Soil Syst., Volume 7, Issue 4 (December 2023) – 33 articles

Sustainable-forage production is globally increasing, especially in marginal areas where the edaphic conditions for plant growth are not optimal. Soil salinization influences the symbiotic interaction between alfalfa and rhizobia. The efficiency of different symbiotic pairs (Sinorhizobium meliloti—Medicago sativa) was evaluated in relation to NaCl application (100 mM) on two different alfalfa cultivars (Marina and Etrusca) and 21 S. meliloti strains isolated in Algeria. At 100 mM NaCl, it was observed that there was a higher variability of plant dry weight compared to the control. The strains able to improve plant growth at 100 mM NaCl were different and specific for each alfalfa cultivar, highlighting that (symbiont) G × (host) G interaction is magnified under stressed (saline) conditions (E). Three strains were then identified as candidate inoculants for M. sativa cv Marina and used for an in-field experiment with induced stress (no irrigation), together with S. meliloti GR4 (a highly competitive strain). In-field experiments, showed a high variability, and a significant difference of plant biomass was observed only for those inoculated with S. meliloti GR4. Obtained results suggest that multiple traits should be considered for inoculant-strain selection, and for an efficient translation from lab to field, it requires extensive comprehension of the mechanisms driving G × G × E interaction. Full article

The ingestion of vegetables grown in soils or in cultivation substrate contaminated with heavy metals (HMs) and irrigated with wastewater is a potential problem for human health and food quality. The increasing disappearance of fertile soils has led to an increase in the practice of soil-less cultivation and the use of growing substrates, but the choice of the right substrate and its sustainable management is essential to ensure the production of quality and safe vegetables for all while minimizing the impact on the environment and human health. The present study measures the combined effects of different HMs (V, Ni, Cd, Pb, Cu, Cr) on microbial biomass, respiration, and enzyme activities (EAs) in an artificially contaminated commercial growing substrate. The concentrations of HMs were estimated by Atomic Absorption Spectroscopy; enzyme activities via spectrophotometric assays; respiration via CO₂ evolution; and microbial biomass C via the fumigation extraction method. The results showed a reduction in both respiration and all enzyme activities. The reduction in EAs highlighted a notable influence on microorganism-mediated C, N, S, and P cycles, strongly reducing substrate health. Microbial biomass did not show significant differences, but the increase in the metabolic quotient highlighted how the toxicity of HMs reduces the energy use efficiency of microbial metabolic processes. Full article

Microplastic (MP) pollution is a widespread global environmental concern, representing an emerging contaminant with major implications for ecosystems and human well-being. While extensive research has focused on MPs in aquatic environments, their impact on sediments and soils remains inadequately explored. Studies have confirmed the harmful effects of MPs on soil and sediment biota, as well as on the properties of these ecosystems. Furthermore, the long-term persistence of MPs within the environment contributes to their accumulation in terrestrial and marine food chains, with potential consequences for groundwater quality. Although several methods have been applied to mitigate MP pollution, some methods have drawbacks and some are not studied well, necessitating the urgent exploration of novel, sustainable, and eco-friendly approaches. Biochar is a remarkable solution for pollution removal; recently it has been used in addressing the increasingly concerning issue of microplastic contamination. This review aims to shed light on the difficulty posed by MPs in soils and sediments, while highlighting the remediation methods and the potential advantages of utilizing BC as an environmentally friendly solution for MP removal and remediation. Full article

This manuscript delves into the pivotal role of sustainable agriculture in addressing environmental challenges and meeting the nutritional demands of a burgeoning global population. The primary objective is to assess the impact of a recently developed eco-friendly fertilizer, denoted as SBO, which arises from the blend of organic and mineral components derived from agricultural waste, sulfur, and residual orange materials. These elements are bound together with bentonite. This study compares SBO with distinct fertilizer treatments, including horse manure (HM) and nitrogen–phosphorous–potassium (NPK), on two diverse tomato-growing soils, each characterized by unique chemical and biological properties. Furthermore, the research extends to evaluate the environmental implications of these fertilizers, with a specific focus on their carbon and water footprints. Soils have been chemically and biochemically analyzed, and carbon and water footprints (CF and WF, respectively) have been assessed. The results reveal substantial enhancements in soil quality with the application of SBO fertilizer. Both soils undergo a transition towards near-neutral pH levels, an increase in organic matter content, and heightened microbial biomass. SBO-treated soils exhibit notably superior enzyme activities. The Life Cycle Assessment (LCA) results affirm the sustainability of the SBO-based system, boasting the lowest CF, while NPK demonstrates the highest environmental impact. Consistently, the WF analysis aligns with these findings, indicating that SBO necessitates the least water for tomato production. In summary, this study underscores the critical importance of adopting sustainable fertilization practices for enhancing soil quality and reducing environmental footprints in agriculture. The promising results offer potential benefits for both food production and environmental conservation. Full article

