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Liming is essential for enhancing economic viability and increasing crop production in acidic soil in tropical and subtropical regions. However, continuous limestone application has been associated with cationic micronutrient deficiency, including zinc (Zn). In an experiment under greenhouse conditions using three soils of different textural classes (Typic Alfisol, Typic Oxisol, and Typic Entisol), we evaluated the growth of soybean after fertilization with limestone and Zn. We applied dolomitic limestone at two rates (equivalent to 0 and 5.0 Mg ha−1) and Zn at four rates (0, 5, 10, and 20 mg kg−1), each with four replicates. These three soil types exhibited distinct nutrient availability. Liming significantly altered soil chemical attributes, particularly causing considerable reduction in Zn availability in Typic Alfisol. Furthermore, liming led to a reduction in Zn concentration in soybean leaves and grains in all the three soil types. Grain yield (GY) increased in the presence of liming, and yield was further enhanced with increasing Zn concentrations. Positive effect was also seen on photosynthetic rate (A), stomatal conductance (gs), and leaf N, Ca, and Zn concentrations, except on P concentration. Even with adequate nutrient concentrations and limestone application, sandy soils had a lower GY. [ABSTRACT FROM AUTHOR]

Knowledge of plant growth dynamics is essential where constraints such as COVID-19 lockdown restrictions have limited its field establishment. Thus, modeling can be used to predict plant performance where field planting/monitoring cannot be achieved. This study was conducted on the growth dynamics of rubber planted on two acid soils treated with either dolomitic limestone (GML), kieserite or Mg-rich synthetic gypsum (MRSG) to supply the Mg required by rubber seedlings. To understand the effect of applied treatments on the changes in rubber growth, data on plant height, stem diameter and biomass were regressed against months after transplanting (MAT) using the equation y = A/ (1+be-ct), and its derivative dydt=Abce−ct(1+be−ct)z was utilized for estimating the growth rate of the parameters. The dynamics in plant height, stem girth and plant biomass were modelled using an exponential function of y = Aebt and their rate of change was derived using dx/dy = Abebt. The experiment indicated that the logistic growth curve model expressed as y = A/ (1+be-ct), closely described the growth in terms of each parameter against months after transplanting. A high probability level (a = 0.0001) was recorded in the model for all the treatments in the study. The growth of rubber seedlings in the glasshouse was improved by MRSG treatment in the two studied soils (Ultisol and Oxisol), giving comparable results to other Mg fertilizer treatments. The plant performed better on the Ultisol compared to the Oxisol. The results indicate the potential of using MRSG to replace conventional Mg-fertilizers to sustain rubber seedling growth. [ABSTRACT FROM AUTHOR]

Considering the fixation and low availability of conventional phosphatic fertilizer in acidic soil, zeolite based nano phosphatic fertilizer was synthesized to investigate its release characteristics in acidic soil system via invitro studies. Result revealed that surface modification through a cationic surfactant improved the adsorption capacity of zeolite for phosphorus by 60%. Under the incubation study, the zeolite based nano phosphatic fertilizer sustained the release of phosphorous up to 90 days of incubation against 32 days under conventional SSP. The 100% replacement of RDP through nano fertilizer registered the maximum release of P in soil up to 9.36 mg/kg which was 23.80% higher than conventional SSP (7.56 mg/kg). The study release kinetics also revealed parabolic diffusion equation (3.012 µg/g/day) as the most suitable module for describing the P release as compared to other kinetic modules. Thus, zeolite can be used as carrier material for preparation of nano fertilizer for sustainable release of P for longer period of time under acidic soil. [ABSTRACT FROM AUTHOR]

This research aimed to select N2-fixation purple nonsulfur bacteria (PNSB) from saline acidic soils (SAS) in rice-shrimp system to enhance rice growth and yield. Two PNSB with highest nitrogen-releasing strains Luteovulum sphaeroides S01 and S06 were used, and the SAS was collected from Hong Dan and Thanh Phu districts. The 4 × 4 factorial experiment was carried out in a completely randomized block design, including a main factor as the liquid biofertilizers and the minor factor as the N fertilizer levels, with four replicates in a greenhouse. Both individual and mixed PNSB liquid biofertilizers significantly increased pH value and NH4+ content and reduced the exchangeable Na+ in both SAS sites. This led to 24.8–113.2% higher N uptake in rice and 6.48–30.5% lower Na accumulation in straw and 16.3–47.6% Na in grain. These results were considered as an evidence to improve rice grain yield by 27.5–56.6%. The L. sphaeroides S01 and S06 was greatly suitable for using as a biofertilizer for rice under saline acidic conditions. [ABSTRACT FROM AUTHOR]

Soil acidity has negative effects on both plants and soil. Furthermore, liming is the most common and effective management practice used to neutralize the acid produced in the soil and the problems associated with soil acidification. The study evaluated whether liming impacts wheat growth, yield, nutritional status basis exchangeable, and their related soil acidity indices. A greenhouse experiment was performed under a completely randomized arrangement, with four lime application rates equivalent to (0, 4.0, 8.0, and 12.0 Mg ha−1). The results showed that all yield components significantly increased with increasing lime addition rate. The grain yield, shoot and root dry weight, and plant and spike height improved quadratically (R2 = 0.909, 0.950, 0.976, 0.902, and 0.891, respectively). Additionally, the lime rate influenced P and Mg concentrations in the shoot, and the concentrations of Cu and Zn. With increasing lime rate, the soil exchangeable Ca and Mg concentrations increased quadratically (R2 = 0.969 and 0.984), while the soil exchangeable K and Al concentrations decreased significantly. The pH of the soil solution increased linearly (R2 = 0.994) with the lime addition rate. Liming significantly reduced the exchangeable Al3+ and Al + H in the soil. Finally, liming improves wheat yield in acid soil by reducing the negative effects of Al and H by increasing soil pH, Ca2+, and Mg2+ concentration, consequently improving root growth and resulting in wheat yield. Liming increased the grain yield by 188.7, 198.2, and 322.8% following the increase of lime rate, if compared to the control. Furthermore, lime enhances plant resilience by raising pH and improving soil nutrient availability and the root system. [ABSTRACT FROM AUTHOR]

Sustainable Kikuyu (Pennisetum clandestinum) production in the Peruvian highlands was evaluated through productivity, growth, and chemical composition. This study assessed the effects of nitrogen (N) rate, organic matter application, and cutting frequency on Kikuyu grass's yield, chemical composition, plant height, and growth rate. The experiment followed a randomised block design with split plots. A multivariate analysis of variance (MANOVA) assessed the differences across study factors. Applying 120 kg of N ha−1 yr−1 raised the protein yield to 3454.53 kg ha−1, with a crude protein (CP) content of 23.54%. Moreover, fencing with cypress (Cupressus lusitanica) trees influenced the Kikuyu biomass, producing 19,176.23 kg of dry matter (DM) ha−1 yr−1 at 8.5–11.5 m from the tree base. Organic matter enhanced the Kikuyu aboveground biomass. While dry matter production showed no significant difference between 30- and 60-day cutting intervals, CP content was higher at 30 days (p < 0.05). Peak daily dry matter (DM) production occurred at 45 days, achieving a biomass accumulation of 21,186.9 kg of DM ha−1 yr−1. Given its high yield and favourable chemical composition, Kikuyu is a viable option for dairy cattle feed, especially in highland areas. Implementing a plant improvement programme for Kikuyu could further enhance its nutritional value for high-production dairy cows. [ABSTRACT FROM AUTHOR]

In order to reveal the effects of microplastics (MPs) on the growth and rhizosphere soil environmental effects of wheat (Triticum aestivum L.), three microplastic types (polypropylene MPs (PP-MPs), high-density polyethylene MPs (HDPE-MPs), and polylactic acid MPs (PLA-MPs)), particle sizes (150, 1000, and 4000 μm), and concentrations (0.1, 0.5, and 1 g·kg−1) were selected for a pot experiment under natural environment conditions. The differences in germination rate (GR), germination inhibition rate (GIR), growth characteristics, physicochemical properties, and enzymatic activities of wheat in rhizosphere soil were analyzed using statistical analysis and variance analysis. The results show that the germination rate of wheat seeds decreased under different MPs, and the HDPE-MPs, medium particle size (1000 μm), and medium concentration (0.5 g·kg−1) had the greatest inhibitory effect on wheat seed germination. The effects of MPs on wheat seed growth characteristics were inconsistent; the germination potential (GP), germination index (GI), and vitality index (VI) showed a significant decreasing trend under the PLA-MPs and medium-concentration (0.5 g·kg−1) treatment, while the mean germination time (MGT) showed a significant increasing trend; the GP and MGT showed a significant decreasing and increasing trend under the high-particle-size (4000 μm) treatment, respectively, while the GI and VI showed a significant decreasing trend under the medium-particle-size (1000 μm) treatment. The growth characteristics of wheat plants showed a significant decreasing trend under different MPs, with the SPAD, nitrogen concentration of the leaves, and plant height decreasing the most under PLA-MP treatment, the SPAD and nitrogen concentration of leaves decreasing the most under low-particle-size (150 μm) and low-concentration (0.1 g·kg−1) treatments, and the decreases in plant height under the high-particle-size (4000 μm) and high-concentration (1 g·kg−1) treatments being the largest. There were significant increasing trends for ammonium nitrogen (NH4+), total phosphorus (TP), soil urease (S-UE), soil acid phosphatase (S-ACP), and soil sucrase (S-SC) under different microplastics, while the PLA-MPs had a significant increasing trend for nitrate nitrogen (NO3−) and a significant decreasing trend for pH; there was a significant decreasing trend for total nitrogen (TN) under the HDPE-MPs and PLA-MPs, and for each particle size and concentration, the PLA-MPs and low-concentration (0.1 g·kg−1) treatments showed a significant decreasing trend for soil catalase (S-CAT). The research results could provide certain data and theoretical bases for evaluating the effects of MPs on crop growth and soil ecological environments. [ABSTRACT FROM AUTHOR]

