Mineral Amendments Research Articles

Nutrient removal efficacy and microbial dynamics in constructed wetlands using Fe(III)-mineral substrates for low carbon-nitrogen ratio sewage treatment.

This study evaluated the roles of two common sources of Fe(III)-minerals-volcanic rock (VR) and synthetic banded iron formations from waste iron tailings (BIF-W)-in vertical flow-constructed wetlands (VFCWs). The evaluation was conducted in the absence of critical environmental factors, including Fe(II), Fe(III), and soil organic matter (SOM), using metagenomic analysis and integrated correlation networks to predict nitrogen removal pathways. Our findings revealed that Fe(III)-minerals enhanced metabolic activities and cellular processes related to carbohydrate decomposition, thereby increasing the average COD removal rates by 10.7% for VR and 5.90% for BIF-W. Notably, VR improved nitrogen removal by 1.70% and 5.40% compared to BIF-W and the control, respectively. Fe(III)-mineral amendment in bioreactors also improved the retention of denitrification and nitrification bacteria (phylum Proteobacteria) and anammox bacteria (phylum Planctomycetes), with increases of 3.60% and 3.20% using VR compared to BIF-W. Metagenomic functional predictionindicated that the nitrogen removal mechanisms in VFCWs with low C/N ratios involve simultaneous partial nitrification, ANAMMOX, and denitrification (SNAD). Network-based analyses and correlation pathways further suggest that the advantages of Fe(III)-minerals are manifested in the enhancement of denitrification microorganisms. Microbial communities may be activated by the functional dissolution of Fe(III)-minerals, which improves the stability of SOM or the conversion of Fe(III)/Fe(II). This study provides new insights into the functional roles of Fe(III)-minerals in VFCWs at the microbial community level, and provides a foundation for developing Fe-based SNAD enhancement technologies.

Mine waste rock as a soil amendment for enhanced weathering, ecosystem services, and bioenergy production

Enhanced weathering of terrestrial rock material is a promising method for the removal of anthropogenic CO2 emissions from the atmosphere. Herein, we demonstrate that an ameliorated mining waste product can be effectively weathered in the soil environment when used as a soil amendment in conjunction with the cultivation of fast-growing willows (Salix matsudana Koidz. ⨯ S. alba L. “Austree”) in a pot study environment. Utilizing this locally sourced amendment minimizes emissions associated with grinding and transportation of enhanced weathering materials. Results showed that the willows were able to tolerate the relatively high metal concentrations of this amendment and sequester inorganic carbon (C) through the production of bicarbonate in soil solution. During the period of peak plant growth (10 weeks after planting), alkalinity measurements of soil solution from pots with willows and the addition of 25% by mass mine waste product indicated an additional 10 mg of inorganic C sequestration per liter of leached soil solution compared to unamended soils with willows. This represents 4.5 times the inorganic C sequestration rate of unamended soils. The addition of ameliorated mining waste also increased the pH of the soil solution by up to two units (pH of 6 in control vs. pH of 8 with the addition of 25% by mass mineral amendment). In addition to inorganic C sequestration, weathering of the ameliorated mining waste product may also provide base cations (such as calcium and magnesium) which could improve soil fertility. These results are encouraging for future investigation of ameliorated mine waste rock to sequester carbon and enhance the production of willows grown for ecosystem services and phytotechnologies.

Degradation Rate/Vulnerability Potential and Fertility Status of Luvisols in the Mandara Mountains (Far-North Cameroon).

