Soil Iron Research Articles

Silicon and calcium controls on iron and aluminum mobility in Arctic soils

Arctic permafrost soils store large amounts of organic carbon and nutrients. With deepening of the perennial thawing upper active layer due to rising temperatures in the Arctic, not only the mobility of organic matter (OM), but also those of elements like silicon (Si) or calcium (Ca) may increase. It is known that major elements like Si and Ca can affect mineralization rates of OM, consequently influencing the carbon cycle. But only little is known about the interactions of Si and Ca with inorganic nutrients like iron (Fe) or potentially toxic elements like aluminum (Al) in Artic soils. In this study, we analyzed the effect of Si and Ca fertilization in laboratory incubation experiments with soil samples from several Arctic regions. Our results show a significant increase in Fe and Al mobility (Mehlich-3 extractable) after increasing Si. Using high resolution X-ray microscopy (STXM/NEXAFS), we show that Si promotes Fe(II) phases and by this increases Fe mobility. Al mobility was increased for acidic and neutral pH soils but decreased for alkaline soils after increasing Si. Furthermore, we show a decreased Al mobility after increasing Ca, independent on the original pH values and the OM content of the soils. These results demonstrate the importance of interactions between Si and Ca on one hand and Fe and Al mobility on the other hand for Arctic soils.

Remediation of lead and cadmium co-contaminated mining soil by phosphate-functionalized biochar: Performance, mechanism, and microbial response

The remediation of heavy metals contaminated soils is of great significance for reducing their risk to human health. Here, pristine pinewood sawdust biochar (BC) and phosphate-functionalized biochar (PBC) were conducted to investigate their immobilization performance towards lead (Pb) and cadmium (Cd) in arable soils severely polluted by Pb (9240.5 mg kg−1) and Cd (10.71 mg kg−1) and microbial response in soils. Compared to pristine BC (2.6–12.1%), PBC was more effective in immobilizing Pb and Cd with an immobilization effectiveness of 45.2–96.2% after incubation of 60 days. Moreover, the labile Pb and Cd in soils were transformed to more stable species after addition of PBC, reducing their bioavailability. The immobilization mechanisms of Pb and Cd by PBC were mainly to facilitate the formation of stable phosphate precipitates e.g., Cd3(PO4)2, Cd5(PO4)3OH, Cd5H2(PO4)4‧4H2O, and pyromorphite-type minerals. Further, PBC increased pH, organic matter, cation exchange capacity, and available nutrients (phosphorus and potassium) in soils. High-throughput sequencing analysis of 16 S rRNA genes indicated that the diversity and composition of bacterial community responded to PBC addition due to PBC-induced changes in soil physicochemical properties, increasing the relative abundance of beneficial bacteria (e.g., Brevundimonas, Bacillus, and norank_f__chitinophagaceae) in the treated soils. What's more, these beneficial bacteria could not only facilitate Pb and Cd immobilization but also alter nutrient biogeochemical transformation (nitrogen and iron) in co-contaminated soils. Overall, PBC could be a promising material for immobilization of Pb and Cd and the simultaneous enhancement of soil quality and available nutrients in co-contaminated mining soils.

Understanding the Mechanisms of Fe Deficiency in the Rhizosphere to Promote Plant Resilience.

One of the most significant constraints on agricultural productivity is the low availability of iron (Fe) in soil, which is directly related to biological, physical, and chemical activities in the rhizosphere. The rhizosphere has a high iron requirement due to plant absorption and microorganism density. Plant roots and microbes in the rhizosphere play a significant role in promoting plant iron (Fe) uptake, which impacts plant development and physiology by influencing nutritional, biochemical, and soil components. The concentration of iron accessible to these live organisms in most cultivated soil is quite low due to its solubility being limited by stable oxyhydroxide, hydroxide, and oxides. The dissolution and solubility rates of iron are also significantly affected by soil pH, microbial population, organic matter content, redox processes, and particle size of the soil. In Fe-limiting situations, plants and soil microbes have used active strategies such as acidification, chelation, and reduction, which have an important role to play in enhancing soil iron availability to plants. In response to iron deficiency, plant and soil organisms produce organic (carbohydrates, amino acids, organic acids, phytosiderophores, microbial siderophores, and phenolics) and inorganic (protons) chemicals in the rhizosphere to improve the solubility of poorly accessible Fe pools. The investigation of iron-mediated associations among plants and microorganisms influences plant development and health, providing a distinctive prospect to further our understanding of rhizosphere ecology and iron dynamics. This review clarifies current knowledge of the intricate dynamics of iron with the end goal of presenting an overview of the rhizosphere mechanisms that are involved in the uptake of iron by plants and microorganisms.

