Effects of soil amendments on soil acidity and crop yields in acidic soils: A world-wide meta-analysis

Psychrophilic insights into petroleum degradation: Gene abundance dynamics

Petroleum degradation by psychrophiles can be enhanced on the basis of omics analyses, which offer better sensitivity than traditional biochemical methods do. A metagenomic analysis focusing on gene abundance comparisons may provide new guidance to optimize soil decontamination under cold environmental conditions. The soil used in this study was sampled from Dalian, from which an indigenous consortium was isolated. The degradative soil systems, initially categorized into control (DLC) and experimental (DLD) groups, were kept at room temperature (20 ± 5 °C) for six weeks. The DLD group was subsequently transferred to a low-temperature environment (5-10 °C) for 90 days and renamed DDL. A petroleum removal rate of 74.59 % was achieved in the process from DLD to DDL groups. Each soil sample was subjected to analysis and metagenomic sequencing. The abundance of genes of interest was compared between pathways to determine trends. The findings demonstrate that psychrophilic degradation is more effective than natural remediation is. The soil microbial community structure displayed site specificity, with 802 genes in DDL associated with 249 pathways, indicating greater abundance of psychrophilic genes in DDL than in DLC. The abundance of key genes was at different orders of magnitude but showed similar trends. The abundance of genes associated with hydrocarbon-related metabolism surpassed that of genes associated with sphingolipid, fatty acid, or benzene metabolism. This study provides valuable insights into psychrophilic microbe-driven petroleum degradation and indicates the need for precise supplementation of biosurfactants to improve remediation efficiency.

Effect of applying oyster shell powder on soil properties and microbial diversity in the acidified soils of pomelo garden

The application of oyster shell has recently been used to increase soil pH in Southern China. However, little is known about causal shifts in the rhizosphere microbial community of pomelo trees, especially in orchards that have experienced natural accumulation of heavy metals over many years due to continuous fertilization and soil acidification. This study evaluated the effects of oyster shell powder applied for 1 year (T1), 2 years (T2) and 3 years (T3), alongside a control group with no soil amendments (Control; CK), on soil acidification and microbial diversity. Our findings demonstrated that the application of oyster shell significantly increased soil pH and reduced the concentrations of heavy metals such as thallium (Tl), chromium (Cr), and manganese (Mn). Illumina sequencing-based community analysis revealed that oyster shell application significantly increased the alpha diversity indices of both bacterial and fungal communities and influenced their distribution in the soil. Notably, all oyster shell-treated groups (T1-T3) showed significantly higher relative abundances of beneficial microbes (e.g., Nitrolancea, Vicinamibacterales) and those involved in carbohydrate degradation and nitrogen fixation compared to the control. Conversely, the relative abundances of Acidibacter and Chujaibacter (associated with heavy metal degradation and soil-borne diseases), Trichoderma and Acremonium (plant-beneficial fungi), as well as functionally annotated groups linked to nitrogen assimilation and pathotrophic modes (predicted via FUNGuild analysis), decreased significantly. Our results suggest that the application of oyster shell powder amendments contributes to improved soil properties and microbial environments; however, the effects on soil nitrogen cycling and fungal function are complex, warranting further research.

Synergistic Bio-Organic Fertilization Enhances Tobacco Antioxidative Defense and Soil Health for Sustainable Agriculture

The extensive use of chemical/inorganic fertilizer application over the past few decades has significantly enhanced global food production potentials. However, the excessive application of these fertilizers has resulted in environmental issues, soil nutrient imbalances, and poor quality of food. The study aimed to evaluate the impact of various blends of bio-organic fertilizer, farm manure, and compound fertilizer on soil health, focusing on soil nutrient content, soil enzymatic parameters, physio-biochemical attributes, and quality traits of tobacco. The experimental treatments incorporated different combinations of conventional compound fertilizer with organic and bio-organic fertilizers. The findings revealed that the application of these bio-organic fertilizers with various combinations to the soil significantly improved tobacco growth, photosynthetic traits, antioxidant enzyme activity, and soil enzymatic activities. These amendments significantly improved the tobacco leaf quality by limiting the proline accumulation (62.17 and 77.31%) and malondialdehyde content (35.33 and 41.91%) at the reefing and flowering stages, respectively. Soil treated with a combination of bio-organic fertilizer, farm manure, and compound fertilizer (B4) showed an increased soil enzyme activities with acid phosphatase improving by 19.91%, urease by 40.00%, and catalase activity by 7.41%, which results in enhanced soil nutrient status compared with other treatments. Based on these findings, it can be concluded that combined application of organic amendments resulted in better growth, improved antioxidative defense system, and improved quality of tobacco by reducing the use of compound fertilizer (10%) and activating soil enzymatic attributes, thereby boosting the tobacco productivity in agricultural systems.