Soil degradation emerges as one of the major problems in the locality of Sir in the Mandara Mountains, Far-North Cameroon. Inappropriate agricultural techniques resulting in land use change affect soil functions and seriously harm forest ecosystems. This study was conducted to analyse the current character of soils and access their degradation and their level of fertility. Twenty soil samples were taken at 15 cm depth. This includes ten in the plot under forest reserve and ten others in the plot under cultivation. Cultivation is responsible for the increase in bulk density (BD) (1.59 to 2.23 g/cm3), Mg (4.76 to 6.40 cmol·kg-1), Ca (10.44 to 11.26 cmol·kg-1), P (7.93 to 9.93 g/kg), and Mg/K (2.28 to 5.84) and decrease in CEC (38 0.15 to 31.46 cmol·kg-1), OM (2.76 to 1.08%), OC (1.66 to 0.62%), total nitrogen (0.08 to 0.05%), K (4.59 to 1.15 cmol·kg-1), Na (1.32 to 0.91 cmol·kg-1), C/N (25.69 to 13.86), and Ca/Mg (2.32 to 1.89). This variability in physicochemical properties reflects progressive soil degradation. Cultivated soils are subject to severe degradation or potential vulnerability (SDR/Vp = 4/2) due to texture, organic carbon, soil aggregate stability, sealing index, and total nitrogen. On the other hand, soils under forest reserve are subject to severe degradation or vulnerability due to the total nitrogen and sodium absorption ratio. The soils of the study area are subject to severe and extreme potential degradation or vulnerability due to BD, respectively, under forest reserve and cultivation. Two classes of fertility were identified: class II (plots under forest reserve) having a good level of fertility, characterized by good physical properties and severe limitations in nitrogen and phosphorus and class IV (cultivated plots) with a low level of fertility due to severe limitations in organic matter, phosphorus, and poor physical characteristics. The best indicator of the good quality of the luvisols of Sir is the pH, while the bulk density is an indicator of severe to very extreme degradation or high to very high vulnerability. The application of organic and mineral amendments is essential for raising the organic matter and nitrogen and phosphorus contents in these soils.

Soil organic carbon pools under long-term mineral and organic amendments: a multisite study

Soil organic carbon (SOC) has various pools with different stabilization mechanisms. It is unclear how these SOC pools respond to various mineral and organic amendments depending on a large climate-soil gradient. Here, we studied in three zonal soils: Ferralic Cambisol (subtropic), Calcaric Cambisol (warm-temperate) and Luvic Phaeozem (mid-temperate) under 23-year mineral, straw and manure amendments. Six SOC sub-pools were isolated: unprotected, physically, chemically, biochemically, physico-chemically and physico-biochemically protected pools. Compared to initial level, SOC and most sub-pools increased in the three soils under manure application (p < 0.05), but little under straw and mineral amendments. The Luvic Phaeozems had much higher sequestration efficiencies of bulk SOC (27%) and its five sub-pools (5–7%) more than the Calcaric Cambisol (9%, 1–2%) and Ferralic Cambisol (9%, 0.5–1%). In contrast, Ferralic Cambisol had highest sequestration efficiency of unprotected pool (7%). The Calcaric Cambisol had divergent patterns of the six SOC pools compared with Luvic Phaeozems and Ferralic Cambisol, due to the low clay content. With the build-up of bulk SOC, the building-up abilities of non-protected, physically-, chemically- and biochemically-protected pools depended on soil type, while the building-up abilities of physico-chemically- and physico-biochemically-protected pools were convergent (12–19%) among soils. In conclusion, the Luvic Phaeozems had much higher build-up ability of bulk SOC and most sub-pools than the other two soils. With the build-up of SOC, the physico-chemically- and physico-biochemically-protected pools (most stable) had convergent response rates among soils, while the other pools had divergent response rates.Graphical

Comparative Liming Power of Chicken Manure and Selected Dolomitic Sources on an Acidic High Altitude Burundi Surface Soil

A research initiative was set up to evaluate the comparative liming power of locally available dolomitic products and chicken manure, using an amaranth (Amaranthus viridis L.) test crop. The soil used was acidic, of low % base saturation and risks of Al toxicity, deficient in available P, exchangeable Mg, Ca and K. The experimental setup was a completely randomized design with 11 treatments and 3 replicates which included: a control treatment (equivalent to 100 kg DAP/ha), 4 mineral amendments (Moso Lime, Moso Ground Dolomite, Bubanza Ground Dolomite and Busiga Ground Dolomite) applied at equivalents of 1 T/ha and 2 T/ha, and chicken manure applied at equivalent of 10 and 20 T/ha. The study duration was three months withthree test crop harvests at one-month interval. Monthly measured plant growth and production parameters were plant height, root length, shoot length, root biomass, shoot biomass and their summation (total biomass). Soil pH, available P and exchangeable acidity (Al3++ H+) were assessed at the start and the completion of the pot study. Obtained results could be summarized as follows: (i) the highest available P accumulation was associated with the equivalent of 20 T/ha of chicken manure; (ii) application of equivalents 20 T/ha of chicken manure, 2 T/ha Moso Ground Dolomite and 2 T/ha Moso Lime increased soil pH by 0.2 to 0.5 pH-unitsand reduced exchangeable acdity ; (ii) DAP fertilized treatment was characterised by the lowest pH value and the highest Al3+and H+exchangeable acidity, illustrating the acidifying effect of this NH4+-bearing fertilizer; (iv) amarant growth (root and height) and biomass (root + shoot) production were highest with 20 T/ha chicken manure, 2 T/ha Moso Ground Dolomite and 2 T/haMoso lime. Application rate was only statisticallt detectable for Moso Ground Dolomite (+ 162 %) and chicken manure (+ 182 %). Overall, 20 T/ha chicken manure showed the highest and most stable amaranth root + shoot biomass yields, demonstrating its potential residual effect, which should be evaluated and confirmed under field conditions.

