Soil Buffering Capacity Research Articles

Effect of vegetable residues incorporation on soil fertility, rhizosphere microbial community structure, and plant growth of continuously cropped cucumber in a solar greenhouse

PurposeIncorporating crop residues into the soil is considered a sustainable and valuable method to alleviate soil deterioration caused by continuous monoculture in greenhouse production. However, the effect of vegetable residues retention on soil amendments is poorly understood. In the present study, we investigated the impacts of sweet pepper, tomato, and cucumber plant residues on soil microbial communities and plant growth of continuously cropped cucumber in a solar greenhouse.MethodsThe 16S rRNA and ITS1 rRNA genes were amplified, and high-throughput sequencing was performed to explore the impacts of vegetable residues incorporation on soil microbial communities. Additionally, soil chemical properties, cucumber root vigor, and fruit yield were measured to assess the impacts of vegetable residues incorporation on continuously cropped soil and cucumber growth.ResultsThe results showed that incorporating vegetable residues could improve soil buffering capacity, increase the content of soil organic matter and available nutrients, and increased the diversity of soil microorganisms and improved community structure; vegetable residues increased the abundance of beneficial bacteria such as Actinobacteria, Firmicutes, Proteobacteria, and Chloroflexi, while reducing the quantity of soil-borne pathogens such as Bacillariophyta and Acidobacteria. Similar results were observed for the fungal communities: the relative abundance of Ascomycota was decreased to varying degrees, while the relative abundance of Rozellomycota and Basidiomycota was raised. The results demonstrated that vegetable residues incorporation significantly increased cucumber root vigor and enhanced fruit yield. The effects of different types of residues on improving soil properties were ordered sweet pepper plant residues > cucumber plant residues > tomato plant residues, and 20% of sweet pepper plant residues incorporation had the most significant effect on crop yield.ConclusionIn summary, returning vegetable residues alleviated soil continuous cropping obstacles by improving the soil fertility and the diversity and community structure of soil microorganisms, and consequently promoting the growth and yield of greenhouse-grown cucumbers. The findings demonstrated that returning vegetable residues was an effective and sustainable measure for soil amendment during continuous cropping in greenhouse production.

Spatial distributions of salt-based ions, a case study from the Hunshandake Sandy Land, China.

Soil water soluble base ion salt-based ion concentrations are critical parameters for estimating soil buffer capacity and vegetation productivity. Ionic content clearly covaries with the distribution of plant communities. Previous studies on salt-based ions in soils focused primarily on ion migration and its relationships with vegetation growth. Few studies have sought to characterize larger scale spatial distribution of salt-based ions or correlation with climatic and plant community characteristics. This study used ion chromatography to analyze the salt-based ion content (Ca2+, Mg2+, Na+ and K+) of surface soils from the Hunshandake sandy lands. Statistical methods were used interpret spatial variation. Results showed that the average content of salt-based ions in Hunshandake sandy land was 86.57 mg/kg. Average values ranked as Ca2+ > Na+ > K+ > Mg2+ but concentrations also exhibited uneven spatial distributions. Horizontal spatial variation in Ca2+, Mg2+ and Na+ ions showed these ions gradually decrease from northwest to southeast. Potassium ions (K+) showed no obvious spatial variation trends. Ions varied significantly across different soil layers but their average concentrations ranked as K+>Na+>Ca2+>Mg2+ (from shallow to deep). The 20–30 cm soil layer contained the highest salt ion concentrations. Of the four base ions, only K+ ions appeared in surface samples. In terms of water soluble base ion available salt-based ions, Ca2+ occurred in the highest concentrations along the north and west side of the study area. K+ ions occurred in the highest concentrations along the south and east sides of the study area. Na+ concentrations did not show a consistent spatial pattern. Statistical analysis detected significant correlations of normalized ion concentration parameters (Ca2+/CECT, K+/CEC, effective water soluble base ion salt-based ions) and the total species number, average species number and total biomass of the plant communities (P <0.05). This study can help inform understanding of soil water transport in sandy areas and provide a reference for interpreting ecosystems in arid regions.