Commercial harvesting of American ginseng (Panax quinquefolius) results in root debris in the soil, but the rate of decay is unknown. In this study, post-harvest root debris decayed mostly over the fall and winter, with almost no ginseng debris remaining in the soil by late spring of the following year. However, a small number of intact pencil-shaped roots were able to survive after harvest and sprout the following spring without any evidence of root decay. Root rot lesions were observed, which included many associated with the root rot pathogen Ilyonectria mors-panacis, with disappearing root rot symptoms observed in the following spring. Ginsenosides in soil were highest just prior to harvest, declining until an increase the following spring. Soil bacterial and fungal populations changed over time after harvest with several peaks in bacterial populations mostly in the fall, but this was less clear for fungal populations, which were dominated by only a few taxa. Harvesting ginseng can leave considerable debris in the soil, impacting its chemistry and microbiota. Ginseng replant disease, where the second crop shows high levels of root rot due to I. mors-panacis infection compared to low levels in the first crop, could be related to the decay of post-harvest crop debris, but additional research is needed to demonstrate this. Full article

The application of Cd-contaminated phosphate fertiliser has enriched concentrations of this non-essential element in many agricultural soils. Consequently, concentrations of the metal in some agricultural products exceed the Maximum Limit in foods. Composts can reduce the transfer of Cd from soil to plants; however, it is unclear how long this beneficial effect endures. We aimed to determine temporal changes of phytoavailable Cd in two market garden soils (an Allophanic Orthic Granular Soil and a Recent Silt Loam). Soils were amended with either municipal green waste compost or sawdust and animal waste compost at a rate of 2.5% w/w under three incubation regimes: at 19 °C, at 30 °C, and at 30 °C with additional N added as urea at 0.6 g urea/kg soil added over 1 year. Each replicate was sampled after 1, 5, 9, 13, 21, 31, and 49 weeks, and phytoavailable Cd was estimated through 0.05 M Ca(NO₃)₂ extraction. Seed potato (Solanum tuberosum), ‘Nadine’ variety, was grown in the Pukekohe Allophanic Orthic Granular Soil, freshly amended with municipal compost and the same soil aged for one year. The concentration of Cd in all samples was analysed using an ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer). The C concentration in the soil—compost mixtures decreased over the year, with the greatest decreases occurring in the soils incubated at 30 °C with added N. Unexpectedly, the concentration of Ca(NO₃)₂-extractable Cd in the compost-amended soils did not increase over time and in some cases even decreased. This was confirmed through a pot experiment, which showed the Cd concentration in potato was reduced by 50% in both the freshly amended soil and the amended soil aged for one year. Cadmium immobilisation in soils might be due to both the sorption of Cd by organic matter and the occlusion of sorbed Cd by oxy-hydroxides of iron and aluminium. Over 49 weeks, soluble Cd does not increase as organic matter oxidises. The application of municipal compost to soil will reduce both plant Cd solubility and plant Cd uptake for at least one year in the soils tested. Full article

Climate change negatively affects crop productivity, threatening the survival of entire populations from many vulnerable hotspot regions of the world with the risk of exacerbating hunger, malnutrition and international inequality. Selecting plant species manifesting abiotic stress-tolerant adaptive traits represents a challenge towards ensuring that crops are more resistant and resilient to environmental perturbations. The rhizosheath, defined as the complex of root hair, exudates and soil that strongly adheres to plant roots, is a promising root adaptive trait in facing conditions of water and nutrient deficits, as well as acidic soil. Several beneficial ecological functions are attributed to the rhizosheath, such as enhancing water and nutrient uptake; protecting from dehydration, heat and acid stresses; and stimulating microbial activities. It has been described in several Angiosperm species, including crops grown in severe habitats. The aim of this review was to collect the relevant literature produced to date regarding rhizosheaths, focusing on (i) the various processes involved in its formation, including both physicochemical and biological ones; (ii) the evolutionary and ecological role of rhizosheaths; and (iii) the most frequently used methodologies for its investigation and characterization. The present work provides a comprehensive overview of this revolutionary root’s great agronomic importance in order to address future research aiming to fill the existing knowledge gaps and define a common and shared methodology. Full article

Africa, specifically Nigeria, has witnessed a dramatic increase in population over the last century, prompting efforts to ensure sustainable food production and quality. Concerns for soil sustainability and food security have led to the exploration of cost-effective methods, such as biochar, to enhance soil quality. Researchers in Nigeria and Africa as a whole have investigated biochar’s potential to improve soil fertility and crop performance across various agroecological zones. This paper aims to review recent biochar research priorities on soil fertility and crop performance with an emphasis on various sole biochar applications and combinations with fertilizers to determine the research gaps that need to be developed more in biochar research in Nigeria. From the papers reviewed, sole biochar applications and biochar + macronutrients and biochar + manure combinations were studied more dominantly, while biochar + micronutrients research projects were scanty despite their low content in the semi-arid soils of Nigeria. The studies were spread across the country with the majority taking place in derived savanna and humid forest, while Sudan savanna and Sahel savanna received less research attention despite being characterized by a low-fertile soil and vast area of land. Research involving BC in the context of Sahel savanna (SLS) and Sudan savanna (SS) soils is strongly encouraged in Nigeria. This research should encompass a wide range of investigations, including sole BC applications and combinations of BC with macronutrients, micronutrients, and manure, as well as exploring its potential as a slow-release fertilizer. Incorporating exclusive biochar in substantial amounts appears economically unfeasible within the context of local biochar production. However, it can be utilized in the synthesis of slow-release fertilizers, requiring smaller quantities and potentially offering cost-effectiveness. This approach enhances soil condition and crop productivity. Challenges are faced due to less commercial production as a result of inadequate power and structural facilities. Exploring the modification of local biochar for slow-release fertilizers through future research offers potential profitability. Full article