Investigating heavy-metal soil contamination state on the rate of stomach cancer using remote sensing spectral features

Heavy metal (HM) contamination in agricultural soils has been a serious environmental and health problem in the past decades. High concentration of HM threatens human health and can be a risk factor for many diseases such as stomach cancer. In order to investigate the relationship between HM content and stomach cancer, the under-study area should be adequately large so that the possible relationship between soil contamination and the patients' distribution can be studied. Examining soil content in a vast area with traditional techniques like field sampling is neither practical nor possible. However, integrating remote sensing imagery and spectrometry can provide an unexpensive and effective substitute for detecting HM in soil. To estimate the concentration of arsenic (As), chrome (Cr), lead (Pb), nickel (Ni), and iron (Fe) in agricultural soil in parts of Golestan province with Hyperion image and soil samples, spectral transformations were used to preprocess and highlight spectral features, and Spearman's correlation was calculated to select the best features for detecting each metal. The generalized regression neural network (GRNN) was trained with the chosen spectral features and metal containment, and the trained GRNN generated the pollution maps from the Hyperion image. Mean concentration of Cr, As, Fe, Ni, and Pb was estimated at 40.22, 11.8, 21,530.565, 39.86, and 0.5mg/kg, respectively. Concentrations of As and Fe were near the standard limit and overlying the pollution maps, and patients' distribution showed high concentrations of these metals can be considered as stomach cancer risk factors.

Release behaviour of iron and zinc in different textured soil and its distribution in rice plant (Oryza sativa L.) in North West of India

Release behaviour of iron and zinc in different textured soil and its distribution in rice plant (Oryza sativa L.) in North West of India

Ecological risk assessment of trace elements (TEs) pollution and human health risk exposure in agricultural soils used for saffron cultivation

Contamination of farmland soils by trace elements (TEs) has become an international issue concerning food safety and human health risks. In the present research, the concentrations of TEs including cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), zinc (Zn) and iron (Fe) in soils of 16 farmlands were determined in Gonabad, Iran. In addition, the human health risks due to exposure to the TEs from the soils were assessed. Moreover, the soil contamination likelihood was evaluated based on various contamination indices including contamination factor (mathrm{CF}), enrichment factor (EF), geo-accumulation index (Igeo), and pollution load index (PLI) calculations. The soil mean concentrations for Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn and Fe ranges as 0.102, 6.968, 22.550, 29.263, 475.281, 34.234, 13.617, 54.482 and 19,683.6 mg/kg in farmland soils. The mean concentrations of the TEs decreased in the order of Fe > Mn > Zn > Ni > Cu > Cr > Pb > Co > As > Cd. Levels of all metals in this study were within the FAO/WHO and Iranian soil standards. The HQ values from investigated elements for adults and children in the studied farms were less than the limit of 1, indicating no health risks for the studied subpopulations. The results of the present research indicated no significant carcinogenic health hazards for both adults and children through ingestion, skin contact and inhalation exposure routes. mathrm{CF} values of Ni and Zn in 100% and 6.25% of farmlands were above 1, showing moderate contamination conditions. EF values of metals in farmlands were recorded as “no enrichment”, “minimal enrichment” and “moderate enrichment” classes. Furthermore, it can be concluded that the all farms were uncontaminated except Ni (moderately contaminated) based on Igeo. This is an indication that the selected TEs in the agricultural soils have no appreciable threat to human health.

Significance of Soil Siderophore-Producing Bacteria in Evaluation and Elevation of Crop Yield

Iron is a vital element for plant and microbial growth; yet, the major portion of iron in soils is in the form of (oxi-)hydroxides with limited bioavailability, resulting in decreased crop yield quality. In response to iron deficiency, soil microorganisms produce siderophores that transform insoluble iron into a soluble form that plants and microorganisms can use. The abundance and activity of siderophore-producing bacteria (SPB) might be used as a biological assessment index for the fertility status of cultivated land. In order to achieve this goal, it is critical to investigate the influences of SPB on plant growth and soil quality. In this study, we performed a mixed-effect model meta-analysis on 342 research studies that compared plant growth with and without SPB. The findings revealed that SPB increased plant growth significantly (up to 30%). The stimulating effects on plants followed the sequences of pant weight, plant height, and germination rate.

