Search Results (2,501)

Cadmium (Cd) and lead (Pb) co-contamination in construction and demolition waste landfill soils presents a significant challenge to ecosystem health, necessitating effective remediation strategies. This study investigated a synergistic approach combining a composite amendment (compost, superphosphate, desulfurized gypsum) with seven plant species to elucidate the interactions driving metal immobilization and phytoextraction. The amendment significantly altered soil properties: it reduced total Cd while increasing its bioavailability, and enhanced soil fertility (e.g., elevated organic matter and total nitrogen). Plant responses varied: Solanum americanum Mill. and Tagetes patula L. exhibited high Cd phytoextraction capacity, whereas Lolium perenne L. sequestered Cd/Pb primarily in roots. The bacterial community shifted from an oligotrophic, stress-tolerant state (e.g., Sphingomonas-dominated) in contaminated soil to a copiotrophic, functionally active state (e.g., Streptomyces-enriched) in amended soil. Community structure was strongly correlated with available Cd, pH, and nutrient levels. Key microbial biomarkers were specifically enriched in different plant rhizospheres. In contrast, the fungal community exhibited minimal responsiveness. These findings demonstrate that remediation efficiency is governed by an integrated “amendment–plant–microbe” framework: amendments regulate metal bioavailability, plants execute extraction or stabilization, and the restructured microbiome supports nutrient cycling and plant health. This integrated remediation strategy directly supports the Sustainable Development Goals of the 2030 Agenda, especially on environmentally sound management of chemicals and wastes and land degradation neutrality. This mechanistic understanding underscores the necessity of combined biological and chemical strategies for sustainable remediation of co-contaminated soils, ultimately enabling ecological reclamation and safe recycling of such urban marginal lands into productive uses. Full article

Long-term fertilization regulates soil microbial communities and is essential for black soil health and sustainable productivity, yet its key drivers remain unclear. Using a 39-year field experiment, we evaluated the effects of four fertilization regimes: no fertilizer (CK), chemical fertilizer (NPK), organic fertilizer (M), and combined organic-inorganic fertilizer (MNPK). Soil properties and bacterial communities were analyzed using Illumina MiSeq sequencing, quantitative real-time PCR (qRT-PCR), and multivariate analyses. Proteobacteria, Actinobacteriota, Acidobacteriota, Chloroflexi, and Gemmatimonadota dominated (>80% of the community), and all treatments significantly altered their relative abundances. Compared with CK, NPK reduced soil pH by 8.3% and bacterial abundance by 29.7%, increased soil organic matter (SOM) by 22.9%, and decreased community evenness. MNPK reduced pH by only 2.0%, increased SOM by 53.8% and bacterial abundance by 38.9%, and improved community evenness, mitigating acidification while maintaining high diversity. M increased pH by 2.3%, SOM by 73.3%, and bacterial abundance by 71.8%. Soil pH, available phosphorus, and SOM were the main drivers of community structure. Overall, MNPK showed the strongest synergistic effects on soil fertility and microbial stability, making it an optimal strategy for sustainable black soil management. Full article

Organic amendments can mitigate soil acidification and degradation, yet their long-term effects on soil microbiome, functions, and crop productivity remain underexplored in latosolic red soils. This study aimed to elucidate how different fertilization regimes reshape soil microbial communities and predicted functions, and how these changes link to sweet potato productivity after 15 years. Soil and plant samples were collected from a 15-year field experiment on latosolic red soil under five treatments: no fertilizer (CK), chemical fertilizer alone (NPK), and chemical fertilizer combined with commercial manure (NPK + CM), pig manure (NPK + PM), or rice straw (NPK + RS). Soil properties, bacterial and fungal communities, and predicted functions (FAPROTAX, FUNGuild) were analyzed. The results showed that long-term NPK alone significantly acidified soil (pH decreased by 1.49 units), whereas NPK + PM increased pH by 1.38 units relative to NPK, and also increased soil organic carbon, available nutrients, and sweet potato yield (by 31% compared with NPK). Soil pH was strongly associated with reshaping the microbial community. NPK + PM enriched beneficial phyla (e.g., Myxococcota, Nitrospirota, Latescibacterota, Entotheonellaeota, and Mortierellomycota) and enhanced predicted chemoheterotrophic, predatory or exoparasitic, and saprotrophic functions. Variance partitioning showed that nutrients, key microbial taxa, and predicted functions jointly explained productivity variation (adjusted R² = 0.9386). Thus, chemical fertilizer combined with pig manure is an effective strategy to mitigate soil acidification and improve sweet potato productivity by regulating soil nutrient-microbiome interactions. Our findings support reshaping the microbiome via organic amendments for sustainable agriculture in acidic soils. Full article

