phosphorus, pH, bulk density, and soil porosity. It was shown that the restoration process required a longer duration to reach a comparable level of recovery as seen in mature forests, particularly in terms of fully restoring soil quality. Additionally, it has been noted that prior land use influences the length of time needed for soil quality recovery. In planted sites, soil quality may keep improving as the site ages, though it tends to stabilize after a certain period.

Impacts of changing weather patterns on the dynamics of water pollutants in agricultural catchments: Insights from 11-year high temporal resolution data analysis

Widespread and long-term shifts in weather patterns are contributing to further degradation of surface water quality. This challenge caused by the increasing frequency of extreme weather events requires appropriate adaptation of current mitigation strategies. But to confirm the need to redesign such strategies, an understanding of the impacts of increasing weather extremes on pollutant losses in different catchment types is required. With this in view, this study investigated the impact of changing weather patterns on the inter-seasonal and inter-annual dynamics of nutrient losses in six agricultural catchments in Ireland over 11 years. The high temporal resolution data (10-min) from these intensively managed catchments represented different characteristics and management practices. Mann-Kendall Trend Analysis and Generalised Additive Models were used to study nutrient concentration trends, and to investigate the significance of water discharge, precipitation, potential evapotranspiration, soil moisture deficit, air temperature, and soil temperature on the losses of nutrients, respectively. The analysis of historical data revealed changes in the trends of daily average nitrate (NO3-N), phosphorus (P), and suspended sediment (SS) concentrations in association with significant increasing trends in air temperature, soil temperature, and precipitation across the same month over 11 years of monitoring. While discharge was significantly contributing to the concentrations of NO3-N, P, and SS across different catchments, air and soil temperature were significantly correlated to NO3-N losses, and precipitation was the major contributor to regulating P (total P and total reactive P) concentrations. In short, air temperature, soil temperature, soil moisture deficit, and precipitation were the main climatic drivers regulating the nutrient concentrations while the soil chemistry and drainage status were the non-climatically related drivers. The results revealed that the extent of the impact of climatic drivers depends on catchment characteristics. Therefore, expanding the application of this type of study would facilitate better understanding of current and future challenges to water management and provision of climate-resilient mitigation strategies for different catchment typologies.

Long-term rice cultivation enhances root development and yields by improving the structural properties of soil aggregates in saline–alkaline environments

Rice cultivation has the ability to improve saline soils. However, the effects of long-term rice cultivation on saline soil chemistry, salt ions, root characteristics, and aggregate formation remain unclear. In this study, the impact of different planting durations (1, 3, 5, 8, and 10 years) on the spatial and temporal transport of soil salts, soil chemical properties, distribution and stability of aggregates, root characteristics, and yields, were assessed. Long-term rice cultivation reduced soil pH, exchangeable sodium percentage (ESP), and EC in the 0-60cm soil layer compared to 1Y (5.45%, 61.57%, and 81.87% reduction in topsoil (0-20cm) and 8.54%, 72.82%, and 71.94 in subsoil (20-60cm), respectively). However, the soil organic matter (OM), alkaline nitrogen (AN), phosphorus (AP), and potassium (AK) increased (217.09%, 90.18%, 89.23%, and 179.18% increase in topsoil and 223.72%, 81.24%, 174.28%, and 172.57% increase in subsoil, respectively). Additionally, the Cl-, K+, and Na+ in the soil gradually leached downward with the increase in the duration of rice cultivation (55.87%、36.08%、59.80%). Simultaneously, the increased duration markedly elevated the soil macroaggregate content (11.43%-20.04% by dry-sieving and 53.48%-288.09% by wet-sieving), clayey grain content (59.17%-198.33%), and soil aggregate stability, especially for 8Y and 10Y. The improved soil structure and root characteristic under long-term rice cultivation conditions increased the yield (28.89-54.81%). Partial least squares path model displayed that rice cultivation affected the aggregate stability, root characteristics, and rice yield via the corresponding chemical properties (pH, EC, and ESP), nutrient contents (AN, AP, AK, and SOM), and salt ion contents (Cl-, K+, and Na+). These findings are critical to understanding aggregate formation in saline soils.