Evaluating the benefits of legacy phosphate

AimsMany soils in the developed world have been fertilized with phosphate for several decades. Appreciable phosphate has accumulated in such soils. This is referred to as “legacy P”. The benefits of legacy P are not widely appreciated. Here, we report the effects of legacy P on buffering capacity and the consequent effects on the effectiveness of plant growth, and its effects on the continuing reaction between soil and P and the consequent effects in decreasing the decline of P effectiveness with time.MethodsWe produced five levels of legacy P by incubating the soil with added phosphate at high temperatures for 30 days. We then measured the effect on sorption/desorption and on plant growth in response to further additions of phosphate.ResultsLegacy P decreased soil buffering capacity, decreased hysteresis of desorption, and increased the amount of P in a similar state to that of the recently sorbed P. There were analogous effects of plant growth; effectiveness of P fertiliser increased; the decline in effectiveness with time decreased; and the amount of soil P accessible to plants increased. We think that soil tests reflect only the amount of soil P accessible to plants. Soil testing services which include estimates of phosphate buffering reflect its decrease and the consequent increase in fertilizer effectiveness. We propose a simple test to reflect the rate of decline in effectiveness with time.ConclusionsManaging phosphate applications using soil tests alone underestimates phosphate status and leads to over application of phosphate. It is necessary to also include estimates of the change in phosphate buffering and the change in the rate of decline in effectiveness with time. A simple way to estimate the rate of decline is suggested.

Biostimulants: Concept, Types and Way to Enhance Soil Health

Soil has immense capacity to function as a vital living ecosystem that not only support plants and animals but also acknowledges survival of people, as a result there has been renewed interest in soil health but due to the environmental repercussions of poor management, such as soil erosion and nutrient contamination, the health of soil is deteriorating with an increasing rate. Application of biostimulants can prove to be a prominent tool for enhancing soil health. Biostimulants are compounds, microorganisms or other materials that are capable of stimulating nutrition processes in plants or in their growth environments. Regardless of their nutritional content they increase the plant's nutrient use efficiency, partial factor productivity, tolerance to abiotic stress and quality of the crop. Many types of biostimulants have been differentiated by their administration technique either soil or foliar, or may be plant or animal derivatives, or by the distinctive procedure involved for their derivation that may be hydrolysis, fermentation or acid/alkali extraction. Stimulants of biological origin that are soil applied can promote the establishment, proliferation of beneficial soil organisms that furnish substrates for plant growth. Biostimulants enhance soil health (physical, chemical, biological properties) by targeting certain major prospects such as enhanced buffering capacity of soil, enhanced stability of aggregates and specific surface area. The use of environmentally friendly natural preparations is especially significant in light of the ongoing processes of soil degradation and air pollution. Enzymes, Protein hydrolysates, and Sea Weed Extracts, Humic substances, Nitrogen-Fixing Bacteria and Phosphorus Solubilising Bacteria, Plant Growth Promoting Rhizobacteria briefly comes under the umbrella of biostimulants. These biostimulants can be extracted from various methods such as alkali hydrolysis, partial hydrolysis, pressurised liquid extraction,etc. Even while a biostimulants may not have a short-term effect, it has the potential to improve soil health with progression, ensuing higher yields in the succeeding years.

Phosphorus sorption characteristics as influenced by major soil units in southern Ethiopia