Wetlands are dynamic ecosystems that provide feeding and nesting grounds for diverse species of waterbirds. The quality of wetland habitat may have an impact on the density, diversity, and species richness of waterbirds. Toxic metal contamination is one of the most significant threats to wetland habitats. Feathers are a key indicator of heavy metal contamination in avian communities as a non-invasive method. We examined the levels of Arsenic (As), Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Lead (Pb), Nickel (Ni), and Zinc (Zn) using ICP-AAS and standards of digestion procedure from the primary feathers of 10 distinct species of waterbirds. The study was conducted at four wetlands, viz., Point Calimere Wildlife Sanctuary (Ramsar site); Pallikaranai Marshland (Ramsar site); Perunthottam freshwater lake (unprotected wetland), Tamil Nadu and the Pulicat Lake, Andhra Pradesh, (Ramsar site), India. The Large crested tern had higher concentrations of As, Co, Cr, and Ni. Cu was greater in the Indian pond heron, and Zn was higher in the Grey heron. The accumulation of metals differed among the waterbirds (p < 0.05), and the inter-correlation of metals found positive influences between the tested metals, i.e., Co was positively associated with As, Cr had a positive correlation with As and Co, and Ni was positively correlated with As, Co, Cr, and Cu. In contrast, Pb had a positive association with Cu and Ni. The Zn was associated with Co, Cr and Cu. The level of metals in waterbirds was Zn > Cu > Cr > Ni > Pb > Co > Cd > As. The results showed that metal levels in the primary feathers of waterbirds were greater than the other species of waterbirds examined across the world. Thus, the study emphasizes that managing wetlands and controlling pollution is crucial to saving waterbirds; otherwise, the population and diversity of waterbirds will decline and become a significant threat to waterbird communities. Full article

Changes in land use can cause degradation of soil physical quality with negative effects on the environment and agricultural production. The effects of different land uses on soil physical-hydric attributes were studied in the Renato River and Caiabi River watersheds in the southern Brazilian Amazon. Three conditions of land use were evaluated: native forest, crops, and pasture in the headwater, middle, and mouth of each watershed. Particle size, particle density, bulk density, total porosity, macroporosity, microporosity, water contents at field capacity and permanent wilting point, and available water capacity in soil were evaluated in three soil layers down to 0.4 m. Data collected were subjected to the Kruskal–Wallis nonparametric test and Pearson’s correlations. Multivariate analyses were also performed using the principal component method. In the Renato watershed, in comparison with native forest, conventional management of pasture and crops caused soil physical degradation, increasing soil density in the surface layer and reducing macroporosity and total porosity. In the Caiabi watershed, converting native forest areas into pasture and crops altered water quality, influencing the water dynamics in the soil, by reducing soil water conductivity. Soil attributes varied by watershed, with texture variations between the headwater and mouth, indicating that changes in soil properties result from both management and the granulometric composition of the soil in different regions of the same watershed. Adoption of crop and pasture conservation practices can improve soil physical attributes in regions bordering agricultural areas in the southern Amazon. Full article

Controlled-release urea fertilization is an innovative approach and effective means to reduce the loss of nitrogen and enhance fertilizer use efficiency to optimize crop yield while minimizing the environmental impact. The objective of this study was to investigate the dynamic process of mineral nitrogen (Nmin) release in Luvisols, Cambisols, Retisols, and Arenosols to understand the interaction between soil characteristics and mineral nitrogen release and evaluate the impact of conventional urea compared to coated urea potassium humate on barley biomass production. A pot experiment was conducted under glasshouse conditions (20 ± 2 °C and 60% Humidity). Five treatments including no fertilization as a control (C), 100 kg·N·ha⁻¹ of urea (U100), 200 kg·N·ha⁻¹ of urea (U200), 100 kg·N·ha⁻¹ of coated urea potassium humate (UPH100), and 200 kg·N·ha⁻¹ of coated urea potassium humate (UPH200) were applied to four soil and texture types. Our findings indicate that there are different patterns of mineral nitrogen release across the different soil and texture types. Ammonium levels reached their peak point in all soils within 2–7 days after application. On the other hand, the concentration of nitrate NO₃⁻–N showed a linear increase over 45 days during the experiment. The Retisol, which had a sandy clay texture, obtained the highest concentration of mineral nitrogen in both forms (NH₄ and NO₃), while the sandy texture of Arenosol showed the lowest accumulation of mineral nitrogen and its forms. The application of potassium humate caused a delay of 1–4 days in the peak of soil ammonium, which at peak accounted for approximately 25–44% of the mineral nitrogen in the soil. Furthermore, the application of urea and coated urea potassium humate exhibited significant effects on barley biomass with an increase of approximately 14–91% compared to the unfertilized treatment (control). This research contributes to our understanding of nutrient dynamics in diverse soil environments and provides insights into optimizing sustainable fertilization strategies such as controlled-release fertilizer application. The implications of these findings highlight the significance of tailored nutrient management practices based on soil texture type, which can lead to improved agricultural productivity and environmental impact. Full article