Sorption, persistence and leaching of clomazone in rice environments under varying severity of alternate wetting and drying irrigation management with and without biochar amendment

Clomazone (CLMZ) is one of the most effective and widely used herbicides in rice cultivation, but it has probable risks for environmental contamination. Alternate wetting and drying irrigation (AWDI), with or without holm oak biochar (B) amendment, is one of the sustainable alternatives to conventional flooding rice cropping. However, its implementation may induce changes in soil characteristics that can strongly affect the environmental behaviour of the CLMZ, although its extent will depend on the degree of severity of AWDI. This three-year study is the first to assess how two different severities of AWDI, without or with fresh or field-aged B, impact CLMZ's sorption, persistence and leaching. The treatments were: conventional continuous flooding (CCF), moderate AWDI (MAWDI) and intensive (IAWDI) in which fields were reflooded when the soil matric potentials at 0-15 cm depth were -20 kPa and -70 kPa, respectively, and the corresponding homologs with B addition (CCF-B, MAWDI-B, and IAWDI-B, respectively). The transition to AWDI increased CLMZ's sorption but only at the intensive severity level. Fresh and aged B-amendment increased CLMZ's sorption particularly in soils from MAWDI regime, with Kd values increasing by 1.4-fold (fresh case, measurements in the first year after B addition) and 1.3 and 1.2- fold (aged cases, measurements 2 and 3 years after B addition, respectively). The B addition leads to more CLMZ persistence, especially for the IAWDI-B case where the t1/2 incremented by factors of 1.6 and 1.2 (fresh year) and 1.4 and 1.3 (second aged year) under flooding and AWDI conditions, respectively. The MAWDI and IAWDI regimes reduced CLMZ leaching by up to a factor on average of 2.3 and 2.8, respectively. The addition of B reduced CLMZ's leaching, particularly for the MAWDI regime where their losses were 2.3 and 4.3 times less in the fresh and second aged year, respectively. Therefore, the change in regime from flooding to AWDI alone or using B as amendment could be considered a useful strategy to greatly mitigate pollution of water by CLMZ in rice-growing environments, particularly in those under MAWDI management and after B aging.

Sustainable soil remediation using nano-biochar for improved food safety and resource recovery

The contamination of agricultural soils with potentially toxic elements (PTEs) poses serious environmental and health risks due to their persistence and adverse effects on crop productivity. The main objective of this study was to evaluate the potential of nano-biochar (n-BC) to immobilize PTEs in contaminated soil and its effect on PTEs bioaccumulation in lettuce (Lactuca sativa L.), with the hypothesis that n-BC-due to their unique and improved physicochemical properties-are more effective than bulk forms in reducing PTEs mobility and bioavailability. Biochars (BCs) were obtained from palm bunch (PB), rice husk (RH) and sewage sludge (SSL) at 550°C and subsequently processed into nanoscale forms. A six-week pot experiment demonstrated that n-BC amendments significantly reduced the bioavailable (extracted with H2O and CaCl2) fractions of Cr, Cu, Fe, Mn, Ni, Zn, and Pb in soil, with higher immobilization efficiencies by 4.2 % to even 305 % than corresponding bulk biochars (b-BC). According to NICA-Donnan modelling, the main immobilization mechanisms were precipitation and ion exchange. Application of n-BC also resulted in a notable decrease in PTEs concentrations in lettuce leaves (ranging from 29.7 % to 100 %), thereby reducing both the bioaccumulation factor and health risk index. Among the different BCs, SSL-derived n-BC demonstrated the highest immobilization capacity and the most substantial reduction in PTEs uptake by plants. These findings highlight the potential of n-BC as a highly effective and low-cost amendment for rapid mitigation PTEs contamination in agricultural soils, enhancing food safety, and supporting circular economy principles by utilizing organic waste materials.