AbstractBackgroundLimited soil nutrients in the soil are threat in crop production in Ethiopian soil. Low availability of phosphorus (P) is one amongst the most important crop yield‐limiting problems among the various reasons limiting P availability in tropical soils, P sorption is that the major one.AimTherefore, this study was done to identify P sorption characteristics of andosols, vertisols, and nitisols in Tachegnawgimbicho, Taba, and DelboAtwaro study sites in southern Ethiopia.MethodsAdsorption isotherms experiment was done using Langmuir and Freundlich models to spot the character of soils in their capability on P sorption and causation and to explain P sorption as influenced by the associated soil properties using SAS version 9.00.ResultsThe P sorption maxima (Xm) of andosols, vertisols, and nitisols were found to be 965, 810, and 706 μg g−1, respectively. Correlation analysis indicated that soil pH was negatively and significantly correlated with Xm (R2 = −0.88). The Langmuir affinity constant “k” was positively and significantly correlated (R2 = 0.981) with maximum phosphorus buffering capacity (MPBC) indicating bonding energy constant is a component of buffering capacity of soils. The Langmuir equation correlated significantly with P sorption maximum “b” and binding energy “k” indicating both parameters can be used for evaluating P sorption characteristics of the soils.ConclusionIn this finding, the path analysis coefficient revealed that clay and pH had direct effects on P sorption parameters. Sorption capacity is high in andosols followed by nitisols and vertisols. Andosols require more P fertilizer to maintain optimum P concentration in soil solution for crop growth as compared with nitisols and vertisols.

Aluminum mobilization as influenced by soil organic matter during soil and mineral acidification: A constant pH study

Soil acidification is an increasing challenge to food security due to the production of free aluminum ion (Al3+) that is toxic to crops. The production of exchangeable Al3+ in soils during acidification is a complex process and its specific mechanism is not clear. In this study, kaolinite, montmorillonite, and three acidic soils (two Ultisols and one Alfisol) were used to investigate the changes in exchangeable and soluble Al with pH using a constant pH automatic potentiometric titrator. The effect of soil organic matter (SOM) on soil pH and Al change was also investigated. The results showed that montmorillonite consumed more acid than kaolinite under the same conditions, which were consistent with the larger cation exchange capacity (CEC) of montmorillonite than kaolinite. When the pH was adjusted from 4.8 to 4.3, the exchangeable Al of montmorillonite was significantly higher than that of kaolinite. This was consistent with their CEC and indicated that montmorillonite adsorbed more H+ than kaolinite at the same pH, resulting in more exchangeable Al on its surface. Besides CEC, SOM shows a significant effect on acid buffering capacity and Al activation of acid soils. When acidified to the same pH, the content of exchangeable Al in Alfisol was larger than that in Ultisols. This observation was consistent with the larger CEC and smaller organic matter content of Alfisol. The presence of more organic matter in the Ultisols not only improved their acid buffering performance, but also inhibited the production of exchangeable and soluble Al. In conclusion, CEC of soils and minerals play an important role in soil acid buffering performance. While, SOM not only improves soil acid buffering performance, but also inhibits the mobilization of soil Al.

EVALUATION OF PHYSICO-CHEMICAL PROPERTIES AND P SORPTION CHARACTERISTICS OF SOIL WITH DIFFERENT LAND USE IN TIGONI, KIAMBU COUNTY, CENTRAL KENYA