This review highlights the potential of vermicompost and its derived products as sustainable and eco-friendly solutions for enhancing production and pest management in grain crops. It assesses their impact comprehensively on crops such as maize, wheat, barley, rice, and pearl millet. Vermicompost improves soil quality, increases nutrient availability, boosts crop productivity, and enhances pest and disease tolerance. It acts as an organic fertilizer, enriching the soil with essential nutrients, humic acids, growth-regulating hormones, and enzymes, improving plant nutrition, photosynthesis, and overall crop quality. Furthermore, vermicompost shows promise in mitigating soil degradation and sequestering organic carbon while demonstrating the potential for pest management, including effectiveness against pests like fall armyworm (Spodoptera frugiperda). This review emphasizes the importance of integrated nutrient management and proper application strategies to maximize the benefits of vermicompost in grain crops. Factors such as the form and timing of application, efficacy against specific pests, and economic viability for different farming scales are discussed. Understanding these factors is crucial for successfully implementing and adopting vermicompost-based pest management strategies in grain crops. This review also explores the potential of vermicomposting as an eco-friendly and cost-effective solution to remediate organic contaminants, emerging contaminants, personal-care and pharmaceutical products, and microplastics. The review further identifies knowledge gaps and highlights the need for future studies to effectively utilize vermicompost and its derived products in cereal production for sustainable agriculture, contributing to global food security. Full article

Sewage sludge (SS) is an organic waste that may potentially be used as a slow-release source of phosphorus (P), despite the necessity for pre-treatment and its lower P content compared to soluble mineral fertilizers. For these reasons, composted sewage sludge was used to manufacture pelletized organomineral fertilizers, by mixing it with the inorganic sources monoammonium phosphate (MAP) and AshDec^® (ASD) (thermochemically incinerated SS). The fertilizers were physiochemically characterized and evaluated for their P solubilization dynamics and lability in the soil. The sources tested were as follows: organic compost of sewage sludge powder (SSC) and its pelletized form (SCP), pelletized organomineral SSC + MAP (S + MAP) and SSC + ASD (S + ASD), ASD alone, compared conventional MAP and a control (nil-P). These fertilizers were applied to columns containing 50 g of soil at the dose of 100 mg P column⁻¹ and were leached daily with 30 mL of water or 2% citric acid for 30 days. We analyzed the leachates for pH and P content. Pelletizing process resulted in denser products and promoted more gradual P release. The organomineral S + MAP was the most water-soluble recycled source, solubilizing about 70% of the total P, while the others presented much lower solubilization (<20%). In contrast, all fertilizers showed high solubility in 2% citric acid (except for S + ASD). After leaching, soil P fractionation disclosed that the P leftover in the soil remained mostly in the labile and moderately labile pools. Composting and the ASD process produced materials with slow P solubilization, being favored in acidic soils and in plant’s rhizosphere. In turn, S + MAP resulted in a promising product with intermediate P solubility, better synchronized with crop demand, potentially increasing P-use efficiency. Our results shed light in the physico-chemical properties and on the solubilization dynamics of novel organomineral products in tropical soil conditions. Full article

Grain and forage legumes are important sources of food and feed, key for sustainable agriculture given the environmental services they provide. However, their cultivation is hampered in the Mediterranean Basin and Near East by the widespread occurrence of the root parasitic weed crenate broomrape (Orobanche crenata). Other broomrape species such as O. minor, O. foetida, and Phelipanche aegyptica are also of local importance. As for other parasitic weeds, a number of management strategies have been proposed, but considering that temperate legumes in the area are low-input crops, these strategies are largely uneconomical or hard to achieve, leaving the use of resistant cultivars as the most desirable option. Breeding for broomrape resistance is not an easy task, but significant progress has been achieved by classical breeding and selection and will profit from recent developments in phenomics and genomics. Here, achievements and prospects in broomrape management and resistance breeding are presented and critically discussed. Full article

In order to assess the influencing factors of the presence of mercury in a river within the Savanna biome (Cerrado), we surveyed total mercury (THg) in bottom sediment from 50 lakes along 750 km of the Middle Araguaia floodplain. The sampling sites included non-urban and urban surroundings over three distinct geomorphologies. We measured water physicochemical parameters at each site and tested statistically if land use nested within the geological formation influenced the THg concentration in bottom sediments and related water parameters. Multivariate results indicate that the interaction between geological groups and land use is statistically significant (p < 0.05). Nested ANOVA and Tukey HSD tests confirmed that the geological formation with its nested land use influences the THg, pH, DO, conductivity, and TDS (p < 0.05). THg was significantly lower in Quaternary terrains (p < 0.05) and differed significantly between non-urban and urban areas in Neoproterozoic terrains (p = 0.02). The spatial projections of the THg eigenvector on the main axes with the scoring factors of the Neoproterozoic/Paleoproterozoic terrains, and urban/non-urban, confirmed the spatial correlations. These results indicate that the association of land use and geology could be the main driver of THg in the bottom sediments of lakes from the Middle Araguaia floodplain. Full article