Soil acidification poses a significant environmental challenge in China's southern red soil regions, impacting the abundance of soil microbes and their capacity for carbon fixation. The effect of vegetation types on soil's biological and abiotic components under acidification, and their regulatory role on the CO2 fixation mechanisms of soil autotrophic microorganisms, is difficult to examine. This gap in understanding constrains the assessment of the carbon fixation potential of red soils. To address this, indoor cultivation coupled with 13C stable isotope labeling was employed to evaluate the disparate abilities of autotrophic microorganisms to assimilate and store CO2 across five vegetation soils from the Qianyanzhou acidic red soil experimental station in China. Findings indicate that carbon fixation rates in these soils spanned from 4.25 to 18.15 mg C kg−1 soil d−1, with paddy field soils demonstrating superior carbon fixation capabilities compared to orchard, coniferous forest, broad-leaved forest, and wasteland soils. The 13C fixation rate in the 0–10 cm soil stratum surpassed that of the 10–30 cm layer across all vegetation types. High-throughput sequencing of 16S rRNA, following cbbL gene purification and amplification, identified Bradyrhizobium , Azospirillum , Burkholderia , Paraburkholderia , and Thermomonospora as the predominant autotrophic carbon-fixing microbial genera in the soil. PERMANOVA analysis attributed 65.72% of the variance in microbial community composition to vegetation type, while soil depth accounted for a mere 8.58%. Network analysis of microbial co-occurrence suggested the soil microbial interactions and network complexity changed with the change of vegetation types. Additionally, multiple linear regression analysis pinpointed the Shannon index and soil organic carbon (SOC) content as primary influencers of carbon fixation rates. Structural equation modeling suggested that iron enrichment and acidification indirectly modulated carbon fixation rates by altering SOC and autotrophic bacterial diversity. This investigation shows the spatial dynamics and mechanisms underpinning microbial carbon fixation across varying vegetation types in southern China's red soil regions. [ABSTRACT FROM AUTHOR]

Due to continuous cultivation, high soil acidity, and low nutrient inputs, soil fertility depletion has been a major threat to northwest Ethiopia's crop productivity and food security. This study aimed to examine the effects of vermicompost and lime rates on soil properties and malt barley (Hordeum distichum L.) productivity under a furrow irrigation system on acidic soil in the Mecha district, northwest Ethiopia. The treatments were combinations of three levels of vermicompost (0, 2.66-, and 5.31-tons ha-1) and three levels of lime (0-, 2.16-, and 3.24-tons ha-1) arranged in a randomized complete block design with three replications. The results showed that the integrated application of 5.31 tons of vermicompost and 3.24 tons of lime ha-1 provided the highest soil pH (6.20), available phosphorus (8.55 mg kg-1), total nitrogen (0.25%), and organic carbon (3.40%). On the other hand, adding vermicompost and lime in combination or separately noticeably decreased the exchangeable acidity and aluminum toxicity. Besides, the integrated application of 5.31 tons vermicompost (VC) and 3.24 tons lime (L ha-1 provided the highest dry biomass (12.22 tons ha-1), grain yield (5.30 tons ha-1), and net benefit (197, 246 Ethiopian Birr (ETB). Overall, the integrated application of vermicompost and lime can substantially increase soil fertility and crop yields. However, this study needs further testing and validation at varied rates in other areas. [ABSTRACT FROM AUTHOR]

The sustainable management of aquaculture by-products is crucial for advancing circular economy practices. Mediterranean mussel shell waste, rich in calcium carbonate, presents a sustainable alternative to conventional liming materials, especially for mitigating soil acidification, a very important and common issue that limits crop productivity. This study evaluated the effectiveness of processed mussel shell waste in enhancing soil pH, organic matter, and nutrient availability. A 180-day pot experiment using highly acidic soil (pH < 4.5) collected from a local field was conducted in a Completely Randomized Design. Treatments involved two grain sizes of mussel shell powder (Fine: <1 mm; Coarse: 1–2 mm) at rates between 0.1 and 6%. Treated soil pH was measured monthly, whereas organic matter, available phosphorus (P), and exchangeable potassium (K) were measured at the beginning and the end of the experiment. The results revealed significant improvements in pH, organic matter, available phosphorus (P), and exchangeable potassium (K), particularly in the Fine Powder treatments. However, total nitrogen (N) remained unaffected. These findings highlight the potential of mussel shells as an eco-friendly and cost-effective amendment, advancing sustainable agriculture and waste recycling, thus contributing to broader conservation efforts by reducing the environmental footprint of aquaculture waste and supporting biodiversity and ecosystem resilience through sustainable resource management. [ABSTRACT FROM AUTHOR]

The sweet basil Ocimum basilicum L. is the subject of numerous studies and is cultivated as a food and ornamental plant. Moreover, O. basilicum could be useful in the prevention of stroke ischemia, and its anticancer properties were recently shown. Caffeic acid derivatives, such as rosmarinic acid (RA), chicoric acid, salvianolic acids, and anthocyanins, provide the medicinal properties of basil. Therefore, investigations of the optimal growth conditions that can provide cost-effective cultivation of highly productive basil plants are relevant and important. The aim of the present work was to study the effects of a combination of soil composition and light conditions on the morphological and biochemical characteristics of O. basilicum. In totally artificial (indoor) environments, light-emitting diodes (LEDs) may provide a broad range of narrowband wavelengths with different intensities. This technology can lower operating costs. In addition to the spectral composition, light intensity (PPFD, µmol m−2s−1) is an important parameter for the optimal growth of plants. In the experiment, we used different spectra of LED lamps with intensities of 300 µmol m−2s−1: warm white, monochromatic (green and red), and a combination of blue and red. Plants were grown under various lighting conditions in soil supplemented with fertilizer, Z-ion, and Crystallon. The results showed that supplementation of soil with Crystallon had a greater effect on the growth of both above- and below-ground parts of O. basilicum plants. Interestingly, growing O. basilicum plants under R and RB light led to a 2-fold increase in the biosynthesis of both the key caffeic acid derivative RA and anthocyanin. However, given that under RB light, there is no positive effect of Crystallon on growth, the productivity of RA and anthocyanin reached a maximum when O. basilicum plants were grown under R light and Crystallon. Under these conditions, the productivity of anthocyanins and caffeic acid derivatives in O. basilicum was more than eight times greater than that in untreated O. basilicum plants. [ABSTRACT FROM AUTHOR]

Soil acidity is a major limiting factor for potato production in Peru's high Andean region. This study aims to predict the spatial variability of soil acidity as a fundamental tool for recommending site-specific liming treatments and to identify the physical–chemical characteristics most closely related to soil acidity. The soil samples were collected from five locations in the province of Pachitea, Huánuco. Descriptive statistics, principal component analysis (PCA), and Pearson correlation analysis were used to identify the soil properties contributing most to total variance and those most strongly correlated with soil acidity. The ordinary geostatistical kriging method evaluated the predictive accuracy for 23 soil properties and liming requirements over a 28,463 ha area, at a spatial resolution of 10 m. Results showed that the Plaza Punta and Buenos Aires locations had more degraded acidic soils, with frequencies between 55% and 100% above the general mean (30.94 ± 24.87%) and the critical threshold (25%) for potato cultivation. Variables such as exchangeable calcium percentage (ECP), Ca2+, Mg2+, sand content, and organic matter strongly correlated with soil acidity, while exchangeable H+ and ECP were the main contributors to the total variance. Geostatistical analysis revealed that Mg2+ and Ca2+ had the highest R2 values (0.87 and 0.76, respectively), indicating a strong fit between observed and predicted values in the spatial analysis of soil acidity. It is concluded that the agricultural dolomite requirements in the localities of Plaza Punta and Buenos Aires exhibit high spatial predictability. Additionally, the analysis of diverse soil physicochemical properties is emphasized as critical for determining precise application rates. [ABSTRACT FROM AUTHOR]

Triticale is recognized worldwide because of its high protein and lysine contents, high production capacity, and adaptability to biotic and abiotic stress conditions, these qualities being taken over from wheat and rye. Triticale is widely used in various fields, such as animal feed in various forms, medicine, baking, beer and alcohol brewing, cellulose, bioethanol industry, and many others. Thus, the demand for triticale grain is increasing, and this has led to the research and improvement in culture technology to obtain superior products, both quantitatively and qualitatively. The purpose of this study was to identify the best varieties of triticale cultivated in the northwest of Romania, sown in different plots, and fertilized on the ground. Additionally, this study was carried out over a period of two years at the Livada Agricultural Research and Development Station, Satu Mare County. This study was located on acidic soil with a pH between 5.19 and 6.65 and a humus content of 2.82%. The climatic conditions in the reference period were extremely variable; in the first year, a deficit of more than 90 mm of precipitation was registered, and in the second year of this study, an increase of more than 34 mm. The effects of additional fertilization were influenced by the level of precipitation. In 2023, additional fertilization with foliar fertilizer brought production increases of 884 kg/ha, compared with 2022, where foliar fertilization in drought conditions led to a decrease in production. The Utrifun variety proved to be the most productive; this foliar fertilized and with biostimulator, sown at 550 seeds/m2, recorded an increase in production of over 4500 kg/ha compared with the Negoiu control and sown at 650 seeds/m2 and fertilized with foliar fertilizer had an increase of over 4370 kg/ha compared with the Negoiu control. It recorded a production of 9700 kg/ha sown at 550 seeds/m2 and fertilized only on the soil, and sown at 450 seeds/m2 and additionally fertilized with foliar fertilizer recorded a production of 10.900 kg/ha. Utrifun was followed by Zvelt which, sown at 450 seed/m2 and fertilized on the soil, recorded 9500 kg/ha, ensuring an increase of 1800 kg/ha compared with the Negoiu control. The lowest production was achieved by the Tulnic variety, which is 2022, sown at 650 seed/m2 and fertilized on the ground, recorded 5874 kg/ha, 1621 kg/ha less than the control variant. The increases in production obtained by these varieties will be confirmed in a subsequent study under different climatic conditions. [ABSTRACT FROM AUTHOR]