&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;Phosphorous is a limiting crop nutrient in highly weathered tropical soils due to fixation, and its availability for plants’ uptake is influenced by soil physico-chemical characterics, land use type and management practices. &lt;strong&gt; &lt;/strong&gt; &lt;strong&gt;Objective:&lt;/strong&gt; To evaluate the relationship between selected physico-chemical properties and phosphorous sorption characteristics of a humic nitisol (Alfisol) from Tigoni, Kiambu County, central Kenya. &lt;strong&gt;Methodology:&lt;/strong&gt; The soil was sampled from the same area with different land uses that include tea plantation, maize field and natural forest at 0-25, 25-50 and 50-75 cm depths. P solution at the rates of 50, 100, 150, 200 mg P L&lt;sup&gt;−1&lt;/sup&gt; in a 24 h contact time were used in the study for maximum sorption. The data was analysed by simple regression and Pearson correlation analysis. &lt;strong&gt;Results:&lt;/strong&gt; The adsorption data was fitted more to Langmuir model (R&lt;sup&gt;2&lt;/sup&gt; = 0.9100-0.9994) compared to Freundlich (R&lt;sup&gt;2&lt;/sup&gt; = 0.6815-0.9971). The values of P sorption maxima ( ) determined by Langmuir model ranged from 3,333-5,000 mg kg&lt;sup&gt;-1&lt;/sup&gt; and bonding energies ( ) ranged from 0.2308-1.5385 L mg&lt;sup&gt;-1&lt;/sup&gt;. The buffering capacity of soil ranged from 769-5000 L kg&lt;sup&gt;-1&lt;/sup&gt; and the external P requirement at 0.2 mg kg&lt;sup&gt;-1&lt;/sup&gt; ( ranged from 147-1176 mg P kg&lt;sup&gt;-1&lt;/sup&gt; both increasing with soil depth. P sorption maxima were negatively and significantly correlated with organic carbon (r&lt;sup&gt;2&lt;/sup&gt; = -0.700*) and Ca&lt;sup&gt;2+&lt;/sup&gt; (r&lt;sup&gt;2&lt;/sup&gt; = -0.703*) contents. The pH of soil and clay content were negatively correlated with adsorption parameters ( ) while Al content was positively correlated though none of them was statistically significant. &lt;strong&gt;Implication&lt;/strong&gt;: The data revealed a highly P-sorbing soil particularly&lt;strong&gt; &lt;/strong&gt;tea plantation, a situation that can be alleviated by management practices such as liming and enhancing soil organic matter content. Field experiments are however, recommended to validate the findings of this study. &lt;strong&gt;Conclusion:&lt;/strong&gt; Land use type influences P-sorption capacity of soil hence, fertilizer recommendations should be based on soil physico-chemical characteristics besides crop nutrient requirements.&lt;/p&gt;

Reagent-free electrokinetic remediation coupled with anode oxidation for the treatment of phenanthrene polluted soil

Electrokinetic in-situ chemical oxidation (EK-ISCO) has attracted much attention during remediation of organic contaminated soil. Oxidants in EK-ISCO brings high cost and negative effects on soil physicochemical properties. In this study, a novel approach of combined electrokinetic treatment and anode oxidation was investigated to remediate phenanthrene polluted soils without adding oxidants. The fabricated Ti4O7 acted as anode, and could generate •OH at the rate of 9.31 × 10−7 mol h−1 at current 5.10 mA cm−2 through direct H2O electrolysis. Electro-osmotic flow (EOF) was used to transport phenanthrene to anode for the subsequent degradation. Sandy soil, fluvo-aquic soil and red soil were selected as typical soil samples, because pH and buffer capacity were two important factors affecting the direction of EOF. Strategies were developed to regulate the direction of EOF, including adding CEM membrane, maintaining soil pH at 3.5–4.0 and mixing solution from anode and cathode chambers. After treatment, more than 81.9% of phenanthrene was removed without adding any oxidants, and the remediated soil had low toxicity for Lolium perenne growth based on 3-d cultivation results. The results indicated that EK-AO had the advantage of less energy consumption and superior environmental friendliness than traditional EK-ISCO.

The exacerbation of soil acidification correlates with structural and functional succession of the soil microbiome upon agricultural intensification

Agricultural intensification driven by land-use changes has caused continuous and cumulative soil acidification (SA) throughout the global agroecosystem. Microorganisms mediate acid-generating reactions; however, the microbial mechanisms responsible for exacerbating SA feedback remain largely unknown. To determine the microbial community composition and putative function associated with SA, we conducted a metagenomic analysis of soils across a chronosequence that has elapsed since the conversion of rice-wheat (RW) to rice-vegetable (RV) rotations. Compared to RW rotations, soil pH decreased by 0.50 and 1.56 units (p < 0.05) in response to 10-year and 20-year RV rotations, respectively. Additionally, acid saturation ratios were increased by 7.3% and 36.2% (p < 0.05), respectively. The loss of microbial beta-diversity was a key element that contributed to the exacerbation of SA in the RV. Notably, the 20-year RV-enriched microbial taxa were more hydrogen (H+)-, aluminium (Al3+)-, and nitrate nitrogen (NO3−-N) -dependent and contained more genera exhibiting dehydrogenation functions than did RW-enriched taxa. “M00115, M00151, M00417, and M00004” and “M00531 and M00135” that are the “proton-pumping” and “proton-consuming” gene modules, respectively, were linked to the massive recruitment of acid-dependent biomarkers in 20-year RV soils, particularly Rhodanobacter, Gemmatirosa, Sphingomonas, and Streptomyces. Collectively, soils in long-term RV rotations were highly acidified and acid-sensitive, as the enrichment of microbial dehydrogenation genes allowing for soil buffering capacity is more vulnerable to H+ loading and consequently promotes the colonization of more acid-tolerant and acidogenic microbes, and ultimately provide new clues for researchers to elucidate the interaction between SA and the soil microbiome.