Biochar can be useful for the functional recovery of soils contaminated with potentially toxic elements (PTEs), even if its effectiveness is variable and sometimes limited, and conflicting results have been recently reported. To shed some light on this regard, softwood-derived biochar was added at 2.5 (2.5-Bio) and 5.0% w/w (5.0-Bio) rates to an acidic (pH 5.74) soil contaminated by Cd (28 mg kg⁻¹), Pb (10,625 mg kg⁻¹), and Zn (3407 mg kg⁻¹). Biochar addition increased soil pH, available P and CEC, and reduced labile Cd, Pb, and Zn (e.g., by 27, 37, and 46% in 5.0-Bio vs. the unamended soil). The addition of biochar did not change the number of total heterotrophic bacteria, actinomycetes, and fungi, while it reduced the number of Pseudomonas spp. and soil microbial biomass. Dehydrogenase activity was reduced in amended soils (e.g., by ~60 and 75% in 2.5- and 5.0-Bio, respectively), while in the same soils, urease increased by 48 and 78%. Approximately 16S rRNA gene amplicon sequencing and the Biolog community-level physiological profile highlighted a significant biochar impact (especially at a 5% rate) on soil bacterial diversity. Tomato (but not triticale) yield increased in the amended soils, especially in 2.5-Bio. This biochar rate was also the most effective at reducing Cd and Pb concentrations in shoots. Overall, these results demonstrate that 2.5% (but not 5.0%) biochar can be useful to restore the soil chemical fertility of PTE-polluted soils with limited (or null) impact on soil microbial and biochemical parameters. Full article

Estuaries are excellent environments for identifying pollution episodes that have affected river basins, as their sediments are the final destination of some of the pollutants. This paper studies the geochemical evolution of five elements (As, Co, Cu, Pb, Zn) in a core extracted from the middle estuary of the Tinto River (SW Spain). The results are based on facies interpretation, ICP atomic emission spectrometry analysis, the application of a regional background to obtain the geoaccumulation index and dating. The main objective of this communication is the detection of natural or anthropogenic pollution episodes in the middle estuary of the Tinto River (SW Spain). Four pollution episodes have been detected: (1) ~5.8 cal. kyr BP, probably caused by natural acid rock drainage processes derived from the oxidation of the Iberian Pyritic Belt deposits found in its drainage basin; (2) 4.7–4.5 kyr BP, coming from the first mining activities and characterized by a significant increase in the concentrations of the five elements analyzed; (3) 1850–1960 interval, coinciding with intensive mining and characterized by increasing values of As and, to a lesser extent, Pb (intensive mining); and (4) the second half of the 20th century, with high element concentrations from mining and industrial effluents. All episodes show an increase in their geochemical classes deduced from the geoaccumulation index. This communication can serve as an example for assessing the impact of different types of pollution in estuarine environments. Full article

Management-intensive Grazing (MiG) has been proposed to sustainably intensify agroecosystems through careful management of livestock rotations on pastureland. However, there is little research on the soil health impacts of transitioning from irrigated cropland to irrigated MiG pasture with continuous livestock rotation. We analyzed ten soil health indicators using the Soil Management Assessment Framework (SMAF) to identify changes in nutrient status and soil physical, biological, and chemical health five to six years after converting irrigated cropland to irrigated pastureland under MiG. Significant improvements in biological soil health indicators and significant degradation in bulk density, a physical soil health indicator, were observed. Removal of tillage and increased organic matter inputs may have led to increases in β-glucosidase, microbial biomass carbon, and potentially mineralizable nitrogen, all of which are biological indicators of soil health. Conversely, trampling by grazing cattle has led to increased bulk density and, thus, a reduction in soil physical health. Nutrient status was relatively stable, with combined manure and fertilizer inputs leading to stabilized plant-available phosphorous (P) and increased potassium (K) soil concentrations. Although mixed effects on soil health were present, overall soil health did increase, and the MiG system appeared to have greater overall soil health as compared to results generated four to five years earlier. When utilizing MiG in irrigated pastures, balancing the deleterious effects of soil compaction with grazing needs to be considered to maintain long-term soil health. Full article

There has been limited research on the effect of eucalyptus harvest residue management on soil organic carbon (SOC) in subtropical environments. This research evaluated the effect on soil C indices of the following eucalyptus harvest residue managements: AR, with all forest remnants left on the soil; NB, where bark was removed; NBr, in which branches were removed; NR, which removed all residues; and NRs, which is same as NR but also used a shade net to prevent the litter from the new plantation from reaching the soil surface. C stocks within the soil depths of 0–20 cm and 0–100 cm increased linearly with the C input from eucalyptus harvest residues. In the layer of 0–20 cm, the lowest soil C retention rate was 0.23 Mg ha⁻¹ year⁻¹, in the NR treatment, while in the AR treatment, the retention rate was 0.68 Mg ha⁻¹ year⁻¹. In the 0–100 cm layer, the highest C retention rate was obtained in the AR (1.47 Mg ha⁻¹ year⁻¹). The residues showed a high humification coefficient (k₁ = 0.23) and a high soil organic matter decomposition rate (k₂ = 0.10). The carbon management index showed a close relationship with the C input and tree diameter at breast height. Full article