Pelatihan Pembuatan Pupuk Hayati di Desa Gondel, Kecamatan Kedungtuban, Kabupaten Blora, Jawa Tengah

The rice productivity in Gondel Village, Kedungtuban District, Blora Regency, Central Java, has declined. Factors such as attacks by plant pests and diseases (OPT), climate change (DPI) impact, and decreasing soil quality are the leading causes of crop failure. This training aims to enhance the understanding and skills of Gondel Village farmers in making biofertilizers and introducing environmentally friendly pest and disease control methods. The activity involved 40 farmers from 8 farmer groups (Gemah Ripah, Margo Mulyo, Ngudi Makmur, Sido Dadi, Sido Makmur, Tambah Makmur, Tambah Rizki, and Sri Mulyo), with each group represented by five farmers. The training methods included analysis of soil chemicals, socialization, practical propagation of Trichoderma sp. on rice media, and biofertilizer production. Pre-test and post-tests were conducted to assess the improvement in farmers' knowledge. Trichoderma biofertilizer was formulated using carriers such as a) Manure and b) Compost, zeolite, and humic acid. The results of the soil chemical properties analysis showed that farmers' use of chemical fertilizers was very intensive, resulting in very high levels of phosphorus (P) and calcium (Ca) and high levels of potassium (K), magnesium (Mg), and cation exchange capacity (KTK). Evaluation results indicated that the training significantly improved the farmers' knowledge of biofertilizer production in theory and practice. However, some farmers still need further guidance on the propagation of the biological agent Trichoderma sp.

Effects of long-term nitrogen and phosphorus fertilization on soil phosphorus forms and dynamics under continuous wheat production in Saskatchewan, Canada

Many agricultural crops require both nitrogen (N) and phosphorus (P) fertilizers to sustain crop yields. However, long-term application of NH4–N fertilizers can cause soil acidification, which alters soil abiotic and biotic processes, including soil P dynamics. Long-term continuous wheat plots in Saskatchewan, Canada, were used to assess effects of N and P fertilization from 1967 and P fertilizer cessation in subplots from 1995. General soil chemical properties and soil P pools and forms were determined and then correlated with soil pH, total N (TN), and total P (TP) concentrations to show the relative importance on soil P dynamics of (a) crop nutrition (TN and TP); (b) soil acidification (pH); or (c) P fertilization/cessation. Fertilization with NH4–N decreased soil pH and altered exchangeable cation concentrations; however, long-term crop growth was poor in no-N plots and was best with both N and P fertilizers, in turn increasing soil carbon and organic matter. Applying P fertilizers without N increased soluble phosphates and the risk of P losses in runoff. Soil organic P (TPo) concentrations were correlated negatively to pH and positively to TN, but the concentrations of P compounds were not correlated to pH. This suggests that TPo accumulation may be from increased long-term crop residue inputs from crops with N and P fertilizers, rather than increased sorption from reduced pH. However, soil pH will continue to decrease with continued NH4–N fertilization, affecting soil chemistry and future P cycling; monitoring with a suite of wet chemistry and spectroscopic techniques is recommended.

Understanding the effect of cropping system on soil health at the Northwestern Ontario Agricultural Research Station in Canada

Anthropogenic activities impact soil in varying degrees, from preserving natural landscapes to intensive agriculture which among the farm practices that impact the soil are the cropping systems. Information on cropping systems and soil impacts in northern territories is still missing. This study assesses the effect of different cropping systems on soil health -physical, chemical and biological soil properties and indicators of soil health - at the Lakehead Agricultural Research Station [LUARS] in northern Ontario, Canada. The study compares three cropping systems (perennial crops-pasture, grass, and annual crops -wheat, barley, corn, soybeans) and two forest areas (conifer plantation and naturally regenerating mixed wood forest) at LUARS. Soil samples were collected at different depths and analyzed for various indicators using the Cornell Soil Health Assessment framework. The results showed the soil health scores varied among cropping systems, with natural forest and perennial crops-pasture having higher scores compared to annual crops -wheat, barley, corn, soybeans. Soil organic matter was found to be lowest in annual crops -wheat, barley, corn, soybeans, while aggregate stability was highest in natural forests. The study also identifies the soil health gap, which represents the difference between the health of a particular cropping system and a benchmark. The soil health gap analysis can help farmers implement practices to improve soil health and increase the resilience and sustainability of agroecosystems. Overall, this study emphasizes the importance of understanding the effect of cropping systems on soil health and provides insights into potential strategies for improving farm practices.

Relationships between abiotic factors, foliage chemistry and herbivory in a tropical montane ecosystem.

