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Volume 9
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Soil Syst., Volume 9, Issue 2 (June 2025) – 32 articles

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17 pages, 879 KiB  
Article
Urban Market Gardening Improves Soil Health: A Case Study in Burkina Faso
by Rayangnéwendé Adèle Ouédraogo, Fabèkourè Cédric Kambiré, Laurent Cournac and Charles L. Bielders
Soil Syst. 2025, 9(2), 59; https://doi.org/10.3390/soilsystems9020059 - 4 Jun 2025
Abstract
In sub-Saharan Africa, urban market gardening is characterized by the intensive use of chemical inputs, which could have adverse effects on soil health. This study therefore aimed to assess the impact of urban market gardening on soil health. Topsoil samples were collected from [...] Read more.
In sub-Saharan Africa, urban market gardening is characterized by the intensive use of chemical inputs, which could have adverse effects on soil health. This study therefore aimed to assess the impact of urban market gardening on soil health. Topsoil samples were collected from 69 plots at a market gardening site in Bobo-Dioulasso, Burkina Faso, with cultivation histories ranging from 0 to over 50 years. Twenty-six chemical, biological, and physical soil properties were analyzed. Principal component analysis was used to identify minimum data sets for the assessment of soil health. The selected variables were standardized and aggregated into two soil health indices on a scale from 0 to 100: an overall index based on all properties combined and an average index based on the mean of the biological, physical, and chemical components of soil health. Both indices revealed a clear improvement in soil health over time, with the overall index rising from an initial value of 0.35 to 0.64 after 60 years and the average index rising from 0.30 to 0.62. The average index, which enables the separate assessment of its three components, accounted for a greater share of the temporal variability (R2 = 0.59) than the overall index (R2 = 0.47). These findings highlight the positive impact of urban market gardening practices on soil health at the study site, which was attributed to the large additions of organic amendments. Full article
(This article belongs to the Special Issue Integrated Soil Management: Food Supply, Environmental Impacts, and Socioeconomic Functions: 2nd Edition)
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14 pages, 1141 KiB  
Article
A Novel Biostimulant–Biochar Strategy for Improving Soil Quality and Salinity Tolerance in Medicinal Mint (Mentha longifolia L.)
by Mamdouh A. Eissa, Modhi O. Alotaibi, Mashael M. Alotibi, Alya Aljuaid, Taghreed Hamad Aldayel and Adel M. Ghoneim
Soil Syst. 2025, 9(2), 58; https://doi.org/10.3390/soilsystems9020058 - 2 Jun 2025
Abstract
This study evaluated the combined application of biochar (BC) and Spirulina platensis (SP) as a sustainable strategy to improve soil quality and salinity tolerance in mint (Mentha longifolia L.) cultivated in sandy soils. A pot experiment was conducted using saline irrigation water [...] Read more.
This study evaluated the combined application of biochar (BC) and Spirulina platensis (SP) as a sustainable strategy to improve soil quality and salinity tolerance in mint (Mentha longifolia L.) cultivated in sandy soils. A pot experiment was conducted using saline irrigation water (5 dS m−1) with four treatments: control, BC alone, SP alone, and BC + SP applied at 1% (w/w), arranged in a randomized complete block design with three replicates. Salt stress reduced plant height and biomass yield by 16% and 27%, respectively, and increased sodium (Na+) in shoots by 74%, causing ionic imbalance and decreased soil microbial biomass carbon by 19%. The combined BC + SP treatment significantly improved soil microbial biomass carbon (SMBC) by 100%, reduced soil Na⁺ by 41%, and enhanced K+/Na+ and Ca2+/Na+ ratios by 138% and 133%, respectively. Under salinity, BC + SP increased nutrient concentrations in mint shoots, including N (120%), P (106%), K (88%), Ca (67%), Fe (70%), Mn (50%), Zn (44%), and Cu (70%), and improved leaf chlorophyll content. These results demonstrate that BC and SP synergistically mitigate salinity stress by improving soil properties, nutrient uptake, and ionic balance, making BC + SP a promising sustainable amendment for saline sandy soils. Full article
(This article belongs to the Special Issue Research on Soil Management and Conservation: 2nd Edition)
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34 pages, 6650 KiB  
Article
Salinity of Irrigated and Non-Irrigated Chernozems and Kastanozems: A Case Study of Causes and Consequences in the Pavlodar Region, Kazakhstan
by Dauren Rakhmanov, Bořivoj Šarapatka, Marek Bednář, Jan Černohorský and Kamilla Alibekova
Soil Syst. 2025, 9(2), 57; https://doi.org/10.3390/soilsystems9020057 - 28 May 2025
Viewed by 78
Abstract
This study investigated soil salinization processes in the Pavlodar region of Kazakhstan by comparing key soil parameters—namely, electrical conductivity (EC), pH, exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR) under irrigated and non-irrigated conditions across different agro-climatic zones and soil types (Haplic [...] Read more.
This study investigated soil salinization processes in the Pavlodar region of Kazakhstan by comparing key soil parameters—namely, electrical conductivity (EC), pH, exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR) under irrigated and non-irrigated conditions across different agro-climatic zones and soil types (Haplic Chernozems, Haplic Kastanozems). The focus was on understanding the effects of irrigation and natural factors on soil salinization. Statistical analysis, including descriptive statistics and significance testing, was employed to evaluate differences between soil types, locations, and management practices. The research revealed secondary salinization (EC > 2 dS/m, ESP > 15%) in the topsoil of irrigated Haplic Kastanozems soils in the central Aksu district. This degradation was markedly higher than in non-irrigated plots or irrigated Haplic Chernozems in the northern Irtysh district, highlighting the high vulnerability of Haplic Kastanozems soils under current irrigation management given Aksu’s climatic conditions, which are characterized by high evaporative demand (driven by summer temperatures) and specific precipitation patterns that contribute to soil moisture deficits without irrigation. While ESP indicated sodicity, SAR values remained low. Natural factors, including potentially saline parent materials and likely shallow groundwater dynamics influenced by irrigation, appear to contribute to the observed patterns. The findings underscore the need for implementing optimized irrigation and drainage management, particularly in the Aksu district, potentially including water-saving techniques (e.g., drip irrigation) and selection of salt/sodicity-tolerant crops. A comprehensive approach integrating improved water management, agronomic practices, and potentially soil amendments is crucial for mitigating soil degradation and ensuring sustainable agriculture in the Pavlodar region. Further investigation including groundwater monitoring is recommended. Full article
(This article belongs to the Special Issue Research on Soil Management and Conservation: 2nd Edition)
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15 pages, 1773 KiB  
Article
Accumulation of Soil Metal(loids) in Fast-Growing Woody Plants of the Post-Mining Area of Freiberg, Germany
by Viktoriia Lovynska, Oliver Wiche, Hermann Heilmeier, Alla Samarska and Roland Bol
Soil Syst. 2025, 9(2), 56; https://doi.org/10.3390/soilsystems9020056 - 23 May 2025
Viewed by 229
Abstract
Soil pollution is a global threat that seriously affects biodiversity in (agro)ecosystems and may compromise water and food quality. Therefore, the ability of tree species (Populus tremula, Salix caprea, and Betula pendula) to accumulate and phytoextract specific toxic heavy metals from [...] Read more.