Sea Bed Mining

The seabed is surely one of the last mining frontiers on earth remaining for mankind, to extract economic mineral deposits. It is hence imperative that India with its Obvious Geological Potential (OGP) area on the land surface amounting to 0.57 million km, for which baseline geoscience data has been generated and mineral exploration activities are ongoing, needs to be supplemented with mineral wealth on our sea beds, within our Territorial Waters (TW) and Exclusive Economic Zone (EEZ). Studies by the Geological Survey of India (GSI) and other agencies for mineralized horizons in the terrestrial OGP areas have been a continuous process. The baseline geoscience and mineral exploration data are published regularly by GSI and Indian Bureau of Mines (IBM) and made available to respective stakeholders. India has a 2.02 million km area under its TW and EEZ. Our East and West Coasts of the Peninsular India are endowed with phosphate, manganese nodules, lime mud and monazite sands with rare earth elements (REE) and thorium that have been surveyed by the Marine and Coastal Survey Division (MCSD) of the GSI with their research vessels to establish the potentiality. According to the data available, 1,53,996 million tons of lime mud within the EEZ off Gujarat and Maharashtra coasts, 745 million tons of construction grade sand, off Kerala coast, 79 million tons of heavy mineral placers in the inner-shelf and mid-shelf, off Odisha, Andhra Pradesh, Kerala, Tamil Nadu and Maharashtra, phosphorite in the Eastern and Western continental margins, polymetallic ferromanganese nodules and crusts in Andaman Sea and Lakshadweep Sea have been reported. The CSIR- National Institute of Oceanography has been embarking on research for seabed mineral deposits. The Offshore Areas Mineral (Development and Regulation) Amendment Bill, 2023, passed by Lok Sabha on 01.08.2023, has amendments to the Offshore Areas Mineral (Development and Regulation) Act, 2002, OAMDR Act (Ministry of Mines, Govt. of India, 2002). It envisages major initiatives to allow auction of mineral blocks 45° X 45° (latitude and longitude) in respect of any mineral or prescribed group of associated minerals, under one or more operating rights (taken together). The Act has a provision for setting up of a non-lapsable Offshore Areas Mineral Trust to maintain a fund under the Public Account of India. This fund will be financed by a yet to be determined, additional levy on the production of offshore minerals that will be used for exploration, research, disaster relief and for mitigation of adverse impacts of seabed mining. We have the National Exploration Trust and the District Mineral Foundation Trust funds, to which royalties are paid by stakeholders for onshore mining.

Agronomic amendments drive a diversity of real and apparent priming responses within a grassland soil

Soil carbon (C) sequestration is often viewed as a nature-based solution to help mitigate climate change. Key to realising this potential is a better understanding of which C inputs promote greater long-term C storage. The priming effect (PE) is the change in rates of microbial soil organic matter (SOM) decomposition caused by the addition of organic or mineral amendments to soil. The apparent PE (changes in CO2 from microbial biomass turnover) of substrates is often studied as a confounding factor, however, the real PE (decomposition of native SOM) is rarely measured due to uncertainties in C pool differentiation. Here, we used a 50-day mesocosm study to compare the effect of various common soil amendments (wood biochar and ash, protein, amino acids, glucose, cellulose, cattle farmyard manure (FYM), cattle slurry, inorganic N fertiliser, and different ratios of wheat straw:shoot mixes) on the real and apparent PEs of soil, using 5-year old quasi-stable 14C-labelled SOM and 14C-labelled active microbial biomass, respectively. Our results show that there are often significant differences in the real and apparent PE, for the same amendment, with variance in magnitude and, in some case, direction. We identified few consistent drivers of PE across the two assays, however, there was a negative relationship between the initial C:N ratio of the treatment and PEs, suggesting that while the nutrient stoichiometry of the C amendment is important, the usability and quality of the substrate for the microbial community are key to determining its priming response. Equally, context is important for interpretation, as treatments that elicit positive priming may still be replenishing or increasing soil C stocks.

