Search Results (696)

Soil micronutrient assessment is crucial for ensuring sustainable crop production and environmental quality, particularly in intensively cultivated regions. This study aimed to evaluate and map the spatial distribution of Diethylenetriamine Pentaacetic Acid (DTPA)-extractable micronutrients (Fe, Mn, Zn and Cu) in agricultural lands of Thirunallar commune, Karaikal, for augmenting site-specific nutrient management. A total of 233 geo-referenced surface soil samples (0–20 cm) were collected using a handheld GPS on a pre-defined grid and analyzed for available micronutrients. The spatial variability and distribution patterns were generated in ArcGIS 10.8.2 using semivariogram-based kriging interpolation. The results indicated that Fe, Mn and Cu were sufficient across the study area, with concentrations ranging from 4.74 to 99.80 ppm, 3.70–97.40 ppm, and 1.46–12.40 ppm, respectively, mainly due to the presence of iron-rich minerals, reduced manganese forms, and continuous application of copper-based inputs. Zinc showed greater variability (0.52–17.20 ppm), ranging from deficient to sufficient levels, likely influenced by fertilizer application and organic matter additions. The findings emphasize the importance of site-specific nutrient management to optimize fertilizer usage and crop productivity, particularly in fine-textured clay soils. This study demonstrates the effectiveness of geostatistical approaches for supporting precision agriculture in micronutrient-deficient areas. Full article

The phaeozem in Northeast China is rich in soil organic carbon (SOC). However, the excessive and inefficient application of chemical fertilizers, particularly nitrogen fertilizers, has primarily led to a decrease in soil pH in this region. Currently, the relationship between soil pH and the stability of soil organic carbon (SOC) remains ambiguous. This study, conducted over 13 years of field experiments, focused on soils exhibiting varying degrees of pH resulting from different nitrogen application rates. The research employed aggregate classification, ¹³C nuclear magnetic resonance spectroscopy, and analysis of microbial community composition to investigate the alterations in the SOC stabilization mechanisms under varying nitrogen application levels. Our results demonstrated that the decline in soil pH led to reductions in macroaggregates (>2 mm) and the soil aggregate destruction rate (PAD) by 4.8–14.6%, and in soil aggregate unstable agglomerate index (E_LT) by 9.7–13.4%. The mean weight diameter (MWD) and geometric mean diameter (GMD) exhibited significant declines (p < 0.05) with decreasing pH levels. According to the ¹³C NMR analysis, the SOC was predominantly composed of O-alkyl carbon and aromatic carbon. At a pH of 5.32, the Alip/Arom values decreased, while the molecular structure of SOC became more complex under different levels of pH. In addition, the increase in [Fe(Al)-OC] (31.4–71.9%) complex indicates a shift in the stability of organic carbon from physical protection to organic mineral binding. Declining soil pH significantly reduced the diversity of soil microbial communities and promoted a shift toward copiotrophic microbial groups. Overall, declining soil pH resulted in a decline in soil aggregate stability and an increase in SOC aromaticity. This drove the shift in the stabilization mechanism of SOC in the black soil ecosystem of meadows in Northeast China from physical protection to chemical stability. Full article