Кинетика изменения окислительно-восстановительного состояния почв при их увлажнении и высушивании

The development of excessive moisture in soils in early spring leads to the emergence of anaerobic conditions that limit the cultivation of agricultural crops. To predict the development of this process, an assessment of soil buffering in the redox interval, the buffer capacity of soils in the redox interval, and an assessment of the kinetics of the development of reducing conditions during soil anaerobiosis is proposed. According to the data obtained in chernozems, in comparison with sod-podzolic soils, the rate of fall of H during flooding is lower, the capacity of soils in the recovery interval is greater. The addition of KNO3 to the soil on the 14th day of flooding changes the Eh mv in sod-podzolic soil from -135 to +125 mv, in chernozem - from -105 to +170, pHO3 in sod-podzolic soil - from 4.0 to 2.0; in chernozem - from 3.0 to 2.0. It is proposed to apply these patterns when adjusting the components of farming systems on soils of excessive moisture in spring. Keywords: SOIL, REDOX STATE, ANAEROBIOSIS, AGROECOLOGICAL ASSESSMENT

Data Integration Analysis Indicates That Soil Texture and pH Greatly Influence the Acid Buffering Capacity of Global Surface Soils

Soil acidification is a global environmental issue that decreases soil functions, and it has been significantly accelerated by anthropogenic activities in recent decades. Soils can resist acidification upon receiving acid inputs due to the resistance or/and resilience capacity of soils, which is termed the acid buffering capacity of soils, and it is often indicated by the soil pH buffering capacity (pHBC). An increasing number of studies have been conducted to quantify soil pHBC at various sites, but to date, integration of global data is lacking; therefore, the variations in large-scale soil pHBC and the factors that influence these variations are still unclear. In this study, we collected previously published data on soil pHBC to analyze its variations on a large scale, as well as investigate the underlying factors influencing these variations. The results showed that soil pHBC varied substantially from site to site, with a mean of 51.07 ± 50.11 mmol kg−1 pH−1. Soil texture and pH, separately or collectively, explained a considerable proportion of the total variation of global soil pHBC. It is well-established that a series of processes contribute to the soil acid buffering capacity in different pH ranges, and the global data analyses showed that pH 5.5 could be a key threshold value; different buffering systems may be active at pH &gt; 5.5 and pH &lt; 5.5. Moreover, tropical soils were more acid-sensitive than temperate and subtropical soils, and forest soils had significantly lower soil pHBCs than grassland and cropland soils. This could be attributed in part to the different soil properties, such as soil texture or pH, among the different climatic zones and ecosystems.

Effect of different soil amendments on soil buffering capacity.