Soil Acidification in Cocoa (Theobrama cocoa) Agrosystems in Côte d’Ivoire (I): Effect of Carbonate Based Mineral Amendments on Soil Chemical Properties and Growth of Cocoa Seedlings (Theobrama cocoa)

Soil Acidification in Cocoa (Theobrama cocoa) Agrosystems in Côte d’Ivoire (I): Effect of Carbonate Based Mineral Amendments on Soil Chemical Properties and Growth of Cocoa Seedlings (Theobrama cocoa)

Effects of rock phosphate and PK mineral fertilizer on soil fertility and cocoa production in south-central Côte d'Ivoire

Côte d'Ivoire is the world's leading cocoa producer, but sustainable cocoa production is threatened by, among other things, the country's dwindling forest reserves and declining soil nutrients, mainly phosphorus. To remedy the decline in soil fertility, a study of a mineral amendment was carried out in south-central Côte d'Ivoire to ensure the sustainability of cocoa production. Specifically, the aim was to evaluate the effects of rock phosphate (RP) and PK mineral fertilizer on soil fertility and cocoa production at Divo, over three years of trials. The experimental set-up was a Fisher block design, with 4 replications for 5 treatments. The results showed that, in terms of soil fertility, treatments receiving rock phosphate generally had good assimilable phosphorus content (≥ 11.5 Cmolkg-1), a Ca/Mg ratio of between 1 and 1.5, Mg/K≥3, (Ca+Mg)/K of between 12 and 40 and Ca/SBE x100 ≥ 68%. These ratios reflect not only good cocoa-growing soil, but also a good balance between Ca and the sum of exchangeable bases (SBE) and between K and the sum of Ca and Mg. On the other hand, all treatments had potassium deficiencies with (K/S) x100 &lt; 8%. As for yield, treatments T1 (100%RP + 100% NPK 0-23-19) with 2953.44 Kgha-1, T2 (90%RP + 100% NPK 0-23-19) with 2962.95 Kgha-1 and T3 (80% RP + 100% NPK 0-23-19) with 2862.10 Kgha-1 were the most expressive.

Porous Mineral Amendments Enhance Nitrogen Mineralization via Improvement of Soil Aeration and Water Retention Characteristics

Porous Mineral Amendments Enhance Nitrogen Mineralization via Improvement of Soil Aeration and Water Retention Characteristics

Reductive soil disinfestation and Fe amendment improve soil microbial composition and Fritillaria production.

The continuous obstacles of cropping cause severe economic loss, which seriously threaten agricultural sustainable development. In addition, managing excess waste, such as potato peel and mineral waste residues, is a vital burden for industry and agriculture. Therefore, we explored the feasibility of reductive soil disinfestation (RSD) with potato peel and amendment with iron mineral waste residues for the production of Fritillaria thunbergii, which is vulnerable to continuous obstacles. In this study, the influences of iron mineral, RSD with different organic maters, as well as the combined effects of iron mineral and RSD on Fritillaria rhizosphere soil physicochemical properties, microbial communities, and Fritillaria production were investigated. The results revealed that the RSD treatments with potato peel significantly reduced the soil salinity and increased the soil pH, microbial activity, organic matter, and the contents of K and Ca. RSD with potato peel also significantly thrived of the beneficial microbes (Bacillus, Azotobacter, Microvirga, and Chaetomium), and down-regulated potential plant pathogens. RSD with potato peel significantly promoted F. thunbergii yield and quality. Moreover, the combined effects of RSD and iron mineral amendment further enhanced soil health, improved microbial community composition, and increased the yield and peimisine content of F. thunbergii by 24.2% and 49.3%, respectively. Overall, our results demonstrated that RSD with potato peel and amendment with iron mineral waste residues can efficiently improve soil fertility, modify the microbial community, and benefit for both the sustainable production of F. thunbergii and the management of waste. KEY POINTS: • RSD increases soil pH, organic matter, microbial activity, and mineral content • RSD with potato peel enriches beneficial microbes and decreases plant pathogens • PP + Fe treatment increases Fritillaria yield by 24.2% and peimisine content by 49.3.