Biochars were produced at 350 °C and applied at varying rates (0, 52, 104, and 156 Mg ha−1 and incubation times up to 120 days. Both biochars and limestone significantly improved soil properties like pH, electrical conductivity, cation exchange capacity (CEC), and nutrient availability. Limestone proved most effective, raising pH by 1.3 units on average and increasing EC and CEC, followed by Cadia purpurea- and Tarchonanthus camphoratus-based biochars. Biochars also increased pH, with Cadia purpurea showing the greatest effect (up to a 1.49 unit increase at the highest rate of application). These findings suggest biochar from these expansive plants holds promise for improving acidic soils. However, the optimal application rate, incubation times, and type of amendment (biochar or limestone) likely depend on specific soil characteristics and goals. Further research is needed to explore long-term effects, combined amendment approaches, and cost-effectiveness for long-term soil health, agricultural productivity, and environmental well-being. [ABSTRACT FROM AUTHOR]

Nitrogen (N) transformation inhibitors have been widely recognized as a promising strategy to enhance crop productivity and mitigate N losses. However, the effectiveness of individual or combined inhibitors can vary significantly across different agroecosystems. Using meta‐analysis and cost–benefit analysis (CBA), we synthesized findings from 41 peer‐reviewed studies (285 observations) globally to evaluate the efficacy of urease inhibitors (UIs), nitrification inhibitors (NIs), and combined inhibitors (UINIs). We assessed their influence on soil inorganic N transformations, greenhouse gas emissions, and crop productivity across diverse climates, soil types, cropping systems, and fertilization practices. Our results indicated that combined UINIs were the most efficient, increasing crop yields by 5% and mitigating gaseous emissions by 51% compared to UIs or NIs alone. UINIs achieved these benefits by enhancing crop ammonium (NH4+) availability through regulating urea hydrolysis and prolonging NH4+ retention by suppressing nitrification in the soil. The CBA revealed that the overall economic benefits of UINIs application outweighed the costs, resulting in a net monetary benefit of $23.36 ha−1, equivalent to a 6.4% increase in revenue. Both meta‐regression and random forest analyses suggested that UINIs performance was strongly influenced by factors such as N application rate, organic matter content, and soil pH. Notably, more substantial responses were observed in fine‐textured soils and/or crops exposed to high N fertilization rates. Acidic soils (pH < 6.5) exhibited the largest effect sizes, with increased crop productivity and reduced NH3 volatilization due to specific inhibitory interactions. In conclusion, these findings highlight UINIs beneficial impacts on crop productivity and environmental conservation, achieving a "win‐win" scenario by addressing various N‐loss challenges while enhancing economic outcomes. Further exploration and optimization of the interaction between climate, soil, plant, and management systems and the use of appropriate inhibitors are crucial for maximizing their positive impact on global climate and reaping corresponding economic benefits. [ABSTRACT FROM AUTHOR]

To evaluate the effects of ocean acidification (OA) on the shell morphology of the gastropods, three different populations of Planaxis sulcatus (Born) in the South China Sea (Coast of Borneo) were investigated. All sites are natural rocky shores sharing a very similar geologic setting of the intertidal zone including, water depth, beach topography, and wave energy. The population densities observed during sampling were similar across all three study sites. However, one population lives under low pH due to geochemical discharge from acidic soils (site E), while the other two populations live under higher pH levels (T and U sites). Quantitative analyses of the shell shape using geometric morphometrics demonstrated that OA had a significant effect on the shell morphology, demonstrating that both allometric growth and the calcification process were affected. Shells from the acidified sites were more rounded and had smaller apertures. Moreover, shell size was significantly reduced as a response to OA stress. These shell changes may have arisen to reduce the cost of shell maintenance. As there is also a significant salinity difference among sites, salinity may have influenced the shell shape of the gastropod Planaxis sulcatus and therefore, the role of OA should be examined in areas where all other physicochemical variables are the same. [ABSTRACT FROM AUTHOR]

Sunflower bottom ash (SBA), rich in potassium (K) and low in heavy metals, making it a potential solution for cadmium (Cd)-polluted acidic farmland. Field experiments were conducted to investigate the effects of adding different concentrations of SBA (0%, 0.1%, 0.3%, 0.5%, 1.0%) to Cd-contaminated acidic soil on heavy metal bioavailability, soil fertility, and bacterial community structure. The results showed that the bioavailability of Cd decreased from 0.29 mg/kg in the CK treatment to 0.08 mg/kg in the 1% treatment, and the pH increased from 5.7 to 8.1. Notably, in the 0.3% treatment, catalase, urease, and alkaline phosphatase activities reaching 20, 560, and 4.3 (a.u), respectively, and 16S rRNA sequencing analysis revealed that the Shannon index of the 0.3% treatment was the highest at 5.364, indicating the most favorable soil environment with the greatest microbial diversity. Terrabacter was significantly positively correlated with heavy metal availability, while Dyella exhibited significant positive correlations with the availability of phosphorus (P), K, and soil pH, and Terrabacter and Dyella in the acidic Cd-contaminated soil contributed to reducing heavy metal toxicity and enhancing soil fertility. This study offers a promising approach for resource utilization of SBA, and provides a new technology for improving Cd-polluted acidic farmland. [ABSTRACT FROM AUTHOR]

Soil aggregation plays a critical role in the maintenance of soil nutrient storage and supply. After five years of crop biomass management, field samples from a sandy loam mountain hilly soil were examined for aggregate distribution, physical subfractions within aggregates, and organic nitrogen (N) fractions, such as nonhydrolyzable N (NHN), hydrolysable ammonium N (HAN), amino-sugar N (ASN), amino-acid N (AAN), and hydrolysable unidentified N (HUN). The total N pool and theoretically mineralizable N were used to calculate the soil N storage and supply capacity, respectively. The total N, mineralizable N, and coefficient of mineralisation rate were all considerably raised by crop biomass incorporation. Analysis of covariance structures showed that the organic N fractions had an impact on the supply and storage of N in the soil, with HUN and AAN contributing the most to the potentially mineralizable N and; also HUN and AAN making up the largest portion of the total soil N pool. In comparison to bulk soils that had not had biomass removed, the amounts of organic N components HAN, ASN, AAN, HUN, and NHN were higher by 98.2%, 87.2%, 71.47%, 38.91%, and 43.27%, respectively. Compared to microaggregates, biomass incorporation enhanced soil macroaggregates by 9.37% and had higher organic N percentages and accumulation efficiency. The mineralizable N was significantly correlated with all fractions of N. The inorganic nitrogen and total nitrogen (TN) were higher in 100% biomass inclusion-T5 (60.01 and 841.58) and lowest in total removal of biomass-T1 (24.92 and 479.74). The > 2 mm aggregate size significantly contributed more in organic N fractions rather than 2–0.25 mm or less. [ABSTRACT FROM AUTHOR]

Background and aims: Cadmium (Cd) pollution in rice is a health hazard. to humans. Amendments often decreases soil Cd bioavailability and Cd accumulation in rice plants. However, a complete and quantitative understanding of the effects of soil amendment on soil properties, Cd availability, rice yield, and Cd accumulation in rice is lacking. Methods: A meta-analysis was conducted using data obtained from 436 peer-reviewed articles to evaluate the impact of 11 types of amendments on different variables in a soil-rice system polluted with Cd. Results: Clay minerals, lime, phosphate fertilizers, nanomaterials, industrial by-products, biochar, manure, composite materials, other organic materials, and other inorganic materials significantly reduced the rice Cd content. Amendments decreased brown rice Cd concentrations by 33.4%, increased crop yields by 12.1%, and decreased the soil available Cd by 26.4%, on average. However, no amendments led to economic improvements. The amendments increased soil pH, CEC, and SOC by 7.94%, 14.73%, and 11.97%, respectively, affecting soil Cd forms. The selection of amendments principally determines their inhibitory effects on Cd in brown rice. Subgroup analysis revealed that during intense precipitation (> 2000 mm), amendments were more efficient at decreasing Cd content in brown rice. However, their effectiveness was diminished in loamy soils. Soil pH was essential for regulating accessible Cd in acidic soils. Conclusion: Amendments successfully lowered Cd levels in rice grains and enhanced soil quality while maintaining rice yield. [ABSTRACT FROM AUTHOR]

Background and aims: Growth of Pinus pinea forests and plantations in native countries is known to be affected by soil and climate characteristics. However, edaphoclimatic drivers of growth and fruiting have been scarcely studied outside the species' native range; in addition, the role of soil nutrients, particularly in juvenile trees' development, has been poorly explored. Methods: Relationships between edaphoclimatic variables and the performance of 54 young plantations were studied in Chile. Vegetative growth and fruiting were measured in 100 randomly selected trees per plantation. Composite soil samples were taken from each site to analyze soil chemical characteristics and texture. A principal component analysis was performed including climatic, soil data, and growth and fruiting variables. Results: Annual growth was 1.3 cm year−1 for stem diameter, 28.3 cm year−1 for crown diameter, and 38.9 cm year−1 for height; cone production per crown area was 0.07 cones m−2. Negative correlation of height growth, crown growth and cone production with EC, Na, and pH were found, along with positive correlations with OM, PP and the index PP × AT. Stem diameter growth was favored by less acidic soils with high sand content, and showed no correlation with cone production. Furthermore, vegetative growth was positively correlated with N, P, Mg and clay content. In young plantations, vegetative growth was higher than in the species' native habitat. Conclusion: Soil properties, in particular low EC and Na were identified as favorable for growth of young stone pine trees, along with high content of soil N, P and Mg, and PP. [ABSTRACT FROM AUTHOR]