Controls on sulfide accumulation in coastal soils during simulated sea level rise

A likely consequence of sea level rise during the next century will be progressive inundation of seawater through the current unsaturated zone in coastal-margin soils. It is unclear how this will change the biogeochemical cycling of iron, sulfur and carbon over different time scales and soil types. A long-term (540 day) laboratory experiment, slowly inundating intact coastal soil cores with seawater from the ‘bottom up’, was conducted to observe how coupled iron and sulfur dynamics change in different soil types. Pore water was extracted from the 60 cm cores at 10 cm depth intervals every 90 days and analysed for pH, electrical conductivity (EC), Fe2+, HS− and dissolved metals (Fe, Mn, As, Cd, Cu, Ni, Pb, Co, Zn) as well as stable sulfur (34S/32S) and radiogenic strontium (87Sr/86Sr) isotopes. Destructive solid phase analyses (for reactive Fe, acid volatile and chromium reducible sulfur (AVS and CRS) and total organic carbon (TOC)) were made at the start and end of the experiment. Iron and sulfate reduction was induced in soils with readily available TOC as anoxic conditions established, evidenced by statistically significant increases (P < 0.001) in dissolved Fe2+ and sulfide concentrations in porewaters, as well as simultaneous and progressive increase in the sulfur isotope (34S/32S) ratios. An increase in AVS indicated formation of metastable iron sulfide (FeS) minerals resulting from Fe2+ and sulfide in porewaters post inundation. This was supported by PHREEQC modelling of local mineral saturation states/indices in the system. Overall, the Fe2+ concentration increased to a peak at between 270 and 360 days, and then began decreasing at some depths, indicating slowing iron reduction, presumably because reactive iron (oxyhydro)oxides became progressively consumed by microbially driven reductive processes. However, microbially mediated sulfate reduction continued as abundant sulfate was still available from seawater. In the absence of free Fe2+, sulfide accumulated in the porewater, but only in those soils inundated the longest (>360 days), and with greater than 5% TOC. The combined use of sulfur (34S/32S) and strontium (87Sr/86Sr) isotopes supported the observed results, and represents a new and robust technique to quantify progressive sulfate reduction and seawater mixing phenomena in coastal soils. This study gives new insights into the biogeochemical cycling of sulfur and iron in soils experiencing seawater inundation from sea level rise over longer timescales. It is likely that sulfidisation (due to in-situ sulfate reduction) will begin to affect coastal wetland soils, especially in areas where TOC is high and where reactive iron depletes over time. This has potential consequences for sulfide toxicity in coastal soils and environments globally.

Response of soil iron oxides in freshwater marsh to different tidal hydrology in the Yellow River Estuary wetland, China

Iron cycles is essential for the transition of matter and energy in wetland ecosystems. The tidal hydrology is a critical factor controlling soil iron biogeochemistry in estuarine wetland, but it remains unclear how iron oxides response to tidal hydrologic regime. A field experiment was manipulated in the Yellow River Estuary wetland for 23 months to differentiate change in iron oxides of freshwater marsh soil under different tidal hydrologic regimes. In June 2019, soil cores were collected in the freshwater marsh on the supratidal zone (FPA), and translocated to be cultured in the tidal salt marshes on the intertidal zone (SPA, TC and SS). Over 23 months, tidal hydrologic regime had obviously affected soil properties and iron oxides. Under the tidal regime, there was an increase in soil pH and electric conductivity (EC), and a decrease in soil water content (SWC), total nitrogen (TN), total phosphorus (TP) and total organic carbon (TOC). A total decrease was found in the contents of soil iron (FeT), iron oxides (Fep, complexed iron; Feo, amorphous iron; Fed, free iron) and their ratios (Fep/Fed, Feo/Fed and Fed/FeT). The duration of tidal hydrology affected the contents of iron oxides and their ratios, i.e., FeT and Fed decreased with culture time in all sites while Fep, Feo and the ratios increased in the supratidal site. Iron oxides and their ratios were positively correlated to redox potential, organic carbon and nutrients, and negatively correlated to soil pH and salinity. The results indicate that tidal hydrologic regime could decrease the contents of soil iron oxides and their activation when freshwater marsh exposed to tide events.