Wood Biomass Ash (WBA) from the Heat Production Process as a Mineral Amendment for Improving Selected Soil Properties

This research concerned the possibilities of the natural management of ash, which is a waste product obtained in the process of burning wood chips in a bio-heating plant. The basis of the research was a pot experiment, which was carried out in a greenhouse of the University of Warmia and Mazury in Olsztyn, Poland. This experiment dealt with the influence of increasing doses of wood biomass ash added to soil on selected soil properties. The soil used for the pot experiment was taken from the arable layer (0–25 cm) of the soil. It was characterized by acidic reaction, low salinity, and an average content of total carbon (TC). The test plant was corn. Soil analysis after plant harvest showed an increase in pH and a significant improvement of soil sorption properties, without causing an excessive increase in soil salinity. In addition, a significant increase in the content of available K, P, and Mg was observed, which at the highest dose of WBA reached: 121.9; 109.3, and 41.33 mg kg−1 of soil, respectively. The content of trace metals: iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cadmium (Cd), lead (Pb), cobalt (Co), chrome (Cr), and nickel (Ni) in the soil was quite varied but did not exceed the permissible values for agricultural soils. The content of available forms of these trace metals at the highest dose of WBA was, respectively, 1004, 129.9, 8.70, 2.08, 5.54, 0.195, 1.47, 0.97, and 1.92 kg−1 of soil. The results confirmed the significant fertilizing potential of wood biomass ash.

Pedological characterization and soil fertility assessment of the selected rice irrigation schemes, Tanzania

Rice (Oryza sativa L.) is the second cereal food crop grown in Tanzania after maize (Zea mays L.) and covers approximately 18% of the agricultural land. Soil degradation due to intensive cultivation along with low organic matter input and nutrient imbalance has led to a decline in rice crop yields. This study was conducted to characterize, classify, and assess the fertility status of soils in two rice irrigation schemes of Morogoro region in Tanzania. The data obtained through this study will contribute significantly to land use planning and will facilitate the transfer of agro-technology and other development of the regions with similar ecological conditions. The studied pedons were named MKU-P1 and MKD-P1 for Mkula and Mkindo irrigation schemes, respectively. A total of seven composite soil samples (0–20 cm) were collected for soil fertility assessments. Landform, soil morphological features, parent material, natural vegetation, drainage, erosion, and laboratory data were used to classify the soils in their respective order as per the United States Department of Agriculture (USDA) Soil Taxonomy and the World Reference Base (WRB) soil classification systems. Results showed that the pedons were sandy clay loam in the topsoil and sandy clay to clay in the subsoil; soil reaction ranged from medium acid (pH 5.7) to strongly alkaline (pH 8.6). The topsoil and subsoil nutrients of the studied pedons including available K+, total N, soil organic matter, and organic carbon are low. Based on the USDA Soil Taxonomy, MKU-P1 is classified as Inceptisols cumulic humaquepts and MKD-P1 as Vertisols Fluvaquentic endoaquerts corresponding to Subaquatic fluvisols (loamic, oxyaquic) and Irragric vertisols (gleyic) in the WRB, respectively. The pedons were ranked as suitable for rice production. However, the chemical fertility of the soil is ranked as low fertile associated with deficient in total N; available P, K+, and Ca2+ with excessive iron and manganese; and likely to pose toxicity to crops. The application of organic and mineral amendments in recommended rates and timing for N and P is therefore essential to increase the nutrient content of these soils and minimize losses. Salinity in the subsurface pedon MKD-P1 needs to be taken into future consideration.

The static and cidal effects of veterinary antibiotics on soil microorganisms in the presence of organic and mineral amendments

The static and cidal effects of veterinary antibiotics on soil microorganisms in the presence of organic and mineral amendments

Coriander (Coriandrum sativum) Cultivation Combined with Arbuscular Mycorrhizal Fungi Inoculation and Steel Slag Application Influences Trace Elements-Polluted Soil Bacterial Functioning.