Soil pollution is a global threat that seriously affects biodiversity in (agro)ecosystems and may compromise water and food quality. Therefore, the ability of tree species (Populus tremula, Salix caprea, and Betula pendula) to accumulate and phytoextract specific toxic heavy metals from soil was investigated. The study was conducted in and near relict mining areas of Freiberg (Germany) and sampling sites selected according to their spatial location relative to potential sources of metal(loid)s. The concentrations of geogenic (P, Fe, Mn, Ca) and pollutant (Pb, Cd, Zn, As) elements in soil and the present trees were measured using ICP-MS. The highest total soil concentrations of As (8978 µg g−1) were found within the Davidschaft mining area, and for soil Pb, both in the Davidschaft vicinity (328 µg g−1) and mining area (302 µg g−1). Unexpectedly, the highest soil Zn (0.64 mg g−1) and Cd (3.5 mg g−1) concentrations were found in Freiberg city Forest. The lowest soil concentrations of pollutants (As, Cd, Pb, and Zn) were recorded for Seifersdorf. Total soil P was highest in Colmnitz, but Ca, Mn, and Fe concentrations were very similar across all sites. The available concentration of all measured toxic elements in the soil generally decreased in the order Davidschaft > Davidschaft vicinity, Colmnitz > Seifersdorf = Freiberg city forest. All studied tree species had higher concentrations of the essential elements in leaves than in branches. Generally, higher values of bioaccumulation coefficients (especially for Cd) were found for Salix caprea compared with Populus tremula and Betula pendula. Full article
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16 pages, 902 KiB  
Article
Effects of Biofertilizers on Soil Quality and Vegetative Development of Mahogany (Swietenia macrophylla) and Yaca (Artocarpus heterophyllus) in the Central Peruvian Jungle
by Andrea Castro-Cárdenas, Juanita Ciriaco-Poma, Juan Z. Dávalos-Prado and Víctor Soto-Aquino
Soil Syst. 2025, 9(2), 55; https://doi.org/10.3390/soilsystems9020055 - 20 May 2025
Viewed by 311
Abstract
The sustainability of agricultural production and the conservation of tropical ecosystems face significant challenges due to processes such as climate change and soil degradation. This study evaluated the impacts of three biofertilizers—biol (T02), vermicompost (T03), and bokashi (T04)—on soil quality and the vegetative [...] Read more.
The sustainability of agricultural production and the conservation of tropical ecosystems face significant challenges due to processes such as climate change and soil degradation. This study evaluated the impacts of three biofertilizers—biol (T02), vermicompost (T03), and bokashi (T04)—on soil quality and the vegetative development of two typical plants, Mahogany (Swietenia macrophylla) and Yaca (Artocarpus heterophyllus), cultivated in the Asháninka locality in the Central Peruvian Jungle. Using a completely randomized experimental design, it was generally found that treatments T04 and, to a lesser extent, T03 improved the soil quality and consequently enhanced the vegetative development of Mahogany and Yaca. Compared with the untreated controls (T01), these biofertilizers generated less dense and more porous soils and increased the water retention, organic matter, pH, and the availability of nitrogen and phosphorus nutrients. They also promoted greater biodiversity. These qualities, in turn, stimulated the vegetative development of Mahogany and Yaca, whose leaves showed considerable content of chlorophyll A and B and total chlorophyll. Thus, T03 and especially T04 proved to be effective biofertilizers for the treatment of tropical soils, promoting efficient plant growth and development in species such as Mahogany and Yaca. These findings highlight the great potential of the biofertilizers T03 and T04 in achieving sustainable agricultural production, as well as for the conservation and improvement of tropical forests. Full article
(This article belongs to the Topic Soil Fertility and Plant Nutrition for Sustainable Agriculture—2nd Edition)
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5 pages, 161 KiB  
Editorial
The Effect of Land Use and Management on Soil Properties and Processes
by Adilson Pacheco de Souza and Frederico Terra de Almeida
Soil Syst. 2025, 9(2), 54; https://doi.org/10.3390/soilsystems9020054 - 20 May 2025
Viewed by 144
Abstract
As we delve deeper into the complexities of soil properties and processes, we must consider traditional methodologies and innovative approaches that take advantage of advances in soil management and conservation processes [...] Full article
(This article belongs to the Special Issue Land Use and Management on Soil Properties and Processes)
33 pages, 3402 KiB  
Article
Advancing Sustainable Practices: Integrated Pedological Characterization and Suitability Assessment for Enhanced Irish Potato Production in Tsangano and Angónia Districts of Tete Province, Mozambique
by Tamara José Sande, Balthazar Michael Msanya, Hamisi Juma Tindwa, Alessandra Mayumi Tokura Alovisi, Johnson M. Semoka and Mawazo Shitindi
Soil Syst. 2025, 9(2), 53; https://doi.org/10.3390/soilsystems9020053 - 19 May 2025
Viewed by 792
Abstract
Irish potato (Solanum tuberosum) is a critical crop for food security and economic growth in Tsangano and Angónia Districts, Central Mozambique. Challenges like inconsistent yields and variable quality are often linked to suboptimal soil conditions, which limit production. This study aimed [...] Read more.
Irish potato (Solanum tuberosum) is a critical crop for food security and economic growth in Tsangano and Angónia Districts, Central Mozambique. Challenges like inconsistent yields and variable quality are often linked to suboptimal soil conditions, which limit production. This study aimed to classify and evaluate the suitability of soils for potato cultivation in Tete Province, where detailed soil assessments remain limited. Four pedons—TSA-P01 and TSA-P02 in Tsangano and ANGO-P01 and ANGO-P02 in Angónia—were examined for bulk density, texture, pH, organic carbon, and nutrient content using a combination of pedological methods and laboratory soil analysis. To determine each site’s potential for growing Irish potatoes, these factors were compared to predetermined land suitability standards. The pedons were very deep (>150 cm) and had textures ranging from sandy clay loam to sandy loam. TSA-P02 had the lowest bulk density (0.78 Mg m−3) and the highest available water capacity (182.0 mm m−1). The soil pH ranged from 5.6 to 7.9, indicating neutral to slightly acidic conditions. Nutrient analysis revealed low total nitrogen (0.12–0.22%), varying soil organic carbon (0.16–2.73%), and cation exchange capacity (10.1–11.33 cmol(+) kg−1). Pedons TSA-P01, ANGO-P1, and ANGO-P02 were characterized by eluviation and illuviation as dominant pedogenic processes, while in pedon TSA-P02, shrinking and swelling were the dominant pedogenic processes. Weathering indices identified ANGO-P01 as most highly weathered, while TSA-P02 was least weathered and had better fertility indicators. According to USDA Taxonomy, the soils were classified as Ultisols, Vertisols, and Alfisols, corresponding to Acrisols, Alisols, Vertisols, and Luvisols in the WRB for Soil Resources. All studied soils were marginally suitable for potato production (S3f) due to dominant fertility constraints, but with varying minor limitations in climate, topography, and soil physical properties. The findings hence recommended targeted soil fertility management to enhance productivity and sustainability in potato cultivation. Full article
(This article belongs to the Special Issue Land Use and Management on Soil Properties and Processes: 2nd Edition)
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19 pages, 6962 KiB  
Article
Topographic Wetness Index as a Factor of the Toxic Metals’ Accumulation by the Alkaline Sorption Barrier and the Choice of Revegetation Strategy in the Subarctic
by Marina Slukovskaya, Yury Dvornikov, Tatiana Ivanova, Ekaterina Kopeina, Anna Petrova, Anna Shirokaya, Andrey Novikov, Liubov’ Ivanova and Irina Kremenetskaya
Soil Syst. 2025, 9(2), 52; https://doi.org/10.3390/soilsystems9020052 - 16 May 2025
Viewed by 120
Abstract
Creation of alkaline bulk layers from mining waste is economically viable way to prevent the migration of toxic metals down the soil profile and revegetate heavy polluted soils over large areas. We have conducted perennial experiments on the revegetation of industrial barren located [...] Read more.
Creation of alkaline bulk layers from mining waste is economically viable way to prevent the migration of toxic metals down the soil profile and revegetate heavy polluted soils over large areas. We have conducted perennial experiments on the revegetation of industrial barren located near the operating nonferrous smelter in humid subarctic climate. A vermiculite–lizardite material from closed phlogopite mining, containing 10% layered silicates, was used to create the alkaline sorption barrier on the sites with high level of Cu/Ni pollution and wide range of topographic wetness index (TWI). We have revealed the strong effect of TWI on metal accumulation by mineral material with the highest effectiveness for the most wet sites. At the same time, the stable Ca and Mg content over seasons revealed the prolonged material effect for the maintenance of alkalinity and macronutrient supply. Further, we demonstrate the potential of Festuca rubra, Festuca ovina, Achillea millefolium, Deschampsia cespitosa, Dactylis glomerata, Rumex acetosella, Silene suecica, and for the revegetation of mineral material in dry locations. We demonstrated the effectiveness of alkaline geochemical barrier for the accumulation of toxic metals and successful plant growth in a wide range of topographic units. Full article
(This article belongs to the Special Issue Research on Trace and Hazardous Elements and Emerging Pollutants in Soils and Sediments)
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24 pages, 3507 KiB  
Article
Dynamics of Pharmaceuticals in the Soil–Plant System: A Case Study on Mycorrhizal Artichoke
by Francesco De Mastro, Gennaro Brunetti, Claudio Cocozza, Sapia Murgolo, Giuseppe Mascolo, Carlo Salerno, Claudia Ruta and Giuseppe De Mastro
Soil Syst. 2025, 9(2), 51; https://doi.org/10.3390/soilsystems9020051 - 15 May 2025
Viewed by 264
Abstract
Contaminants of emerging concern, such as pharmaceuticals (PhACs), are continuously introduced into agro-ecosystems through irrigation with treated wastewater (TWW). While this practice is increasingly common in drought regions, only limited information is available on the fate of PhACs within the soil–plant system. For [...] Read more.