Lignosulfonate Improves Soil Fertility by Promoting Exchangeable Al3+ Immobilization and Facilitating Its Interaction with Soil Enzymes through Active Functional Group Surfaces

Soil acidification threatens soil health and sustainable agriculture, and conventional mitigation strategies have various limitations, underscoring the need for the creation of more effective and sustainable alternatives. In this study, we evaluated the effects of calcium lignosulfonate (CL) on the physicochemical properties of acidic soils (Rs, K2j, and J2s) through pot experiments. Additionally, molecular modeling calculations were employed to investigate the interaction mechanisms between CL and soil exchangeable acidity and active enzyme. The results showed that CL was superior to lime in reducing phytotoxic exchangeable Al3+, enhancing soil acidification buffering capacity, and improving soil fertility and plant biomass accumulation. These benefits were attributed to the strong competitive adsorption of exchangeable Al3+ by the CL surface active functional groups, enhanced interactions between CL and soil enzymes, and the restructuring of microbial communities. These findings provide valuable insights for developing efficient soil amendments to mitigate the effects of acidification, ultimately enhancing soil health and agricultural productivity.

Effects of bacterial fertilizer and soil amendment on Spuriopinella brachycarpa (Kom.) Kitag. growth and soil microbiota

Introduction

Spuriopinella brachycarpa (Kom.) Kitag. is a nutritious wild vegetable, but its quality deteriorates during artificial cultivation due to soil condition alterations. Microbial fertilizers and soil amendments hold promise for improving cultivation outcomes, yet their combined effects remain under - explored.

Methods

A field experiment was conducted with seven treatments, including a control (CK) and six combinations of Trichoderma harzianum, Bacillus subtilis, and earthworm polysaccharide. Plant samples were analyzed for yield, quality, and root architecture, while soil samples were tested for fertility and microbial community characteristics.

Results

Treatments T3 (dual bacterial fertilizers) and T6 (dual bacterial fertilizers + soil amendment) significantly enhanced yield, nutritional quality, and root development. T6 also maintained high soil fertility and optimized the soil microbial community in terms of richness, diversity, and beneficial species abundance.

Discussion

The positive effects of T3 and T6 are likely due to the synergy between the bacterial fertilizers and the soil amendment, which improves nutrient cycling, soil structure, and microbial functions. However, the study has limitations, such as the need for long - term research and more in - depth exploration of microbial functions.

Unraveling the synergistic effect of biochar and potassium solubilizing bacteria on potassium availability and rapeseed growth in acidic soil

Potassium (K) is an essential macronutrient for plant growth. However, its bioavailability is low in acidic soils. Excessive K fertilization deteriorates the soil health, thus highlighting the need for sustainable alternatives. In previous studies, biochar application has been proven to be an effective amendment. Meanwhile, various potassium solubilizing bacteria (KSB) have been identified in soil that contributes to K bioavailability. However, their interaction under combine (co) application in acidic soil and its effects on K availability remain poorly understood. Therefore, a pot experiment was conducted to investigate the synergistic effect of co-application of rice straw biochar (BC) and KSB consortium on K availability to promote rapeseed growth. The treatment plan consisted of CK (control), recommended K fertilizer, 2 % BC (2 % w/w), KSB consortium, KSB consortium + 2 % BC (2 % w/w). Results of soil analysis conducted after crop maturity showed that co-application of 2 % BC and KSB consortium significantly improved the soil pH and organic matter contents by 0.62 and 12.52 units respectively, relative to CK. Meanwhile, soil available nutrients were greatly enhanced, as available K content increased by 52.1 %, which indicated that co-application of 2 % BC and KSB consortium could facilitate the better conversion of different forms of soil K and make it available for plant uptake. Furthermore, it also improved extracellular enzymatic activities (26.7-71.6 %) and soil bacterial community (Actinobacteriota and Firmicutes). These improvements greatly enhanced plant biomass (46 %) and yield (31 %). Overall results proved that co-application of 2 % BC and KSB effectively enhanced K availability for sustainable plant growth. Still, there is a need to identify the most efficient KSB strains that, in conjugation with BC, reduce the K fertilizer usage.

