Significant acidification in major Chinese croplands

Integrated bio-straw resources and chemical fertilizer management for food and environmental security in Chinese wheat-based production

High environmental costs can be incurred in wheat-based agricultural systems (WBASs), from wheat grain production to straw management. Carbohydrate accumulation and partitioning determine the grain and straw yields, and the related food security and environmental cost in the whole system. We systemically investigated the wheat carbohydrate partitioning pattern to develop the new regional grain/straw yield models for China. Based on the newly developed models and a life cycle assessment, we assessed the carbon (C) mitigation potential for different grain yield increases scenarios. When the grain yield increased by > 9 t ha-1, more carbohydrates were allocated to aboveground straw. Grain carbohydrate partitions could be significantly diminished by cultivar types, inappropriate N supply, modest early sowing, and manure addition, particularly in central China where total biomass and harvest index (HI) are highest. Combined with national farmers survey campaign, the estimated straw yield was overestimated by 30.2 %, 29.3 %, and 23.5 % by official figures and other meta-analyses value using a fixed HI regardless of grain yield levels in North China Plain (NCP), Yangtze River Plain (YR), and southwest (SW) regions, respectively. The estimated C emissions from straw management (recycling and open-field burning) were 1.3-13.2 times lower than for grain production in the northeast (NE), northwest (NW), NCP, and SW regions, but were 26.7 % greater in the YR. A scenario analysis suggested that the estimated C mitigation potential was in the range of 5.4-57.6 % through the region-specific integrated straw resources and chemical fertilizer management, while the grain yield simultaneously increased by more than 30 %. The environmental cost of the WBASs should be significantly reduced based on the region-specific optimal combination of inorganic resource inputs, straw management, and balanced carbohydrate partitioning, which would simultaneously further enhance the grain yield potential. This conceptual framework could serve as a reference for simultaneously ensuring food and environmental security apart from China and wheat agricultural systems.

New insights into soil active substances enhance the biochar/periodate process for remediation of sulfadiazine: The changes of soil properties and toxicity

In recent years, periodate (SPI)-based advanced oxidation processes have been successfully applied in wastewater treatment. However, their application in soil pollution remediation remains limited. To our knowledge, this study represents the first attempt to utilize SPI catalyzed by the Eichhornia crassipes biochar (EBC) system for the remediation of sulfadiazine (SD)-contaminated soil. In the EBC/SPI system, the degradation performance of SD-spiked soils was significantly improved, achieving complete degradation within 60 min, which indicates a clear synergistic effect between SPI and EBC. Notably, our findings highlighted that active soil constituents play crucial roles in SPI activation. Specifically, free Fe-oxides in soil were essential for SPI activation to form reactive species (RS) compared to amorphous Fe-oxides and dissolved Fe, leading to superior SD degradation. Soil organic matter (SOM) also contributed to RS formation and conversion. Adding Fe3+, Cl-, and humic acid accelerated SD elimination, whereas Mn2+ and HCO3- inhibited it. Quenching experiments and electron paramagnetic resonance spectroscopy confirmed the formation of singlet oxygen, superoxide radicals, and iodate radicals, which actively degraded SD. Analysis of soil properties, including SOM content, total phosphorus, functional groups, crystal structure, and pH value, showed negligible changes after EBC/SPI treatment. Additionally, potential decomposition pathways of SD were proposed based on identified SD intermediates. Ecotoxicity analyses and phytotoxicity tests indicated a marked reduction in the toxicity of these intermediates compared to SD. These findings provide an efficient strategy for soil remediation and offer new insights into the role of inherent substances in the field of contaminated soil remediation.

Anthropogenic impacts on regional leaching risks posed by trace metal(loid)s in the soil of an industrial city

The leaching risks associated with trace metal(loid)s (s) in regional soil are complex due to the intricate interplay between pollution levels and soil properties. A Kd-based regional leaching risk assessment method was developed to assess the leaching risks posed by soil TMs. The random forest model was used to identify the effects of the soil environment on the soil Kd and the leaching risks. The reliability of the established method was successfully validated by field monitoring data (R2 = 0.84). The mean total soil groundwater risk was 1.59, the high mobility of Cd contributed the most to total risks. High-risk areas were mainly located in the farmland and forestland around a smelter and areas with severe soil acidification. The high mobility and moderate contamination of TMs resulted in the highest leaching risks. Furthermore, soil acidification and the conversion of farmland to forestland would increase the leaching risk by 33.5 % and 46.4 %, respectively, while urban expansion would reduce the leaching risk by 60.3 %. The Kd-based leaching risk assessment method provided a critical framework for decision-makers to efficiently identify high-risk areas on a regional scale, facilitating a deeper understanding of how anthropogenic activities influenced the leaching risks of TMs in soil.

Response of abundant and rare microbial species to 40-year long-term fertilization practices irrespective of bulk and rhizosphere soils

Fertilization practices could exert significant influence on the diversity, interactions, and functions of soil microorganisms. However, little is known about how specific microbial groups and their interactions adapt or evolve in response to agricultural practices, especially long-term mineral fertilization. Here we explored the community assembly process shaping the microbial community and co-occurrence networks of abundant and rare groups based on a high-throughput sequencing approach in a field experiment with 40 years of mineral nitrogen (N) and phosphorus (P) fertilization. The results indicated that fertilization (25-51 %) had a strong impact on microbial community structure, while little difference were found between rhizosphere and bulk soils irrespective of abundant and rare microbial groups. Deterministic processes primarily govern the assembly of both abundant and rare bacterial and fungal taxa. Random forest analysis revealed that soil pH and N-related nutrients (i.e. nitrate nitrogen (NO3--N), dissolved organic nitrogen (DON) and ammonium nitrogen (NH4+-N)) were the key factors influencing microbial community structure. Structural equation modeling and mantel test further indicated that deterministic factors, particularly soil pH, influence co-occurrence network complexity by modulating the microbiome. Overall, these findings provide insights into factors shaping the microbial community assembly and co-occurrence network dynamics in agroecosystems subjected to long-term fertilization.