Contaminants of emerging concern, such as pharmaceuticals (PhACs), are continuously introduced into agro-ecosystems through irrigation with treated wastewater (TWW). While this practice is increasingly common in drought regions, only limited information is available on the fate of PhACs within the soil–plant system. For this purpose, a two-year study was conducted by irrigating artichokes, non-inoculated and inoculated with different arbuscular mycorrhizal fungi, with water containing PhACs at different concentrations. The experiment, conducted in both open field and pot conditions, aimed to evaluate their potential accumulation in the soil and plant tissues. Results showed that PhACs concentrations varied according to the physicochemical properties of the compounds and the duration of irrigation. The study revealed minimal accumulation of contaminants in the soil and non-edible plant parts. This was observed only at the end of the second growing cycle, when the plants were irrigated with TWW containing trace PhAC levels. In contrast, during both pot cultivation cycles, PhACs accumulated in the soil were translocated into plant organs when irrigated with water enriched to 200 μg L−1 with eight PhACs. At the end of the trial, climbazole had the highest concentration in soil, while carbamazepine and fluconazole showed greater accumulation across all plant organs compared to other PhACs. In both trials, plants inoculated with Septoglomus viscosum absorbed less PhACs compared to those inoculated with Rhizophagus irregularis + Funneliformis mosseae. These results suggest that, while the long-term use of TWW containing PhACs may improve artichoke yield, it could present different degrees of risk to both environmental and human health, depending on the concentration levels of contaminants. Full article
(This article belongs to the Special Issue Emerging Contaminants in Soil and Water: Sources, Behaviour, and Environmental and Human Health Risks)
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17 pages, 2591 KiB  
Article
Elemental Release from Egyptian Glauconite Sediments: An Extraction Study by Various Acids
by Nada Eldawwy, Márk Horváth, Heba Naser, Abdulrahman Maina Zubairu, Gábor Halász, Éva Lehoczky, Eszter Takács, András Székács and Miklós Gulyás
Soil Syst. 2025, 9(2), 50; https://doi.org/10.3390/soilsystems9020050 - 14 May 2025
Viewed by 668
Abstract
Glauconite, a diagenetic sedimentary phyllosilicate mineral, holds significant importance in soil science, as it is commonly used in soil characterization (as in greensands) and can be identified in the field by its color and morphology. It is a potential fertilizer, rich in essential [...] Read more.
Glauconite, a diagenetic sedimentary phyllosilicate mineral, holds significant importance in soil science, as it is commonly used in soil characterization (as in greensands) and can be identified in the field by its color and morphology. It is a potential fertilizer, rich in essential macronutrients like potassium, phosphorus, calcium, and numerous micronutrients such as manganese, zinc, copper, cobalt, and nickel. In this meticulously conducted study, we extracted five individual elements (potassium, calcium, magnesium, sodium, and zinc) from washed glauconite samples separated into five different size fractions using a suite of acids. The acids employed were nitric acid, hydrochloric acid, acetic acid, and phosphoric acid, each prepared at the same molarity of 0.1 M. Water was used as the control solubilizing medium. The extractant behavior of the acids was assessed by measuring concentrations of each element by the ICP-OES device. The results demonstrate that nitric acid consistently exhibits the highest efficacy in releasing elements, followed by hydrochloric acid and phosphoric acid, while acetic acid results in the lowest release of these nutrients. These findings support the use of acidification treatment of glauconite, enhancing elemental release and potentially reducing the amount of glauconite needed as an alternative fertilizer, thus adding economic value. Full article
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17 pages, 1948 KiB  
Article
Biochar and Kitchen Stove Ash for Improving Nutrient Availability and Microbial Functions of Tropical Acidic Soil
by Isaac Asirifi, Lars Makarowsky, Stefanie Heinze, Michael Herre, Steffen Werner, Kwame Agyei Frimpong, Robin Pierburg and Bernd Marschner
Soil Syst. 2025, 9(2), 49; https://doi.org/10.3390/soilsystems9020049 - 13 May 2025
Viewed by 328
Abstract
Tropical acidic soils exhibit inherently low fertility and reduced microbial activity, driven by low pH and accelerated organic matter mineralization, phosphorus (P) fixation, and aluminum (Al3+) and iron (Fe3+) toxicity. These constraints limit agricultural productivity, necessitating sustainable and low-cost [...] Read more.
Tropical acidic soils exhibit inherently low fertility and reduced microbial activity, driven by low pH and accelerated organic matter mineralization, phosphorus (P) fixation, and aluminum (Al3+) and iron (Fe3+) toxicity. These constraints limit agricultural productivity, necessitating sustainable and low-cost soil amendments essential for improving the soil fertility in such regions. This study investigated the effects of biochar, kitchen stove ash (KSA), and their combined application on the soil chemical properties, nutrient dynamics, and microbial functions in a tropical acidic soil. The treatment included the unamended control and two doses of 0.25% w/w (B10) and 0.5% w/w (B20) corncob biochar, 0.03% w/w kitchen stove ash (Ash), and 0.027% w/w commercial-grade calcium carbonate (Lime). Each biochar dose was added alone or in combination with either ash (Ash + B10 and Ash + B20) or calcium carbonate (Lime + B10 and Lime + B20). After eight weeks of laboratory incubation at 20 °C, the soil pH, N and P bioavailability, microbial biomass, and extracellular enzyme activities were measured. The combined application of 0.5% w/w biochar with 0.03% w/w KSA (Ash + B20) resulted in the most significant improvements in all of the examined soil fertility indicators than the individual amendments. Specifically, the soil pH was increased by 40% (+1.9 pH units) compared with the unamended control. Available phosphorus, mineral nitrogen, and total potassium were increased by 49%, 22%, and 36%, respectively, compared with the unamended control. Regarding the microbial parameters, the Ash + B20-treated soil showed the highest microbial respiration (+56%), microbial biomass (+45%), and extracellular C- and N-cycling enzyme activities compared with the unamended soil. The ash supplied minerals (P, K, and Mg) provided a more beneficial effect on the soil’s nutrient content and microbial functions than the calcium carbonate. The study demonstrated that underutilized kitchen ash may supplement biochar’s liming and nutrient supply potentials, even at a lower application rate, to improve the fertility of weathered acidic soil. Full article
(This article belongs to the Special Issue Integrated Soil Management: Food Supply, Environmental Impacts, and Socioeconomic Functions: 2nd Edition)
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16 pages, 3194 KiB  
Article
Quantitative Source Identification, Pollution Risk Assessment of Potentially Toxic Elements in Soils of a Diamond Mining Area
by Anna Gololobova and Yana Legostaeva
Soil Syst. 2025, 9(2), 48; https://doi.org/10.3390/soilsystems9020048 - 13 May 2025
Viewed by 259
Abstract
Potentially toxic elements (PTEs) are the most important indicators of environmental pollution and represent a potential risk to the ecology and human health in industrial regions. Eight potentially toxic elements (Mn, Ni, Co, Cr, Pb, Zn, Cd, As) in soils formed on the [...] Read more.