Contrasting Effects of Nitrogen and Organic Fertilizers on Iron Dynamics in Soil after 38–Year Fertilization Practice

Various environmental factors and anthropogenic practices can affect the Fe biogeochemical cycles in soils. Nitrogen and carbon states are closely associated with Fe dynamics. However, we still have a limited understanding of the complex response of Fe biogeochemical processes to long–term nitrogen– and organic–fertilization regimes. This study investigated the Fe fraction and distribution, as well as the link between Fe and nitrogen/carbon, in bulk soil and in soil aggregates. The results showed that the long–term application of the nitrogen fertilizer increased the contents of water–soluble iron (Ws–Fe) and carbonate–bound iron (Ca–Fe) in the bulk soil and various sizes of aggregates, as well as the iron contents in soybeans. The decreased pH and enhanced Feammox reaction in response to the nitrogen–fertilizer treatments were responsible for the increase in the Ws–Fe and Ca–Fe fractions. By contrast, the long–term application of the organic fertilizer decreased the contents of Ws–Fe and Ca–Fe, while it increased the contents of Ox–Fe and Or–Fe. Moreover, the contents of Ox–Fe and Or–Fe were positively correlated with the organic–carbon contents in the micro–aggregates of 0.053–0.25 mm and &lt;0.053 mm. These results indicated that the long–term use of the organic fertilizer encouraged Fe immobilization in organo–inorganic compounds. However, the application of the nitrogen fertilizer alleviated the Fe retention induced by the organic fertilizer. In conclusion, long–term nitrogen and organic fertilization have contrasting influences on the mineralogy and availability of Fe in soil. This study is useful for understanding the mechanism underlying the interaction between Fe and nitrogen/carbon, as well as Fe’s phytoavailability in response to different fertilization practices in brown soil.

3D Printing Functionally Graded Porous Materials for Simultaneous Fabrication of Dense and Porous Structures in Membrane‐Integrated Fluidic Devices

3D printing provides access to complex multilevel architectures, though the capability to routinely print and integrate structures of controlled porosity is limited. Herein, grayscale digital light projection 3D printing of a polymerization‐induced phase separation ink is introduced to directly 3D print functionally graded porous within a single layer from the same ink formulation. The structural properties of materials printed from a single ink are tuned from an effectively dense to a porous material with interconnected pores up to 250 nm. Heterostructures with the physically dense structure of porosity 0.8% and porous structures with up to 23% can be concurrently formed within a layer, with high spatial resolution inherent of this 3D printing technique. Materials with densities from 1.01 to 1.21 g cm−3 are 3D printed in a wicking device and show wicking rates (H2O) from complete diffusion blockage up to 4.5 mm h−1. Furthermore, a proof‐of‐concept membrane‐integrated fluidic device is used for the elemental metal sensing of iron in soil. The presented single‐step fabrication of functionally graded materials with pixel‐based control within a single layer holds potential for manufacturing and integrating membranes or sorbents for environmental, biotechnology, and healthcare applications.

Effects of Pretreatment and Polarization Shielding on EK-PRB of Fe/Mn/C-LDH for Remediation of Arsenic Contaminated Soils

In this study, coupling electrokinetic (EK) with the permeable reactive barriers (PRB) of Fe/Mn/C-LDH composite was applied for the remediation of arsenic-contaminated soils. By using self-made Fe/Mn/C-LDH materials as PRB filler, the effects of pretreatment and polarization shielding on EK-PRB of Fe/Mn/C-LDH for remediation of arsenic contaminated soils were investigated. For the pretreatment, phosphoric acid, phosphoric acid and water washing, and phosphate were adopted to reduce the influence of iron in soil. The addition of phosphate could effectively reduce the soil leaching toxicity concentration. The removal rate of the soil pretreated with phosphoric acid or phosphoric acid and water washing was better than with phosphate pretreatment. For the polarization shielding, circulating electrolyte, electrolyte type, anion and cation membranes, and the exchange of cathode and anode were investigated. The electrolyte circulates from the cathode chamber to the anode chamber through the peristaltic pump to control the pH value of the electrolyte, and the highest arsenic toxicity removal rate in the soil reaches 97.36%. The variation of total arsenic residue in soil using anion and cation membranes is the most regular. The total arsenic residue gradually decreases from cathode to anode. Electrode exchange can neutralize H+ and OH- produced by electrolyte, reduce the accumulation of soil cathode area, shield the reduction of repair efficiency caused by resistance polarization, enhance current, and improve the removal rate of arsenic in soil.