Effects of soil mechanical stability aggregates on maize grain amylose content under equivalent application of straw nitrogen instead of chemical fertilizers

Soil mechanical stability aggregates (MSA) are key to soil structure. This 8-year study (2016-2023) assessed the impact of straw substitution (at 25 %, 50 %, 75 %, 100 % ratios: S25, S50, S75, and S100) compared to chemical fertilizer (CF) on soil aggregate stability in maize fields (loess-like brown soil). Results revealed that amylose positively correlated with >5 mm mechanical stability aggregates (MSA), mean weight diameter (MWD), and geometric mean diameter (GMD), while negative correlated with 0.25-5 mm MSA. S75 demonstrated superior performance: (1) in the 0-10 cm layer: compared to CF, >5 mm MSA increased by 57.49 % (2018) and GMD rose by 53.69 % (2018). (2) In the 10-20 cm layer: compared to CF, >5 mm MSA increased by 67.01 % (2019), while MWD rose by 36.86 % (2018) and 34.34 % (2019); moreover, fractal dimension (D) decreased by 10.61 % (2022). (3) In the 20-30 cm layer: 0.5-1 mm MSA peaked under S75 in 2021 (51.61 %-103.61 % significantly higher than other treatments). MWD and GMD were strongly correlated with larger aggregates, whereas a reduction in D signified enhanced structural uniformity. S75 application enhanced soil stability by promoting macro-aggregate formation and reducing fragmentation, establishing it as the most effective straw substitution ratio for improving farmland soil quality.

Enhancing soil fertility and organic carbon stability with high-nitrogen biogas slurry: Benefits and environmental risks

Large-scale livestock farming has increased the amount of excrement, leading to ecological and environmental issues. To address this, sustainable solutions like biogas slurry (BS) are needed to enhance soil fertility and soil organic carbon (SOC). This study investigated the effects of conventional nitrogen fertilizer (NPK), standard BS (BS1), and high-nitrogen input BS treatments (BS5, BS7, and BS11) on soil quality, nutrient dynamics, SOC fractions, and environmental risks across soil depths (0-20, 20-40, and 40-60 cm). Field experiments revealed that BS application significantly enhanced the soil quality index (SQI) by 32.5 %-61.6 % in the 0-20 cm soil layer and ecosystem multifunctionality (EMF) by 42.3 %-169.0 % across all layers compared to NPK. Mineral-associated organic carbon (MOC) dominated SOC stabilization (57.2 %-91.3 % of total SOC), with BS11 increasing MOC content by 76.3 % in the 40-60 cm soil layer. High-nitrogen BS treatments increased microbial biomass carbon (MBC) by 318.1 % (BS11) and β-glucosidase activity by 144 % (BS7) in 0-20 cm soil, indicating enhanced soil enzyme activities. However, excessive nitrogen inputs induced nitrate accumulation in the 40-60 cm soil layer, where NO3--N concentrations surged to 97.2 %-200.6 % above NPK levels. Vertical nutrient migration also triggered subsoil acidification, with the pH decreasing by 5.0 % under the BS11 treatment. These results underscore the dual role of BS: while it enhances SOC stability (via MOC dominance) and multifunctionality, nitrogen inputs must be capped below 300 kg N ha-1 yr-1 to mitigate leaching risks. The findings provide actionable insights for optimizing BS applications in sustainable agriculture, balancing soil health improvements with environmental safeguards.

Genome-wide association study and BSR-seq identify nitrate reductase-related genes in rice landraces (Oryza sativa L.)

Nitrogen (N) is an essential nutrient for rice (Oryza sativa L.) growth and development. However, the lower nitrogen use efficiency (NUE) results in an N fertilizer surplus, which causes many environmental problems. In this study, genome-wide association studies were used to detect nitrate reductase (NR)-related loci in 419 rice landraces. Using the general linear model (GLM), mixed linear model (MLM), linear model (LM), and linear mixed model (LMM), we found six, nine, seven, and six significant single-nucleotide polymorphisms (SNPs) associated (p < 1 × 10-5) for three traits. Moreover, 98 significant SNPs were associated (logarithm of odds ≥ 3) with three traits through 3 V multi-locus random-SNP-effect mixed linear model. Interestingly, we found that Chr1_15896481 was significantly associated in the GLM, MLM, LM, and LMM models. Meanwhile, this significant locus overlapped with a candidate region in bulked segregant RNA sequencing. Through integrated analysis, we identified a most likely candidate genomic region 15,627,420-16,084,761 bp on chromosome 1. By performing functional annotation, RNA sequencing, and real-time quantitative polymerase chain reaction (RT-qPCR) analysis for the genes within this interval, we identified five candidate genes that may affect NR activity. Os01g0378400 exhibits a gene expression pattern highly similar to that of OsNR1.2. It belongs to the NAC transcription factor family, which is involved in plant N metabolism. Os01g0377700 is homologous to an ammonium transporter gene (Cre06g293051). Os01g0383700 encodes a WD40 domain protein, Os01g0379400 encodes an F-box protein, and Os01g0382800 encodes a DYW-type PPR domain protein. These findings will provide valuable genetic resources for NUE genetic improvement in rice breeding.