Future space missions to Mars will depend on the development of bioregenerative life support systems. Mars regolith contains most of the nutrients needed for plant growth, but not organic matter (OM). Although Mars simulants have been deeply characterized and tested as growing media, no data are available about their possible modification occurring during terraforming, including the interaction of exogeneous OM with iron (Fe) oxides, particularly abundant in Mars regolith. The aim of this study was to investigate the mineral transformation and the OM evolution occurring in the early stages of the terraforming process. Potato was grown for 99 days on Mojave Mars Simulant MMS-1, alone (R100) and mixed with a compost 70:30 v:v (R70C30), and on a fluvial sand, alone (S100) and mixed with compost (S70C30), for comparison. Bulk (BK) and potato tubero/rhizo-sphere (RH) soils were fractionated to obtain particulate OM (POM) and mineral-associated OM (MAOM). Bulk samples and corresponding fractions were characterized for total nitrogen and organic carbon (C) and analyzed by Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy. Organic C increased by 10 and 25 times in S70C30 and R70C30, respectively, compared to S100 and R100. Most of the organic C accumulated in the POM fraction of both growing substrates, while its content in the MAOM was 3 times higher in R70C30 than in S70C30. No significant differences between BK and RH were found. Finally, ferrihydrite mediated exogenous OM stabilization in regolith-based substrates, while Fe(III)-OM complexes were detected exclusively in sand-based growing media. Understanding mechanisms and testing potential sustainable practices for creating Mars regolith similar to terrestrial soil will be fundamental to sustain food crop production on Mars. Full article

Perfluorooctanoic acid (PFOA) is a perfluoro compound that contains an eight-carbon perfluoroalkyl chain followed by a carboxylic acid function group. The C-F bound possesses a strong bond energy of approximately 485 kJ/mol, rendering PFOA thermally and chemically stable. It has found applications in water-resistant coating and is produced either by degrading other long-chain perfluorinated carboxylic acids or fluorotelomer alcohol. PFOA is challenging to further degrade during water treatment processes, leading to its accumulation in natural systems and causing contamination. Research has been conducted to develop several methods for its removal from the water system, but only a few of these methods effectively degrade PFOA. This review compares the most common chemical degradation methods such as photochemical, electrochemical, and sonochemical methods, to the cutting-edge biodegradation method. The chemical degradation and biodegradation methods both involve the stepwise degradation of PFOA, with the latter capable of occurring both aerobically and anaerobically. However, the degradation efficiency of the biological process is lower when compared to the chemical process, and further research is needed to explore the biological degradation aspect. Full article

Conservation tillage practices, such as reduced tillage and no-tillage, have recently garnered significant attention as core elements of the regenerative agriculture and carbon farming concepts. By minimizing mechanical soil disturbance, these practices preserve soil carbon and facilitate CO₂ fixation in the soil. Despite the widely acknowledged benefits, many farmers still approach no-tillage with skepticism. Their primary concerns are weed management and soil compaction. While weeds can be effectively controlled with the deployment of integrated weed management strategies, urgent soil compaction problems can be rapidly resolved only with mechanical interventions. That is why many no-till farmers resort to occasional heavy tillage, in a scheme characterized as rotational tillage, inadvertently sacrificing their regenerative assets in soil carbon. This is also a pivotal issue within carbon farming: the fate of soil carbon at the end of a compliant scheme focused on carbon fixation. The present study explores data of soil organic matter (SOM), soil penetration resistance (PR), and dry bulk density (DBD) from the initial, six-year period of a long-term tillage experiment in Greece. During that period, modifications to the experimental design allowed diverse combinations of five tillage methods (conventional tillage, 3 reduced tillage methods, and no-tillage). The findings indeed underscore the farmers’ concerns about soil compaction. High levels of PR and DBD were observed even at the topsoil layer of the no-tillage (NT). Conventional, moldboard plowing (MP) or reduced, chisel plowing (CP) applied after four years of uninterrupted no-tillage ameliorated most of the soil compaction; however, at the same time, this induced unfavorable consequences for SOM. In contrast, NT applied permanently for six years resulted in a substantial enhancement in SOM that reached 2.24%, for a sampling depth 0–0.30 m compared to 1.54% for permanent MP. When no-tillage was rotated with plowing in the fifth year, almost 50% of the sequestered carbon was lost and the SOM dropped to 1.87%. Nevertheless, the amount of SOM observed at the deeper 0.15–0.30 m layer was greater compared to permanent NT. This suggests that while plowing induced some loss of SOM, it also facilitated the uniform distribution into the soil profile, in contrast with the accumulation in the topsoil at prolonged NT. The permanent CP method and the NT/CP rotation provided comparative outcomes in terms of both soil compaction and soil carbon sequestration with the rotational NT/MP scheme, while all the other tillage combinations were inferior. Full article