Potentially toxic elements (PTEs) are the most important indicators of environmental pollution and represent a potential risk to the ecology and human health in industrial regions. Eight potentially toxic elements (Mn, Ni, Co, Cr, Pb, Zn, Cd, As) in soils formed on the territory of the industrial site of the Udachny Mining and Processing Division were considered in this study. The potential ecological risk index (RI) was calculated to determine environmental risks of soil contamination. The concentrations of PTEs decreased in the following order Mn > Ni > Zn > Co > Pb > Cr > As > Cd. In total, 19.51% of the sites in the study area exhibited a high potential ecological risk for Mn and Ni, while only 4.87% exhibited a low potential ecological risk for other PTEs. The greatest impacts on soil contamination are exerted by the areas of the Udachny and Zarnitsa pipes, tailings ponds, and the area’s highly mineralized water outlet. The results of correlation analysis (CA) and hierarchical cluster analysis (HCA) revealed that the same groups of elements were present: Co-Cr-Ni and Cd-Zn. The PMF findings demonstrate that the five main diverse sources of PTEs in this study area’s soils were natural, mining activities, transportation, and industrialization, as well as highly mineralized waters. Full article
(This article belongs to the Special Issue Emerging Contaminants in Soil and Water: Sources, Behaviour, and Environmental and Human Health Risks)
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18 pages, 3451 KiB  
Article
Cutting-Edge Technology Using Blended Controlled-Release Fertilizers and Conventional Monoammonium Phosphate as a Strategy to Improve Phosphorus Coffee Nutrition During the Coffee Development Phase
by Mateus Portes Dutra, Leonardo Fernandes Sarkis, Damiany Pádua Oliveira, Hugo de Almeida Santiago, Gustavo Tadeu de Sousa Resende, Maria Elisa Araújo de Melo, Adrianne Braga da Fonseca, Cristhian José Hernández López, Euler dos Santos Silva, Aline dos Santos Zaqueu, Gustavo Henrique Furtado de Lima, João Marcelo Silva, Adélia Aziz Alexandre Pozza and Douglas Guelfi
Soil Syst. 2025, 9(2), 47; https://doi.org/10.3390/soilsystems9020047 - 13 May 2025
Viewed by 274
Abstract
Controlled-release fertilizers contain polymeric coatings that modify the dynamics of phosphorus (P) release in soil. This study aimed to characterize P release from physical mixtures between conventional and controlled-release fertilizers (CRFs), quantify soil P availability, and assess agronomic responses of coffee plants during [...] Read more.
Controlled-release fertilizers contain polymeric coatings that modify the dynamics of phosphorus (P) release in soil. This study aimed to characterize P release from physical mixtures between conventional and controlled-release fertilizers (CRFs), quantify soil P availability, and assess agronomic responses of coffee plants during the establishment phase. Two main types of P fertilizer were evaluated: conventional monoammonium phosphate (MAP) and a blend (physical mixture of conventional MAP and controlled-release P fertilizers). Both fertilizers were applied at 0, 134, 268, and 403 kg ha−1 of P2O5. Our findings revealed a blend longevity of 3 and 6 months. P fertilization contributed to an increase in leaf area (1134.7 cm2 plant−1) and shoot biomass (602.8 kg ha−1) and raised P in the soil (0.061 mg dm−3 per kg of P2O5 applied). P accumulation in the coffee plants ranged between 3 and 4 kg ha−1. Other macronutrient accumulations in aerial parts were of the following ranges (in kg ha−1): 47–60 for N, 36–46 for K, 18–22 for Ca, 5–7 for Mg, and 3–4 for S. Micronutrients accumulated (in g ha−1): 454–657 for Fe; 117–160 for B; 117–149 for Mn; 58–71 for Cu; and 34–43 for Zn. Up to 74% of the nutrients were distributed in the leaves. We concluded that the use of blends did not impose any limitation on P nutrition for coffee plants and led to biomass gains (18.9%) in plagiotropic branches. P fertilization proved essential for supporting the initial growth of coffee plants and increasing coffee leaf area and P levels in the soil and promotes adequate levels of P accumulation in plants, leading to improvements in coffee crop nutrition in the establishment phase. Full article
(This article belongs to the Topic Soil Fertility and Plant Nutrition for Sustainable Agriculture—2nd Edition)
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14 pages, 853 KiB  
Article
Conservation Reserve Program Soils Show Potential as a Soil Health Benchmark—A Southern Minnesota Case Study
by Oliver Hoffman, Christopher E. Chorpenning, Tad Trimarco, Nathan Carr, Cassidy Buchanan and James A. Ippolito
Soil Syst. 2025, 9(2), 46; https://doi.org/10.3390/soilsystems9020046 - 12 May 2025
Viewed by 287
Abstract
Soil health is an important concept in promoting sustainable agriculture and food security, yet the absence of universally accepted benchmarks limits its utility in assessing soil function. This study explored the use of Conservation Reserve Program (CRP) soils as a potential benchmark to [...] Read more.
Soil health is an important concept in promoting sustainable agriculture and food security, yet the absence of universally accepted benchmarks limits its utility in assessing soil function. This study explored the use of Conservation Reserve Program (CRP) soils as a potential benchmark to quantify the soil health gap (SHG) in Faribault County, Minnesota. Using the Soil Management Assessment Framework (SMAF), we evaluated physical, chemical, biological, and nutrient soil health indicators to derive a combined overall score that was used to quantify the SHG (i.e., benchmark soil minus test soil) between CRP and corn-based agricultural production (AP). Three paired farms were assessed, each consisting of CRP tall grass prairie established in 2001 and adjacent long-term AP. The results showed higher overall SMAF scores in CRP soils, with a mean SHG of 0.09. Land use had a strong influence on overall scores, largely driven by biological indicators such as soil organic carbon, microbial biomass carbon, and β-glucosidase activity. However, the SMAF demonstrated limited applicability in CRP systems, potentially under-representing their soil health status due to the SMAF’s agricultural emphasis and lack of ecosystem-specific factors such as pH. Full article
(This article belongs to the Special Issue Research on Soil Management and Conservation: 2nd Edition)
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31 pages, 7056 KiB  
Article
Agronomic Effectiveness of Biochar–KCl Composites for Corn Cultivation in Tropical Soils
by Gabrielly Nayara Tavares Silva Rodrigues, Carlos Alberto Silva and Everton Geraldo de Morais
Soil Syst. 2025, 9(2), 45; https://doi.org/10.3390/soilsystems9020045 - 9 May 2025
Viewed by 360
Abstract
Potassium chloride (KCl) is the main source of potassium (K) in Brazilian agriculture, but its high import dependency and the need for split applications increase costs and expose the system to supply and efficiency risks. Understanding the availability and release kinetics of potassium [...] Read more.
Potassium chloride (KCl) is the main source of potassium (K) in Brazilian agriculture, but its high import dependency and the need for split applications increase costs and expose the system to supply and efficiency risks. Understanding the availability and release kinetics of potassium (K) from biochar-based fertilizers (K-BBFs) is crucial for optimizing their use as full or partial substitutes for KCl in Brazilian agriculture. This study evaluated biochars derived from banana peel (BP), coffee husk (CH), and chicken manure (CM), both in their pure form and co-pyrolyzed with KCl (composites) at 300 °C and 650 °C, as K sources for corn grown in two contrasting Oxisols. For pure biochars, feedstock type and pyrolysis temperature significantly influenced K content and release kinetics. Higher pyrolysis temperatures increased K content in BP and CH biochars but not in CM, while also slowing K release in CH and CM. Co-pyrolysis with KCl increased biochar yield, ash content, and K availability. Composites released more K than pure biochar but less than KCl, and at a slower rate. Notably, banana peel biochar co-pyrolyzed with KCl at 650 °C (CBP650) exhibited 36% slower K release and reduced KCl use by 82% while maintaining similar K use efficiency and corn growth. All K-BBFs matched KCl in promoting robust corn growth in clay soil, increasing biomass by 5.3 times and K uptake by 9 times compared to unfertilized (no K addition) plants. In sandy Oxisol, K-BBFs boosted biomass by up to 3.5 times compared to unfertilized plants, though some pure biochars were less effective than KCl in supporting full corn growth. Soil texture strongly influenced K availability, with sandier soils exhibiting higher K levels in solution. These findings suggest that kinetic release studies in abiotic systems, such as lysimeters with sand, are not suitable for evaluating K-BBFs as slow-release fertilizers. Due to lower K retention in sandy soil and solution K levels exceeding 1100 mg L−1, split applications of some K-BBFs are recommended to prevent corn cation uptake imbalances and soil K leaching. Additionally, granulating biochar–KCl composites may enhance K retention and regulate its release in sandy Oxisols. Full article
(This article belongs to the Special Issue Integrated Soil Management: Food Supply, Environmental Impacts, and Socioeconomic Functions: 2nd Edition)
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10 pages, 2273 KiB  
Article
Bacterial Community in Sugarcane Rhizosphere Under Bacillus subtilis Inoculation and Straw Return
by Francisco de Alcântara Neto, Danielly Araújo Pinheiro, Sandra Mara Barbosa Rocha, Marcos Renan Lima Leite, Romário Martins Costa, Janderson Moura da Silva, Sabrina Hermelindo Ventura, Mayanna Karlla Lima Costa, Thâmara Kelly dos Santos Apollo Sousa, Rafael de Souza Miranda, Karolayne Ribeiro Caetano, Erika Valente de Medeiros, Arthur Prudêncio de Araujo Pereira, Lucas William Mendes and Ademir Sérgio Ferreira Araujo
Soil Syst. 2025, 9(2), 44; https://doi.org/10.3390/soilsystems9020044 - 4 May 2025
Viewed by 335
Abstract
Straw return enhances soil biological properties by increasing carbon and energy availability, thereby improving conditions for microbial communities. However, the introduction of beneficial bacteria, such as Bacillus subtilis, can further shape the rhizosphere bacterial composition. In this study, we combined sugarcane straw [...] Read more.