The cultivation of aromatic plants for the extraction of essential oils has been presented as an innovative and economically viable alternative for the remediation of areas polluted with trace elements (TE). Therefore, this study focuses on the contribution of the cultivation of coriander and the use of arbuscular mycorrhizal fungi (AMF) in combination with mineral amendments (steel slag) on the bacterial function of the rhizosphere, an aspect that is currently poorly understood and studied. The introduction of soil amendments, such as steel slag or mycorrhizal inoculum, had no significant effect on coriander growth. However, steel slag changed the structure of the bacterial community in the rhizosphere without affecting microbial function. In fact, Actinobacteria were significantly less abundant under slag-amended conditions, while the relative proportion of Gemmatimonadota increased. On the other hand, the planting of coriander affects the bacterial community structure and significantly increased the bacterial functional richness of the amended soil. Overall, these results show that planting coriander most affected the structure and functioning of bacterial communities in the TE-polluted soils and reversed the effects of mineral amendments on rhizosphere bacterial communities and their activities. This study highlights the potential of coriander, especially in combination with steel slag, for phytomanagement of TE-polluted soils, by improving soil quality and health.

Effects of different amendments on aggregate stability and microbial communities of coastal saline–alkali soil in the Yellow River Delta

AbstractOrganic amendments have been widely used in coastal saline–alkali soil remediation; however, the mechanisms involved and the interactions between organic and inorganic amendments are still unclear. In this work, furfural residue (particulate; C/N ratio: 51.87; O‐alkyl C + di‐O‐alkyl C: 42.35%, aromatic C: 40.89%) and black liquor (dissolved; C/N ratio: 3.11; O‐alkyl C + di‐O‐alkyl C: 32.20%, aromatic C: 28.32%) were tested to examine their effects on chemical properties, water‐stable aggregate fractions, chemical compositions of solid‐state soil organic matter (SOM), gloaming‐related soil protein contents, and microbial communities of coastal saline–alkali soil under a 400‐day incubation experiment. Furthermore, organic amendments mixed with mineral amendment (4:1) were employed to explore the interactions between organic and inorganic amendments. Furfural residue had stronger and longer effects on soil macroaggregate stability (~240 days, intense) than black liquor (~15 days, weak), and mineral amendment addition had a positive effect on the stability of microaggregates. Our results revealed that qualities (primary form, C/N ratio, and chemical composition) of organic amendment which can change microbial communities by increasing soil C/N ratio and effective chemical compositions of solid‐state SOM, are the key factors in promoting the rapid formation and longer stability of coastal saline–alkali soil aggregates. Moreover, inorganic amendment addition can further improve the formation and stability of microaggregates rather than those of macroaggregates. This study provided a much‐needed technical basis for remediation of coastal saline–alkali soil.

Nutrient-doped synthetic silicates for enhanced weathering, remineralization and fertilization on agricultural lands of global cold regions- A perspective on the research ahead.

There is now a dire demand for negative emissions technologies (which sequester CO2 from the atmosphere) that can be rapidly deployed, are scalable, and are demonstrably safe and effective. Enhanced weathering of silicate minerals has demonstrated a significant potential for CO2 capture and sequestration by the formation of pedogenic carbonates in soils, subsoils, and sediments. This technique has also been shown to deliver fruitful results in terms of improving soil health, and in turn plant health, through remineralization. The silicate minerals that possess the highest weathering rates (e.g., wollastonite), are relatively rare in nature, whereas the abundant ones (e.g., anorthite and forsterite) have a slower pace of weathering, especially in colder and drier climates such as found in the extensive agricultural lands of Western Canada and the Western United States. Herein, we offer a perspective on the opportunities for computational studies targeting atomic-scale interaction of CO2 with silicates and synthesis of fast-weathering silicates (such as larnite and bredigite), whose composition can be tuned to also support soil fertilization and remineralization, and whose production must be integrated with green and carbon-neutral technologies to ensure net-negative life cycle emissions.