Cadmium (Cd) accumulation in agricultural soils from prolonged phosphate fertilizer application threatens food safety in Southeast Asia, yet the combined performance of vermicompost (VC), biochar (BC), and Azolla microphylla for Cd immobilization remains poorly characterized. We evaluated their individual and combined effects in a Cd-spiked Korat soil (100 mg kg⁻¹ Cd as Cd(NO₃)₂) under controlled laboratory conditions. A completely randomized pot experiment with eight treatment combinations (four amendment regimes × two Azolla levels, n = 3) was incubated for five weeks; total and exchangeable Cd, selected soil properties, and Eisenia fetida growth were assessed before and after treatment. The combined of soil, cadmium vermicompost and biochar (SCVB) + Azolla treatment reduced total Cd by 41.13% and exchangeable Cd by 81.02%, significantly outperforming single amendments, while raising organic matter to 6.31% and nitrogen (N), phosphorus (P), and potassium (K) availability. Principal component analysis (PCA) explained >98% of the variance and separated SCVB clearly from the unamended control along soil-quality and Cd axes. Strong negative correlations between Cd and fertility indicators (r = −0.86 to −0.96) indicated coupled immobilization and fertility recovery. A 5-day acute earthworm bioassay confirmed reduced soil toxicity under SCVB + Azolla, with growth inhibition reduced from 55.9% to 23.6%, mortality reduced from 26.7% to 10%, and tissue Cd accumulation reduced from 44.08 to 25.17 mg kg⁻¹ (42.9% reduction). The integrated VC + BC + Azolla system offers a cost-effective amendment-assisted Cd immobilization strategy for tropical soils, pending field validation. Full article

Polyacrylamide (PAM), as a widely used effective soil conditioner, can decrease sandy soil infiltration, but its function may decline significantly in a short time. Previous study results showed that the annual degradation rate of PAM in soil is about 10%, and the migration ability of PAM in soil is fairly weak; thus we hypothesized that the functional group of PAM is prone to aging caused by physical and biological factors, which is different from degradation caused by the breaking of long main chains into short ones. The sandy loam soil was selected to conduct column infiltration experiments to (1) determine the effects of PAM application and drying and wetting intensity on infiltration and (2) identify the causes of the aging effect. Soil samples were treated with three doses of PAM (0, 1, and 2 g·kg⁻¹) and incubated in three soil water conditions (constant wetting, moderate and strong drying/wetting cycles). Under constant wetting condition, the stable infiltration rates of soils were decreased by PAM. However, after two strong drying and wetting cycles, the decrement of infiltration rates of PAM-treated soils was reversed. The results of FTIR suggested that drying and wetting cycles led to the hydrolysis of amide groups in PAM, resulting in the weakening of PAM’s function on soil infiltration characteristics. The leaching amounts of NH₄⁺-N generated by the amide group hydrolysis increased through the drying/wetting alternation and the application of PAM. Therefore, based on the findings of this column study using a specific sandy loam soil under controlled intense drying–wetting cycles, reapplication of polyacrylamide (PAM) after two cycles may facilitate the sustained lowering of infiltration. However, this recommendation should be confined to analogous experimental conditions and necessitates further validation under field scenarios or for alternative soil types. Full article