Straw return enhances soil biological properties by increasing carbon and energy availability, thereby improving conditions for microbial communities. However, the introduction of beneficial bacteria, such as Bacillus subtilis, can further shape the rhizosphere bacterial composition. In this study, we combined sugarcane straw return with B. subtilis inoculation to test whether this synergy reduces microbial specialization in the sugarcane rhizosphere. Three treatments were evaluated: (I) bulk soil (bulk), (II) rhizosphere soil with straw return but no B. subtilis inoculation (straw), and (III) rhizosphere soil with straw return and B. subtilis inoculation (straw + Bacillus). The bacterial community, including plant-growth-promoting bacteria (PGPB), was analyzed via 16S rRNA amplicon sequencing. Neither straw return nor B. subtilis inoculation significantly altered bacterial richness, diversity, or phylum-level abundance in the rhizosphere. Actinobacteria, Firmicutes, and Proteobacteria dominated the community, with Bacillus, Bradyrhizobium, and Paenibacillus as the predominant PGPB genera. Notably, only Bradyrhizobium abundance increased in the rhizosphere when straw was co-applied with B. subtilis. A co-occurrence network analysis revealed stronger microbial interactions under straw return, while B. subtilis enhanced connectivity among the PGPB. Although niche occupancy remained stable, PGPB specialization was higher with straw alone, suggesting that B. subtilis fosters a more generalist community. In conclusion, while straw return and B. subtilis inoculation did not affect overall bacterial diversity, B. subtilis increased PGPB interactions and reduced functional specialization, promoting a more generalized microbial community. Full article
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13 pages, 653 KiB  
Article
The Influence of Black Soldier Fly Residue on Watermelon Growth and the Properties of a Coarse-Textured Ultisol
by Benedict Onyebuchi Unagwu, Chidiebere Fransica Odu, Chinedu Felix Amuji, Michael Onyedika Eze, Nancy Ekene Ebido, Chidike Ude Abara, Chioma Rosita Igboka and Uchechukwu Paschal Chukwudi
Soil Syst. 2025, 9(2), 43; https://doi.org/10.3390/soilsystems9020043 - 3 May 2025
Viewed by 241
Abstract
Improving the fertility status of nutrient-depleted soils is critical to achieving food security. The negative effects of chemical fertilizers on soils necessitate the global quest for eco-friendly, effective, and sustainable alternatives. This work assessed the effect of black soldier fly (BSF) residue application [...] Read more.
Improving the fertility status of nutrient-depleted soils is critical to achieving food security. The negative effects of chemical fertilizers on soils necessitate the global quest for eco-friendly, effective, and sustainable alternatives. This work assessed the effect of black soldier fly (BSF) residue application on soil properties and watermelon growth. The study was set up in a completely randomized design with six replications. The treatments were BSF1 (BSF applied at 10 t ha−1), BSF2 (20 t ha−1), BSF3 (30 t ha−1), and control. The plant data collected in this study were vine length, leaf width, number of leaves, and stem girth, and the soil’s physicochemical properties were determined. The results show that BSF residue-treated soils had 20.4–49.5% higher aggregate stability and 50–160% higher hydraulic conductivity than the control treatment. BSF residue-treated soils had significantly (p ≤ 0.05) higher pH, total N, available P, exchangeable K, and organic carbon than the control treatment. BSF3 treatment had the highest effect on available P and soil pH relative to other amended treatments. High rates of BSF residue application did not significantly increase the total available N and P contents, which could suggest that BSF application at 30 t ha−1 may not pose a risk of N and P pollution to water systems. BSF residue-treated soils improved (p < 0.05) watermelon growth parameters relative to the control. Watermelon leaf length was significantly (p ≤ 0.05) longer for BSF residue-treated soils than the control treatment. A similar trend was observed for the number of leaves, leaf width, and stem girth. At 4, 6, and 10 weeks after sowing, BSF residue-treated plants had 38.2–104%, 22.7–118%, and 25.7–103% longer vine lengths than the control treatment, respectively. The study results suggest that BSF residue application can enhance the fertility status of a coarse-textured ultisol for watermelon production. Full article
(This article belongs to the Special Issue Integrated Soil Management: Food Supply, Environmental Impacts, and Socioeconomic Functions: 2nd Edition)
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18 pages, 16483 KiB  
Article
Rill Erosion and Drainage Development in Post-Landslide Settings Using UAV–LiDAR Data
by Xinyu Chen, Albertus Stephanus Louw, Ali P. Yunus, Saleh Alsulamy, Deha Agus Umarhadi, Md. Alamgir Hossen Bhuiyan and Ram Avtar
Soil Syst. 2025, 9(2), 42; https://doi.org/10.3390/soilsystems9020042 - 1 May 2025
Viewed by 428
Abstract
Accurate microtopography data are an important input for characterizing small-scale rill erosion and its progression following disturbances. UAV–LiDAR systems are increasingly accessible and have successfully been used to measure microtopography data for several applications. Yet, the use of UAV–LiDAR systems for rill erosion [...] Read more.
Accurate microtopography data are an important input for characterizing small-scale rill erosion and its progression following disturbances. UAV–LiDAR systems are increasingly accessible and have successfully been used to measure microtopography data for several applications. Yet, the use of UAV–LiDAR systems for rill erosion studies in post-landslide landscapes have not been well investigated. Therefore, the purpose of this study was to implement and evaluate a UAV–LiDAR-based workflow to capture the microtopography of a post-landslide landscape, and by doing so, to help to determine best practices for UAV–LiDAR-based rill analysis. A commercial UAV–LiDAR system was used to map three post-landslide slopes and generate digital elevation models with a 1 cm-per-pixel ground resolution. Using data captured over multiple years, temporal rill development was assessed by comparing rill cross-sections and calculating changes to rill density and erosion volume. A flow-accumulation algorithm was adopted to automatically extract the rill network. We found that a flow accumulation algorithm with a threshold value of 5000 detected the rill network with overall accuracies of >88% and F1-scores of >93%. Vertical cross-sections of individual rills revealed an increase in the depth and width of rills over a one-year period. This study demonstrates that a commercial UAV–LiDAR system can effectively describe microtopography in a post-landslide landscape and facilitate analysis of small-scale rill characteristics and the progression of rill erosion. Full article
(This article belongs to the Special Issue Land Use and Management on Soil Properties and Processes: 2nd Edition)
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12 pages, 1057 KiB  
Article
Impact of Starter Phosphorus Fertilizer Type and Rate on Maize Growth in Calcareous Soil Irrigated with Treated Wastewater
by Majed B. Almutairi, Ibrahim Ahmed, Khaled D. Alotaibi, Saud S. Aloud and Mohamed Abdalla
Soil Syst. 2025, 9(2), 41; https://doi.org/10.3390/soilsystems9020041 - 30 Apr 2025
Viewed by 447
Abstract
Phosphorus (P) is an essential macronutrient, but its limited availability in calcareous soils remains a major constraint to crop nutrition. Treated wastewater (TWW) offers a sustainable irrigation source in arid regions, enhancing water supply and contributing nutrients such as P. This study evaluates [...] Read more.