Copper and iron metal resistant rhizospheric bacteria boost the plant growth and bacoside A content in Bacopa monnieri under stress conditions.

Bacteria that enhance plant growth and development and are found in the vicinity of roots are referred to as plant growth-promoting rhizobacteria. Some beneficial bacteria help plant tolerance to many hazardous chemical elements. In this context, Cupriavidus basilensis, Novosphingobium humi, Bacillus zanthoxyli, Bacillus sp., Paenibacillus alvei, Ancylobacter aquaticus and Ralstonia syzygii metal-tolerant rhizospheric bacteria were isolated from rhizospheric soil associated with Bacopa monnieri. The beneficial effects of rhizospheric bacteria on B. monnieri plant physiology and biochemical responses were investigated under pot conditions at two levels (100μM and 500μM) of CuSO4 or FeCl3. N. humi, A. aquaticus and R. syzygii bacterial strains were associated with significantly increased height and biomass under normal and stress conditions. An assay for indole acetic acid in isolated rhizospheric bacteria found differential secretion except Bacillus zanthoxyli. Bacoside A is a major phytocompound in B. monnieri with medicinal value; maximum induction was observed in the R. syzygii treatment. High concentration of copper and iron salts negatively influenced height, biomass and photosynthetic pigments; however N. humi, A. aquaticus, Bacilllus sp. and R. syzygii beneficial bacterial helped plants under stress conditions. Moreover, a significant enhancement in chlorophyll a and b was noticed in C. basilensis, B. zanthoxyli, Bacilllus sp., P. alvei and R. syzygii treatments, without much influence on carotenoid levels. Therefore, the present study emphasises the importance of isolating plant growth-promoting rhizobacteria for use in bacopa plants exposed to metals such as copper and iron in soil.

Improving water management technology in rice systems for sustainable rice production

Purpose: to reduce rice irrigation rates by developing water management in rice systems for sustainable rice production. Materials and methods. The materials for the study were data obtained for 2020–2022 in production experiments in three experimental farms in Krasnodar Territory, the total area of which was 59,636 hectares. The idea of decreasing the irrigation rate by reducing the duration of flooding period, the number of discharges, the rate of one-time irrigation, the repeated flooding, the intensity of vertical filtration and physical evaporation is discussed. Water consumption, transpiration and seepage effluent were determined when defining the irrigation rate for the shortened flooding and the combined irrigation using the method of vegetation vessels with an area of 3000 cm². For an environmentally friendly technology, evaporation and transpiration were additionally determined using a GGI-500-50 evaporator at the stage of two or three leaves in rice crop during sprinkling irrigation. Results. The analysis (water-physical properties of soil, chemical analysis of soil samples, content of ferrous and ferric iron in soil) of existing (basic) rice cultivation technologies: shortened flooding and combined irrigation, was carried out. Integral curves of evaporation and evapotranspiration were constructed on the basis of observational data on vegetal discharge. Conclusions. A new environmentally friendly technology for rice cultivation was developed. As a result of evaluation the declared technology, its efficiency expressed in a reduction in irrigation rate by 10 % due to a decrease in evaporation, daily transpiration and vertical filtration was proven.