Optimizing orchard mulching regimes is a pivotal strategy for mitigating the detrimental effects of water scarcity and soil degradation on kiwifruit productivity in the Guanzhong Plain, China. To characterize the integrated effects of varying mulching patterns, a two-year field study was conducted in a kiwifruit (Actinidia deliciosa) orchard, evaluating four treatments: (1) FG: intra-row fabric with inter-row grass (multiple mulch); (2) FN: intra-row fabric with inter-row bare soil; (3) NG: intra-row bare soil with inter-row grass; and (4) NN: intra-row bare soil with inter-row bare soil. Understanding the impacts of these regimes on the edaphic environment, photosynthetic performance, and sugar metabolism is essential for improving kiwifruit production under semi-arid conditions. The results demonstrated that the FG treatment significantly improved soil water storage (SWS), with an increase of 1.83–55.16 mm, and enhanced the soil nutrient content (NH₄⁺-N, NO₃⁻-N, and soil organic matter), thereby optimizing the rhizosphere environment. During the critical phenological stages, the FG treatment increased the leaf photosynthetic parameters, such as the net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs), while reducing the intercellular CO₂ concentration (Ci). Specifically, grass mulching (FG and NG) elevated the chlorophyll a content during early growth and carotenoids levels throughout reproduction, whereas fabric mulching (FG and FN) enhanced the chlorophyll b content throughout the entire reproductive period. Collectively, these improvements bolstered photosynthetic efficiency and may have contributed to improved carbon allocation and sugar accumulation. All three mulching treatments (FG, FN, and NG) significantly improved the fruit yield-related parameters, including the total fruit number per plant (PFN), single fruit weight (SFW), and yield (Y), as well as the fruit sugar-related indices, such as soluble solids content (TSS), total soluble sugar content (TS), reducing sugar (TRS), and the sugar–acid ratio (SAR). The partial least squares path modeling (PLS-PM) revealed that these improvements were primarily driven by the synergistic optimization of SWS and photosynthetic productivity. Notably, the model identified a physiological trade-off between yield formation and sugar accumulation, while the overall fruit quality exerted a strong positive influence on sugar metabolism. The correlation analysis indicated that the higher fruit sucrose accumulation under the FG and FN treatments were associated with increased sucrose phosphate synthase (SPS) and sucrose synthase (SS) activities, suggesting a potential link between mulching-induced improvements in plant physiological status and sucrose metabolism. These findings suggest that the combined use of intra-row fabric and inter-row grass mulching (FG) provides a sustainable strategy for enhancing soil conditions and fruit quality in water-limited kiwifruit orchards. Full article

Soil organic matter (SOM) is a recognized determinant of nitrogen-use efficiency (NUE), but its quantitative control over the fate of fertilizer N remains unclear. Using a ¹⁵N tracer study within a winter wheat–summer maize region, we quantified the recovery of initially applied N from wheat and subsequent crops in relation to SOM and N application rates. We found that while N fertilization boosted yields by 85–340% in low-fertility soil, its effectiveness exhibited diminishing returns in high-fertility soils. Crucially, the total recovery efficiency of fertilizer N (cumulative ¹⁵NUE) across three cropping seasons was fundamentally governed by SOM content, following a linear–plateau relationship. The model revealed that the maximum ¹⁵NUE (54.3%) at an optimal application rate (105 kg N ha⁻¹) was achieved when SOM exceeded a critical threshold of 21.3 g kg⁻¹ (equivalent to 57.51 t ha⁻¹ in the 0–20 cm soil layer). Below this threshold, ¹⁵NUE increased linearly with SOM (R² = 0.956). Furthermore, residual ¹⁵N in soil was primarily stabilized in organic forms (58–64%), while recovery by subsequent crops was minimal (≤4.3%). This confirms that high SOM content minimizes the amount of unaccounted ¹⁵N by enhancing N fixation within the soil organic pool. Our findings establish a quantifiable SOM threshold for maximizing NUE, thereby providing a scientific basis for reducing fertilizer waste and enhancing the sustainability of intensive agriculture in the region. Full article

The decline of soil organic matter in Kazakhstan due to long-term monoculture and intensive fertilizer use has increased the need for sustainable soil management strategies. This study aimed to develop a new composting technique to produce more performant organic fertilizers from cattle manure to contribute to the broader strategy to increase soil organic matter and to improve fertility in northern Kazakhstan soils. Composting experiments were conducted using oxidized coal at 5%, 10%, and 20% dosages combined with two microbial consortia, and physicochemical and microbiological parameters were monitored throughout the process. The addition of microbial consortia and oxidized coal significantly enhanced composting dynamics by accelerating the transition to the thermophilic phase and increasing microbial activity. Treated systems exhibited higher temperatures (up to 48–49 °C), greater microbial abundance, and improved nitrogen transformation, characterized by increased NH₄⁺–N accumulation followed by NO₃⁻–N formation. Organic matter degradation was more efficient in amended treatments, while oxidized coal contributed to improved moisture retention and pH stabilization. However, excessive coal addition (20%) reduced microbial activity at later stages. Among the treatments, the combination of Consortium 3 with 10% oxidized coal showed the most balanced performance, with enhanced microbial activity, efficient nutrient transformation, and stable compost maturation. These findings demonstrate that the integration of microbial consortia with oxidized coal is an effective strategy for improving composting efficiency and producing high-quality organo-mineral fertilizers, with potential for improving compost quality and nutrient stabilization, and supporting sustainable and regenerative soil management in degraded agricultural systems. Full article