The buffering capacity of the soil is a very important property of the soil, which determines the ability of the soil to resist external influences, especially changes in pH and thus create good living conditions for plants and microorganisms in the soil. The buffering capacity thus significantly contributes to maintaining the health and quality of the soil. Buffering capacity is an important indicator of soil quality, because it is related to the overall condition of the soil ecosystem and other soil properties. The goal of this paper is to determine the effect of applying different soil amendments on the soils, 10 years after application. We compared the effect of 6 different treatments in closed plots: Natural conditions (N = control); Bare soil (B); Straw mulching (S); Pine mulch (P); TerraCottem hydroabsorbent polymers (H); Prescribed burn (F); and Sewage sludge (M). Our results have shown that the application of different amedments leads to an effect on the plowing capacity of the soil. While in the case of the control variant (Natural conditions, N) the buffering capacity of the soil was measured at 144.93 ± 0.25, the addition of different amendments decreased the buffering capacity in the following order: Bare soil (B) 142.73±0.21 > TerraCotem hydroaborbent polymer (H) 142.23±.15 > Pine mulch (P) 140.40±0.30, Prescribed burn (F) 138.20±0.30, Sludge (S) 127.47±0.15. In the case of all variants, these are statistically significant differences (p ≤ 0.05). Thus, soil amendments have been shown to have a statistically significant effect on soil buffering capacity.

IMPACT OF FERTILIZATION ON AGROFORESTRY SYSTEM COMBINING ROWS OF WILD CHERRY AND SMALL-LEAVED LIME WITH PERENNIAL GRASSES AND LEGUMES IN LATVIA

Interest in agroforestry as land use practice continues to revive due to it's social, economic, and especially environmental and climate change mitigation benefits. This article encompasses results of productivity of hemiboreal agroforestry system combining rows of wild cherry and small-leaved lime with perennial grasses (Phalaris arundinacea L. and Festulolium pabulare) and legumes (Galega orientalis Lam.). Experimental plot of agroforestry system was established in agricultural land on mineral soil in central part of Latvia in the spring of 2011. Different fertilizers such as by-products of bioenergy production (wood ash, digestate), municipal waste (wastewater sludge) and mineral fertilizers were used to compensate nutrients in the soil and soil buffer capacity. Survival rate of the trees (especially for wild cherry) in agroforestry systems was relatively very low, mostly due to winter frosts and later browsing by hares. Nevertheless, results of our study highlighted that both used fertilizers and interactions between trees and herbaceous plants impact total productivity of system including tree growth, yields of biomass and seeds of herbaceous plants as well as chemical composition of biomass of herbaceous plants. Whereas obtained biomass of herbaceous plants can be used for both forage and energy production purposes, the benefits and risks of fertilization must be assessed on a case-by-case basis depending on the intended use of biomass.

Assessment of the Soil Buffer Capacity in the Sea of Azov Basin Under Heavy Metal Pollution

Heavy metals (HM) are among the most hazardous soil pollutants. The intensity of accumulation and distribution of HM in soils directly depends on the ecological conditions of pedogenesis and its buffering properties. At the same time, a significant accumulation of HM in the soil as a result of anthropogenic impacts reduces the buffering capacity of the soil and its resistance to pollution. The purpose of this work was to assess the buffering capacity of soils to HM pollution in the Don River delta and the coast of the Taganrog Bay of the Sea of Azov undergoing the great anthropogenic impact. The buffer capacity of experimental soils was carried out using the Il’in’s method (1995), based on the calculation of the inactivation ability of soils: organic matter, clay fraction (particle size &lt; 0.01 mm), carbonates, sesquioxides, and pH. The content of HM was compared with soil Clarke and the maximum permissible concentration of HM in soils accepted in the Russian Federation. It was found that the experimental soils could be ordered by buffer capacity value as following (in decreasing order): haplic chernozem ≥ alluvial-meadow light loamy ≥ solonchak &gt; alluvial-meadow sandy and sandy loamy &gt; sandy primitive soil ≥ stratified alluvial soil.&#x0D; Keywords: trace elements, contamination, impact territories