Greenhouse gas (GHG) emissions from paddy fields depend on water management practices and rice varieties. Lysimeter experiments were conducted to determine the effect of rice varieties (lowland; Koshihikari (KH) and upland; Dourado Precoce (DP)) on GHG emissions under two water management practices: alternate wetting and drying (AWD) and continuous flooding (CF). A repeated cycle of drying and wetting in AWD irrigation was performed by drying the soil to −40 kPa soil matric potential and then rewetting. Consequently, the closed chamber method was used to measure direct emissions of methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂). The result revealed that water management significantly affected CH₄ and N₂O emissions (p < 0.05), while no significant effect was observed between different rice varieties. Although, AWD irrigation reduced CH₄ emissions, it increased N₂O emissions compared to CF irrigation, likely due to increased oxygen supply. AWD irrigation decreased GWP by 55.6% and 59.6% in KH and DP, respectively, compared to CF irrigation. Furthermore, CH₄ and N₂O emissions significantly correlated with soil redox potential and volumetric water content. These results suggest that AWD irrigation might be an effective water management method for mitigating GHG emissions from rice fields in central Japan. Full article

The digital twin concept has found widespread application across diverse industries. Herein, we present a comprehensive conceptual framework for the cognitive soil digital twin, which embodies the intricate physical reality of the soil ecosystem, aiding in its holistic monitoring and comprehension. The digital twin can seamlessly integrate a multitude of sensor data sources, including field Internet of Things sensors, remote sensing data, field measurements, digital cartography, surveys, and other Earth observation datasets. By virtue of its duality, this digital counterpart facilitates data organisation and rigorous analytical exploration, unravelling the intricacies of physical, chemical, and biological soil constituents while discerning their intricate interrelationships and their impact on ecosystem services. Its potential extends beyond mere data representation, acting as a versatile tool for scenario analysis and enabling the visualisation of diverse environmental impacts, including the effects of climate change and transformations in land use or management practices. Beyond academic circles, the digital twin’s utility extends to a broad spectrum of stakeholders across the entire quadruple helix, encompassing farmers and agronomists, soil researchers, the agro-industry, and policy-makers. By fostering collaboration among these stakeholders, the digital twin catalyses informed decision-making, underpinned by data-driven insights. Moreover, it acts as a testbed for the development of innovative sensors and monitoring frameworks, in addition to providing a platform that can educate users and the broader public using immersive and innovative visualisation tools, such as augmented reality. This innovative framework underscores the imperative of a holistic approach to soil ecosystem monitoring and management, propelling the soil science discipline into an era of unprecedented data integration and predictive modelling, by harnessing the effects of climate change towards the development of efficient decision-making. Full article

Rainfall simulators are important pieces of equipment to investigate hydrological processes and soil erosion. Here, we investigated the operational characteristics, the rainfall characteristics, and the soil erosion process under collecting plots and rainfall patterns using the InfiAsper simulator. We evaluated the standard plot of the simulator in a rectangular shape (1.0 × 0.7 m), as well as a circular plot (0.8 m diameter), and four precipitation patterns, characterized as advanced (AV), intermediate (IN), delayed (DL), and constant (CT). In the laboratory, uniformity and water consumption tests were carried out for shutter-disk rotations from 138 to 804 rpm, and in the field, simulated rains were applied on a Dystric Acrisol. Rains with different patterns were simulated and presented a uniformity coefficient above 83% for the circular plot and 78.2% for the rectangular plot. The soil erosion varied as a function of the precipitation patterns and, to a lesser extent, according to the shape of the experimental plot. However, runoff and soil loss in AV were 2.1 and 3.5 times greater when using a circular plot. Concerning IN and DL, the length of the rectangular plot may have influenced the formation of small furrows throughout most of the simulated rainfall event, providing greater runoff (13.1 mm) and soil loss (13.6 g m⁻²). The results obtained are promising, but plots with different shapes associated with rainfall patterns simulated by InfiAsper must be evaluated in other classes and soil use and cover conditions. Full article

Saline and gypsic soils impede or condition the establishment of farms in many regions worldwide. Stress caused by the accumulation of sodium or calcium ions in the soil drastically limits plant growth and is a limiting factor in the production of many crops. For this reason, saline and gypsic soils were preferentially exploited for mineral extraction. However, nowadays, they can be a source of new biotechnological tools to help in the osmotic stress to which some crops are exposed. In these environments, despite being traditionally characterized by their low biodiversity, we can find well-adapted microbiota that may be able to interact with plants to deal with different environmental stresses. These mechanisms may consist of a very important contribution to the development of new osmotic stress-dealing bioinoculants. The present study sought to elucidate the diversity of the cultivable population of such environments and use them as regulators of soil nutrients and stress-relieving symbionts in plants under osmotic stress. Among the candidate strains selected to cover more scenarios, we found that the strains Stutzerimonas stutzeri A38 and Bacillus pumilus A49 were able to increase root size under osmotic stress in Medicago sativa and Medicago polymorpha plants. Moreover, Peribacillus frigoritolerans A70 and Bacillus licheniformis A46 also enhanced the performance in M. polymorpha, showing interesting potential for a future use in wasteland use for production to livestock feeding or other relevant industries. Full article