Spatial variation of soil quality limiting indicators in the North China

The identification of cultivated land obstacle indicators and their spatial distribution are preconditions to soil quality and productivity improvement. This study takes the North China as the objective, using principal component analysis (PCA), entropy TOPSIS and obstacle degree (OD) models to establish a systematic evaluation framework to identify the major limiting indicators. Results reveal that 17.0% of the cultivated land faces severe obstacles, 32.1% and 41.9% experience moderate and slight obstacles, respectively. Only 9.0% of the land shows no significant obstacles. Soil pH and the available potassium content (AK) emerged as the most critical limiting indicators, severely affecting 42.0% and 27.2% of the land, respectively. Other indicators like soil total nitrogen (TN), organic matter (OM) content and cultivated-layer thickness (CLT) exhibited slight obstacles, while AP and BD showed no significant limitations. Spatial analysis highlighted that the pH, AP and BD present notable obstacle incidences, followed by OM and TN. Furthermore, spatial overlap of multiple obstacle indicators was also revealed, 87.1% of the area were limited by more than 3 indicators in the North China. The systematic framework proposes an effective tool for guiding the accurate regional cultivated land quality improvement.

The Effects of Sewage Sludge Biochar on Rhizosphere Microbial Community, Soil Quality, and Ryegrass and Cosmos Growth in Pot Culture

Sewage sludge biochar (SSB) is an innovative environmental material with remediation capabilities and significant potential for soil enhancement. This study aimed to accurately assess the dual regulatory effects of SSB on plant growth and soil quality. We conducted potting experiments with ryegrass and cosmos to analyze the impacts of SSB on plant growth, soil quality, and microbial communities. The partial least squares path model (PLS-PM) analysis was employed to elucidate the intrinsic relationships between SSB application and soil environmental factors, microbial communities, and plant growth. The results indicated that the application of SSB significantly enhanced the growth of ryegrass and cosmos, improved the soil quality, and increased the quantity of soil beneficial bacteria in the inter-root soil microbial communities. The addition of 9% and 3% (w w-1) SSB resulted in the most substantial growth of ryegrass and cosmos, with aboveground biomass increasing 68.97% and 68.12%, respectively, and root biomass increasing by 49.87% and 45.14%. PLS path analysis revealed that SSB had a significant effect on the number of bacteria, which also played an important role in soil environmental factors such as pH and conductivity. This study provides a scientific basis for the utilization of sludge resources, green agriculture, and soil improvement. Additionally, it offers technical support for optimizing the application strategy of sludge biochar.

Comparative and synergistic impacts of lime and biochar on soil properties, nitrogen transformation, and microbial function in acidic soils under tobacco cropping

Introduction

Lime and biochar are widely utilized to enhance nitrogen utilization in crops grown on acidic soils, though each has its own set of limitations. Understanding their combined effects is crucial for optimizing soil remediation strategies.

Methods

This study investigates the impact of lime and biochar on nitrogen utilization efficiency (NUE) in a tobacco monoculture system, which has been practiced for 20 years on acidified soils in Fuzhou, southeastern China, over the period from 2021 to 2022. Four treatments were applied: control (CK), lime alone (L), biochar alone (B), and a lime-biochar combination (L+B).

Results

The results indicated that all treatments significantly improved NUE, with increases ranging from 20.07% to 27.17% compared to CK. Biochar (B) was more effective than lime (L), and the combined treatment (L+B) showed comparable effects to biochar alone. Correlation analysis revealed that increases in soil pH and exchangeable base cations facilitated nitrogen transformation, thereby enhancing NUE. Lime treatments (L, L+B) promoted nitrification potential in rhizosphere soil, whereas biochar application (B, L+B) resulted in elevated nitrate nitrogen content. Microbial functional analysis indicated that lime (L, L+B) enhanced nitrification, while biochar (B, L+B) fostered dissimilatory nitrate reduction, thereby improving nitrogen retention. Pearson correlation analysis demonstrated a strong positive relationship between dissimilatory nitrate reduction and both soil alkali-hydrolyzable nitrogen and nitrate nitrogen contents.