Urea is the most widely used nitrogen fertilizer worldwide, and its application leads to soil acidification, which can potentially change the behavior of agrochemicals such as glyphosate and its main degradation product, aminomethylphosphonic acid (AMPA). This study assessed how urea-induced acidification influences the adsorption of glyphosate and AMPA in an Andisol. Batch equilibrium experiments were conducted to evaluate adsorption kinetics and isotherms with and without urea (200 kg N ha⁻¹), as well as under controlled pH conditions (pH 4, 5, and 6). Kinetic data were analyzed using pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models, while adsorption isotherms were described using the Freundlich model. Results showed clear differences in sorption behavior between both compounds. AMPA exhibited higher sorption capacity, faster equilibrium, and minimal effect from urea addition. In contrast, glyphosate adsorption was significantly reduced by urea, showing lower kinetic parameters. Mechanistic analysis indicated that AMPA retention is governed by chemisorption and intraparticle diffusion processes, whereas glyphosate adsorption is more influenced by surface interactions and competition with urea. Overall, urea application may increase glyphosate mobility in Andisols, while AMPA remains strongly retained, highlighting the role of fertilization in herbicide fate. Full article

Surface and subsurface acidity (pH < 4.4) limit nutrient availability, restrict root exploration, and impair crop yields in agricultural and agropastoral systems. Subsurface acidity (0.4–0.8 m layer) is a critical limiting factor for mature tropical soils. Methodologies that provide amelioration of surface and subsurface acidity and improvements in soil chemical fertility are necessary to decrease production costs and increase crop yields. This study evaluated the long-term ability of different methodologies for applying calcium (Ca) compounds (limestone (LS), phosphogypsum (PG), and hydrated lime (HL)) to ameliorate surface and subsurface acidity and improve soil chemical fertility. The results showed that the correction of surface acidity by treatments T2 (no-till/LS + PG), T3 (conventional tillage/LS + PG), T5 (no-till/HL + PG) and T6 (minimum tillage/HL + PG) persisted two years after application, as evidenced by higher pH and base saturation (BS) and lower total acidity in the 0.0–0.2 m layer compared with the control. By contrast, the improvement in acidity in the 0.4–0.8 m layer that was previously observed after subsurface application of HL in the 2017–2018 season (T6 and T7, minimum tillage/HL + PG) was lost. Moreover, the improvements in Ca²⁺ content and Ca²⁺/cation exchange capacity (CEC) observed after applying LS plus PG persisted in the 0.0–0.1 m layer only. However, the improvements in Mg²⁺ content and Mg²⁺/CEC after applying HL plus PG were not maintained. In addition, the positive effects of Ca compounds on sulfate-S (S-SO₄²⁻) content throughout the soil profile (0.0–0.8 m) did not persist. By contrast, after two seasons, Ca compound application had residual positive effects on P content in the 0.1–0.8 m layer and organic matter (OM) content in the 0.2–0.8 m layer, which were previously not observed. Full article

We hypothesized that the application of digestate (D) to winter oilseed rapeseed would have the same effect on seed production as nitrogen fertilizer (N_f). It impacts yield by altering the mass of readily available N in the vegetative and reproductive periods of plant growth. This allows for a good yield forecast. This hypothesis was assessed in field experiments with rapeseed carried out in 2015/2016, 2016/2017, and 2017/2018. The experiment included three N fertilization systems (FSs): AN, based on ammonium nitrate (AN); D, with digestate-based N; DAN, using ²/₃ of digestate + ¹/₃ of AN—and five N_f doses: 0, 80, 120, 160, and 240 kg N ha⁻¹. The net seed yield increase due to N application was 1.44 t ha⁻¹ in the AN system, 1.53 t ha⁻¹ in D, and 1.77 t ha⁻¹ in DAN. The optimal N rates were 160, 250, and 224 kg N ha⁻¹. The N economy of winter oilseed rapeseed was assessed in two periods: vegetative—before anthesis (from the rosette stage to the beginning of anthesis, BBCH 30–BBCH 60) and reproductive (from the beginning of anthesis to full maturity, BBCH 60–BBCH 89). The mass of available N at the beginning of anthesis increased by 54.3% (151 kg N ha⁻¹ to 233 N ha⁻¹) and doubled (151 kg N ha⁻¹ to 302 kg N ha⁻¹) compared to its value at the rosette stage, taking into account the mass of N in the rapeseed canopy and its total mass in the soil/rapeseed continuum. No differences in NUE were found for the tested N carriers. The net increase in N available resources resulting from the application of N fertilizer was 55.1, 104.9, 102.8, and 93.0 kg N ha⁻¹ for respective plots fertilized with 60, 120, 180, and 240 kg N ha⁻¹. Three N indices were measured at the beginning of rapeseed anthesis—N in crop biomass (NAF, r = 0.87 ***), N balance (Nb60, r = 0.87 ***), and N released from soil resources (Ngain60, r = 0.79 ***)—and showed potential for seed yield (SEY) prediction. The linear dependence of SEY on these indicators indicates that the potential of the rapeseed canopy to effectively accumulate N during the vegetative growth was too low. This limitation was fully confirmed by analogous N management indicators, but developed for rapeseed during the seed-filling period. The key indicator of SEY at harvest was the N mass in rapeseed biomass (NAH, r = 0.95 ***). N from digestate acted as a slow-release fertilizer, giving it an advantage over ammonium nitrate. In summary, digestate is an optimal N carrier under conditions of average rapeseed yield. Full article