Aims: Aluminum (Al) toxicity in acid soil significantly reduces plant growth, agricultural productivity and ecosystem health. The Al-tolerant barley cultivars were reported to mainly rely on the Al-activated efflux of citrate from root apices, but the key mechanisms for Al tolerance may differ for wild relatives of barley adapted to acid soil. Methods: Here, we investigated plant Al tolerance from evolutionary physiological, molecular, and ecological perspectives. Results: Phylogenetic analysis of Al tolerance-associated gene families showed that most of these genes were conserved from streptophyte algae to angiosperms, indicating land plants have evolved gradually in adaption to Al-rich acid soil during plant terrestrialization. Vacuolar phosphate transporter SPX-major facility superfamily (SPX-MFS) and inorganic phosphate transporter 1 family (PHT1s) of streptophyte algae showed high genetic similarity to land plants. PHT1s exhibited a significant expand during the evolution from streptophyte algae to liverworts and then eudicots. Al-tolerant Tibetan wild barley accession, XZ29 showed high levels of P-containing glycolytic intermediates including Glu-6-P, Fru-6-P, 3-PGA, 2-PGA and PEP under Al stress. Some primary metabolites were evolutionarily conserved in liverwort, gymnosperm and three tested angiosperms. Furthermore, we found that Al-induced Pi efflux from root elongation zone to chelate rhizosphere Al3+, and immobilization of Al with P at the inner epidermal layer of root mature zone to reduce Al accumulation in the cortical layer in barley. Conclusions: These results indicated that Tibetan wild barley has evolved unique P transport and metabolism for the adaptation to harsh conditions in eastern and southeastern Tibet where acid soils contain high P. [ABSTRACT FROM AUTHOR]

Soil acidification is a significant problem in intensive agricultural systems, particularly in tea plantations. Guizhou province, located in the center of the karst mountainous region of southwest China, has the largest tea plantation area in China. However, the soil acidification characteristics in the tea plantations of Guizhou province, as well as their temporal changes, have not yet been adequately studied. Therefore, soil acidification and associated soil properties in the major tea‐planting counties of Guizhou province were extensively assessed, and the temporal changes in soil acidity over the past 11 years were also evaluated through long‐term and short‐term experiments. The results showed that the average soil pH in the tea plantations in Guizhou province varied from 4.08 to 4.87, with a mean of 4.47. The average cation exchange capacity (CEC), TEA (total exchangeable acidity, TEA), EH (exchangeable H+), and EA (exchangeable Al3+) values were 9.6, 3.7, 5.8, and 19.0 cmol/kg, respectively. Seasonal changes in tea plantation soil pH were observed in low‐ and moderately acidic soils but not in highly acidic soils. The soil pH values did not significantly change during three consecutive years of in situ observations but significantly decreased over the past 11 years at an average of 0.03 yearly. Correlation analysis revealed that the soil pH in tea plantations was significantly positively correlated with the content of specific amino acids, such as glutamic acid, arginine, and valine, but was significantly negatively correlated with certain soil physicochemical properties. The findings of this study indicate that soil acidification in tea plantations of the Guizhou province is severe and possesses distinctive attributes that should be considered for its effective management. [ABSTRACT FROM AUTHOR]

To investigate the effects of kitchen waste on the chemical properties of acidic red soil and the community structure of ammonia–oxidizing archaea (AOA) and ammonia–oxidizing bacteria (AOB), a study was conducted in the flue–cured tobacco farmland ecosystem of the Erlongtan small watershed in central Yunnan. Eight fertilization methods were applied: no fertilization control CK, single application of chemical fertilizer T1 (1 t·hm−2), kitchen waste combined with a chemical fertilizer (T2:12 t·hm−2 + 1 t·hm−2, T3:15 t·hm−2 + 1 t·hm−2, T4:18 t·hm−2 + 1 t·hm−2), and single application of kitchen waste (T5:12 t·hm−2, T6:15 t·hm−2, T7:18 t·hm−2). The numbers twelve, fifteen, and eighteen in brackets represent the amount of food waste applied, and one represents the amount of chemical fertilizer applied. The study evaluated the effects of kitchen waste on soil chemical properties, the community structure and composition of AOA and AOB, and the relationship between soil chemical properties and these microbial communities in acidic red soil. The results showed that: (1) single application of kitchen waste (T5, T6, T7) effectively improved soil nutrient status (SOC increased by 15.79–217.24%; TN increased by 1.53–92.99%; NH4+–N increased by 18.19–520.74%; NO3−–N) increased by 15.54–750.61%), and alleviated acidification. (2) Temporal variations had a more significant effect on the community structure of AOA and AOB than different treatments. The dominant phyla of AOA were Thaumarchaeota, Crenarchaeot. The dominant phylum of AOB was Proteobacteria, and the dominant genera were Nitrosospira and norank_Bacteri. (3) The number of AOA co–occurrence network nodes were equivalent to that of AOB, but AOB had more connection edges, indicating a more complex interaction network. In contrast, AOA exhibited higher modularity, reflecting tighter internal connections and greater stability. The AOA co–occurrence network showed stronger performance during the maturity and fallow stages, while AOB interactions were most active during the topping stage. (4) AOA demonstrated a strong correlation with soil chemical properties during the topping and maturity stages, whereas AOB showed a stronger correlation at the rosette and fallow stages. Among soil chemical factors, pH and SOC were identified as the primary drivers influencing AOA and AOB community abundance and structural differentiation. In conclusion, kitchen waste application enhances the nutrient content of acidic red soil and influences the niche differentiation of AOA and AOB, thereby affecting nitrogen recycling. This approach represents an environmentally friendly and sustainable fertilization method. [ABSTRACT FROM AUTHOR]

Incorporation of plant residues in soil affects microbial community structure and ecological function, which can improve soil fertility. It is reported that substrate qualities could regulate microbial keystone taxa and their interactions, wielding an important effect on nutrient cycling in ecosystems, such as soil labile phosphorus (P) transformation. However, there is little understanding of the specific microbial mechanisms governing P's availability in acidic soils following the incorporation of plant residues of various qualities. In this 210-day incubation experiment, two high-quality residues of pumpkin stover and mango branch and one low-quality residue of rice straw, different in terms of their labile carbon (C) content and carbon/phosphorus ratio (C/P), were separately mixed with an acidic soil. The aim was to investigate how the residues affected the community composition, keystone species, and interaction patterns of soil bacteria and fungi, and how these microbial characteristics altered soil P mineralization and immobilization processes, along with P availability. The results showed that adding high-quality pumpkin stover significantly increased the soil's available P content (AP), microbial biomass P content (MBP), and acid phosphatase activity (ACP), by 63.7%, 86.7%, and 171.7% compared to the control with no plant residue addition, respectively. This was explained by both the high abundance of dominant bacteria (Kribbella) and the positive interactions among fungal keystone species. Adding mango branch and rice straw induced cooperation within fungal communities while resulting in lower bacterial abundances, thereby increasing AP, MBP, and ACP less than the addition of pumpkin stover. Moreover, the labile C of plant residues played a dominant role in soil P transformation and determined the P availability of the acidic soil. Therefore, it may be suitable to incorporate high-quality plant residues with high labile C and low C/P into acidic soils in order to improve microbial communities and enhance P availability. [ABSTRACT FROM AUTHOR]

This study explored the effects of salicylic acid on the growth and biochemical responses of peppermint (Mentha piperita L.) under different soil salinity levels, a major challenge in agricultural productivity. The experiment was conducted using a factorial design with salicylic acid applied at concentrations of 0, 5, 10, and 50 ppm, combined with sodium chloride-induced salinity at 0, 1,000, 2,000, and 3,000 mg kg–1 soil. Results demonstrated that increasing soil salinity negatively impacted plant growth, reducing plant height, leaf number, and the dry weight of aerial parts. Salinity stress also led to reduced nutrient uptake, particularly for essential elements like calcium and potassium, while increasing sodium levels in plant tissues. However, the foliar application of salicylic acid, especially at 50 ppm, significantly improved growth parameters and mitigated the detrimental effects of salinity. Notably, at the highest salinity level (3,000 mg kg–1), salicylic acid enhanced plant height by 11.1% and leaf number by 30.9% compared to untreated plants. Salicylic acid also boosted biochemical responses, such as increasing total phenolic and flavonoid content, which are critical for stress tolerance. This study underscores the potential of salicylic acid as a stress mitigator, promoting better growth and physiological resilience in peppermint under saline conditions, offering valuable insights for improving crop performance in salinity-affected regions. [ABSTRACT FROM AUTHOR]

Aluminum toxicity in acidic soils threatens rice (Oryza sativa L.) cultivation, hindering agricultural productivity. This study explores the potential of plant growth-promoting rhizobacteria (PGPR) as a novel and sustainable approach to mitigate aluminum stress in rice. Two rice varieties, INIAP-4M and SUPREMA I-1480, were selected for controlled laboratory experiments. Seedlings were exposed to varying aluminum concentrations (0, 2, 4, 8, and 16 mM) in the presence of four PGPR strains: Serratia marcescens (MO4), Enterobacter asburiae (MO5), Pseudomonas veronii (R4), and Pseudomonas protegens (CHAO). The INIAP-4M variety exhibited greater tolerance to aluminum than SUPREMA I-1480, maintaining 100% germination up to 4 mM and higher vigor index values. The study revealed that rhizobacteria exhibited different responses to aluminum concentrations. P. protegens and S. marcescens showed the highest viability at 0 mM (2.65 × 1010 and 1.71 × 1010 CFU mL−1, respectively). However, P. veronii and S. marcescens exhibited the highest viability at aluminum concentrations of 2 and 4 mM, indicating their superior tolerance and adaptability under moderate aluminum stress. At 16 mM, all strains experienced a decrease, with P. protegens and E. asburiae being the most sensitive. The application of a microbial consortium significantly enhanced plant growth, increasing plant height to 73.75 cm, root fresh weight to 2.50 g, and leaf fresh weight to 6 g compared to the control (42.75 cm, 0.88 g, and 3.63 g, respectively). These findings suggest that PGPR offer a promising and sustainable strategy to bolster rice resilience against aluminum stress and potentially improve crop productivity in heavy metal-contaminated soils. [ABSTRACT FROM AUTHOR]