Phosphorus (P) is an essential macronutrient, but its limited availability in calcareous soils remains a major constraint to crop nutrition. Treated wastewater (TWW) offers a sustainable irrigation source in arid regions, enhancing water supply and contributing nutrients such as P. This study evaluates the effects of TWW and tap water (TW) irrigation, combined with varying rates of phosphorus fertilizers, such as single superphosphate (SSP) and diammonium phosphate (DAP), on maize (Zea mays L.) growth, nutrient uptake, and soil properties. A greenhouse experiment was conducted using maize grown in sandy calcareous soil. TWW irrigation with SSP (40 kg/ha) and DAP (20 kg/ha) resulted in the highest shoot dry matter (2.6 g), while TW with DAP at 20 kg/ha produced 2.2 g. Root biomass was generally higher, peaking at 8.3 g under TWW-SSP (40 kg/ha) and 5.7 g under TW-SSP (40 kg/ha). Nitrogen uptake was highest under TWW, with TWW-DAP (40 kg/ha) yielding the highest N content in shoots (1.9%) and roots (1.2%). Phosphorus content peaked at TWW-DAP (30 kg/ha) in shoots (0.52%) and roots (0.26%). Potassium uptake also improved with TWW, particularly in shoots (4.5%) under TWW-SSP (40 kg/ha) and roots (2.6%) under TWW-DAP (40 kg/ha). Post-harvest soil analysis showed TWW maintained stable EC (0.3–0.5 dS/m) and neutral pH (7.6–7.8). Higher DAP rates (40 kg/ha) with TWW increased soil organic matter, nitrogen (266.2 mg/kg), phosphorus (38.0 mg/kg), and potassium (385.3 mg/kg). In contrast, TW irrigation had lower nutrient enhancement, though high DAP rates still improved soil fertility. These findings highlight the potential of integrating TWW with phosphorus fertilizers to improve crop performance and soil fertility in calcareous soils. This approach offers a sustainable alternative to conventional practices, supporting sustainable crop production in water-limited environments. Further long-term studies are recommended to assess the sustainability of TWW irrigation in arid soils. Full article
(This article belongs to the Special Issue Integrated Soil Management: Food Supply, Environmental Impacts, and Socioeconomic Functions: 2nd Edition)
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14 pages, 1194 KiB  
Article
Microplastic Transport by Overland Flow: Effects of Soil Texture and Slope Gradient Under Simulated Semi-Arid Conditions
by Fabio Corradini
Soil Syst. 2025, 9(2), 40; https://doi.org/10.3390/soilsystems9020040 - 29 Apr 2025
Viewed by 347
Abstract
Microplastic pollution in soils and surface waters is a growing environmental concern, yet the mechanisms governing transport by overland flow remain unclear. This study investigated the influence of soil texture and slope gradient on the movement of microplastics with different shapes and polymer [...] Read more.
Microplastic pollution in soils and surface waters is a growing environmental concern, yet the mechanisms governing transport by overland flow remain unclear. This study investigated the influence of soil texture and slope gradient on the movement of microplastics with different shapes and polymer compositions under simulated rainfall and typical agricultural conditions in a semi-arid climate. Small soil flumes were subjected to controlled rainfall simulations replicating typical rain patterns, and microplastic transport was quantified using collection flasks. The results indicated that neither soil texture nor slope gradient significantly affected total microplastic transport. However, fibres exhibited greater retention in the soil compared to other shapes. Polymer composition did not play a major role in microplastic mobility, except for polystyrene pellets, which were transported more readily than polyethylene pellets. Field observations of agricultural soils with a history of sludge application confirmed a predominance of fibres in the topsoil, reinforcing the tendency of this shape to resist mobilisation. These findings suggest that microplastic transport by surface runoff is primarily governed by particle shape and buoyancy rather than soil properties or slope inclination. Future research should explore the roles of particle size, rainfall intensity, and organic matter content in microplastic mobility under natural field conditions. Full article
(This article belongs to the Special Issue Migration and Transformation Processes and Environmental Effects of Microplastics in Soil)
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19 pages, 1049 KiB  
Article
Genetic Diversity and Plant Growth-Promoting Activities of Root-Nodulating Bacteria in Guar Plants Across Jazan Province
by Mosbah Mahdhi, Boshra Yami, Mohamed Al Abboud, Emad Abada and Habib Khemira
Soil Syst. 2025, 9(2), 39; https://doi.org/10.3390/soilsystems9020039 - 24 Apr 2025
Viewed by 491
Abstract
Guar (Cyamopsis tetragonoloba L. Taub.) is a significant summer legume used as food for both humans and livestock. In Saudi Arabia, the root nodule bacteria of guar have not been studied. The present work investigated the phenotypic and genetic diversity of guar [...] Read more.
Guar (Cyamopsis tetragonoloba L. Taub.) is a significant summer legume used as food for both humans and livestock. In Saudi Arabia, the root nodule bacteria of guar have not been studied. The present work investigated the phenotypic and genetic diversity of guar microsymbionts. Eighty-eight bacterial strains were isolated from the root nodules of guar grown in different locations of Jazan region of Saudi Arabia. The strains were analyzed based on their phenotypic characteristics and variations in their 16S rRNA gene sequences. A significant proportion of the isolates (90%) were fast-growing rhizobia, with 77% showing tolerance to 3–4% NaCl and 91% capable of thriving at temperatures reaching 40 °C. Several isolates exhibited strong plant growth-promoting traits, particularly in IAA production and phosphate solubilization. Genetic analysis indicated considerable diversity, with isolates classified under the genera Rhizobium, Ensifer, Mesorhizobium, Bradyrhizobium, and Agrobacterium. To the best of our knowledge, this study is the first to report on the phenotypic and genetic diversity of guar microsymbionts in Saudi Arabia. Full article
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21 pages, 3188 KiB  
Article
Biochar Amendment in Remediation of Heavy Metals in Paddy Soil: A Case Study in Nobewam, Ghana
by Kwadwo Owusu Boakye, Matt Dodd, Maxwell Darko Asante, Vincent Logah and Godfred Darko
Soil Syst. 2025, 9(2), 38; https://doi.org/10.3390/soilsystems9020038 - 22 Apr 2025
Viewed by 1096
Abstract
Biochar is a stabilised, carbon-rich material created when biomass is heated to temperatures usually between 450 and 550 °C, under low-oxygen concentrations. This study evaluated the effectiveness of sawdust, cocoa pod ash and rice husk biochars in remediating metal-contaminated paddy soil in Nobewam, [...] Read more.
Biochar is a stabilised, carbon-rich material created when biomass is heated to temperatures usually between 450 and 550 °C, under low-oxygen concentrations. This study evaluated the effectiveness of sawdust, cocoa pod ash and rice husk biochars in remediating metal-contaminated paddy soil in Nobewam, Ghana. Biochar was applied 21 days before cultivating the rice for 120 days, followed by soil sampling and rice harvesting for metals and physicochemical analyses. Compared to the untreated soils, biochar treatments exhibited an enhancement in soil quality, characterised by an increase in pH of 1.01–1.20 units, an increase in available phosphorus (P) concentration of 6.76–13.05 mg/kg soil and an increase in soil total nitrogen (N), and organic carbon (OC) concentration, ranging from 0.02% to 0.12%. Variabilities in electrical conductivity and effective cation exchange capacity were observed among the treated soils. Concentrations of potentially toxic metals (arsenic, cadmium, copper, mercury, lead and zinc) in paddy soils and rice analysed by atomic absorption spectroscopy showed significant differences (p < 0.05) among the sampled soils. The concentrations of arsenic and lead in all soil samples exceeded the Canadian Council of Ministers of the Environment soil quality guideline for agricultural soils, with untreated soils having the highest levels among all the soils. Cadmium had a potential ecological risk index > 2000 and a geoaccumulation index above 5, indicating pollution in all samples. In contrast, arsenic and mercury contamination were only found in the untreated soils. Among the tested treatments, rice husk and its combinations, particularly with cocoa pod ash, showed significant efficacy in reducing metal concentrations in the soils. The potential non-carcinogenic human health risks associated with the consumption of rice grown in biochar-treated soils were lower for all the metals compared to the control samples. Future research should focus on long-term field studies to validate these findings and explore the underlying mechanisms governing metal immobilization in paddy fields. Full article
(This article belongs to the Special Issue Integrated Soil Management: Food Supply, Environmental Impacts, and Socioeconomic Functions: 2nd Edition)
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23 pages, 4214 KiB  
Article
The Impacts of Ethanol and Freeze–Thaw Cycling on Arsenic Mobility in a Contaminated Boreal Wetland
by Joseph Radford, Kimber E. Munford, Nadia Mykytczuk and Susan Glasauer
Soil Syst. 2025, 9(2), 37; https://doi.org/10.3390/soilsystems9020037 - 21 Apr 2025
Viewed by 331
Abstract
Pyrite-bearing waste rock from legacy gold mines is a source of elevated arsenic, sulfate, and iron in the surrounding environments due to leaching. Waste rock in environments that experience cold winters is of particular concern because freeze–thaw cycling may mobilize elements through degradation [...] Read more.