Impacts of future climate change and management practices to yield, eco-efficiency and global warming potential for rice-wheat rotation system

BACKGROUND

The rice-wheat rotation system (RWRS) is a predominant cropping pattern in mid-eastern China, playing a crucial role in ensuring food security. However, its intensive water and fertilizer inputs contribute significantly to greenhouse gas (GHG) emissions. With global climate warming, RWRS confronts the dual imperative of simultaneously enhancing productivity and eco-efficiency while significantly curtailing GHG emissions.

RESULTS

Future warming climate under most global climate models (GCMs) had adverse impacts on yield, water-use efficiency (WUE), nitrogen-use efficiency (NUE) and GHG intensity (GHGI) of RWRS in the central and southern regions of mid-eastern China. Compared to traditional management (TM) with high water and nitrogen inputs, optimized water and nitrogen management (OM) - utilizing intermittent irrigation and a nitrogen application rate of 390 kg ha-1 - can significantly enhance WUE and NUE while reducing GHGI, without compromising yield. Moreover, no tillage, as a conservation tillage (CT) practice could effectively mitigate the negative impacts of future climate change. The combination of OM and CT (OM + CT) can improve yield and eco-efficiency while reducing global warming potential. For RWRS with OM + CT, GHGI decreased by 45.6-60.9% under future climate scenarios compared to TM.

CONCLUSIONS

By using knowledge-based optimum management strategies, environmental risks can be reduced without sacrificing the yield of RWRS yield. This study demonstrates a useful approach with crop modelling to ensure yield for agriculture system at a lower environment cost, which can be adjusted and applied in other farming systems and regions. © 2025 Society of Chemical Industry.

The impact of soil acidification on cementing substances and aggregate stability

The excessive utilization of chemical fertilizers, particularly nitrogen fertilizers, is leading to decline in the pH level of the black soil in Jilin Province. Acidification of black soil leads to reduced salt base saturation, decreased organic matter content, and increased soil degradation, which, in turn, leads to diminshed aggregate stability and poor soil structure, negatively affecting soil fertility. As a result, the sustainability of food production and farmland ecosystem stability are at risk. The precise relationship between alterations in cementing substances and changes in soil aggregate stability during the acidification of black soil remains unclear, and the ultrasonic thermal difference method allows for the quantitative description of changes in soil aggregate stability. Therefore, this study employed the ultrasonic thermal difference method to investigate the impact of acidification on the stability of black soil aggregates and their cementing substances through a simulated fertilizer drenching experiment, thus elucidate the relationship between primary cementing materials and the stability of aggregates under varying degrees of black soil acidification, and to provides theoretical basis and data for alleviating and preventing acidification of black soil in Jilin Province. The results disclosed a gradual decline in soil organic carbon (SOC) levels during the acidification experiment, while water-soluble organic carbon (WSOC) first increased and then decreased. After 25 years of simulated leaching, SOC decreased by 1.34% and WSOC declined by 15.63%. Acidification has a minimal impact on Fe-Al bonded organic carbon but significantly reduces calcium-bonded organic carbon by 17.07% over 25 years. The content of exchangeable Ca2+ and Mg²⁺ decreases as acidification intensifies. After 25 years, exchangeable Ca2+ and Mg²⁺ decreased by 9.42% and 7.00%, respectively. The acidification of the test soil resulted in a 46.5% reduction in the aggregate stability energy (E) of water-stable microaggregates, with an average decrease of 14.04 J/g for every 0.1 unit decrease in pH. Additionally, the soil critical stabilization energy (Ecrit) exhibited a 51.48% reduction. The results demonstrated that a decrease of 0.32 J/g in E was associated with a 0.1 unit decrease in pH on average. Furthermore, the multivariate linear regression analysis revealed that the reduction in soil organic carbon (SOC) content contributed the most to the decline in E, followed by Calcium bond-bound soil organic carbon (Ca-SOC). Notably, Ca-SOC exerted the greatest influence on the reduction in sand grain Ecrit, followed by SOC.

Soil total nitrogen content and pH value estimation method considering spatial heterogeneity: Based on GNNW-XGBoost model

Soil nitrogen content and pH value are two pivotal factors that critically determine soil fertility and plant growth. As key indicators of soil health, they each play distinct yet complementary roles in the soil ecosystem. Nitrogen is one of the essential nutrients for plant growth, while soil pH directly influences the activity of soil microorganisms. These microbes are essential for breaking down minerals and organic materials, which in turn affects the availability and conversion of key nutrients like nitrogen and phosphorus. A comprehensive understanding of the distribution of total nitrogen content and pH value is crucial for ensuring the sustainability of agricultural production and maintaining soil and ecosystem health. Existing models for estimating soil property based on near-infrared (NIR) spectral data often overlook the spatial non-stationarity of the relationship between soil spectra and composition content. Therefore, we proposed a new model for estimating soil total nitrogen content and pH value, which combined geographically neural network weighted regression (GNNWR) with extreme gradient boosting (XGBoost), utilizing neural networks to improve the accuracy of predicting total nitrogen content and pH value, efficiently captured the spatial heterogeneity between spectral reflectance and soil total nitrogen content and pH value in different regions. Using the soil nutrient and visible near-infrared spectral samples collected by Eurostat in 2009 for the land use and coverage area frame survey of the 23 members of the European Union, the Geographically Neural Network Weighted-eXtreme Gradient Boosting (GNNW-XGBoost) model was used to estimate total nitrogen content and pH value. The spatial correlation between reflectance of spectral characteristic bands and soil total nitrogen content, pH value was trained in the model to verify its robustness and superiority, and the experimental process was improved by 10-fold cross-validation. In terms of model evaluation, compared to the standalone XGBoost and GNNWR models, the GNNW-XGBoost model demonstrated superior predictive accuracy. It achieved a highest coefficient of determination (R2) of 0.84 for total nitrogen and 0.80 for pH. Additionally, it reduced the root mean square error (RMSE) by 7.64 %, 7.61 % for total nitrogen, and 8.96 %, 4.69 % for pH, respectively. This study not only provides a new method for accurate prediction of soil total nitrogen content and pH value, but also has significant reference value for other estimation issues involving geographic data, which can help to improve the accuracy of environmental monitoring, optimize resource management strategies, and promote the development of sustainable agriculture.