Polyphosphate hydrolysis, sorption, and conversion in two different soils

AbstractPolyphosphate fertilizer is an alternative to traditional orthophosphate fertilizer, but it is unclear whether it provides greater soil phosphorus (P) mobility and availability than orthophosphate fertilizer. This study aimed to examine the chemical behaviour of polyphosphate after its application to the soil. The hydrolysis, sorption, and P transformation of two types of polyphosphate fertilizers (short‐chain and long‐chain) were examined for two types of soils (acidic Acrisol and calcareous Cambisol), with orthophosphate serving as the control treatment. 31P NMR spectroscopic analyses indicated that polyphosphate in soil was rapidly converted to pyrophosphate, which was then hydrolyzed to orthophosphate at a slower rate. In general, in the calcareous Cambisol, the addition of short‐chain polyphosphate fertilizer resulted in greater soil P mobility as measured by greater soil pore water orthophosphate concentration than the control. Thus, short‐chain polyphosphate fertilizer tended to be more effective than orthophosphate in calcareous soils. This was in contrast to the result of an aqueous incubation experiment, in which a lower pH increased the rate of polyphosphate hydrolysis. Indeed, in both soils, the sorption of total P was greater when P was added as polyphosphate than when it was added as orthophosphate. Moreover, polyphosphate sorption appeared to be mainly controlled by soil iron and aluminium minerals, because the Acrisol showed stronger polyphosphate sorption than the Cambisol due to its greater amorphous iron content. It appears that polyphosphate was first adsorbed on soil minerals before being hydrolyzed to release orthophosphate, and calcium may have played an important role in the hydrolysis of polyphosphate as evidenced by the greater P release in calcareous Cambisol. Our results suggest that soil characteristics, such as acidity, iron, aluminium, and calcium content, should be considered when evaluating the P efficiency of polyphosphate fertilizers.Highlights 31P NMR spectroscopy successfully tracked the fate of added Poly‐P in soil Poly‐P was rapidly converted to Pyro‐P, and then hydrolyzed to Ortho‐P slowly P supplied as Poly‐P had stronger sorption affinity than Ortho‐P in all soils Short‐chain Poly‐P induced greater P mobility than Ortho‐P in Cambisol but not in Acrisol

Status of copper, iron, manganese and zinc in soil, fodder and blood serum of cattle from Parbhani district of Maharashtra

Status of copper, iron, manganese and zinc in soil, fodder and blood serum of cattle from Parbhani district of Maharashtra

Using fixed-potential electrodes to quantify iron and manganese redox cycling in upland soils.

Although metal redox reactions in soils can strongly affect carbon mineralization and other important soil processes, little is known about temporal variations in this redox cycling. Recently, potentiostatically poised electrodes (fixed-potential electrodes) have shown promise for measuring the rate of oxidation and reduction at a specific reduction potential in situ in riparian soils. Here for the first time, we used these electrodes in unsaturated soils to explore the fine-scale temporal redox fluctuations of both iron and manganese in response to environmental conditions. We used three-electrode systems with working electrodes fixed at 100mV (vs. SHE) and 400mV at 50cm and 70cm in the valley floor soil of a headwater watershed. Electrodes fixed at 100mV to mimic iron oxides and at 400mV to mimic manganese oxides allowed real-time reduction and oxidation rates to be calculated from temporal variations in the electric current. Electrode measurements were compared to soil porewater chemistry, pCO2, pO2, groundwater level, resistivity measurements, and precipitation. The fixed-potential electrodes recorded fluctuations over timescales from minutes to weeks. A consistently negative current was observed at 100mV (interpreted as oxidation of Fe), while the 400-mV electrode fluctuated between negative and positive currents (Mn oxidation and reduction). When the water table rose above the electrodes, reduction was promoted, but above the water table, rainfall only stimulated oxidation. Precipitation frequency thus drove the multi-day reduction or oxidation events (return interval of 5-10days). These measurements represent the first direct detections of frequency, period, and amplitude of oxidation and reduction events in unsaturated soils. Fixed-potential electrodes hold promise for accurately exploring the fast-changing biogeochemical impacts of metal redox cycling in soils and represent a significant advance for reactions that have been difficult to quantify.