Micronutrients, particularly boron (B), iron (Fe), manganese (Mn), and zinc (Zn), are pivotal for cotton (Gossypium spp.) growth, reproductive success, and fiber quality. However, their critical roles are often overlooked in fertility programs focused primarily on macronutrients. This review synthesizes recent advances in the physiological, molecular, and agronomic understanding of B, Fe, Mn, and Zn in cotton production. The overarching goal is to elucidate their impact on cotton nutrient use efficiency (NUE). Drawing from the peer-reviewed literature, we highlight how these micronutrients regulate essential processes, including photosynthesis, cell wall integrity, hormone signaling, and stress remediation. These processes directly influence root development, boll retention, and fiber quality. As a result, deficiencies in these micronutrients contribute to significant yield gaps even when macronutrients are sufficiently supplied. Key genes, including Boron Transporter 1 (BOR1), Iron-Regulated Transporter 1 (IRT1), Natural Resistance-Associated Macrophage Protein 1 (NRAMP1), Zinc-Regulated Transporter/Iron-Regulated Transporter-like Protein (ZIP), and Gossypium hirsutum Zinc/Iron-regulated transporter-like Protein 3 (GhZIP3), are crucial for mediating micronutrient uptake and homeostasis. These genes can be leveraged in breeding for high-yielding, nutrient-efficient cotton varieties. In addition to molecular hacks, advanced phenotyping technologies, such as unmanned aerial vehicles (UAVs) and single-cell RNA sequencing (scRNA-seq; a technology that measures gene expression at single-cell level, enabling the high-resolution analysis of cellular diversity and the identification of rare cell types), provide novel avenues for identifying nutrient-efficient genotypes and elucidating regulatory networks. Future research directions should include leveraging microRNAs, CRISPR-based gene editing, and precision nutrient management to enhance the use efficiency of B, Fe, Mn, and Zn. These approaches are essential for addressing environmental challenges and closing persistent yield gaps within sustainable cotton production systems. Full article

Shallot (Allium hirtifolium Boiss.) is of considerable nutritional and medical significance due to its strong antioxidant properties; however, no nanophytotoxicity studies have assessed whether the use of nanofertilizers would improve shallot performance, micronutrient iron (Fe) enrichment, and yield in semi-arid regions. Herein, we evaluated the effects of magnetite nanoparticles (nFe₃O₄) on shallot grown for a full lifecycle in two semi-arid regions through bulb-priming followed by foliar application and compared them with conventional ferrous sulfate (FeSO₄) fertilizer and untreated control. Our results showed remarkable cellular adaptations to semi-arid climate upon nFe₃O₄ treatment as leaves displayed thickened cell walls, distinct chloroplasts featuring organized thylakoid grana and stroma, normal mitochondria, abundant starch grains, and plastoglobuli around chloroplasts compared to FeSO₄ or untreated control. At 900 mg/L nFe₃O₄, chlorophyll-a, chlorophyll-b, and carotenoid increased by 27–55%, 108–126%, and 77–97%, respectively, compared to FeSO₄ applied at recommended field rate (1800 mg/L). Significant increments in bulb diameter (38–39%) and sister bulb number (300–500%) were observed upon 900 mg/L nFe₃O₄ treatment compared to FeSO₄ (1800 mg/L) and control. Furthermore, with 900 mg/L nFe₃O₄ treatment, total phenol, flavonoids, and Fe in bulbs increased by 27–46%, 29–73%, and 486–549%, respectively, compared to FeSO₄ (1800 mg/L). These findings demonstrate that bulb-priming followed by foliar application of 900 mg/L of nFe₃O₄ could significantly promote cellular adaptation, thereby improving photosynthetic efficiency, bulb yield, antioxidant activities, and Fe biofortification in shallot, and may serve as a novel approach for improving shallot production in semi-arid regions. Full article

For future Mars colonization, crop production will be a challenge due to the chemical composition of the Martian Regolith, which contains perchlorates and heavy metals. This research was conducted to determine if the use of Arbuscular Mycorrhizal Fungi (AMF), Plant Growth-Promoting Bacteria (PGPB), and fertilization have a positive effect on tomato growth in a Martian Regolith Analog. The analog contains 52.54% SiO₂, 1.81% TiO₂, 17.66% Al₂O₃, 9.46% Fe₂O₃, 0.145% MnO, 3.43% MgO, 7.09% CaO, 3.95% Na₂O, 1.96% K₂O, and 0.55% P₂O₅. Two hundred and forty tomato plants were grown for 45 days. One hundred and twenty tomato plants grown over perchlorate-polluted analog (1% m/m) died in less than 2 weeks, while 120 tomato plants grown in a non-polluted analog survived. Forty-eight plants supplemented with Long–Ashton solution increased their shoot length 100% more than the control plants and the plants inoculated with the commercial AMF formulation TM-73^MR and PBB; the latter showed 25% mycorrhizal colonization. There was no significant difference between the growth parameters of inoculated plants and non-inoculated plants. However, there was a significant difference compared to the plants supplemented with Long–Ashton solution. The perchlorate is toxic to tomato plants, and the metal content of the analog was not a limiting factor for tomato growth or AMF colonization. Full article