It is challenging to accurately analyze and monitor the environmental quality of soils globally because data on precise baseline concentrations are lacking. Colombia is a country where baseline data is practically missing. This study focused on the highly weathered soils of the Piedmont Llanero (hyperhumid equatorial environment). The baseline vanadium (V) concentration was assessed and the possible influence of agricultural land use was examined. The results showed clear variability in V concentrations across land uses. The V content in soils in the natural environment was 5.8–76.7 mg kg−1 with a mean of 31.5 mg kg−1 and in agricultural soils was 20.7–88.6 mg kg−1 with a mean of 51.8 mg kg−1. The overall average was 41.7 mg kg−1 with a range of 5.8–88.6 mg kg−1, which are widely scattered values. The V concentration was compared to the world average values and was within normal ranges versus other areas. The calculated reference value (RV) for V was 38.4 mg kg−1. Based on the contamination factor, contamination was moderate (1.1) in the whole area. No contamination was detected when analyzed with I‐geo (−0.6). These findings clearly suggest that V was moderately contaminating in cultivated soils, but posed no ecological risks in the study area. No simple relation was found between V concentrations and investigated litho‐ and pedogenic factors. This work contains valuable information for not only legislative purposes but also for soil quality RVs in a hyperhumid equatorial climate. [ABSTRACT FROM AUTHOR]

An experiment was performed to understand the effects of aluminium toxicity (AlCl3·6H2O) on Kachai lemon growth and development. The toxic effects of aluminium were assessed for 45 days in sand media. With untreated pots serving as the control, seedlings of 1 month old were exposed to three concentrations of AlCl3·6H2O: 300 μM, 600 μM and 900 μM. The nutrient Hoagland solution was also given to seedlings along with the Aluminium (Al) treatment. The outcome demonstrated that the chlorophyll content and carotenoids declined with the increase of the concentration levels of AlCl3·6H2O and interval of treatment. The contents of O2·− (Super oxide anion), H2O2 (Hydrogen peroxide) and OH (Hydroxyl radical) in seedlings increased with the higher concentration levels of aluminium and longer exposure to Al. Additionally, the activity of the enzymes catalase, superoxide dismutase, ascorbate peroxidase, peroxidase and glutathione reductase were increased in seedlings. Different non-enzymatic antioxidants' actions like tocopherol and Vitamin C played important defence mechanisms for the maintenance of tolerance in aluminium toxicity by increasing their content with an increase in the concentration of treatment levels in Kachai Lemon. [ABSTRACT FROM AUTHOR]

Boron (B) release mechanism is vital in supplying available B, particularly in acidic soils, because a temporary B deficiency can be triggered when liming the soil. This research was conducted with the aim at elucidating the role of Ca on B release kinetics in three acidic soils of Thailand to ascertain the kinetic release of B as affected by added calcium (Ca) from two sources: ground limestone (GL) and calcium chloride (CaCl2). Topsoil samples were incubated with either GL or CaCl2 at 0, 0.5, 1.0, or 1.5 times of the lime requirement for 7 days; thereafter, the soil pH and the kinetics of B release were analyzed based on successive extractions with 0.01 M CaCl2 solution for 72 h, which was comparatively described using four kinetic models: Elovich, parabolic diffusion, power function, and first‐order of which each model would differently provide unique insights into the kinetic release of plant nutrient from soil. The added Ca significantly affected B release into the soil with the release kinetics of B in the two‐time segments only conforming to the power function model in which approximately 70% of B was released rapidly during the initial phase and the rest was in a slow‐release phase later on. Compared at the same rates of Ca applied, CaCl2 accelerated more B release than GL with no statistical difference in some soils. This was directly impacted by a decrease in soil pH as significantly caused by the addition of CaCl2. In addition, the B release rate significantly correlated with soil organic matter (r = 0.699∗∗, p < 0.01). Our findings suggested that increasing soil organic matter should be recommended to provide more B availability but liming or using GL as a Ca source should be cautious as it can lead to B deficiency for plants grown in these acidic soils. [ABSTRACT FROM AUTHOR]

Cement deep mixing piles, as representatives of deep mixing technology, are mature and widely applied. However, effective application cases of cement deep mixing piles are relatively scarce in countries like Malaysia in Southeast Asia. In this paper, the application of cement deep mixing pile reinforcement in Malaysia is presented. Solidifying material was selected for deep mixing piles based on the soil conditions using unconfined compressive strength (UCS) tests. The relationship between the strength of deep mixing piles on-site and soil properties (type, organic matter content, and ion content) was analyzed. And a quality evaluation of the deep mixing piles in the project is conducted based on Kolmogorov-Smirnov (K-S) tests and relevant standards. Results show that fly ash cement is suitable as a solidifying agent for acidic soil layers containing organic matter in the local area. The strength of piles is significantly related to the soil condition. The UCS of cement mixing piles in silty clay and peat soils is smaller than clay. The overall correlation between organic matter content in the soil and UCS is negative, particularly when the organic matter content ranges from 10% to 14%, resulting in a significant drop in UCS. The bilateral significance probability is greater than 0.05 in K-S test, indicating that the UCS results in the projectconform to a normal distribution. Additionally, the evaluation of the overall quality of the mixing piles aligns with the requirements in the Japanese standard "Manual of Deep Mixing Construction Technology for Harbors and Airports" and the Chinese standard "Technical Code for Building Foundation Detection". [ABSTRACT FROM AUTHOR]

Introduction: The Dicranopteris dichotoma fern community plays vital roles in nutrient sequestration, succession regulation, and ecological threshold control. However, the mechanisms underlying the formation of the D. dichotoma –dominant community remain unclear. Methods: This study established four different community types to investigate the effects of environmental factors on the formation of a D. dichotoma –dominant community. Results: We found that climate was the primary factor affecting the formation of patches dominated by D. dichotoma at the regional scale. Specifically, higher annual mean temperature and annual mean precipitation were associated with larger single-dominant-species patches of D. dichotoma. Understory light intensity was the major factor affecting the formation of the D. dichotoma community at the community scale. Light intensity ranging from 200 to 500 µmol·m⁻²·s⁻¹ was most conducive to the development of a large D. dichotoma community. Additionally, understory light intensity enhanced the importance value of D. dichotoma in the herb community by decreasing its biomass proportion of support modules and increasing its biomass proportion of photosynthetic and reproductive modules. Soil properties and D. dichotoma characteristics showed interactions with each other. Acidic red-yellow soil was most suitable for the formation of single-dominant-species patches of D. dichotoma , and the growth of D. dichotoma further decreased the soil pH. Soil total phosphorus content was identified as a limiting factor for formation of the D. dichotoma community. Discussion: In summary, the formation of single-dominant-species patches of D. dichotoma is mainly influenced by a combination of climate, community, and soil. [ABSTRACT FROM AUTHOR]

Aluminium (Al)-tolerant beneficial bacteria confer resistance to Al toxicity to crops in widely distributed acidic soils. However, the mechanism by which microbial consortia maintain Al tolerance under acid and Al toxicity stress remains unknown. Here, we demonstrate that a soil bacterial consortium composed of Rhodococcus erythropolis and Pseudomonas aeruginosa exhibit greater Al tolerance than either bacterium alone. P. aeruginosa releases the quorum sensing molecule 2-heptyl-1H-quinolin-4-one (HHQ), which is efficiently degraded by R. erythropolis. This degradation reduces population density limitations and further enhances the metabolic activity of P. aeruginosa under Al stress. Moreover, R. erythropolis converts HHQ into tryptophan, promoting the synthesis of peptidoglycan, a key component for cell wall stability, thereby improving the Al tolerance of R. erythropolis. This study reveals a metabolic cross-feeding mechanism that maintains microbial Al tolerance, offering insights for designing synthetic microbial consortia to sustain food security and sustainable agriculture in acidic soil regions. The mechanism of soil microbial consortia resistant to aluminium toxicity is unclear. Here, the authors show that the quorum sensing signaling molecular HHQ produced by one member of the consortium can server as the nutritional resource for the other consortium member for aluminium tolerant cell wall component synthesis. [ABSTRACT FROM AUTHOR]

The six phenoxyalkanoic acid herbicides currently used in the European Union have similar molecular structures. Therefore, we assumed the soil components involved in the adsorption mechanisms of these herbicides to be identical. The values of the adsorption distribution coefficient Kd, obtained via batch experiments involving typical Polish Arenosol, Luvisol, and Chernozem profiles with a native pH of 4.2–7.7, were examined using Lasso regression, as well as adsorption on isolated fractions of humic substances, Al2O3, and goethite. The neutral forms of the herbicides were adsorbed on the surface of fulvic acids available to them, covering soil mesopores with a size of > 2.5 nm. The models revealed that fulvic acids had a lognormal-like distribution in soil pores. Herbicide anions were adsorbed on the pH-dependent sites of Al oxyhydroxides and on the sites created by the Al+3 species adsorbed on the surface of fulvic acids (both sites were active up to pH 7.5), the sites of humic acids associated with the adsorbed Al3+ species, sites of Fe oxyhydroxides (active at pH < 5), and, to a limited extent, sites of humins. Two models describing the adsorption of phenoxyalkanoic acid herbicides in soils were created. A simpler model was based on humic substance fractions and the variables related to the potential acidity of soils. In the more extensive model, humic substance fractions and Al and Fe oxyhydroxide contents were used as predictors, and, where necessary, the predictors were combined with the modified Henderson–Hasselbalch formula to estimate the activity ranges of pH-dependent sorption sites. The study findings revealed that fulvic and humic acids were the main adsorbents of phenoxyalkanoic herbicides in soils, indicating that transporting of the herbicides with dissolved organic matter is an important mechanism of groundwater and surface water contamination with these chemicals. [ABSTRACT FROM AUTHOR]