Prediction of material composition in lateritic soil using spectroradiometer

Laterite soil products are vital in coastal region construction. Conventional identification methods are slow and require significant labour. Remote sensing expedites large-scale identification, making it essential in the process. Soil samples were randomly collected from the study area for laboratory analysis to determine soil iron content. Additionally, spectral signatures were obtained from a spectroradiometer to assess iron content variability. The considerable variability in material composition underscores its significance as an indicator of soil characteristics. The iron content serves as a crucial indicator of soil development and can be utilized as an index for assessing material composition in soil. The iron content in soil samples is analysed using Analytical Spectral Device (ASD) Field Spec 4 Spectroradiometer, which operates within the spectral wavelength range of 350–2500 nm. The Vis-NIR reflectance spectroscopy is an innovative and efficient method for predicting soil iron content, requiring less effort compared to conventional techniques. The study uses Partial Least Squares Regression (PLSR), a statistical regression method employed to predict iron content in soil from spectral reflectance data. The application of PLSR resulted in moderate prediction accuracy, with coefficient of determination R2 value for calibration and validation are 0.74 and 0.73, respectively. The analysis revealed that the spectroradiometer in combination with PLSR can accurately predict the material composition in lateritic soil with an efficiency of 70%.

Soil Characteristics Interrelationship with Treated Soil Micronutrients in Nigerian Southern

We investigated the influence of soil properties on the availability or otherwise of micronutrients in agricultural soils impacted by inorganic and organic manures in the South-South Area of Nigeria. The levels of pH, organic matter (OM), cation exchange capacity (CEC), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) in the understudy soil were examined. The measured pH, OM, CEC, Cu, Fe, Mn and Zn levels revealed: 6.04±0.49, 17.68±4.78 %, 7.97±0.81 Cmolkg-1, 5.27±0.82 mgkg-1, 232.49±16.01 mgkg-1, 109.30±9.85 mgkg-1, and 8.40±1.15 mgkg-1, for pH, OM, CEC, Cu, Fe, Mn, and Zn, respectively. The values were within the acceptable limits set by national and international standards.&#x0D; The study revealed variable relationships between the soil properties and micronutrients in the studied soils at p &lt; 0.05. Soil pH exhibited a strong negative association with all the micronutrients except Zn. However, a strong positive correlation (p&lt; 0.10) was recorded between pH and Zn. OM showed a significant positive correlation (p&lt; 0.10) with Fe, a weak positive correlation with Zn, and a non-significant negative correlation (p&lt; 0.10) with Cu and Mn at p &lt; 0.10. CEC exhibited a fair positive association with Fe and Zn, and a non-significant negative correlation (p&lt; 0.10) with Cu and Mn. The principal component analysis (PCA) identified a combination of anthropogenic and natural impact and the impact of agrochemicals applied as the major factors influencing the properties determined in the studied soils. The study concluded that soil properties have a strong influence on the availability or otherwise of micronutrients in the soil.

Melatonin promotes iron uptake and accumulation in peach

• Melatonin promoted growth of peach. • Melatonin increased iron content in peach. • Melatonin increased chemical form of iron content that can be absorbed by plants. Iron deficiency leads to stunted growth in fruit trees and reduces the yield and quality of fruits. To increase the uptake of iron in fruit trees and provide a reference to control iron deficiency, the effects of different concentrations of melatonin (MT) on iron uptake in peach ( Prunus persica ) were studied by a pot experiment. Concentrations of 0, 50, 100, 150, and 200 µM MT were used in this experiment. MT increased the biomass of peach. Concentrations of 100, 150, and 200 µM MT increased the contents of total and active iron in peach. Concentration of 150 µM MT got the maxmiums of total iron contents in stems and leaves, which increased by 28.79% and 36.11%, respectively, compared with the control. Correspondingly, concentrations of 100 and 150 µM MT upregulated the genes related to iron absorption, including the ferric reduction oxidase 7 ( FRO7 ), vacuolar iron transporter 1 ( VIT1 ), and ferric reduction oxidase 4 ( FRO4 ), while downregulating the vacuole genes vacuolar iron transporter homolog 4 ( VITH4 ) and natural resistance-associated macrophage protein 3 ( NRAMP3 ) that are related to vacuolar iron transport. The concentrations of absorbable iron forms, including the water soluble iron, adsorbed iron, carbonate and strongly adsorbed iron, and manganese oxide bound iron, in the soil increased, and the soil pH value decreased following the addition of 100, 150, and 200 µM MT. A correlation analysis showed that the contents of total and active iron in peach correlated with the biomass, soil pH value, absorbable soil iron forms, and level of expression of the iron absorption related genes. These observations indicate that treated with 100–200 µM MT could promote the iron uptake and accumulation in peach by regulating the physiological metabolism related to iron.