Радиальные геохимические барьеры в почвах Пермского края

Geochemical barriers in soils control the composition and intensity of geochemical fluxes of natural and technogenic substances in landscapes. The Perm Territory is an industrial region. The total volume of emissions from enterprises of the chemical industry, oil and gas industry, transport, mechanical engineering, metallurgy, electric power industry in 2020 exceeded 380 thousand tons. A sharp spatial change in relief elements, a wide range of temperature parameters of the climate and moisture conditions create a diverse combination of soil-forming factors and, as a result, the diversity of the soil cover of the region, determine the manifold of geochemical settings and differences in the buffer capacity of soils. The objectives of the study included mapping radial geochemical barriers to assess their spatial heterogeneity in terms of anchoring mechanisms and barrier capacity. The soil map of the Russian Federation at a scale of 1:2500000 served as the thematic basis. The database of soil properties was compiled on the basis of the data of the Unified State Register of Soil Resources of Russia with the involvement of regional sources. All maps and attribute databases for them were created using QGIS version 3.2.2 (Maderia). The mapping technique is based on the “horizon approach,” according to which genetic soil horizons are considered as radial geochemical barriers. Two maps of radial barriers were created: surface biogeochemical barriers and physicochemical barriers of the middle horizons. The estimate of the capacity of the surface organic and organomineral barriers of soils in the region was carried out according to the following indicators: the thickness of organogenic and organomineral horizons, humus content, and granulometric composition. The capacity of surface biogeochemical barriers follows a geographical pattern: from north to south of the region, the capacity of organic barriers decreases and the capacity of organo-mineral barriers increases. Among the intrasoil physical and chemical barriers of the soils of the region, the following were distinguished: carbonate, gley and sorption. In general, the region is dominated by oxidizing conditions with a high-capacity sorption-sedimentation barrier in soils. Podzolic and soddy-podzolic soils, occupying 62 % of the region’s area, have a sorption-sedimentation barrier. Podzols, podburs, brown-taiga soils have a low- and moderately capacious chemisorption barrier. The soils of the forest-steppe are characterized by a moderate sorption-sedimentary barrier. Gley barriers of hydromorphic soils occupy approximately 20 % of the area. These maps can be recommended for inclusion in the “Soils” section of the regional comprehensive geographic atlas.

Assessment of joint soil ecosystem services supply in urban green spaces: A case study in Northern Italy

The multiple functions of urban soils secure the supply of ecosystem services to the urban population, but they are seldom taken into account in current urban planning. The purpose of this study is to highlight the multifunctionality of the soils of urban green spaces and to assess the influence of different types of urban green (i.e. parks and gardens, roadside green and agricultural fields) on the joint supply of soil-based ecosystem services. In a case study area in the city of Carpi (NE Italy), we focused on a set of soil functions underpinning ecosystem services and on possible synergies and trade-offs between them. We surveyed and sampled 19 urban green areas to assess the following soil functions: biological fertility, potential habitat for organisms, water regulation and storage, soil buffering capacity and carbon stock. Results showed differences and trends in the bundles of ecosystem services provided by the soils of urban green areas, highlighting the relevance of soil disturbance and vegetation cover density in affecting soil functions. For biological indicators, results showed a negative significant correlation to CaCO3 content, which is associated with the degree of soil disturbance, and that soils in urban areas do not always have compromised soil fauna and may provide the same level of biological quality as agricultural soils or forests.

Changes in soil pH and mobility of heavy metals in contaminated soils

AbstractIn the present paper, the authors attempt to explain the importance of pH in soil environment studies and show what mistakes to avoid when measuring pH and interpreting the results obtained. The tests conducted (i.e., extraction in aqua regia, buffer capacity determination, and the impact of acidification on the amount of heavy metals extracted from soils) demonstrated how soil pollution and buffer capacity affect the pace of extracting cadmium (Cd), lead (Pb) and zinc (Zn) cations from heavily polluted and unpolluted soils following gradual acidification. It was shown that soil acidification caused a significant increase in metal mobility in the following order Cd &gt; Zn &gt; Pb and that the highest decrease in pH was observed after adding the first portion of acid. Further addition of acid caused a gradually lower decrease in pH. Soils from the polluted area presented a high buffer capacity. The control samples displayed a distinctly poorer resistance to pH changes in the soil environment. Special focus was placed on cadmium due to its high mobility in soils, even with neutral and slightly alkaline pH. The analyses revealed that in areas heavily polluted by long‐term industrial activity (Igeo &gt; 5 for Zn, Pb and Cd), it is very important to conduct extensive geochemical studies related to the presence and circulation of particularly toxic elements. This is because every environmental factor, especially pH, may significantly affect their mobility, causing metal ions to become more or less active or increasing or decreasing environmental risk related to their presence.Highlights Soil acidification caused a significant increase in metal mobility in the following order: Cd &gt; Zn &gt; Pb. A special focus needs to be placed on Cd due to its high mobility in soils (up to 70% of total concentration), even with neutral and slightly alkaline pH. A higher pH buffering capacity would lead to a lower increase in percentage of bioavailable pollutants with an increase in acidity.