Population expansion within agricultural lands applies pressure on natural resources, particularly water resources, and leads to contamination through different types of pollutants, such as heavy metals, that consequently alter the ecosystem and impact human health. In the present work, several heavy metals in sediment along the Kitchener drain were assessed using different soil quality and health indices; the Kitchener drain is one of the major drains in the Nile Delta. Sediments were collected from six stations along the drain from upstream to downstream. Soil physical and chemical properties were analyzed as well as four metal pollution indices and five ecological risk indices. Additionally, carcinogenic and noncarcinogenic risks for adults and children were evaluated. The data showed that the Kitchener drain is mainly contaminated with Cd, Pb, and Zn, where the concentrations decreased from upstream to downstream. The eco-toxicological indexes showed that Pb, Zn, and Cr were the most hazardous metals along the drain, mainly at upstream stations. The human health risk indices data revealed that the noncarcinogenic risk of the studied metals can be ordered as follows: Co > Cr > Pb > Mn > Ni > Cd > Cu > Zn for adults, while for children it was Cr > Mn > Co > Pb > Ni > Cd > Cu > Zn. The carcinogenic risk data showed that heavy metals ranged from low to medium in all sites, except for Pb and Zn, which have high carcinogenic risks. The present study showed more contamination upstream compared to downstream which can be attributed to urbanization and human activity, as shown from the land use/landcover map. This highlighted that the major drains inside the Nile Delta suffer from different anthropogenic activities that should be taken into consideration by researchers, scientists, and policymakers. Also, the source of heavy metal pollution, particularly upstream, should be controlled or treated before discharge into the drain. On the other side, downstream (toward the Mediterranean Sea), the heavy metals could affect the trophic levels of the marine ecosystem on the Mediterranean Sea which should be taken into consideration. Full article

Prolonged drought conditions in New Mexico have led growers to use brackish groundwater for crop irrigation. Desalination of the groundwater with reverse osmosis (RO) is possible, but the concentrated waste requires environmentally safe disposal, such as by irrigating native halophytic plants, Atriplex, which could be cultivated to feed livestock. We hypothesized that ions from the brackish irrigation would increasingly accumulate in the soil away from the roots as the wetting front expanded further from the emitter, while not affecting the aboveground growth of the plants. Atriplex species were irrigated with brackish water at two irrigation levels for three years. Soil samples were collected at the beginning, middle, and end of the study at two depths and three distances from the emitter. Electrical conductivity (EC), soil ion accumulation, and plant growth were recorded. The average EC of the soil increased with brackish water irrigation. As the ions accumulated along the wetting front of the percolating water rather than near roots, a favorable environment for root growth was provided. While sodic levels of ion accumulation were not reached in this study, aboveground growth still declined. This leads to the recommendation that RO-concentrated waste could be used to irrigate Atriplex species for livestock fodder, with further plans to irrigate with fresh water to remove accumulated ions as a potential sustainable waste management process. Additional studies are necessary to develop guidelines for Atriplex tolerance and harvesting. Full article

Enhanced efficiency fertilizers, such as urea treated with a urease inhibitor, controlled-release fertilizers (CRFs), and fertilizer blends, compose important strategies for improving efficiency in nitrogen (N) use by plants and mitigating ammonia (N-NH₃) emissions. The physical mixture of fertilizers in blends can favor synchronization of N-release from the fertilizers and N-uptake by coffee plants and also dilute the costs of acquiring a pure CRF, making fertilizer blends more accessible to growers. To investigate this, a field experiment was conducted over two consecutive crop years with Coffea arabica with the aim of evaluating nitrogen fertilizer technologies at application rates ranging from 0 to 450 kg N ha⁻¹. The fertilizers were characterized, and analyses were performed to quantify N-release from the fertilizers, ammonia volatilization, and nutritional and yield aspects of the coffee plant. The fertilizers used were urea (UCon), urea treated with N-(n-butyl) thiophosphoric-triamide (UNBPT), urea-coated with polymer of the E-Max technology (with 41%N (EMax41) or 43%N (EMax43)), and blends of UNBPT with E-Max (Blend41–Blend43). The cumulative N-release for EMax41 always remained below that for EMax43, just as occurred for Blend41 in relation to Blend43. Over the two crop years, the greatest volatilization of N-NH₃ occurred with UCon (~25%) and the least with EMax41 (9%). The results indicate that the technologies mitigated the N-NH₃ emissions in relation to UCon [EMax41 (63% mitigation) > Blend41 (43%) > EMax43 (32%) > UNBPT (28%) > Blend43 (19%)]. Crop management affects coffee yield. The yield increase went from 20% in the first crop year to 75% in the second, with better results from fertilizers containing CRF. We present information that can assist fertilizer producers and coffee growers, and, above all, we seek to contribute to environmental action for the reduction of agricultural NH₃, clarifying potential strategies for mitigation of these emissions and strategies that generate advances in research on technologies for coffee growing. Full article