Conclusion

These findings suggest that lime enhances nitrification, while biochar promotes nitrate retention, together increasing soil nitrogen availability. The combined application of lime and biochar integrates these benefits, yielding results comparable to biochar alone. This study offers valuable insights into the synergistic use of lime and biochar for mitigating soil acidification and optimizing nitrogen management in agricultural systems.

Density functional theory calculation for understanding the roles of biochar in immobilizing exchangeable Al3 + and enhancing soil quality in acidic soils

Soil acidification poses a significant threat to agricultural productivity and ecological balance. While lime is a common remedy, it can have limitations, including nutrient deficiencies and potential soil compaction. Therefore, exploring alternative and sustainable amendments is crucial. This study investigated the efficacy of biochar as a substitute for lime in reducing soil acidification and improving soil quality. Through incubation experiments, we compared the effects of biochar and lime on soil properties. Additionally, we employed density functional theory (DFT) calculations to elucidate the mechanisms underlying biochar's ability to immobilize exchangeable Al3+. Furthermore, we conducted 15N double-labeled incubation experiments to examine the impact of biochar on soil nitrogen (N) transformation in acidic conditions. Our results indicated that biochar was as effective as lime in enhancing soil quality and mitigating acidification. Soils developed from the Jurassic Shaximiao Formation (J2s) purple mudstone with 3 % biochar addition exhibited a 31.15 % and 17.43 % increase in total N compared to soils treated with 0.1 % and 0.2 % lime, respectively. Similarly, soils developed from the Cretaceous Jiaguan Formation (K2j) purplish red sandstone with 1 % and 3 % biochar addition showed a 38.75 % and 64.30 % increase in soil organic carbon compared to soils treated with 0.2 % lime. DFT calculations revealed that biochar's functional groups exhibited a stronger affinity for immobilizing exchangeable Al3+ than other soil cations. This preferential adsorption was attributed to the stronger interaction and higher bond dissociation energy between biochar functional groups and Al3+. These findings collectively highlight the potential of biochar as a sustainable and effective amendment to reduce Al toxicity in acidic soils, thereby promoting soil quality and sustainable agricultural and ecological practices.

Evaluating a Soil Amendment for Cadmium Mitigation and Enhanced Nutritional Quality in Faba Bean Genotypes: Implications for Food Safety

Soil amendments combined with low cadmium (Cd)-accumulating crops are commonly used for remediating Cd contamination and ensuring food safety. However, the combined effects of soil amendments and the cultivation of faba beans (Vicia faba L.)-known for their high nutritional quality and low Cd accumulation-in moderately Cd-contaminated soils remain underexplored. This study investigates the impact of a soil amendment (SA) on agronomic traits, seed nutrition, and Cd accumulation in 11 faba bean genotypes grown in acidic soil (1.3 mg·kg-1 Cd, pH 5.39). The SA treatment increased soil pH to 6.0 (an 11.31% increase) and reduced DTPA-Cd by 37.1%. Although the average yield of faba beans decreased marginally by 8.74%, it remained within the 10% national permissible limit. Notably, SA treatment reduced Cd concentration in seeds by 60% and significantly mitigated Mn and Al toxicity. Additionally, SA treatment enhanced levels of essential macronutrients (Ca, Mg, P, S) and micronutrients (Mo, Cu) while lowering Phytate (Phy)/Ca, Phy/Mg, and Phy/P ratios, thus improving mineral nutrient bioavailability. Among the genotypes, F3, F5, and F6 showed the most favorable balance of nutrient quality, and yield following SA application. This study provides valuable insights into the effectiveness of SA for nutrient fortification and Cd contamination mitigation in Cd-contaminated farmland.