Herbivore-plant interactions are fundamental processes shaping ecosystems, yet their study is challenged by their complex connections within broader ecosystem processes, requiring a nuanced understanding of ecosystem dynamics. This study investigated the relationship between nutrient availability and insect herbivory in the Australian Wet Tropics. Our objectives were threefold. Firstly, to understand what factors influence nutrient availability for plants and herbivores across the landscape; secondly, to investigate how trees of different species respond to nutrient availability; and thirdly, to unravel how the relationships between resources and plant chemistry affect herbivory. We established a network of 25 study sites covering important abiotic gradients, including temperature, precipitation, and geology. Employing a hierarchical modelling approach, we assessed the influence of climate and geology on resource availability for plants, primarily in the form of soil nutrients. Then, we explored the influence of the above factors on the interaction between herbivory and foliage chemistry across three widespread rainforest tree species, comparing how these relationships emerged across genera. Our findings suggest an overarching influence of climate and geology over soil chemistry, foliar nitrogen, and insect herbivory, both directly and indirectly. However, individual constituents of soil fertility showed equivocal influences on spatial patterns of foliage chemistry once site geological origin was accounted for, suggesting a questionable relationship between individualsoil nutrients and foliar composition. We have demonstrated that herbivore-plant interactions are complex dynamics regulated by an intricate web of relationships spanning different biogeochemical processes. While our results provide some support to the notion that herbivory is affected by resource availability, different species growing under the same conditions can show differing responses to the same resources, highlighting the importance of identifying specific limiting factors rather than simpler proxies of resource availability.

Irrigation of rangeland soils with coal seam water - A lysimeter study on soil physico-chemical properties

Groundwater extracted from coal seams may be a resource for irrigation of land in areas with low rainfall, but the effect of this water on soil properties needs to be established. A lysimeter study was conducted using intact soil cores (0.75 m diameter, 1.4 m deep) of four different soil types (Sodic Vertisol, Calcic Solonetz, Haplic Solonetz and Xanthic Lixisol) from southern Queensland, Australia, to study changes in soil physical and chemical properties under accelerated rates of irrigation with coal seam (CS) water (electrical conductivity (ECw) of 3 dS/m, pH of 8.8, and a sodium adsorption ratio (SAR) of 100). Cores were also alternately irrigated with deionised water to simulate rainfall, and either lucerne (Medicago sativa L) or Rhodes grass (Chloris gayana Kunth.) where grown in the lysimeters. The soil surface was treated with stoichiometric rates of elemental sulfur (1.4 t/ha) and gypsum (2.5 t/ha) prior to every 450 mm CS water irrigation to minimise changes in SAR and pH. Three of the soils (Vertisol, both Solonetz) had low leaching fractions (≤ 0.1 %) due to their clay texture and were initially saline in the subsoil (ECse 1.4–4.4 dS/m). Irrigation with CS water resulted in a gradual increase in salt content (EC) and SAR throughout the soil profile, but pH was not increased due to surface-applied elemental sulfur. The Lixisol had a higher hydraulic conductivity and leaching fraction (6.7 %) due to is loamy texture – in this soil, accumulated salts could be leached and no increase in salinity or pH were measured. Despite an increase in SAR for this loamy soil, no structural degradation was observed, and it could be sustainably irrigated with up to 3200 mm CS water (with cumulative irrigation volume of 5400 mm). Hence, leaching fractions rather than soil chemistry are good indicators to identify soils suitable for irrigation with CS water that is saline, alkaline, and sodic.

Mobility of trace elements in a coastal contaminated site under groundwater salinization dynamics

Water pollution is a significant issue resulting from past long-term actions. The remediation projects carried out under law constraints for industrial plants, which have been the major contributors to environmental and water pollution, are currently providing a significant amount of data about contaminated soil, surface waters, and groundwater. Most of such plants worldwide are in coastal zones. Based on a significant amount of chemical and environmental data for a coastal contaminated site subject to variable groundwater salinization, this study aimed to understand the mobility of some trace elements because of coastal zone dynamics. Data concerned 688 groundwater samples, including As, Hg, Cd, Crtot, Cu, Ni, Pb, V, Se, Zn, pH, electrical conductivity, chlorides, total organic carbon and organic contaminants as quantitative variables, enhanced by additional qualitative variables such as groundwater salinity, season, water level, precipitation, and industrial activity type to make the dataset as representative as possible of the site under investigation. The study used robust multivariate statistical analyses to analyse the complex dataset and explain the relevant factors influencing contaminant behaviour under different environmental conditions. The Multivariate Statistical Analysis distinguished three clusters of trace elements with diverse reactivity to changes in groundwater salinization. The first includes Se, Cu, Crtot, V, and Ni, showing the highest correlation with electrical conductivity and chlorides because of their high affinity to form chloride or organic chloride complexes and for ion competition. Zn and Pb cluster in the second group: they are less reactive to groundwater salinization and more influenced by cation and anion competition and organic matter. The mobility of Hg and As (third cluster) significantly correlates with Fe and Mn, underlining the dominant role of reductive dissolution of trace elements-bearing minerals (Fe/Mn/Al-oxy-hydroxides) and metal-organic complexes. The correlation between the clustering of variables in groundwater and soils shows the influence of sediment structure, mineral composition, and physical and chemical soil conditions on the distribution in soils of trace elements and their transport to groundwater. The study proposes a valuable approach for assessing the effects of salinization in contaminated coastal aquifers. It supports planning multi-purpose characterization and monitoring campaigns of contaminated coastal sites and provides guidance on the correct associated remediation projects.