Climate variability and widespread synthetic agrochemical use have increased interest in biostimulants (BS) that enhance plant growth, stress tolerance, and yield by stimulating natural plant processes. A two-site field study, conducted under no-till and tilled systems, evaluated the effects of the foliar biostimulant “Source” on soybean growth and yield at three phosphorus (P) rates (0%, 50%, and 100% of soil test recommendations) because of its potential to replace phosphorus inputs. A complementary greenhouse study was conducted to evaluate the effect of the biostimulant on different soybean hybrids. Measured at various dates after planting (DAP), leaf relative water content (LRWC) and normalized difference vegetation index (NDVI) mostly showed insignificant responses to P treatments, but significant responses to BS. Grain yield increased significantly with individual BS and P applications in both tillage systems. Under no-till conditions, BS increased yield by 13.0% (3.05 vs. 2.70 Mg ha⁻¹), and P100 increased yield by 13.5% (3.0 vs. 2.65 Mg ha⁻¹). Under tilled conditions, BS and P100 increased yield by 19.6% (2.75 vs. 2.30 Mg ha⁻¹) and 19.2% (2.72 vs. 2.28 Mg ha⁻¹), respectively, compared with the control. Yield gains were primarily driven by increased pod density and grain number. Greenhouse experiments supported these trends, with BS-treated plants producing more grains per plant (187.6 vs. 171.3) and higher yield per plant (28.8 vs. 25.7 g). Results indicated that biostimulant application improved physiological performance and increased soybean yields, comparable to full-rate phosphorus, highlighting its potential as a sustainable approach under increasing environmental and input-related challenges. Full article

Soybean is a globally important legume crop which fulfills most of its nitrogen (N) requirement through Biological Nitrogen Fixation (BNF) in symbiosis with Bradyrhizobium species, thereby reducing dependence on synthetic fertilizers and supporting more sustainable production systems. This review synthesizes current knowledge on the mechanism, capacity, and regulation of BNF in soybean, including nodule formation, nitrogenase activity and response to soil and environmental conditions. The evidence shows that BNF can provide a substantial share of the crop’s N uptake, although high-yielding systems frequently experience the “N gap”, which is a difference between a higher crop demand and a lower N supplied from BNF and existing soil reserves. This can be partially managed with strategies like inoculation, co-inoculation, re-inoculation or judicial application of N. This review further highlights the advances in microbial inoculant technologies, plant growth-promoting rhizobacteria (PGPR), soybean breeding and genetic engineering aimed at improving BNF stability, efficiency and capacity across different soil environments. Overall, the maximization of soybean BNF has strong potential to reduce synthetic fertilizer use, improve yield and seed quality, and enhance the economic and environmental sustainability of soybean-based systems. Full article

Microalgae-based wastewater treatment can support sustainable crop production. This study evaluated whether ethanol supplementation improves swine wastewater (SW) treatment by Dictyosphaerium sp. and enhances algal biofertilizer production. Across the ethanol levels tested, 500 mg/L ethanol significantly promoted algal growth and enhanced liquid-phase net removal of total salts, carbonate/bicarbonate, ammonium, phosphate, and calcium. Ethanol supplementation also reduced apparent nitrogen loss, and no residual ethanol was detected at the end of the culture. In the biofertilizer production experiment, peak algal biomass, algal nitrogen, and algal phosphorus increased by 320.0–407.4%, 122.7–158.1%, and 100.0–170.0%, respectively. Metatranscriptomic analysis showed active transcription of adh, aldh/aldB, and acs in Dictyosphaerium sp. and some bacterial taxa, mainly Flavobacterium, Chryseobacterium, Comamonas, and Brevundimonas. Community and transcriptomic results indicate enhanced photosynthetic activity and taxon-specific N- and P-related transcriptional responses, consistent with altered nitrate/nitrite transformation potential and increased nitrogen retention in the algal–bacterial system. Under the tested conditions, ethanol supplementation shows promise for SW treatment and algal biofertilizer production. Full article