Soil Acidification Destabilizes Terrestrial Ecosystems via Decoupling Soil Microbiome

Soil microbiome is essential for terrestrial ecosystem preservation. β-diversity information on the former, although dynamic due to its sensitivity to environmental conditions driven by climate change, is limited. Our knowledge becomes poorer for microbiomes subjected to environmental gradients, especially for those across multiple ecosystems-information important for biological conservation management. In this study, using next generation sequencing and machine learning at samples from 207 locations among 4300 km of transects that spanned among six typical terrestrial ecosystems of China, we established the divergent distance-decay relationships between bacterial and eukaryotic communities in response to soil pH (pH as proxy of climate and edaphic conditions). The findings, pH-decrease results in lower β-diversity (convergent tendency) among the bacterial communities opposite to the eukaryotic ones (low pH-high β-diversity (divergent tendency)). Meanwhile, competition between bacteria and eukaryotes intensifies at lower pH while the predominant genera and communities are re-structured. Under these circumstances, potential soil acidification due to climate change or other factors could alter soil bacteria and eukaryotes into decoupling directions influencing ecosystems' stability. Thus, soil pH is a pivotal environmental variable that not only describes, but also controls, soil microbiome dynamics at a large scale under ongoing global changes; hence, a cornerstone variable for the biodiversity conservation of China's nature protected areas and not only.

Livestock Slurry and Sustainable Pasture Management: Microbial Roles, Environmental Impacts, and Regulatory Perspectives in Ireland and Europe

Pastures serve as the primary source of grass and forage plants for grazing livestock, requiring adequate nutrient input to sustain growth and soil fertility. Slurry from the livestock industry is widely utilized as a sustainable and cost-effective alternative to chemical fertilizers. Microorganisms within the slurry-pasture system are essential for breaking down organic matter, facilitating nutrient cycling, and improving soil health. However, mismanagement or inefficient microbial decomposition can lead to significant issues, such as nutrient leaching into water bodies, causing eutrophication, antimicrobial resistance, and reduced nutrient availability in pastures, which, in turn, may negatively impact livestock productivity. Thus, this paper investigates the composition and benefits of livestock slurry in pasture management, highlights microbial roles in nutrient cycling, and evaluates regulatory frameworks in Ireland and Europe. Additionally, it examines the environmental risks associated with improper slurry application, providing insights to support sustainable management practices.

Legacy effects cause systematic underestimation of N2O emission factors

Agricultural soils contribute ~52% of global anthropogenic nitrous oxide (N2O) emissions, predominantly from nitrogen (N) fertilizer use. Global N2O emission factors (EFs), estimated using IPCC Tier 1 methodologies, largely rely on short-term field measurements that ignore legacy effects of historic N fertilization. Here we show, through data synthesis and experiments, that EFs increase over time. Historic N addition increases soil N availability, lowers soil pH, and stimulates the abundance of N2O producing microorganisms and N2O emissions in control plots, causing underestimates of EFs in short-term experiments. Accounting for this legacy effect, we estimate that global EFs and annual fertilizer-induced N2O emissions of cropland are 1.9% and 2.1 Tg N2O-N yr-1, respectively, both ~110% higher than IPCC estimates. Our findings highlight the significance of legacy effects on N2O emissions, emphasize the importance of long-term experiments for accurate N2O emission estimates, and underscore the need for mitigation practices to reduce N2O emissions.

Managing Ammonia for Multiple Benefits Based on Verified High-Resolution Emission Inventory in China

Atmospheric ammonia (NH3) has multiple impacts on the environment, climate change, and human health. China is the largest emitter of NH3 globally, with the dynamic inventory of NH3 emissions remaining uncertain. Here, we use the second national agricultural pollution source censuses, integrated satellite data, 15N isotope source apportionment, and multiple models to better understand those key features of NH3 emissions and its environmental impacts in China. Our results show that the total NH3 emissions were estimated to be 11.2 ± 1.1 million tonnes in 2020, with three emission peaks in April, June, and October, primarily driven by agricultural sources, which contributed 74% of the total emissions. Furthermore, employing a series of quantitative analyses, we estimated the contribution of NH3 emissions to ecosystem impacts. The NH3 emissions have contributed approximately 22% to secondary PM2.5 formation and a 16.6% increase in nitrogen loading of surface waters, while ammonium deposition led to a decrease in soil pH by 0.0032 units and an increase in the terrestrial carbon sink by 44.6 million tonnes in 2020. Reducing agricultural NH3 emissions in China would contribute to the mitigation of air and water pollution challenges, saving damage costs estimated at around 22 billion US dollars due to avoided human and ecosystem health impacts.