This study is based on a long-term field trial with spring barley monoculture that was established in 1970 on Gleyic Fluvisol in the Žabčice, Czech Republic. The aim was to clarify the long-term impact of straw management and mineral nitrogen (N) application on grain yields and soil aggregate stability (SAS), and to determine the mineralogical and geochemical properties crucial for soil aggregate stability changes. Variants of the experiment included a combination of incorporated and harvested straw with doses of 0, 30, 60, and 90 kg N ha⁻¹ in the form of ammonium sulphate (NH₄)₂SO₄. The incorporated straw variants had a higher average grain yield of 0.51 t ha⁻¹. The SAS values were in the range 54–64% and increased in all variants with N application compared to the 0N control. Ammonium sulphate fertilisation caused soil acidification, which was not reduced even by the incorporation of straw. SAS increased with decreasing pH value, although cation exchange capacity and exchangeable Ca²⁺ decreased, and the soil organic carbon content was similar in all variants. The relatively high content of Fe- and Al-(oxo)hydroxides extracted with ammonium oxalate (Fe_ox and Al_ox) in all samples caused an increase in SAS due to decreasing pH in the N fertilised variants compared to the control. SAS should be considered in relation to other soil properties when evaluating soil quality and fertility. Full article

Electron transfer (ET) is a foundational biogeochemical process in paddy soils, distinctively molded by alternating anaerobic-aerobic conditions from flooding-drainage cycles. Despite extensive research on heavy metal(loid) (denoted as “HM”, e.g., As, Cd, Cr, Hg) dynamics in paddies, ET has not been systematically synthesized as a unifying regulatory mechanism, and the trade-offs of ET-based mitigation strategies remain unclear. These critical gaps have drastically controlled HMs’ mobility, which further modulates bioavailability and subsequent accumulation in rice (Oryza sativa L., a staple sustaining half the global population), posing substantial food safety risks. Alongside progress in electroactive microorganism (EAM) research, extracellular electron transfer (EET) mechanism delineation, and soil electrochemical monitoring, ET’s role in orchestrating paddy soil HM dynamics has garnered unparalleled attention. This review explicitly focuses on the linkage between ET processes and HM biogeochemistry in paddy ecosystems: (1) elucidates core ET mechanisms in paddy soils (microbial EET, Fe/Mn/S redox cycling, organic matter-mediated electron shuttling, rice root-associated electron exchange) and their acclimation to flooded conditions; (2) systematically unravels how ET drives HM valence transformation (e.g., As(V) to As(III), Cr(VI) to Cr(III)), speciation shifts (e.g., exchangeable Cd to oxide-bound Cd), and mobility changes; (3) expounds on ET-regulated HM bioavailability by modulating soil retention capacity and iron plaque formation; (4) synopsizes ET-modulated HM accumulation pathways in rice (root uptake, xylem/phloem translocation, grain sequestration); (5) evaluates key factors (water management, fertilization, straw return) impacting ET efficiency and associated HM risks. Ultimately, we put forward future avenues for ET-based mitigation strategies to uphold rice safety and paddy soil sustainability. Full article