Acidic Stress Induces Cytosolic Free Calcium Oscillation, and an Appropriate Low pH Helps Maintain the Circadian Clock in Arabidopsis

Acidic stress is a formidable environmental factor that exerts adverse effects on plant growth and development, ultimately leading to a potential reduction in agricultural productivity. A low pH triggers Ca2+ influx across the plasma membrane (PM), eliciting distinct responses under various acidic pH levels. However, the underlying mechanisms by which Arabidopsis plant cells generate stimulus-specific Ca2+ signals in response to acidic stress remain largely unexplored. The experimentally induced stimulus may elicit spikes in cytosolic free Ca2+ concentration ([Ca2+]i) spikes or complex [Ca2+]i oscillations that persist for 20 min over a long-term of 24 h or even several days within the plant cytosol and chloroplast. This study investigated the increase in [Ca2+]i under a gradient of low pH stress ranging from pH 3.0 to 6.0. Notably, the peak of [Ca2+]i elevation was lower at pH 4.0 than at pH 3.0 during the initial 8 h, while other pH levels did not significantly increase [Ca2+]i compared to low acidic stress conditions. Lanthanum chloride (LaCl3) can effectively suppress the influx of [Ca2+]i from the apoplastic to the cytoplasm in plants under acid stress, with no discernible difference in intracellular calcium levels observed in Arabidopsis. Following 8 h of acid treatment in the darkness, the intracellular baseline Ca2+ levels in Arabidopsis were significantly elevated when exposed to low pH stress. A moderately low pH, specifically 4.0, may function as a spatial-temporal input into the circadian clock system. These findings suggest that acid stimulation can exert a continuous influence on intracellular calcium levels, as well as plant growth and development.

Effects of soil acidification on humus, electric charge, and bacterial community diversity

Soil acidification due to the long-term application of nitrogenous fertilizers and the consequent impact on crop growth have been frequently reported. The effects of acidification on soil humus, charge, and microbial communities need to be studied. In this experiment, fertilizer drenching was used to simulate the effects of multiple years of fertilizer application on the black soil. The results showed that 25 years of soil acidification treatment resulted in a decrease of 8.97% in the content of stable humus and led to a decrease of 58% and 51.18% in the humic acid (HA) content and degree of humification (PQ) value in stable humus, respectively. In addition, soil acidification leads to a significant decrease in total negative charge (CEC8.2) and variable negative charge (CECv), with both decreasing by 63.28% and 88.67%, respectively, at 25 years. Acidification treatments affected both soil microbial community abundance and diversity, with a significant decrease in Acidobacteriota and Gemmatimonadota abundance and an increase in Bacteroidia abundance and Acidobacteriota abundance at 25 years.

Silicon Nanomaterials Enhance Seedling Growth and Plant Adaptation to Acidic Soil by Promoting Photosynthesis and Antioxidant Activity in Mustard (Brassica campestris L.)

Soil acidity is a divesting factor that restricts crop growth and productivity. Conversely, silicon nanomaterials (Si-NMs) have been praised as a blessing of modern agricultural intensification by overcoming the ecological barrier. Here, we performed a sequential study from seed germination to the yield performance of mustard (Brassica campestris) crops under acid-stressed conditions. The results showed that Si-NMs significantly improved seed germination and seedling growth under acid stress situations. These might be associated with increased antioxidant activity and the preserve ratio of GSH/GSSG and AsA/DHA, which is restricted by soil acidity. Moreover, Si-NMs in field regimes significantly diminished the acid-stress-induced growth inhibitions, as evidenced by increased net photosynthesis and biomass accumulations. Again, Si-NMs triggered all the critical metrics of crop productivity, including the seed oil content. Additionally, Si-NMs, upon dolomite supplementation, further triggered all the metrics of yields related to farming resilience. Therefore, the present study highlighted the crucial roles of Si-NMs in sustainable agricultural expansion and cropping intensification, especially in areas affected by soil acidity.