Phenotype Assessment and Putative Mechanisms of Ammonium Toxicity to Plants

Ammonium (NH4+) and nitrate (NO3-) are the primary inorganic nitrogen (N) sources that exert influence on plant growth and development. Nevertheless, when NH4+ constitutes the sole or dominant N source, it can inhibit plant growth, a process also known as ammonium toxicity. Over multiple decades, researchers have shown increasing interest in the primary causes, mechanisms, and detoxification strategies of ammonium toxicity. Despite this progress, the current investigations into the mechanisms of ammonium toxicity remain equivocal. This review initially presents a comprehensive assessment of phenotypes induced by ammonium toxicity. Additionally, this review also recapitulates the existing mechanisms of ammonium toxicity, such as ion imbalance, disruption of the phytohormones homeostasis, ROS (reactive oxygen species) burst, energy expenditure, and rhizosphere acidification. We conclude that alterations in carbon-nitrogen (C-N) metabolism induced by high NH4+ may be one of the main reasons for ammonium toxicity and that SnRK1 (Sucrose non-fermenting 1-related kinase) might be involved in this process. The insights proffered in this review will facilitate the exploration of NH4+ tolerance mechanisms and the development of NH4+-tolerant crops in agricultural industries.

GmSTOP1-3 Increases Soybean Manganese Accumulation Under Phosphorus Deficiency by Regulating GmMATE2/13 and GmZIP6/GmIREG3

Mineral nutrient deficiencies and metal ion toxicities coexist on acid soils. Phosphorus (P) deficiency in plants is generally accompanied with significant levels of leaf manganese (Mn) accumulation. However, the molecular regulatory mechanisms underpinning remain unclear. The present study found that P-deficient soybean plants accumulated more Mn compared to P-sufficient ones on acid soils in both field and greenhouse experiments. Meanwhile, both P deficiency and Mn toxicity enhanced the expression of GmSTOP1-3. Over-expressing GmSTOP1-3 enhanced Mn accumulation in transgenic soybean hairy roots, but RNA-interference did not show obvious differences. Moreover, transgenic soybeans with GmSTOP1-3-overexpression showed enhanced root citrate exudation and augmented Mn accumulation. RNA-sequence identified four downstream genes of GmSTOP1-3, including multidrug and toxic compound extrusion (GmMATE2/13) and metal transporter genes (GmZIP6/GmIREG3), which encode plasma membrane proteins. GmSTOP1-3 activated the transcription of these four genes by directly binding to their promoter regions. In addition, both GmZIP6 and GmIREG3 functioned in Mn uptake as manifested by the higher Mn concentration and decreased growth of soybean hairy roots with their overexpression. Taken together, it is suggested that upregulation of GmSTOP1-3 by low P stress on acid soils activates transcripts of GmMATE2/13 and GmZIP6/GmIREG3, which consequently result in enhanced Mn accumulation in soybean.

Long-term oyster shell powder applications increase crop yields and control soil acidity and cadmium in red soil drylands

The intensification of agricultural production has significantly reduced land availability, necessitating continuous cropping cycles that degrade soil quality and inhibit crop growth. While the short-term use of soil amendments has shown significant potential for mitigating these challenges, few studies have explored their long-term effects on acidified soils and heavy metal accumulation. Between 2013 and 2018, a field experiment was conducted in the peanut (Arachis hypogaea L)-growing region of Jinxian County, Jiangxi Province, to investigate the long-term effects of oyster shell powder applied to upland red soil. Before the experiment, the soil properties were as follows: pH, 4.54, total soil cadmium (Cd) content, 0.49 mg kg-¹; and available Cd content, 0.25 mg kg-¹. The experiment included three treatments combining chemical fertilizers with oyster shell powder at application rates of 750, 1500, and 2250 kg ha-¹ (L750, L1500, L2250) and a control with only chemical fertilizer (L0). From 2013 to 2018, peanut yield among all treatments was assessed at maturity. Soil pH was then measured using a pH meter with a 2.5:1 water-to-soil ratio. Exchangeable hydrogen and aluminum were determined using the potassium chloride exchange-neutralization titration method. Meanwhile, available Cd content was extracted using 0.1 M CaCl2 and measured with a flame atomic absorption spectrophotometer. While all treatments showed an annual decline in peanut yield from 2013 to 2018, but oyster shell applications significantly reduced the rate of crop yield decline. Compared to L0, the yields of L750, L1500, and L2250 treatments increased by 5.55%-19.42%, 8.64%-28.74%, and 15.43%-37.01%, respectively. Soil pH values in the L750, L1500, and L2250 treatments were higher than the L0 treatment by 0.03-0.31, 0.16-0.48, and 0.28-0.65 units, respectively. Their exchangeable hydrogen contents decreased by 10.17%-24.24%, 16.67%-27.94%, and 23.40%-29.44%. In addition, exchangeable aluminum contents decreased by 5.05%-26.09%, 23.23%-46.27%, and 39.73%-66.97%. In contrast, soil available Cd contents in the L750, L1500, and L2250 treatments were lower than the L0 treatment by 7.96%-19.29%, 9.56%-30.71%, and 13.94%-34.65%, respectively. Correlation analysis revealed that soil pH was positively associated with peanut yield and negatively correlated with exchangeable hydrogen, exchangeable aluminum, and available Cd. For every 0.1 unit increase in soil pH, peanut yields increased by 119.62-389.82 kg ha-¹, while available Cd decreased by 0.06-0.12 mg kg-¹. Therefore, these findings demonstrate the efficacy of continuous oyster shell powder application in controlling soil acidification and reducing Cd levels in upland red soil.