Availability and chemical associations of cadmium in contaminated tropical soils amended with mineral and organic amendments

A study was performed to evaluate the variation in pH, availability, and chemical associations of Cd in two previously contaminated Latosols amended with mineral and organic amendments. The Latosols were contaminated with Cd and amended with vermicompost, sugarcane f ilter cake, palm kernel pie, lime, phosphate rock, or zeolite. Cadmium availability was evaluated monthly in the contaminated soil/soil amendment mixtures with the DTPA and Mehlich-3 extractants for twelve months of incubation. At the end of this period, a sequential extraction procedure was performed in the mixtures to identify the Cd forms present in the several geochemical fractions. Lime immobilized Cd at a larger extension (60%), being the metal transferred to less available fractions. The Mehlich-3 extractant had a high correlation (0.96**) with the available fraction examined by the sequential extraction procedure. In general, organic amendments produced small ef fects on the f inal pH of soil/soil amendment mixtures as compared with the initial soil pH. Mineral amendments caused enhancement of soil pH and the most pronounced ef fect occurred with the use of lime.

Assessment of soil fertility status in cotton-based cropping systems in Cote d’Ivoire

Cotton is the main cash crop in northern Côte d’Ivoire, where intensive cultivation along with low external inputs has led to a decline in crop yields due to soil degradation. The present study aims to assess the evolution of soil fertility during the 2013 and 2021 periods in the cotton basin area of Côte d’Ivoire. More specifically, the study (i) identified the limiting physico-chemical parameters of soil fertility, and (ii) analysed the state of evolution of soil fertility in 2013 and 2021 in the cotton basin of Côte d’Ivoire. For this purpose, a total of 64 soil samples were taken in 2013 and in 2021 on the same cotton plots on the 0-20 cm horizon. Chemical analyses of the soil samples in the laboratory were carried out on the following parameters: particle size distribution, pH water, total nitrogen (NT), Potassium (K+), Calcium (Ca2+), Magnesium (Mg2+), Sodium (Na+) and Cation exchange capacity (CEC). The results of the soil analyses showed that the sandy-clay textured topsoils dominate the whole study area in both years. This leads to a low retention capacity of exchangeable bases. Determination of the soil pH showed that the pH varies from slightly acidic to neutral (6.5&amp;lt;pH&amp;lt;7). The most limiting chemical properties are Cation exchange capacity (CEC) and the sum of the exchangeable bases (SEB) in the department of Korogho, Boundiali, and Ferkessedougou and the most limiting chemical properties in the department of Mankono are CEC. However, during the period from 2013 to 2021 the content of exchangeable cations (Ca2+, Mg2+ and K+) and the base saturation (BS) increased significantly in all the departments, more precisely in the department of Mankono. Although we observed a slight increase in the chemical properties of the soils in 2021 compared to 2013, the values were still below the minimum required threshold. This result implies that the soils have poor physico-chemical properties and consequently a low level of fertility, which compromises the sustainability of the cotton production system. The application of organic and mineral amendments is therefore essential to increase the nutrient content of these soils.

Gypsum mining spoil improves plant emergence and growth in soils polluted with potentially harmful elements

PurposeSoil pollution is a major problem worldwide. Some anthropogenic activities, such as mining, may exceed soil capacity, causing relevant health and ecosystem hazards. The use of mineral amendments can help reduce soil pollution. Gypsum mining spoil (GS) is a waste material highly produced in gypsum mining industry, which has never been used in soil remediation despite its high potential as amendment of polluted soils. In this study, we carried out an ex-situ experiment to assess for the first time the capacity of GS to both reduce the availability of Potentially Harmful Elements (PHEs) in soils and promote seed emergence.MethodsSoils affected by residual pollution after the Aznalcóllar mine spill were collected, treated with GS in three different proportions, and sown with seeds of two non-genetically related species. Seed emergence and biomass production were monitored, and PHE content in soils and plants were analysed.ResultsWe have observed a direct and very positive relation between GS and both the reduction of PHE availability and PHE uptake by plants, and the increase of plant emergence and growth, especially with the addition of the highest doses of the amendment.ConclusionThis study highlights the promising results of GS as a novel soil amendment to be used in the remediation of polluted soils and vegetation recovery. Moreover, using GS as soil amendment will bring the opportunity to sustainably manage this waste material and reduce its social and environmental impact parallelly to the mitigation of PHE hazards.