Biostimulants have emerged as effective tools for enhancing both the productivity and quality of crops. In this study, we assessed the impact of the two commercial biostimulant products (Kiana Earth^® and Kiana Climate^®) on the growth, yield, and quality of lettuce (Lactuca sativa L.). Eight treatments were established, comprising six different biostimulant formulations, a normal control (no fertilizer applied), and a positive control (chemical fertilizer application). Biostimulant treatments significantly improved plant and stem diameters, fresh and dry biomass, and yield (p < 0.01). The best yields and morphological performance were obtained with samples receiving T6 (Kiana Climate^® + 75:50:75 kg ha⁻¹ N:P:K) and T7 (Kiana Earth^® + 150:100:150 kg ha⁻¹ N:P:K) applications, which comprised biostimulant–fertilizer combinations. Chlorophyll a, chlorophyll b, and total chlorophyll levels were significantly higher with than without biostimulant treatment, indicating that the biostimulants enhanced photosynthetic efficiency. Biochemical analyses further identified significant increases in vitamin C levels, total antioxidant capacity, total phenolic compounds, and flavonoid contents, especially with treatments T5 (Kiana Earth^® + 75:50:75 kg ha⁻¹ N:P:K)–T8 (Kiana Climate^® + 150:100:150 kg ha⁻¹ N:P:K). Nitrogen assimilation analysis showed that leaf NO₃⁻ levels were lower with the combined treatment than with chemical fertilizer alone, suggesting that the biostimulants improved nitrogen-use efficiency. Micronutrient (Fe, Zn, Cu, Mn, Na) and macronutrient (N, P, K, Ca, Mg, S) levels were significantly increased with biostimulant-enriched treatments, alongside a rise in soil organic matter. Biostimulants, especially when combined with mineral fertilization, significantly enhanced lettuce growth, yield, and nutritional quality, while also promoting soil fertility. These findings highlight the potential of biostimulants as valuable tools in conventional, regenerative, and organic agricultural practices, offering a sustainable approach to enhancing agricultural productivity while ensuring long-term soil fertility. Full article

This study aimed to determine the nutrient use efficiency of the yacon potato under NPK fertilization at different rates. The experiment followed a randomized block design with four replications and a split-plot arrangement. The main plots consisted of three fertilization levels (60%, 100%, and 140% of the reference dose—50:80:60 kg ha⁻¹ of NPK), with subplots to data collection intervals, performed every 30 days, for a total of 7 collections, generating 21 treatments. The dry biomass of whole plants and tuberous roots was determined. Samples were taken to determine the content of N, P, K, Ca, Mg, Cu, Fe, Mn, and Zn. The biological utilization coefficient (BUC) was calculated by dividing the mean values of dry biomass in kilograms of plant parts by the kilogram of nutrient found in that biomass. The application of 100% of the reference dose led to the highest use efficiency of P, K, Ca, and Mg, and intermediate efficiency for N in yacon tuberous roots and total biomass production throughout the cycle, provides a significant contribution to fertilization planning for this crop. The amount applied which was 100% of the reference dose was 17, 80, and 20 kg ha⁻¹ of N, P₂O₅, and K₂O, respectively, at planting, supplemented with 33 and 40 kg ha⁻¹ of N and K₂O as topdressing. Full article

Understanding hydrochemical evolution and apportioning pollution sources are prerequisites for effective groundwater protection at the regional scale; nevertheless, the governing processes and anthropogenic drivers in arid regions remain poorly constrained. Here, we present a comprehensive geochemical survey of the Datong River Basin, a representative arid catchment in north-western China. Thirty-seven groundwater samples were analyzed with hydrochemical methods and Positive-Matrix Factorization (PMF) to delineate natural controls and contaminant sources. Results showed that the aquifer is dominated by HCO₃–Ca(Mg) water controlled predominantly by silicate and carbonate weathering, modified locally by evapo-concentration and human activities. Water-quality indices classify 70.3% of the samples as excellent, but spatially restricted degradation is evident. PMF resolved three independent sources: a natural end-member enriched in Mn, Na⁺ and Cl⁻; a mixed source reflecting domestic wastewater, agricultural fertilizers and rock weathering; and an industrial source dominated by Fe. The mixed source contributes most major ions and chemical oxygen demand (COD), whereas the industrial source accounts for 75.7% of total Fe. These findings provide a robust scientific basis for groundwater management and pollution mitigation in arid regions under similar hydrogeological settings. Full article