Nondestructive estimation of leaf chlorophyll content in banana based on unmanned aerial vehicle hyperspectral images using image feature combination methods

Introduction

Nondestructive quantification of leaf chlorophyll content (LCC) of banana and its spatial distribution across growth stages from remotely sensed data provide an effective avenue to diagnose nutritional deficiency and guide management practices. Unmanned aerial vehicle (UAV) hyperspectral imagery can document abundant texture features (TFs) and spectral information in a field experiment due to the high spatial and spectral resolutions. However, the benefits of using the fine spatial resolution accessible from UAV data for estimating LCC for banana have not been adequately quantified.

Methods

In this study, two types of image features including vegetation indices (VIs) and TFs extracted from the first-three-principal-component-analyzed images (TFs-PC1, TFs-PC2, and TFs-PC3) were employed. We proposed two methods of image feature combination for banana LCC inversion, which are a two-pair feature combination and a multivariable feature combination based on four machine learning algorithms (MLRAs).

Results

The results indicated that compared to conventionally used VIs alone, the banana LCC estimations with both proposed VI and TF combination methods were all significantly improved. Comprehensive analyses of the linear relationships between all constructed two-pair feature combinations and LCC indicated that the ratio of mean to modified red-edge sample ratio index (MEA/MSRre) stood out (R 2 = 0.745, RMSE = 2.17). For multivariable feature combinations, four MLRAs using original or two selected VIs and TFs-PC1 combination groups resulted in better LCC estimation than the other input variables. We concluded that the nonlinear Gaussian process regression model with the VIs and TFs-PC1 combination selected by maximal information coefficient as input achieved the highest accuracy in LCC prediction for banana, with the highest R 2 of 0.776 and lowest RMSE of 2.04. This study highlights the potential of the proposed image feature combination method for deriving high-resolution maps of banana LCC fundamental for precise nutritional diagnosing and operational agriculture management.

Enhancing soil nitrogen measurement via visible-near infrared spectroscopy: Integrating soil particle size distribution with long short-term memory models

Good quality of soil nitrogen data, which is essential for the advancement of both enhanced agricultural management and ecological environment, traditionally depends on labor intensive chemical procedures. Visible near-infrared (Vis-NIR) spectroscopy, acknowledged for its efficiency, environmental compatibility and rapidity, merges as a promising alternative. However, the effectiveness of Vis-NIR measurement models are significantly compromised by soil particle size distribution (PSD), presenting a substantial challenge in improving the measurement accuracy and reliability. Here an innovative deep learning methodology that integrates PSD with Vis-NIR spectroscopy was proposed for the measurement of nitrogen content in soil samples. By leveraging the LUCAS dataset, different strategies for integrating PSD with Vis-NIR spectral data in deep learning models were explored, revealing that our proposed InSGraL framework, which incorporated mixed features of PSD and spectra as LSTM inputs achieves superior performance. Compared to models utilizing solely Vis-NIR data, InSGraL exhibits a 39.47 % reduction in RMSE and a 42.55 % decrease in MAE, and demonstrates robust performance across various land cover types, achieving an R2 of 0.94 on grassland samples. Moreover, Shapley Additive exPlanations (SHAP) analysis revealed that incorporating PSD modifies the spectral input importance distribution, effectively mitigating spectral interference from particle size while highlighting critical wavelengths previously obscured. This study provides an innovative modeling strategy to mitigate the influence of PSD by integrating it within deep learning framework using Vis-NIR, contributing a deeper understanding of the relationship between PSD and Vis-NIR spectra for the measurement of nitrogen content and offering an effective means to attain soil nitrogen data.

Effects of amino acid value-added urea on rice growth and nitrogen utilization

To investigate the impact of amino acid value-added urea on rice growth and nitrogen utilization, this study aimed to provide insights into enhancing the quality and efficiency of traditional nitrogen fertilizers using small molecule active substances. Amino acids were added at 5‰ and 5% levels to create different levels of amino acid value-added urea (AU0.5 and AU5) by blending with urea as test materials. Pot experiments were conducted using 'Liangyouhua 6' rice as the test crop, with four treatment groups: non-urea (CK), regular urea (U), and amino acid value-added urea (AU0.5, AU5) at two different addition ratios. All treatments, except the control, had the same application rates of nitrogen, phosphorus, and potassium. After harvesting the rice, plant and soil samples were collected from various depths to analyze the nutrient composition of rice, nitrogen content of fertilizer in different soil layers, and 15N abundance. The results showed that amino acid-added urea significantly enhanced biomass accumulation in different parts of rice. Compared to U, rice straw and grain biomass increased by 25.27% to 32.74% and 21.71% to 27.77% under AU0.5 and AU5 treatments, respectively. In terms of nitrogen application, effective panicle and grain numbers per panicle in AU0.5 and AU5 rice were 17.37% to 21.05% and 8.76% to 15.33% higher than in U, with a significant difference between AU0.5 and U. Furthermore, total aboveground nitrogen and fertilizer nitrogen accumulation in rice treated with AU0.5 and AU5 increased by 3.59% to 5.09% and 3.31% to 8.49%, respectively, compared to U. The accumulation of fertilizer nitrogen in grains and leaves also showed increases of 2.86% to 6.32% and 4.38% to 16.25%, respectively, compared to U. This study found that the application of amino acid value-added urea had a significant impact on the accumulation of fertilizer nitrogen in straw. Further analysis showed that it improved both the apparent nitrogen utilization efficiency and fertilizer nitrogen utilization efficiency. Compared to ordinary urea, the apparent nitrogen utilization efficiency of AU0.5 and AU5 increased by 23.71% and 33.93%, respectively, while the utilization efficiency of 15N increased by 15.66% and 6.78%, respectively. The residual fertilizer nitrogen in soil treated with amino acid value-added urea was mainly found in the 0-30cm soil layer, reducing nitrogen leaching downwards. Additionally, the nitrogen loss rate was significantly lower (reduced by 12.39%-12.97%) compared to regular urea. The difference between AU0.5 and AU5 was not significant, but AU5 showed an 18.80% higher fertilizer nitrogen residual rate than U. Overall, the study concluded that amino acid value-added urea promoted rice growth by enhancing nitrogen absorption, improving transport to grains, increasing nitrogen fertilizer efficiency, reducing nitrogen leaching, and lowering nitrogen loss rate. The best results were observed with the addition of 5‰ amino acid.