The carrot cyst nematode Heterodera carotae: a major plant-parasitic nematode requiring more investigation

Summary The present study reviews the knowledge to date on the carrot cyst nematode Heterodera carotae, which has become the primary threat to the carrot sector following the withdrawal of the last chemical soil fumigants in Europe. A keyword co-occurrence network was used to structure this review into five research areas: i) biology and epidemiology of H. carotae; ii) molecular identification and phylogeny; iii) population genetics and genomics; iv) control methods and strategies; and v) root exudates and hatching stimulation. Our findings indicate that H. carotae is an under-studied plant-parasitic nematode species, with several identified alternative control methods that require further investigation.

Relationship between root system-soil C:N:P and soil microbial diversity at different evolutionary stages of Caragana tibetica scrub in arid desert grassland, Northern China.

Scrub root systems play a crucial role in preventing soil erosion and nutrient loss. However, the effects of the root system configuration on soil nutrient dynamics and microbial changes at various evolutionary stages remain poorly understood. In this study, we investigated the relationship between soil physical and chemical properties and the diversity of bacteria and fungi throughout the evolutionary stages of the scrub root systems. This was achieved through a combination of whole-root excavation and root tracing techniques. The results indicated that root diameter was the main factor contributing to the continuous increase in carbon (C): phosphorus (P) and nitrogen (N): P ratios as the scrub sand pile developed. The soil organic carbon (SOC), total soil nitrogen (TN), and total soil phosphorus (TP) contents in the soil in the four evolutionary stages were the highest during the developmental stage, but the change in TP content was not statistically significant (P > 0.05). Partial least squares path modeling and redundancy analysis (RDA) indicated that root system stoichiometric C and N contents were positively correlated with microbial diversity (R2 = 0.85). There was no correlation between the evolutionary stage and soil nutrient TN, whereas soil nutrient TN was negatively correlated with microbial diversity (R2 = -0.92). These findings elucidate the relationship between the evolutionary stage of root chemical measurement characteristics, soil elements and microorganisms, and their subsequent effects on root elemental composition and microbial diversity. This study enhances the current understanding of plant-soil interactions in desert steppe ecosystems.

Key Chemical Soil Parameters for the Assembly of Rhizosphere Bacteria Associated with Avocado Cv Hass Grafted on Landrace Rootstocks

Avocado cultivation holds significant economic importance in many countries, ranking Colombia as the fifth largest global producer. Particularly, the Hass cultivar plays a pivotal role in Colombia’s avocado industry, especially in the Department of Antioquia, the primary export region. This cultivar is grown under diverse soil and climate conditions and exhibits considerable genetic polymorphism due to the hybridization of varieties of agronomic significance, leading to a diverse array of landrace rootstocks. However, the role of soil conditions and rootstock genotype in structuring rhizosphere bacterial communities is still lacking. In addressing this knowledge gap, we investigated the influence of two soil conditions on the structure of rhizosphere bacterial communities associated with two landrace genotypes of Persea americana cv. Hass, utilizing 16S rRNA sequencing. Notably, no significant differences related to genotypes were observed. This study reports that the rhizosphere bacterial microbiome remains consistent across avocado landrace rootstocks, while variations in key parameters such as phosphorus, pH, Mg, and Ca drive distinct rhizosphere effects. Our results reveal that despite the soils having similar management, increases in these crucial parameters can lead to bacterial communities with lower alpha diversity and a more complex co-occurrence network. In addition, we found substantial variations in beta diversity, bacterial composition, and metagenome predictions between the two farms, underscoring the role of soil variables in shaping the bacterial microbiome. These findings provide valuable insights into the factors influencing the bacterial communities that may play a role in the health and productivity of crops with agro-industrial potential, such as Hass avocado.