The small freshwater lakes of Spitsbergen remain poorly studied compared to surrounding marine ecosystems despite their sensitivity to rapid environmental changes. During the short ablation season, these shallow lakes exhibit physicochemical variability influenced by the harsh Arctic climate, local geology, and hydrology. This study analyzed six lakes located on marine terraces, moraine areas, and outwash plains in the Bellsund region to assess how physicochemical variability in their waters affects phytoplankton development. The lakes exhibited local and temporal variations in temperature, conductivity, ion composition, and nutrient levels, with generally low nutrient availability limiting biological productivity. Phytoplankton communities were quantitatively and qualitatively poor, dominated by green algae, either flagellates or mixed communities, including cyanobacteria. Green algae clearly dominated in lakes closest to the fjord shoreline, while dinoflagellates and cryptophytes dominated in inland lakes. Phytoplankton abundance and biomass were extremely low in one of the lakes situated on the raised marine terraces within the tundra vegetation zone (3 × 10³ ind L⁻¹ and 0.004 mg L⁻¹, respectively). In contrast, the much larger lake situated within the tundra zone nearer the fjord shoreline had values that were comparable to fertile lakes in the temperate zone (~30 thousand × 10³ ind L⁻¹ and ~28 mg L⁻¹, respectively). It should be noted that Monoraphidium contortum and Rhodomonas minuta dominated some of the lakes almost entirely. Phytoplankton abundance was related to physicochemical conditions: green algae increased with increasing ion concentrations (Cl⁻, Na⁺, K⁺, SO₄²⁻), P_min, Fe, and Mn; flagellates preferred colder waters with higher N_min and low TOC; cyanobacteria occurred in waters with lower COND, TOC, Ca²⁺, Si, Cu, and Zn. Phytoplankton biomass increased in July with increasing water temperature. Bird activity likely facilitated phytoplankton dispersal, increasing taxonomic diversity in frequently visited lakes. Full article

Chinese yam (Dioscorea polystachya) serves as both a food crop and a traditional Chinese medicine herb, yet it suffers from severe continuous cropping obstacles, typically requiring a six-year fallow period before replanting. Long-term continuous cropping changes soil properties, including the concentration of N, P, and K, as well as bacterial composition, but the overall impact of short-term continuous cropping on important soil factors such as mineral elements, enzymes, and microbial composition still remains poorly understood. To elucidate how monoculture affects soil health, we collected rhizosphere soils from D. polystachya fields under one-, two-, and three-year continuous cropping in Chenji Town, and analyzed soil properties using general chemical methods, as well as microbial composition by Illuminar high-throughput sequencing of 16S rRNA and ITS1 regions. Furthermore, the correlation between soil properties and microbial communities was examined. The results showed that soil pH, cation exchange capacity, and organic matter content increased significantly in continuous cropping soil, whereas the concentrations of soil mineral elements (N, P, K, Ca, Mg, Na, Cu, Fe, Mn, Zn, S, and Si) decreased significantly, with the concentration of available P, K, Cu, and Zn decreased by 72.8%, 64.1%, 99.3%, and 79.4%, respectively, in 3-year continuously cropped soil. Enzyme activities, including sucrase, urease, and alkaline phosphatase, also showed a decrease of more than 81%. Fungal diversity and abundance were markedly reduced with cropping duration, whereas bacterial communities showed less response. Notably, pathogenic fungi such as Dactylonectria, Neocosmospora, and Ilyonectria, along with bacteria Streptomyces, became enriched. These microbial shifts were primarily associated with soil pH, available potassium, and alkaline phosphatase. Our study demonstrates that the decline in soil fertility coupled with pathogen buildup constitutes a major cause of the continuous cropping obstacle in Chinese yams. The results provide a scientific basis for developing targeted strategies to mitigate continuous cropping obstacles in Chinese yam production. Full article