Environmental tipping points for global soil nitrogen-fixing microorganisms

Nitrogen-fixing microorganisms (NFMs) are important components of soil N sinks and are influenced by multiple environmental factors. We established a random forest model optimized by the distributed delayed particle swarm optimization (RODDPSO) algorithm to analyze the global NFM data. Soil pH, organic carbon (OC), mean annual precipitation (MAP), altitude, and total phosphorus (TP) are factors with contributions greater than 10% to NFMs. pH, OC, and MAP are the top three factors at the global scale. The tipping points of pH and OC for the NFMs were 7.84 and 2.71%, respectively. The contribution of MAP first increased but then decreased with peak value at 1,265.65 mm. Under the scenario SSP 8.5, 12% of the NFMs increase occur in Africa in 2100; 16% and 36% of the NFMs decrease in North America and Oceania in 2100, respectively. Our work created a global NFMs map and identified the critical tipping points.

Physio-biochemical and molecular mechanisms of low nitrogen stress tolerance in peanut (Arachis hypogaea L.)

Nitrogen (N) is a major plant nutrient and its deficiency can arrest plant growth. However, how low-N stress impair plant growth and its related tolerance mechanisms in peanut seedlings has not yet been explored. To counteract this issue, a hydroponic study was conducted to explore low N stress (0.1 mM NO3-) and normal (5.0 mM NO3-) effects on the morpho-physiological and molecular attributes of peanut seedlings. Low-N stress significantly decreased peanut plant height, leaf surface area, total root length, and primary root length after 10 days of treatment. Meanwhile, glutamate dehydrogenase, glutamine oxoglutarate aminotransferase activities, chlorophyll, and soluble protein contents were substantially decreased. Impairment in these parameters further suppressed photochemical efficiency (Fv/Fm), and chlorophyll fluorescence parameters (PIABS), under low-N stress. Transcriptome sequencing analysis showed a total of 2139 DEGs were identified between the two treatments. KEGG enrichment annotation analysis of DEGs revealed that 119 DEGs related to 10 pathways, including N assimilation, photosynthesis, starch, and sucrose degradation, which may respond to low-N stress in peanuts. Combined with transcriptome, small RNA, and degradome sequencing, we found that PC-3p-142756_56/A.T13EMM (CML3) and PC-5p-43940_274/A.81NSYN (YTH3) are the main modules contributing to low N stress tolerance in peanut crops. Peanut seedlings exposed to N starvation exhibited suppressed gene expression related to nitrate transport and assimilation, chlorophyll synthesis, and carbon assimilation, while also showing improved gene expression in N compensation/energy supply and carbohydrate consumption. Additionally, low N stress tolerance was strongly associated with the miRNA.

Microalgae and microbial inoculant as partial substitutes for chemical fertilizer enhance Polygala tenuifolia yield and quality by improving soil microorganisms

Excessive utilization of chemical fertilizers degrades the quality of medicinal plants and soil. Bio-organic fertilizers (BOFs) including microbial inoculants and microalgae have garnered considerable attention as potential substitutes for chemical fertilizer to enhance yield. In this study, a field experiment was conducted to investigate the effects of BOF partially substituting chemical fertilizer on the growth and quality of medicinal plant Polygala tenuifolia. The growth parameters, bioactive component contents, soil properties and composition of rhizosphere microorganisms were measured. The results indicated that substituting 40% of chemical fertilizer with microalgae showed the most pronounced growth-promoting effect, leading to a 29.30% increase in underground biomass and a 19.72% increase in 3,6'-disinapoylsucrose (DISS) content. Substituting 20% of chemical fertilizer with microalgae improved soil quality, significantly increasing soil organic matter content by 15.68% (p<0.05). Microalgae addition significantly affected the rhizosphere bacterial community composition of P. tenuifolia, reducing the relative abundance of Cladosporium by 33.33% and 57.93%, while increasing the relative abundance of Chloroflexi by 31.06% and 38.27%, under 20% and 40% chemical fertilizer reduction, respectively. The relative abundance of Chloroflexi positively correlated with both the underground biomass and DISS content (p<0.05), indicating that microalgae may stimulate Chloroflexi species associated with carbon cycling, thereby enhancing soil fertility, nutrient absorption, and ultimately leading to increased biomass accumulation and production of bioactive components in P. tenuifolia. In addition, there was no significant difference in underground growth and bioactive component contents between reduced chemical fertilizer dosage combined with solid microbial inoculant (SMI) and polyglutamic microbial inoculant (PMI), compared with 100% chemical fertilizer. Correlation analysis revealed that PMI could increase soil phosphorus availability through Streptomyces recruitment. In conclusion, our findings demonstrated that bio-organic fertilizers can partially substitute chemical fertilizer to improve soil properties and microorganisms, enhancing the growth and quality of P. tenuifolia. This provides a theoretical basis for increasing medicinal plant productivity under chemical fertilizer reduction.