Biochar Amendments and Phytoremediation: A Combined Approach for Effective Lead Removal in Shooting Range Soils

The increasing contamination of soil with heavy metals poses a problem to environmental sustainability. Among these pollutants, lead is particularly concerning due to its persistence in the environment, with harmful effects on human health and ecosystems. Various strategies that combine phytoremediation techniques with soil amendments have emerged to mitigate lead contamination. In this context, biochar has gained significant attention for its potential to enhance soil quality and remediate metal-contaminated environments. This study aims to investigate the combined effect of biochar amendments on the phytoremediation of lead-contaminated shooting range soils. A series of experiments were conducted to determine the impact of the amount and distribution of biochar on lead removal from soil. Soil samples were incubated with biochar for one week, after which two types of seeds (Brassica rapa and Lolium perenne) were planted. Plant and root lengths, as well as the number of germinated seeds, were measured, and a statistical analysis was conducted to determine the influence of the amendments. After one month, the Pb concentration decreased by more than 70%. Our results demonstrate that seed germination and plant growth were significantly better in soil samples where biochar was mixed rather than applied superficially, with the optimal performance observed at a 10% wt. biochar amendment. Additionally, the combined use of biochar and phytoremediation proved highly effective in immobilizing lead and reducing its bioavailability. These findings suggest that the combination of biochar, particularly when mixed at appropriate concentrations, and Brassica rapa significantly improved lead removal efficiency.

Fertilization Type Differentially Affects Barley Grain Yield and Nutrient Content, Soil and Microbial Properties

The use of artificial fertilizers follows the intensification of agricultural production as a consequence of population growth, which leads to soil depletion, loss of organic matter, and pollution of the environment and production. This can be overcome by increasing the use of organic fertilizers in agriculture. In the present study, we investigated the effect of using vermicompost, biochar, mineral fertilizer, a combination of vermicompost and mineral fertilizer, and an untreated control on alluvial-meadow soil on the development of fodder winter barley Hordeum vulgare L., Zemela cultivar. We used a randomized complete block design of four replications per treatment. Barley grain yield, number of plants, and soil and microbiological parameters were studied. We found statistically proven highest grain yield and grain protein values when applying vermicompost alone, followed by the combined treatment and mineral fertilizer. The total organic carbon was increased by 70.2% in the case of vermicompost and by 44% in the case of combined treatment, both compared to the control. Thus, soil microbiome activity and enzyme activities were higher in vermicompost treatment, where the activity of β-glucosidase was 29.4% higher in respect to the control, 37.5% to the mineral fertilizer, and 24.5% to the combined treatments. In conclusion, our study found the best overall performance of vermicompost compared to the rest of the soil amendments.

Effects of soil pH on the growth, soil nutrient composition, and rhizosphere microbiome of Ageratina adenophora

Ageratina adenophora is an invasive weed species found in many countries. Methods to control the spread of this weed have been largely unsuccessful. Soil pH is the most important soil factor affecting the availability of nutrients for plant and impacting its growth. Understanding the mechanisms of the influence of soil pH on the growth of A. adenophora may help to develop effective control measures. In this study, we artificially changed the soil pH in pot experiments for A. adenophora. We studied the effects of acidic (pH 5.5), weakly acidic (pH 6.5), neutral (pH 7.2), and alkaline (pH 9.0) soils on the growth, availability of soil nutrients, activity of antioxidant enzymes, levels of redox markers in the leaves, and the structure and diversity of the rhizosphere microbiome. Soil with a pH 7.2 had a higher (47.8%) below-ground height versus soils of pH 5.5 at day 10; plant had a higher (11.3%) above-ground height in pH 7.2 soils than pH 9.0 soils at day 90; no differences in the fresh and dry weights of its above- and belowground parts, plant heights, and root lengths were observed in plants growing in acid, alkaline, or neutral pH soil were observed at day 180. Correspondingly, the antioxidant enzymes SOD (superoxide dismutase), POD (peroxidase), CAT (catalase) and redox markers GSH (glutathione) and MDA (malondialdehyde) were measured in the leaves. Significant differences existed in the activities of CAT and the levels of GSH between those growing in acidic and alkaline soils and those in neutral pH soil at day 90; however, only lower (36.8%) CAT activities in those grown at pH 5.5 than those grown at pH 7.2 were found at day 180. Similarly, significant differences in available P (16.89 vs 3.04 mg Kg-1) and total K (3.67 vs 0.96 mg Kg-1), total P (0.37 vs 0.25 g Kg-1) and total N (0.45 vs 1.09 g Kg-1) concentrations were found between the rhizosphere soils of A. adenophora grown at pH 9.0 and 7.2 at day 90; no such differences were seen at day 180. High throughput analyses of the 16S rRNA and ITS fragments showed that the rhizosphere microbiome diversity and composition under different soil pH conditions changed over 180 days. The rhizosphere microbiomes differed in diversity, phylum, and generic composition and population interactions under acid and alkaline conditions versus those grown in neutral soils. Soil pH had a greater impact on the diversity and composition of the prokaryotic rhizosphere communities than those of the fungal communities. A. adenophora responded successfully to pH stress by changing the diversity and composition of the rhizosphere microbiome to maintain a balanced nutrient supply to support its normal growth. The unusual pH tolerance of A. adenophora may be one crucial reason for its successful invasion. Our results suggest that attempts use soil pH to control its invasion by changing the soil pH (for example, using lime) will fail.