Pyrite-bearing waste rock from legacy gold mines is a source of elevated arsenic, sulfate, and iron in the surrounding environments due to leaching. Waste rock in environments that experience cold winters is of particular concern because freeze–thaw cycling may mobilize elements through degradation and release of organic matter and accelerated mineral weathering. In boreal zones, wetlands are common recipients of mine-waste run-off, and microbial processes in wetland soil may promote the retention of mobilized elements, such as arsenic. We investigated the impacts of freeze–thaw cycling and ethanol amendment on soil from an arsenic-contaminated wetland in anoxic microcosms. Ethanol-amended microcosms exhibited enhanced microbial sulfate reduction, leading to sulfide precipitation and increased retention of arsenic in the soil. Sequential extraction studies indicated a shift of arsenic into more stable sulfide-bound fractions. The addition of ethanol significantly increased the growth of Geobacter spp. and other select sulfate-reducing bacteria. Freeze–thaw cycling increased dissolved arsenic over short time periods only and had no detectable impacts on microbial activity. These findings suggest that the use of ethanol as an amendment to wetlands during spring thaw may enhance arsenic sequestration in mining-impacted soils and may provide a viable remediation strategy for cold-climate environments, where seasonal freeze–thaw cycling could otherwise contribute to arsenic mobilization. Full article
(This article belongs to the Special Issue Soil Bioremediation)
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15 pages, 2951 KiB  
Article
Cowpea (Vigna unguiculata) Water Relations, Growth, and Productivity as Affected by Salinity in Two Soils with Contrasting Mineralogies
by Jaciane Rosa Maria de Souza, Lucas Yago de Carvalho Leal, Martha Katharinne Silva Souza Paulino, José Alfredo Nunes, Rafael Luís Silva de Medeiros, Monaliza Alves dos Santos, Cintia Maria Teixeira Lins, Valdomiro Severino de Souza Júnior, Bruce Schaffer and Edivan Rodrigues de Souza
Soil Syst. 2025, 9(2), 36; https://doi.org/10.3390/soilsystems9020036 - 21 Apr 2025
Viewed by 464
Abstract
Soil salinity affects crop growth and production, especially in arid and semi-arid regions of the world. The interactions between salt ions and soil particles vary depending on soil texture, mineralogy, and ion composition. The relationship between soil ions and particles and the effects [...] Read more.
Soil salinity affects crop growth and production, especially in arid and semi-arid regions of the world. The interactions between salt ions and soil particles vary depending on soil texture, mineralogy, and ion composition. The relationship between soil ions and particles and the effects of this interaction on crop plants remains underexplored. This study evaluated the plant water relations, growth, and yield of cowpea (Vigna unguiculata) as affected by the salinity of the irrigation water in two different soil types with varying weathering levels and contrasting mineralogies. The treatments consisted of six salinity levels based on the electrical conductivity (EC) of the irrigation water (0, 1.5, 3, 4, 5, 6.0, or 9 dS m−1) and were tested in Ultisol (well-weathered soil) and Alfisol (less-weathered soil). The experiment was conducted over 80 days with 4 repetitions. The results showed that the plant salinity tolerance, growth, and yield in response to salinity varied depending on the soil type. Irrigation with saline water exceeding an EC of 3 dS m−1 completely halted cowpea production in Ultisol, whereas in Alfisol, production ceased at an EC above 6 dS m−1. Although it accumulates more salts under saline irrigation, Alfisol promotes better cowpea growth and yield than Ultisol. Full article
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24 pages, 1419 KiB  
Review
Soil Remediation: Current Approaches and Emerging Bio-Based Trends
by Micaela Santos, Sofia Rebola and Dmitry V. Evtuguin
Soil Syst. 2025, 9(2), 35; https://doi.org/10.3390/soilsystems9020035 - 17 Apr 2025
Viewed by 1281
Abstract
Currently, increasing anthropogenic pressure and overexploitation expose soils to various forms of degradation, including contamination, erosion, and sealing. Soil contamination, primarily caused by industrial processes, agricultural practices (such as the use of pesticides and fertilizers), and improper waste disposal, poses significant risks to [...] Read more.
Currently, increasing anthropogenic pressure and overexploitation expose soils to various forms of degradation, including contamination, erosion, and sealing. Soil contamination, primarily caused by industrial processes, agricultural practices (such as the use of pesticides and fertilizers), and improper waste disposal, poses significant risks to human health, biodiversity, and the environment. Common contaminants include heavy metals, mineral oils, petroleum-based hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, and polycyclic aromatic hydrocarbons. Remediation methods for contaminated soils include physical, physicochemical, chemical or biological approaches. This review aims to specify these methods while comparing their effectiveness and applicability in different contamination scenarios. Biochemical methods, particularly phytoremediation, are emphasized for their sustainability, effectiveness, and suitability in arid and semiarid regions. These methods preserve soil quality and promote resource efficiency, waste reduction, and bioenergy production, aligning with sustainability principles and contributing to a circular economy. The integrated phytoremediation–bioenergy approaches reviewed provide sustainable and cost-efficient strategies for environmental decontamination and green development. Special attention is given to the use of lignin in bioremediation. This work contributes to the existing knowledge by outlining priorities for the selection of the most appropriate remediation techniques under diverse environmental conditions, providing a comprehensive overview for future developments. Full article
(This article belongs to the Special Issue Soil Bioremediation)
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20 pages, 4409 KiB  
Article
A Method for the Extraction and Analysis of Microplastics from Tropical Agricultural Soils in Southeastern Brazil
by John Jairo Arevalo-Hernandez, Angela Dayana Barrera de Brito, Nilton Curi, Junior Cesar Avanzi and Marx Leandro Naves Silva
Soil Syst. 2025, 9(2), 34; https://doi.org/10.3390/soilsystems9020034 - 11 Apr 2025
Viewed by 588
Abstract
Microplastics (MP) are widespread pollutants that pose a risk to soil ecosystems globally, especially in agricultural soils. This study introduces a method to extract and identify MP in Brazilian tropical soils, targeting debris of low-density polyethylene (LDPE) and polyvinyl chloride (PVC) polymers, commonly [...] Read more.
Microplastics (MP) are widespread pollutants that pose a risk to soil ecosystems globally, especially in agricultural soils. This study introduces a method to extract and identify MP in Brazilian tropical soils, targeting debris of low-density polyethylene (LDPE) and polyvinyl chloride (PVC) polymers, commonly present in agricultural settings. The method involves removing organic matter and extracting MP using density separation with three flotation solutions: distilled water, NaCl, and ZnCl2. Extracted MP are then analyzed through optical microscopy and Fourier transform infrared spectroscopy. The organic matter removal efficiency ranged from 46% to 89%, depending on the initial organic matter content in the soil. Recovery rates for LDPE ranged from 81.0% to 98.8%, while PVC samples showed a range of 59.7% to 75.2%. Finally, this methodology was tested in four agricultural raw soil samples (i.e., without any polymer enrichment) The values found in the soil samples were 2517.5, 2245.0, 3867.5, and 1725.0 items kg−1, for ferralsol, nitisol, gleysol, and cambisol samples, respectively, with MP having diverse shapes including fragments, granules, films, and fibers. This approach lays the groundwork for future studies on MP behavior in Brazilian tropical agricultural soils. Full article
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17 pages, 2075 KiB  
Article
Co-Application of Bokashi and Biochar Alleviates Water Stress, Improves Soil Fertility and Enhances Wheat Production Under Water-Deficit Conditions
by Gyanendra Dhakal, Takeshi Fujino, Srijana Thapa Magar and Yuji Araki
Soil Syst. 2025, 9(2), 33; https://doi.org/10.3390/soilsystems9020033 - 8 Apr 2025
Viewed by 831
Abstract
Water stress and nutrient stress are major limiting factors affecting crop productivity. Biochar-based organic fertilizers improve soil nutrient availability, water use efficiency (WUE), and crop yields under these adverse conditions. This study investigated the mechanistic effects of biochar–bokashi mixtures under a controlled glasshouse [...] Read more.