Changing the buffer capacity of soils of teaagrocenoses after removing the long-term fertilizer load

Changing the buffer capacity of soils of teaagrocenoses after removing the long-term fertilizer load

Zinc Plant Uptake as Result of Edaphic Factors Acting.

The influence of soil characteristics on the lability and bioavailability of zinc at both background and phytotoxic concentrations in Albic Retisol soil (Loamic, Ochric) was studied using various methods. Ranges of insufficient, non-phytotoxic, and phytotoxic zinc concentrations in soil solutions were established in an experiment with an aqueous barley culture. It was experimentally revealed that for a wide range of non-toxic concentrations of Zn in the soil corresponding to the indicative type of plant response, there was constancy of the concentration ratio (CR) and concentration factor (CF) migration parameters. As a result, a new method for assessing the buffer capacity of soils with respect to Zn (PBCZn) is proposed. The transformation processes of the chemical forms and root uptake of native (natural) zinc contained in the Albic Retisol (Loamic, Ochric) through the aqueous culture of barley were studied using a cyclic lysimetric installation and radioactive 65Zn tracer. The distribution patterns of Zn(65Zn) between different forms (chemical fractions) in the soil were established using the sequential fractionation scheme of BCR. The coefficients of distribution and concentration factors of natural Zn and 65Zn, as well as accumulation and removal of the metal by plants were estimated. The values of the enrichment factor of natural (stable) Zn contained in sequentially extracted chemical fractions with the 65Zn radioisotope were determined and the amount of the pool of labile zinc compounds in the studied soil was calculated.

Acid Soils Nitrogen Leaching and Buffering Capacity Mitigation Using Charcoal and Sago Bark Ash

Soil acidity compromises agricultural output in tropical acid soils. Highly weathered tropical acidic soils are characterized by low pH, organic matter, nutrient availability, but high aluminium and iron concentration. Hence, N availability becomes a limiting factor in such soils. To this end, these leaching and pH buffering capacity studies were conducted to determine the effects of co-application of charcoal and sago bark ash on the N leaching or retention and pH buffering capacity of acid soils. The soil leaching experiment was conducted for 30 days by spraying distilled water to each container with soil such that the leachates were collected for analysis. The rate of urea used was fixed at 100% of the recommended rate. The rates of charcoal and sago bark ash were varied by 25%, 50%, 75%, and 100%, respectively, of the recommended rates. The pH buffering capacity was calculated as the negative reciprocal of the slope of the linear regression. The leaching study revealed that the combined use of charcoal, sago bark ash, and urea does not only reduce leaching of NH4+ and NO3− but the approach also improves soil pH, total C, and soil exchangeable NH4+. This effect is related to the fact that the sago bark ash deprotonates the functional groups of charcoal because of its neutralizing components such as Ca, Mg, Na, and K ions. As a result, the combined use of charcoal and sago bark ash was able to retain NH4+ in the soil. The carbonates in the sago bark ash and functional groups of charcoal improve pH buffering capacity. Thus, the combined use of charcoal and sago bark ash improved soil exchangeable NH4+, soil pH, and soil total C, but reduced exchangeable acidity and amount of NH4+ leached out from soil. This study will be further evaluated in a pot trial to confirm the results of the present findings.