Long-term liming mitigates the positive responses of soil carbon mineralization to warming and labile carbon input

Liming, as a common amelioration practice worldwide, has the potential to alleviate soil acidification and ensure crop production. However, the impacts of long-term liming on the temperature sensitivity (Q10) of soil organic carbon (SOC) mineralization and its response to labile C input remain unclear. To fill the knowledge gap, soil samples were collected from a long-term (∼10 years) field trial with unlimed and limed (CaO) plots. These soil samples were incubated at 15 °C and 25 °C for 42 days, amended without and with 13C-labeled glucose. Results showed that compared to the unlimed soil (3.6-8.6 mg C g-1 SOC), liming increased SOC mineralization (6.1-11.2 mg C g-1 SOC). However, liming significantly mitigated the positive response of SOC mineralization to warming, resulting in a lower Q10. Long-term liming increased bacterial richness and Shannon diversity as well as their response to warming which were associated with the decreased Q10. Furthermore, the decreased Q10 due to liming was attributed to the decreased response of bacterial oligotrophs/copiotrophs ratio, β-glucosidase and xylosidase activities to warming. Labile C addition had a strong impact on Q10 in the unlimed soil, but only a marginal influence in the limed soil. Overall, our research highlights that acidification amelioration by long-term liming has the potential to alleviate the positive response of SOC mineralization to warming and labile C input, thereby facilitating SOC stability in agroecosystems, especially for acidic soils in subtropical regions.

Mitigating life-cycle environmental impacts and increasing net ecosystem economic benefits via optimized fertilization combined with lime in pomelo production in Southeast China

Excessive fertilization is acknowledged as a significant driver of heightened environmental pollution and soil acidification in agricultural production. Combining fertilizer optimization with soil acidity amendment can effectively achieve sustainable crop production in China, especially in Southeast China. However, there is a lack of long-term studies assessing the environmental and economic sustainability of combining fertilizer optimization with soil acidity amendment strategies, especially in fruit production. A four-year field experiment was conducted to explore pomelo yield, fruit quality, and environmental and economic performance in three treatments, e.g., local farmer practices (FP), optimized NPK fertilizer application (OPT), and OPT with lime (OPT+L). The results showed that the OPT+L treatment exhibited the highest pomelo yield and fruit quality among the three treatments. The OPT treatment had the lowest net greenhouse gas (GHG) emissions among the three treatments, which were 90.1 % and 42.6 % lower than those in FP and OPT+L, respectively. It is essential to note that GHG emissions associated with lime production constitute 40.7 % of the total emissions from fertilizer production. The OPT+L treatment reduced reactive nitrogen (Nr) emissions and phosphorus (P) losses, compared to FP and OPT. Moreover, the OPT+L treatment increased the net ecosystem economic benefit by 220.3 % and 20.3 % compared with the FP and OPT treatments, respectively. Overall, the OPT and OPT+L treatments underscore the potential to achieve environmentally friendly and economically sustainable pomelo production. Our study provides science-based evidence to achieve better environmental and economic performance in pomelo production through optimized NPK fertilization and alleviating soil acidification by lime.