Microplastics have polluted agricultural soils, posing a substantial risk to crop productivity. Moreover, the presence of microplastic pollution has caused a disturbance in the composition of the microbial community in the soil surrounding plant roots, therefore impacting the growth of beneficial bacteria. A study was conducted to examine if humic acid (HA) can counteract the harmful effects of microplastics (MPs) on the growth of black gram crops and the composition of the rhizosphere soil microbial community, to reduce the negative impacts of microplastics on these microorganisms and crops. The research was carried out using mud pots and the plastic utilized for the experiment consisted of 60% high-density polyethylene (HDPE) and 40% polypropylene (PP). The soil was enriched with lignite-based potassium humate, which had a pH range of 8.0–9.5 and with 65% humic acid. The experiment consisted of six treatments: T1, which served as the control without HA and MP; T2, which involved the use of HA at a concentration of 0.15% w/w; T3, which involved the use of MP at a concentration of 0.2% w/w; T4, which involved the use of MP at a concentration of 0.4% w/w; T5, which involved the combination of HA at a concentration of 0.15% w/w and MP at a concentration of 0.2% w/w; and T6, which involved the combination of HA at a concentration of 0.15% w/w and MP at a concentration of 0.4% w/w. The plant growth characteristics, including germination percentage, nodule number, and chlorophyll content, were measured. In addition, the DNA obtained from the rhizosphere soil was analyzed using metagenomics techniques to investigate the organization of the microbial population. Seedlings in soil polluted with MP exhibited delayed germination compared to seedlings in uncontaminated soil. Following 60 days of growth, the soil samples treated with T5 (0.2% MP and 0.15% HA w/w) had the highest population of bacteria and rhizobium, with counts 5.58 ± 0.02 and 4.90 ± 0.02 CFU g−1 soil. The plants cultivated in T5 had the most elevated chlorophyll-a concentration (1.340 ± 0.06 mg g−1), and chlorophyll-b concentration (0.62 ± 0.02 mg g−1) while those cultivated in T3 displayed the lowest concentration of chlorophyll-a (0.59 ± 0.02 mg g−1) and chlorophyll-b (0.21 ± 0.04 mg g−1). Within the phylum, Proteobacteria had the highest prevalence in all treatments. However, when the soil was polluted with MPs, its relative abundance was reduced by 8.4% compared to the control treatment (T1). Conversely, treatment T5 had a 3.76% rise in relative abundance when compared to treatment T3. The predominant taxa found in soil polluted with MP were Sphingomonas and Bacillus, accounting for 19.3% of the total. Sphingomonas was the predominant genus (21.2%) in soil polluted with MP and supplemented with humic acid. Humic acid can be used as a soil amendment to mitigate the negative effects of MPs and enhance their positive advantages. Research has demonstrated that incorporating humic acid into soil is a viable method for maintaining the long-term integrity of soil's physical, chemical, and biological characteristics. [ABSTRACT FROM AUTHOR]

Introduction: Phenolic acids are believed to play a significant role in tobacco continuous cropping obstacles, but the strength and potential mechanisms of different phenolic acids remain unclear. Methods: This study evaluated the allelopathic effects of six phenolic acids that exhibited cumulative effects in our previous research. Different concentrations of phenolic acids with the strongest allelopathic effects were added to potting soil to explore their impacts on tobacco growth and physiological characteristics, as well as on soil chemical properties and microbial community structure. Results: The results showed that coumaric acid exhibited the strongest direct allelopathic effect. Exogenous coumaric acid significantly reduced soil pH and shifted the soil microbial community from bacteria-dominated to fungi-dominated. Simultaneously, the abundance of bacteria related to nutrient utilization (e.g., Flavisolibacter , Methylobacterium) and fungi related to disease resistance (e.g., Fusicolla , Clonostachys) gradually decreased, along with a reduction in soil catalase, urease, invertase, and acid phosphatase activities. Leaf MDA levels increased continuously with higher concentrations of coumaric acid, while the root resistance hormone (jasmonic acid and the jasmonate-isoleucine complex) levels show the opposite trend. Discussion: Coumaric acid may inhibit tobacco growth by influencing the physiological processes in tobacco plants directly and the broader soil microecological balance indirectly. This study provides theoretical guidance for precise mitigation of continuous cropping obstacles in future tobacco cultivation. [ABSTRACT FROM AUTHOR]

Introduction: Long-term use of chemical fertilizers (CFs) can cause soil compaction and acidification. In recent years, bio-organic fertilizers (BOFs) have begun to replace CFs in some vegetables and cash crops, but the application of CFs or BOFs has resulted in crop quality and disease occurrence. Methods: This study aimed to analyze the microbial mechanism of differences between CFs and BOFs in root disease, quality, and yield of tuber Chinese herbal medicine. We studied the effects of CFs, organic fertilizers, commercial BOFs, biocontrol bacteria BOFs, and biocontrol fungi BOFs on rhizosphere microbial community structure and function, root rot, quality, and yield of Codonopsis pilosula at different periods after application and analyzed the correlation. Results and discussion: Compared to CFs, the emergence rate and yield in BOF treatments were increased by 21.12 and 33.65%, respectively, and the ash content, water content, and disease index in the BOF treatments were decreased by 17.87, 8.19, and 76.60%, respectively. The structural equation model showed that CFs promoted the quality and yield of C. pilosula by influencing soil environmental factors, while BOFs directly drove soil bacterial community to reduce disease index and improve the quality and yield of C. pilosula. There was a stronger interaction and stability of soil microbial networks after BOF treatments. Microlunatus , Rubrobacter , Luteitalea , Nakamurella , and Pedomicrobium were identified as effector bacteria, which were related to disease prevention and yield and quality increase of C. pilosula. Microbial functional analysis indicated that the signal transduction and amino acid metabolism of soil bacteria might play a major role in improving the quality and yield of C. pilosula in the early and middle growth stages. In conclusion, compared to CFs, BOFs obtained a lower disease index of root rot and a higher quality and yield of C. pilosula by changing the structure and function of the rhizosphere bacterial community. [ABSTRACT FROM AUTHOR]

To explore the specific effects of pig manure and rice straw on cadmium‐contaminated soils and the effect of different mass fractions of calcium carbonate on cadmium efficacy, a pot experiment was conducted with different rates of pig manure, rice straw, and calcium carbonate. The results showed that pig manure addition increased the soil humic acid/fulvic acid ratio, thereby reducing the available Cd. The addition of calcium carbonate increased the soil pH and reduced the available Cd. The addition of pig manure and calcium carbonate significantly reduced the Cd content of wheat grains by 51.96% and 45.95%, respectively, at 3% and 5% application rates. Rice straw application reduced the soil pH, improved the soil Cd availability, and increased the accumulation of Cd in wheat grains. Compared with that in the control, the grain biomass increased significantly with 3% pig manure and 3% rice straw application, and the grain biomass increased significantly, by 58.86% and 39.11%, and 93.3% and 75.08%, respectively, in 2020 and 2021. With the application of calcium carbonate, the grain biomass of wheat first decreased and then increased. Additionally, the grain biomass significantly increased by 26.36% and 71.22%, respectively, at the 5% calcium carbonate application rate. Therefore, high application rates of pig manure (3% and 5%) have potential application in the safe production of wheat in Cd‐contaminated soils. Core Ideas: The increase in soil humic acid/fulvic acid was the main reason for the reduction in diethylenetriaminepentaacetic acid‐extractable Cd in pig manure‐treated soils.The increase in pH was the main reason for the inhibition of soil Cd by calcium carbonate, and rice straw promoted.The application of pig manure and calcium carbonate increased wheat biomass and inhibited Cd uptake by wheat.The application of pig manure and calcium carbonate increased wheat biomass, inhibited Cd uptake by wheat.Pig manure with a low Cd content has potential for application in the safe production of wheat in Cd‐contaminated soils. [ABSTRACT FROM AUTHOR]

Rice paddies account for approximately 9% of human‐induced methane (CH4) emissions. Nitrogen (N) fertilization affects CH4 emissions from paddy soils through several mechanisms, leading to conflicting results in field experiments. The primary drivers of these N‐related effects remain unclear and the contribution of N fertilization to CH4 emissions from the rice paddies has not yet been quantified for global area. This uncertainty contributes to significant challenges in projecting global CH4 emissions and hinders the development of effective local mitigation strategies. Here, we show through a meta‐analysis and experiments that the impact of N fertilization on CH4 emissions from rice paddies can be largely predicted by soil pH. Specifically, N fertilization stimulates CH4 emissions most strongly in acidic soils by accelerating organic matter decomposition and increasing the activities of methanogens. Accounting for the interactions between soil pH and N fertilization, we estimate that N fertilization has raised current area‐scaled and yield‐scaled CH4 emissions across the total global paddy area by 52% and 8.2%, respectively. Our results emphasize the importance of alleviating soil acidification and sound N management practices to mitigate global warming. [ABSTRACT FROM AUTHOR]