Complex interactions of deer herbivory, soil chemistry, and competing vegetation explain oak–hickory forest tree regeneration in central Pennsylvania, USA

The root causes of forest tree regeneration failure are difficult to resolve, although numerous studies show ungulate herbivory, soil conditions, and competition from undesirable vegetation as likely contributors. To better understand the relative importance of each issue, we conducted a 7-year manipulative experiment to assess the interactive effects of white-tailed deer ( Odocoileus virginianus) herbivory, soil acidity, and competing vegetation on tree regeneration in oak–hickory forests of central Pennsylvania, USA. Outcomes depended on initial tree seedling abundance, and all three factors had significant interactions. At low initial seedling abundance, fencing resulted in the greatest increase, but all treatments had a positive effect on seedling growth and abundance. At higher initial seedling abundance, abundance failed to recover 7 years after herbicide treatment and soil pH was an important predictor. When soil pH was >4.6 from lime application, seedling growth and abundance in unfenced controls with high initial abundance was comparable to the fenced-only treatment. Competing vegetation, assumed to be a symptom of excessive, long-term deer herbivory, does not seem to be the primary factor limiting tree regeneration in our study area. Ameliorating acid deposition warrants greater consideration as a management action because it could provide long-lasting benefits compared to short-term fence installations.

No-till, crop residue management and winter wheat-based crop rotation strategies under rainfed environment

Rainfed agriculture is primarily limited by unstable low precipitation, poor soil fertility and monocropping, which are the main factors leading to decreased crop production. This long-term research was conducted under a rainfed agroecosystem from 2019 to 2023 on the sierozem soil of the Karshi steppe, Uzbekistan. Along with winter wheat (WW) which was the main crop covering 50% of each proposed cropping pattern, chickpea (CH), safflower (SA), flax (FL), barley (BA) and canola (CA) were evaluated to find the most suitable rotation systems under no-till (NT) i.e. NT1: WW–CH–WW–FL, NT2: CH–WW–SA–WW, NT3: WW–SA–WW–BA and NT4: SA–WW–CA–WW compared against continuous WW produced with conventional tillage (CT). Results showed that the integrated effect of NT x crop diversification x residue retention positively affected crop productivity; however, their impact were significantly higher under the NT2 treatment, but not with continuous WW under CT. The highest grain yield of WW in the 2020-2021 growing season was recorded under NT2 and NT4 treatments with values of 1.47 and 1.30 Mg ha-1, while the lowest index (1.02 Mg ha-1) was found at the CT treatment. The grain yield in the NT treatments increased with the improvement of soil chemical and physical parameters, i.e. NPK and humus content. When comparing NT2 to CT treatment at the project end, the total N, P, and K values at the 0–20 cm soil profile were 27.9%, 13.9%, and 33.9% higher, respectively. This study concluded that implementation of NT along with strategic selection of legumes incorporated into the cropping system and residue management can be prioritized as rehabilitation measures in rainfed croplands.

Biochar aging, soil microbiota and chemistry of charcoal kilns in Mediterranean forests

AbstractCharcoal kilns, old structures used for charcoal production in the forest, preserve a charcoal-enriched topsoil representing a suitable proxy for studying the long-term effect of biochar addition to soil. Two kiln platforms located at Gelbison and Vesole mountain sites in Southern Italy were selected due to their comparable climates but distinct parent rocks. We conducted standard soil chemical analyses and used next-generation sequencing to explore bacterial and fungal microbiome. Anthracology identified charcoal species, while scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) characterized charcoal particles. Reflectance Fourier transform infrared spectroscopy (DRIFTS) assessed biochar surface oxidation. Additionally, a bioassay with soybean, maize, and Tomato investigated the impact of kiln soil on plant performance. Our results showed that kiln soils did not exhibit higher pH, cation exchange capacity, or greater richness in cations. EDS and FTIR analyses showed that charcoal buried in forest soil for decades undergoes significant oxidation, with increased O/C ratio and the presence of oxygenated functional groups. Charcoal surfaces were selectively enriched with Ca2+ on limestone substrate sites but with Al and Si over sedimentary (flysch) substrate. While differences in the kiln soil and its surroundings were noticeable, they were not drastic in terms of microbial diversity and composition. Surprisingly, the bioassay indicated that the kiln microbiota had a more positive impact on plant growth compared to external forest soil. In conclusion, this study highlights the unique nature of kiln microsites and begins to unveil the enduring effects of charcoal accumulation on soil chemistry and microbiota in forest soil. Graphical Abstract