Application of CFA-treated biosolids (NVS) offers multiple benefits to agricultural soils, including fertilizer replacement, soil rehabilitation, and disinfection. It also poses a heavy metal(loid)s threat to the agro-environment. NVS (and CFA to some extent) was tested in lysimeter and field trials, using soils differing in physicochemical properties and a large selection of crops. Consistently, As, Pb, and Cd concentrations in leachate were at or below detection limit, and these and other heavy metal(loid)s (and P) were within the permitted range in plant tissue. Foliage Mo (occasionally also Se, P) concentrations often increased significantly, especially in crops (legumes, potatoes) grown on marginal soils, which also displayed significantly higher yields. CFA and NVS reduced lettuce and legumes foliage Mn (and occasionally Zn) concentrations, which remained, however, adequate. NVS (214 and 642 mT ha⁻¹), digested sewage sludge (ADS) and its compost (24 and 72 mT ha⁻¹), temporarily increased the DTPA-extractability of some elements (NVS: B, Cr; ADS: Cu, Ni, Zn; Compost: Zn) 10–30-fold. The extractabilities of Fe and P increased by up to six times. These increases vanished soon after additive application, supporting the hypothesis of ‘self-attenuation’ by applied biosolids. Our data indicate that long-term application of NVS (and CFA) to calcareous soils poses no heavy metal(loid)s-related threat to the agro-environment. Full article

To explore the impact of combined carbon–nitrogen fertilization on the concentrations of Fe (ferrum) and Zn (zinc) in Dendrobium officinale (D. officinale), and to elucidate the underlying metabolic regulatory mechanisms, two-year-old seedlings of D. officinale were selected as the experimental subjects. Three treatment groups were established: a control group (CK), an α-ketoglutaric acid (AKG) treatment group (C treatment, CT), a urea treatment group (N treatment, NT), and an AKG and urea combined treatment group (CT_NT). Samples were collected at 0, 8, 16, 24, and 32 days post-treatment. Physiological and biochemical analyses measured stem contents of iron, zinc, copper, nitrate nitrogen, soluble proteins, and citric acid. Transcriptomic and metabolomic technologies were employed to elucidate molecular mechanisms. Physiological studies have shown that combined carbon–nitrogen application exerts time-dependent regulation on Fe, Zn, and their key metabolites in the stems of D. officinale, presenting a trend of first increasing and then decreasing. Metabolomic analysis revealed that flavonoids, phenolic compounds, and organic acids are involved in Fe chelation, while quercetin, dopamine, and other substances promote Zn absorption. Transcriptomic analysis indicated that combined carbon–nitrogen application activates the accumulation of Fe and Zn contents by upregulating the expression of related genes. Integrated analysis demonstrated that carbon–nitrogen metabolism affects the metabolic network of D. officinale by regulating primary and secondary metabolic pathways. This study elucidated the physiological and molecular mechanisms underlying the regulation of Fe and Zn contents in D. officinale by combined carbon–nitrogen application, providing theoretical support and a scientific basis for the high-efficiency cultivation and quality improvement of D. officinale. Full article

Zinc oxide nanoparticles (ZnO NPs) have garnered increasing attention in agriculture due to their potential to enhance plant growth and nutrient use. This research investigates the concentration-dependent effects of ZnO NPs on young crabapple (Malus robusta) plants, addressing gaps in understanding how different concentrations influence plant development. A hydroponic experiment was conducted, applying foliar treatments of 200 mg L⁻¹ ZnSO₄ (S200) and 200, 500, and 1000 mg L⁻¹ ZnO NPs (N200, N500, N100). The control group (CK) was treated with deionized water (dH₂O). Growth parameters, antioxidant enzyme activity, and nutrient contents were measured to evaluate the impact of ZnO NPs on plant development and nutrient uptake. The results showed that N200 enhanced growth, increasing plant height by 22.64%, total dry weight by 49.36%, and root length by 116.07%. In contrast, N500 and N1000 induced oxidative stress, elevating H₂O₂ and MDA by 32.02~54.43% and inhibiting growth. N200 also improved nutrient uptake, increasing K, Ca, Fe, and Zn uptake fluxes by 84.92%, 112.12%, 185.15%, and 149.92%, respectively, whereas N1000 suppressed overall nutrient uptake but increased root Ca accumulation by 64.59%. These findings suggest that ZnO NPs can enhance plant growth and nutrient utilization at low concentrations, with potential implications for agricultural practices involving nanoparticle (NP)-based fertilizers. Full article