Aims: Characterizing the roles of abundant and rare soil microorganism is vital for clarifying microbial functions and help optimize agricultural management strategies, but their responses to various amendments in acid soils and correlations with crop biomass remain poorly understood. Methods: A 5-year field experiment was conducted to evaluate the influence of amendments, including canola straw (SC), animal manure (OM), and alkaline slag (AS), on abundant and rare bacteria or fungi in acidic bulk and rhizosphere soils in aspect of microbial diversity, compositions, potential functions, and their relationship with canola biomass. Results: Amendments and canola planting significantly affected both bacterial and fungal community structures. Applying AS had pronounced effect on bacterial communities and sub-communities, and the addition of OM showed the strong influence on fungal communities and sub-communities. The sub-community structures of rare bacterial and rare fungal significantly correlated to canola biomass; this correlation was stronger in the rhizosphere soil than that in the bulk soil. The α-diversity of rare rhizosphere bacteria, but not rare bulk bacteria and rare fungi, was significantly positively related to canola biomass. Rare bacteria accounted for the high proportion of nodes and most keystone species in microbial networks, and the number of edges belonging to rare bacteria positively correlated to canola biomass. The predicted functions of rare bacteria also make large contributions to crop biomass. Conclusions: These findings highlight the important roles that rare microbes play in ameliorating acid soils and suggest that rare bacteria should be more closely associated with crop growth than rare fungi. [ABSTRACT FROM AUTHOR]

Aims: This study aimed at comparing the multi-functions of by-product amendments for ameliorating acidic soils, namely, liming effect, aluminum immobilization and fertility improvement. Methods: An incubation experiment was conducted after mixing acidic soils with alkaline slag (AS), biomass ash (BA) and biochar (BC) at similar amounts of alkaline substances input, based on their Acid Neutralizing Capacity (ANC). Soil pH, exchangeable acidity, aluminum (Al) species, soluble and exchangeable basic cations were determined. Results: Among the three amendments, BA application induced the highest soil pH increment in all three acidic soils, although the same amounts of ANC input. BA increased soil pH by 0.28–1.18 units more than AS and BC at ~ 50 mmol kg−1 ANC input. The active alkalis, such as Ca(OH)2, contributed to the liming efficacy of BA. The decrease of soil active Al after amendments application was consistent with the increment of soil pH. The potential active Al pool and amorphous Al content in BC treatments were lower than that in AS and BA treatments, indicating that the stability of immobilized Al by BC was higher than BA and AS. Additionally, BC comprehensively increased the available K+, Ca2+, and Mg2+ in acidic soils. The ratio between soluble and exchangeable basic cations in acidic soils was also favorably optimized by BC. Conclusion: BA, BC and AS showed multi-functions of ameliorating acidic soils. BA presented the greatest liming efficacy due to its highest active alkalinity. BC played an important role in adjusting the supply and retention of basic cations in acidic soils. [ABSTRACT FROM AUTHOR]

Aim: To assess the bioaccessibility of aluminum (Al) by DGT, and to clarify the main factors affecting Al plant accessibility. Methods: An acidic soil amelioration with Ca(OH)2 and peanut straw biochar was established by determining the acid-neutralizing capacity of amendments with constant pH automatic titration, to determine the amount of amendments required to achieve the target soil pH. A pot trial was conducted, Al available to DGT (CDGT) was compared to plant Al content. Plant accessibility of different Al species in the soil solid phase and solution was analyzed. The DIFS model was used to predict the diffusion potential of labile Al from soil solid. Results: The dynamic of CDGT showed an opposite trend to that of soil pH, with a significant decrease in CDGT as pH was increased. There was a highly significant positive linear correlation between CDGT and Al contents in shoots and roots. CDGT showed highly significant positive correlation with Al-Ex and Al-Solid, and highly significant negative correlation with Al-Hy. In soil solution, Al species of Al3+, Al-OH, Al-F, and Al-SO4 were significantly positively correlated with CDGT. Sorption rate k1 values of labile Al in soil solid phase were predicted as 108.15 ~ 495.32 × 10–5 s−1, and desorption rate k-1 values as 30.09 ~ 204.6 × 10–7 s−1 by DGT-DIFS. Conclusions: DGT was an effective tool to assess plant-accessible Al. The co-application of peanut straw biochar with lime better promoted the conversion of soluble Al to low-toxicity Al-OM and Al-Or and reduced the bioaccessibility of Al. [ABSTRACT FROM AUTHOR]

Aims: Biological nitrogen (N) fixation (BNF) driven by diazotrophs plays an essential role in reducing N fertilizer input in acidic soils. Amendments improve the acidic soil environment and increase crop N utilization; however, whether their effects on soil BNF and diazotrophs contribute to crop N utilization remains unclear. Methods: A 5-year field trial was implemented to assess the effects of the sole or joint application of organic and inorganic amendments (straw, manure and alkaline slag) on soil BNF rates, canola N utilization, and diazotrophic communities of acidic bulk and rhizosphere soils. Results: Amendments, especially joint application of organic and inorganic amendments, significantly increased canola biomass, N utilization, soil BNF rates, and diazotrophic abundance. There were positive correlations among BNF rates, N uptake and physiological N use efficiency of canola. Both amendments and canola planting significantly affected the structure of diazotrophic communities, with the stronger effects in the joint application of organic and inorganic amendments. Influences of soil C/N, SOC and diazotrophic α-diversity on BNF rates in rhizosphere soils were greater than in bulk soils. The dominant genus affecting BNF rates differed between bulk and rhizosphere soils. Rhizosphere BNF rates were positively correlated with the number of nodes, total edges, and positive correlations of edges of rhizosphere diazotrophic network, but not in bulk soils. Conclusion: The improved soil BNF by organic and inorganic amendments in acidic soils have positive effects on crop N utilization, and the mechanisms underlying the contribution of diazotrophs to BNF rates differ in bulk and rhizosphere soils. [ABSTRACT FROM AUTHOR]

The use of biochar as a soil amendment for acid soil, particularly acid sulfate soil, has garnered significant interest due to its capacity to improve soil properties, which is further accentuated when combined with dolomite. However, the extent to which the magnitude and direction of this effect vary with biochar produced at different pyrolysis temperatures remains uncertain. We conducted an incubation by mixing soil with dolomite and biochar types derived from Melastoma malabathricum (MMBC) and Dicranopteris linearis (DLBC) at three temperatures (300, 500, and 700°C). The incorporation of dolomite with both biochar types led to significant improvements in soil pH, available P, available Fe, exchangeable K, and exchangeable Ca compared to soil amended with dolomite only. These enhancements were likely attributed to the release of alkalinity, which further raised soil pH, as well as the direct dissolution of P, K, and Ca from the biochar. Moreover, the reduced Fe availability was likely due to the complexation of Fe onto surface functional groups of biochar. Furthermore, these improvements surpassed the effect of the initial feedstock and became increasingly pronounced with higher pyrolysis temperatures. However, an antagonistic effect of dolomite and biochar co‐incorporation was observed, particularly in the relative reduction of soil exchangeable Mg with both biochar types, and a decrease in the soil available N with MMBC produced at 300 and 500°C compared to dolomite addition alone, which could be due to the adsorption of Mg and N onto biochar surface. The results indicate that concurrent application of dolomite and biochar can change the acid sulfate soil properties to varying magnitudes and in different directions, largely regulated by the characteristics of biochar as well as the probable interplay with dolomite. Consequently, selecting the appropriate biochar that aligns with the desired soil properties is crucial in managing dolomite‐treated acid sulfate soil. [ABSTRACT FROM AUTHOR]

Effective evaluation of cultivated land quality is crucial for sustainable agricultural management. Existing research often focuses on regional scales and lacks sufficient detailed analysis of spatial distribution and limiting factors at localized scales. This study aims to select the key indicators to evaluate cultivated land quality and analyze their influence on cultivated land quality at the county level. Taking Changtu County as the research area, principal component analysis (PCA) was employed to identify the most effective Minimum Data Set (MDS) for evaluation, including cultivated layer thickness, soil organic matter (SOM), pH, bulk density (BD), and cultivated layer texture. Additionally, an obstacle degree model was used to analyze restricting factors and their degrees of impact. Results showed that the constructed MDS could replace all indicators for cultivated land quality evaluation. Quality was higher in central areas and lower in eastern and western regions. SOM content decreases with the decrease of quality grade, significantly affecting the quality distribution, and pH in the medium category (Grades III and VI) cultivated lands were lower compared to other categories. Low organic matter content and low pH levels were the main obstacles affecting cultivated land quality, with average obstacle degrees of 43.5% and 29.3%, respectively. Low SOM content significantly affected land quality, particularly in the western region, whereas acidic soils in the eastern region influenced quality grade distribution. Thus, strategies for pH control and SOM enhancement are essential for improving cultivated land quality. This study provides valuable insights into sustainable agriculture. [ABSTRACT FROM AUTHOR]

Studies of the impact of nitrification inhibitors (NIs), specifically DMPP and DMPSA, on N2O emissions during "hot moments" have produced conflicting results regarding their effectiveness after rewetting. This study aimed to clarify the effectiveness of NIs in reducing N2O emissions by assessing residual DMP concentration and its influence on ammonia-oxidizing bacteria (AOB) in two pot experiments using calcareous (Soil C, Calcic Haploxerept) and acidic soils (Soil A, Dystric Xerochrepts). Fertilizer treatments included urea (U), DMPP, and DMPSA. The experiments were divided into Phase I (water application to dry period, 44 days) and Phase II (rewetting from days 101 to 121). In both phases for Soil C, total N2O emissions were reduced by 88% and 90% for DMPP and DMPSA, respectively, compared with U alone. While in Phase I, the efficacy of NIs was linked to the regulation of AOB populations, in Phase II this group was not affected by NIs, suggesting that nitrification may not be the predominant process after rewetting. In Soil A, higher concentrations of DMP from DMPP were maintained compared to Soil C at the end of each phase. Despite this, NIs had no significant effect due to low nitrification rates and limited amoA gene abundance, indicating unfavorable conditions for nitrifiers. The study highlights the need to optimize NIs to reduce N2O emissions and improve nitrogen efficiency, while understanding their interactions with the soil. This knowledge is necessary in order to design fertilization strategies that improve the sustainability of agriculture under climate change. [ABSTRACT FROM AUTHOR]