Water stress and nutrient stress are major limiting factors affecting crop productivity. Biochar-based organic fertilizers improve soil nutrient availability, water use efficiency (WUE), and crop yields under these adverse conditions. This study investigated the mechanistic effects of biochar–bokashi mixtures under a controlled glasshouse pot experiment on soil fertility, available nutrients, soil moisture, plant water use efficiency (PWUE), and wheat yield parameters under three moisture levels. Four treatments were included, (1) a control, (2) bokashi only, (3) 1% biochar + bokashi, and (4) 2% biochar + bokashi, under 30% (IR30), 50% (IR50), and 60% (IR60) field capacity, totaling twelve treatments in a completely randomized design with three replications. The combined bokashi–biochar application significantly (p < 0.05) improved growth parameters and yields, including plant height, number of fertile tillers (NFT), number of spikes (NS), spike length (SL), 1000-grain weight, biological yield (BY), root biomass, and grain yield (GY), compared to the control and bokashi-only treatments. Bokashi with 1% biochar exhibited superior agronomic performance over the other treatments, including 2% biochar. Biochar addition enhanced soil moisture and PWUE across irrigation levels. Bokashi–biochar treatments under IR30 outperformed the control and bokashi-only treatments under IR60, highlighting biochar’s effectiveness in alleviating water stress and increasing yields. Moreover, co-application significantly increased soil pH while enhancing the organic carbon, total nitrogen, available phosphorous and exchangeable potassium nutrient levels, which positively correlated with yield. Bokashi–biochar mixtures have been proven to be an effective strategy to enhance soil fertility, increase soil moisture to alleviate water stress and support sustainable wheat production under water- and nutrient-limited conditions. Full article
(This article belongs to the Special Issue Soil Fertility Management, Mitigating GHG Emissions and Sustainable Agriculture: 2nd Edition)
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21 pages, 1595 KiB  
Article
Soil Chemical Variation Along a Four-Decade Time Series of Reclaimed Water Amendments in Northern Idaho Forests
by Temesgen G. Wedajo, Eureka Joshi, Ruifang Hu, Daniel G. Strawn and Mark D. Coleman
Soil Syst. 2025, 9(2), 32; https://doi.org/10.3390/soilsystems9020032 - 3 Apr 2025
Viewed by 480
Abstract
Application of municipal reclaimed water to forests for water reclamation is a pragmatic approach that provides water and nutrients to soil and lowers the liability of reclaimed water disposal, yet little is known about the long-term impacts of reclaimed water amendment on forest [...] Read more.
Application of municipal reclaimed water to forests for water reclamation is a pragmatic approach that provides water and nutrients to soil and lowers the liability of reclaimed water disposal, yet little is known about the long-term impacts of reclaimed water amendment on forest soil chemical properties. We hypothesized that reclaimed water constituents will increase plant nutrient availability in soil with the magnitude of response depending on the facility establishment date. We collected samples from three mineral soil depths to 75 cm from treated and control plots at five water reuse facilities that represent a four-decade time series. Depth explained most of the observed variation. Several plant nutrients increased in soil at the different sites in response to reclaimed water treatments, including N, Ca, Fe, S, and B concentration as well as B content, while P was not significantly affected. Increases in cation concentrations positively correlated with pH and salinity. The treatment response was significantly greater at all facilities for total N, B and Na. However, the treatment response only occurred at long-established facilities for NO3-N and Ca concentrations and for Fe and S content. The outcomes of this study are useful for guiding future management of soil at forest water reclamation facilities and for limiting the risk of downstream environmental impacts. Full article
(This article belongs to the Special Issue Soil Bioremediation)
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25 pages, 2839 KiB  
Article
Spatiotemporal Variability of Soil Water Repellency in Urban Parks of Berlin
by Ehsan Razipoor, Subham Mukherjee and Brigitta Schütt
Soil Syst. 2025, 9(2), 31; https://doi.org/10.3390/soilsystems9020031 - 2 Apr 2025
Viewed by 511
Abstract
Urban green spaces are important components of city spaces that are vulnerable to degradation in soil–water–climate processes. This vulnerability is exacerbated by current climate change and park usage density. This study examines the dynamics of soil water repellency in the topsoils of selected [...] Read more.
Urban green spaces are important components of city spaces that are vulnerable to degradation in soil–water–climate processes. This vulnerability is exacerbated by current climate change and park usage density. This study examines the dynamics of soil water repellency in the topsoils of selected urban parks in Berlin, aiming to assess the relationships between weather conditions, soil water content, and soil water repellency. This study is based on monthly sampled soils from spots originating from three selected parks—Fischtal Park, Stadtpark Steglitz, and Rudolph-Wilde Park—between September 2022 and October 2023; two of the parks are exclusively rainwater fed, and one is irrigated during summer months. For each sample soil, water repellency persistence and severity were analyzed. Time series analysis was conducted including soil water content. In addition, the total organic carbon content (TOC) and sample texture were analyzed. The results show that the rainfall amount, number of dry days, and maximum temperature during different time intervals prior to the sampling date predominantly control the variation in the soil water repellency via the soil water content. Soil water repellency variations observed appear more event-related than monthly or seasonal, as rainfall is evenly distributed through the years without a distinct dry or wet season in Berlin. The non-repellency of the soil samples was usually observed when the associated water content was increased, which is linked to high cumulative rainfall and short dry periods. Low rainfall amounts and long dry periods in summer result in the re-establishment of the soil water repellency, possibly affecting increased runoff generation and soil erosion risk. Spatially, the repellency properties were observed at locations under healthy vegetation cover, while soils located on the upper slope locations and on the pathways lacked repellency characteristics. Full article
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Article
Microbial Diversity and Heavy Metal Resistome in Slag-Contaminated Soils from an Abandoned Smelter in Chihuahua, Mexico
by Gustavo Montes-Montes, Zilia Y. Muñoz-Ramírez, Leonor Cortes-Palacios, Javier Carrillo-Campos, Obed Ramírez-Sánchez, Ismael Ortiz-Aguirre, Laila N. Muñoz-Castellanos and Román González-Escobedo
Soil Syst. 2025, 9(2), 30; https://doi.org/10.3390/soilsystems9020030 - 1 Apr 2025
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Abstract
Heavy metal(loid) (HM) contamination in soils from smelting activities poses significant environmental and public health risks, as well as disruptions in microbial community dynamics and HM resistance gene profiles. This study investigates the microbial diversity, resistome, and physicochemical properties of soils from the [...] Read more.
Heavy metal(loid) (HM) contamination in soils from smelting activities poses significant environmental and public health risks, as well as disruptions in microbial community dynamics and HM resistance gene profiles. This study investigates the microbial diversity, resistome, and physicochemical properties of soils from the abandoned Avalos smelter in Chihuahua, Mexico. Through soil analyses, we identified elevated concentrations of certain HMs, which pose serious environmental and health hazards. The metagenomic analysis of the microbial community, composed of bacteria, archaea, and fungi, was dominated by genera such as Streptomyces, Bradyrhizobium, Halobaculum, Nitrosocosmicus, Fusarium, and Aspergillus in rhizospheric soil. Furthermore, a diverse array of metal resistance genes (MRGs) were detected, associated with copper, arsenic, iron, lead, cadmium, zinc, and other HMs. Additionally, metagenome-assembled genomes (MAGs) revealed the presence of functional genes linked to HM resistance, providing deeper insights into the ecological roles and metabolic capabilities of microbial taxa. These findings highlight the significant impact of smelting-derived contamination on microbial diversity and functional potential, offering valuable insights for the development of bioremediation strategies in HM-contaminated environments. Full article
(This article belongs to the Special Issue Microbial Community Structure and Function in Soils)
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