Positive influence of apple trees on soil chemical and biological activities in agroecological garden orchard system

Positive influence of apple trees on soil chemical and biological activities in agroecological garden orchard system

Rapid Uplift, yet Slow Denudation of the Suckling‐Dayman Metamorphic Core Complex in Tropical Papua New Guinea

AbstractA linear relationship between rates of physical erosion and chemical weathering is apparent in slowly eroding landscapes. Whether the relationship remains linear in rapidly eroding landscapes is less clear. Field‐based research into this relationship between erosion and weathering rates has largely been conducted in temperate climates with granitic bedrock. In tropical settings, the contribution of chemical mass loss to total denudation may approach, or even exceed, that of erosion. We report 10Be‐in‐quartz cosmogenic radionuclide and soil chemistry data from the Suckling‐Dayman Metamorphic Core Complex (SDMCC) in Papua New Guinea. Despite being exhumed at cm‐per‐year rates, its lower‐plate domed and striated morphology suggests minimal denudation, which is confirmed by our 10Be‐in‐quartz data (0.02–0.18 mm/yr). We suggest that rolling hinge‐style back‐rotation of the SDMCC's lower plate and the combination of a tropical climate and highly weatherable metabasalt bedrock have played a fundamental role in preserving the tectonic topography of this remarkable metamorphic core complex.

Effects of aerial liming on soil chemical and biological properties in metal contaminated and inaccessible lands in Ontario (Canada).

The manual addition of lime to soil, in addition to tree planting and fertilization have been the dominant strategy described in restoration protocols for ecosystems damaged by acid rain and metal contamination. Investigations on aerial-limed soils in inaccessible lands are limited. The objective of this study was to assess the effects of aerial liming on soil pH, organic matter, microbial biomass, and enzymatic activities, and aboveground plant population quality in metal-contaminated lands in northern Ontario, Canada. Soil samples were collected from three sites around the City of Greater Sudbury with each pair being composed of a reclaimed (areal-limed) site and an adjacent undisturbed (unlimed) area. Soil physico-chemistry, microbial biomass (assessed by Phospholipid fatty acid analysis) and enzymatic activities were analyzed. Soil pH was higher in limed sites compared to unlimed at recently restored sites (Baby Lake and Wahnapitae) but not at the oldest reclaimed site (HWY 80 N). Organic matter was higher in limed areas compared to the unlimed reference site only at most recently reclaimed site at Baby Lake. Aboveground plant population health was visibly improved in limed sites compared to unlimed areas. Metal concentrations of iron (Fe) and arsenic (As), total microbial biomasses, gram-negative bacterial, fungal, and eukaryotic biomasses were all significantly increased in the limed soils compared to the unlimed samples. The same trend was observed for the activities of three of the enzymes tested, β-N-acetylglucosaminidase (BG), aryl sulfatase (AS), and glycine aminopeptidase (GAP). Interestingly, strong positive correlations between the levels of soil organic matter, microbial biomasses, and NAGase and ALP activities were observed. Although expensive, aerial liming is effective in restoring inaccessible sites impacted by smelting operations where other methods cannot easily be used.

Historical development, current practices and future development of multi-elements soil chemistry in archaeology

Historical development, current practices and future development of multi-elements soil chemistry in archaeology

Wild pigs influence tropical forest soil microbial communities in a forest-agriculture mosaic landscape

Edge effects, the altered abiotic and biotic conditions on the borders of natural areas, have rarely been linked to altered soil biota, which shape ecosystem processes including carbon storage, biogeochemical cycling, and plant performance. Here, we investigated if increased wildlife populations (their increase mediated by foraging in nearby oil palm plantations) affect soil biota when they move between plantations and natural habitats. We used a 22-year fenced exclusion experiment in a primary rain forest in Peninsular Malaysia. We found that the presence of wildlife (mainly native pigs; Sus scrofa) was associated with greater bacterial diversity, an altered bacterial community composition, and indications of a reduced abundance of symbiotic ectomycorrhizal fungi. There were only minor effects of pigs on soil chemistry or microclimate, so we suggest that changes in soil communities are driven by pigs’ leaf litter removal and alterations to plant composition. Our study highlights that indirect effects from agriculture can be induced by wildlife more than1 km into protected areas and this could have important repercussions for ecosystem processes and plant-soil feedbacks.