Selenium, as an essential trace element, is intricately linked to the onset and progression of numerous diseases due to deficiencies in selenium intake. Selenium compounds exhibit tumor specificity and can efficiently inhibit the growth of tumor cells, making them potential candidates for cancer treatment. Nevertheless, given its status as one of the most widely consumed crops globally, increasing the selenium content in rice could prove advantageous in alleviating the prevailing issue of selenium intake deficiency, particularly in China. This review explored the regulatory role of selenium in rice growth, the regional distribution characteristics of soil selenium content in various rice-growing regions in China, and the impact of cultivation practices on selenium fortification in rice, aiming to suggest improved rice cultivation management strategies to enhance the capacity for rice selenium biofortification. The findings revealed that: (1) In Northeast and North China, characterized by alkaline soils and severe selenium deficiency, it is advisable to moderately decrease the duration of flooding, elevate the soil redox potential, and apply organic and nitrogen fertilizers in a judicious manner. (2) In Southwest China, which is characterized by acidic soils, alternating wet and dry irrigation should be employed, and the biofortification of selenium can be facilitated by applying lime and foliar spraying of selenium fertilizer. (3) In the south-central region of China, distinguished by acidic soils and double-cropped rice, it is recommended that intermittent or alternating wet and dry irrigation be employed, and the reasonable application of organic, silica, and selenium fertilizers is advocated. (4) In the northwest region, characterized by slightly alkaline soil and mild selenium deficiency, it is recommended to implement various water management practices, including shallow water during the seedling stage, deep water during the booting stage, and wet grain filling. Additionally, a rational application of nitrogen, phosphorus, and potassium fertilizers, along with foliar application of selenium fertilizer, should be employed. (5) Cultivating selenium-enriched, high-yielding, and high-quality rice varieties proves to be an effective strategy in addressing selenium deficiency. In conclusion, the unique characteristics of diverse rice-growing regions in China indicate that suitable water management, fertilization techniques, and varietal selection practices can effectively enhance the selenium content in rice, thereby maximizing the nutritional requirements for selenium. [ABSTRACT FROM AUTHOR]

Humic acid (HA) is considered a promising soil amendment for improving soil fertility. However, the effects of HA application on the microbial community, especially in aeolian sandy soils of semi-arid regions, remain insufficiently elucidated. To address this gap, a field experiment was conducted to investigate the changes in soil properties, bacterial and fungal diversity, and community structure in a buckwheat field in the fourth year after a single application of lignite humic acid (L-HA) at 0 (L-HA0), 2 (L-HA1), 4 (L-HA2), and 6 (L-HA3) ton·ha−1 in an aeolian sandy soil in Inner Mongolia, China. The results demonstrated that four years after L-HA application, there was a significant (p < 0.05) decrease in soil pH, accompanied by an increase in soil water content and nutrient levels, including organic matter and total N, available P, and K. Additionally, the application of L-HA enhanced microbial biomass C and N and stimulated enzyme activities, such as urease and invertase, with these effects being more pronounced at higher application rates (L-HA2 and L-HA3). However, HA addition did not significantly (p < 0.05) affect soil microbial biomass P or alkaline phosphatase activity. The L-HA amendment enhanced the α-diversity indices of soil bacteria but did not significantly (p < 0.05) affect soil fungal diversity. The addition of L-HA induced significant changes in the composition of the soil microbial community at both the phylum and genus levels, with significant variability in microbial responses observed across the different L-HA application rates. The incorporation of L-HA notably enriched the composition of bacterial and fungal communities at the phylum level, particularly those involved in carbon cycling, including the bacterial phyla Proteobacteria and Actinobacteriota and the fungal phyla Ascomycota and Rozellomycota. At the genus level, higher L-HA application rates, specifically L-HA2 and L-HA3, exerted statistically significant (p < 0.05) effects on most bacterial and fungal genera. Specifically, these treatments increased the abundance of bacterial genera, such as Rokubacterium and fungal genera, including Plectosphaerella, Tausonia, Talaromyces, and Clonostachys. Conversely, the relative abundance of the bacterial genera Vicinamibacter and Subgroup_7, as well as the fungal genus Niesslia, was significantly reduced. Redundancy analysis (RDA) indicated that bacterial community compositions were closely associated with soil parameters, such as available P (AP), microbial biomass carbon (SMC), microbial biomass nitrogen (SMN), microbial biomass phosphorus (SMP), and invertase, while all tested soil parameters, except for alkaline phosphatase, significantly influenced the fungal community structure. Given that the changes in these soil parameters were highly correlated with the amounts of L-HA addition, this suggests that the impacts of long-term L-HA amendment on the soil bacterial and fungal communities were linked to alterations in soil physicochemical and biological properties. [ABSTRACT FROM AUTHOR]

The current effective method of mitigating soil acidity is the application of lime. However, the costs associated with acquiring lime make it challenging for small-scale farmers in South Africa. Therefore, the aim of this study was to evaluate the liming potential of ground eggshells relative to aglime and its effect on P availability in two acidic soils differing in textural classes, and its subsequent effect on the growth of Swiss chard (Beta vulgaris L.). Two soils used in the study were sandy clay loam, which had an initial pH of 4.52, and sandy loam with an initial pH of 5.23. Both lime sources were applied at a rate of 0, 1, 2.5, and 5 t/ha through incubation for 120 days. Our results indicated that applying eggshells and aglime significantly increased soil pH within 7 days (p < 0.05) compared to the 0-rate application across all application rates in both soil types. There were no differences (p > 0.05) in pH between the two applied lime sources. Plant-available P was not significantly different between the applied lime sources at all application rates and the 0-rate application; however, the two lime sources increased plant-available phosphorus above 25 ppm, which is the minimum health level of plant-available phosphorus. The results of plant yield showed no differences (p > 0.05) between the plant dry weights. However, Swiss chard growing at the 0-rate application in the sandy clay loam showed poor and stunted growth while Swiss chard growing at the 0-rate application in the sandy loam did not exhibit poor and stunted growth. According to the study's results, eggshells have a similar liming effect as aglime and their dissolution rate is similar; therefore, eggshells can be used as a substitute of aglime to increase soil pH. Using eggshells as a substitute for aglime could offer substantial benefits to small-scale farmers by reducing input costs and providing a locally sourced, sustainable alternative. This approach can also enhance economic sustainability in rural communities by promoting the recycling of agricultural by-products and making essential soil amendments more affordable and accessible. [ABSTRACT FROM AUTHOR]

In order to effectively decrease cadmium (Cd) in rice grains in contaminated paddy soil and maintain the safe production of rice, identifying excessive Cd in rice caused by rice varieties or soil Cd is critical, but it is currently lacking. In the present study, the soil ethylenediaminetetraacetic acid (EDTA)-extractable Cd (EDTA-Cd) and the bioaccumulation factors of rice based on EDTA-Cd (BCFEDTA-Cd) were used to develop an approach to identify excessive Cd in rice caused by rice varieties or soil Cd. Based on an empirical soil–plant transfer model and species sensitivity distribution (SSD), BCFEDTA-Cd and EDTA-Cd were divided into five grades. The results showed that the five grades of the EDTA-Cd (minimum value less than 0.11 mg/kg and maximum value greater than 2.93 mg/kg) and BCFEDTA-Cd (minimum value less than 0.09 and maximum value greater than 1.40) were classified in the normal soil pH range. Further, the conversion equation between EDTA-Cd and diethylene triamine pentaacetic acid (DTPA)-Cd was obtained through linear regression analysis using 67 sets of soil data from the literature. In addition, the four selected rounding thresholds for the percentage of EDTA-Cd to total soil Cd (EDTA-Cd) (%) were 52.5, 67.5, 82.5, and 97.5%. A selected soil EDTA-Cd (%) (about 75%) can be used to identify the status of soil bioavailability, especially in soil with high background Cd. Finally, a set of 1084 pairs of rice and soil data for Cd-contaminated soils was used to investigate the respective contributions of rice varieties and soil Cd when Cd in rice exceeds the limit (0.2 mg/kg). Based on field experiment data, a systematic identification approach for the causes of rice Cd exceeding the limit, soil Cd or rice variety, was established and applied. In conclusion, under Cd exposure conditions, the importance of the causes of Cd in soil and rice varieties can be identified, and their contributions can be distinguished, thus helping to identify the causes of Cd contamination in rice. [ABSTRACT FROM AUTHOR]

Excessive application of phosphorus (P) fertilizers does not alleviate P deficiency in soils and may cause water eutrophication. The available P in acidic soils is bound to minerals, such as iron and aluminum, in forms that are difficult to utilize by plants. The low availability of P is detrimental to soil health and crop growth. To address the P imbalance in the soil, different bioremediation techniques, such as phosphate-solubilizing bacteria (PSB) application, have been employed. However, the systematic analysis of the effects of composite inoculation of PSB on crops remains elusive. In this study, the effects of composite-inoculated PSB on plant growth were systematically evaluated by two scales: plate experiment and soil test. This study employed six different strains of PSB including Lelliottia amnigena 1-1 (A), Kluyvera intermedia 1-2 (B), Pseudomonas tolaasii 1-6 (C), Burkholderia cepacia 2-5 (D), Pseudomonas frederiksbergensis 2-11 (E), and Pseudomonas rhodesiae 2-47 (F). Among the 57 different combinations of these strains, four combinations (AE, AF, ADF, and AEF) indicated higher phosphate-solubilizing abilities than the single strains. These combinations were used for subsequent experiments. The plate experiment revealed that composite strains were more effective than single strains in promoting the growth and development of seedlings and roots of oilseed rape. Furthermore, AE, AF, and AEF combinations indicated excellent growth-promoting effects. Moreover, the soil test revealed that the composite inoculation of AE and AEF significantly enhanced biomass accumulation and root development in oilseed rape. The increased growth-promoting effects of the composite strains were observed to be associated with to their phosphate-solubilizing capacities. Both scales confirmed that compared to single inoculation, composite inoculation of PSB is more beneficial for plant growth. This study provides composite inoculation materials and foundational data to support the bioremediation of P imbalance in soil. [ABSTRACT FROM AUTHOR]