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.

Soil health assessment of dressing and smelting slag field based on heavy metal pollution-buffer-fertility three aspects

The soil health of heavy metals in dressing and smelting slag field varies soil physicochemical properties. This study proposed a new soil health index based on heavy metal pollution-buffer-fertility for dressing and smelting slag field. Consequently, spatial distribution of soil physicochemical properties and heavy metals were varied, and correlated to each other. Soil buffer function and fertility played a much more important role in soil health in the dressing and smelting slag field located in Gejiu city, which can result in that soil health indexes were higher than those in Huili county, although the soil heavy metal pollution in the former was severer than that in the latter. Maximum values of soil health indexes for dressing and smelting slag field in Gejiu city were 3.84, 0.61, and 1.75 corresponding to additive, multiplicative, and maximum value composite methods, which were higher than those in Huili county with 2.25, 0.61, and 0.17. The former's high value is concentrated in southeastern regions and low value in some western areas, the latter's high value occurred in southeastern districts and low value in northwestern places. So this study unveils a novel perspective on the soil health consequences associated with soil heavy metal pollution-buffer-fertility three aspects.

Long-term adoption of plow tillage and green manure improves soil physicochemical properties and optimizes microbial communities under a continuous peanut monoculture system

Continuous monocropping of peanuts (Arachis hypogaea L.) often results in yield decline and soil degradation. The combination of green manure (GM) with tillage practices has been proposed as a sustainable strategy to maintain high crop productivity and improve soil quality. This study investigates the long-term effects of 8 years of GM application combined with plow tillage on soil microbial communities and physicochemical properties under a peanut monocropping system. Treatments included: (i) no tillage (NT); (ii) plow tillage before the winter fallow period (PT); and (iii) growing ryegrass (Lolium perenne L.) during the winter period and applying it as GM before planting next-stubble peanut (PTGM). It was found that both PTGM and PT remarkably decreased the average bulk density (BD), while elevated the mean soil porosity (SP) in 0-30 cm soil layer. Moreover, PTGM significantly increased available potassium (AK), available phosphorus (AP), total nitrogen (TN), and soil organic matter (SOM). Peanut pod yields in the PTGM treatment were 14.1 and 7.2% higher compared to the PT and NT treatments, respectively. Additionally, PTGM could promote shifts in soil bacteria compositions, increasing the abundance of Actinobacteria and Firmicutes while reducing that of Chloroflexi. For fungal abundances, PTGM elevated the abundances of Ascomycota and Basidiomycote. Redundancy analysis demonstrated that SOM, TN, AK, and AP were positively related to dominant flora of fungi and bacteria in PTGM, while negatively related to dominant flora of fungi and bacteria in NT. Overall, tillage practices have the potential to reshape the microbial community during the peanut growing season, primarily due to the influence of SOM, TN, and AP content in shaping microbial diversity and composition. Our study highlights that plow tillage combined with GM application may serve as an effective tillage practice in the future to mitigate continuous cropping obstacles by modulating soil microbial communities, improving soil nutrients and fertility, and enhancing crop productivity.

A meta-analysis of the effects of nitrogen fertilizer application on maize (Zea mays L.) yield in Northwest China

Nitrogen fertilizer application is an important method for the production of high-quality maize. However, nitrogen fertilizer addition patterns vary according to regional climate, field management practices, and soil conditions. In this study, a meta-analysis was used to quantify the yield effects of nitrogen addition on maize, and meta-regression analysis and a random forest model were used to study the main factors affecting the yield effects of nitrogen addition on maize. The results showed that nitrogen addition significantly increased maize yield by 50.26%-55.72%, and a fluctuating increasing trend was observed with the advancement of the experimental year. The increase in maize yield upon nitrogen addition was the highest in Gansu Province, and showed a decreasing trend with the rise in average annual temperature, but did not change significantly with the average annual precipitation. Among the field management factors, the increase in maize yield was better with the variety Qiangsheng 51, topdressing at the jointing and tasseling stages (JS, TS), nitrogen application rate of 175-225 kg·ha-1, and controlled release of nitrogen fertilizer and urea (CRNFU) or the application of a combination of organic and inorganic nitrogen (OIF). Moreover, the positive effects of nitrogen fertilizer application on maize yield improved with soil pH, organic matter, available potassium, available phosphorus, and total nitrogen content; decreased with soil carbon and nitrogen ratio and available nitrogen (AN) content; and were enhanced in chestnut soil, clay, and at a bulk density of 1.2-1.4 g·cm-3. Random forest model and multifactorial optimization revealed that the effects of nitrogen addition on maize yield in Northwest China were primarily influenced by experimental year, variety, soil type, AN, and soil pH.

Effects of fertilizer application on the bacterial community and weathering characteristics of typical purple parent rocks

Introduction

Rock weathering is a fundamental process that shapes Earth's topography, soil formation, and other surface processes. However, the mechanisms underlying the influence of fertilizer application on weathering remain poorly understood, especially with respect to bacterial intervention.

Methods

In this study, purple parent rocks from Shaximiao Group (J2s) and Penglaizhen Group (J3p) were selected to investigate the effects of fertilizer application on the bacterial community and weathering characteristics of these rock by leaching experiment.

Results

The results revealed that: fertilizer application, especially when at high levels, greatly altered the abundance, diversity and composition of the bacterial community in weathered products. Through redundancy analysis, a decrease in pH and increases in available nutrients (AN and AP) resulting from fertilizer application were identified as the key factors driving changes of bacterial community composition in weathered products. Moreover, fertilizer application promotes the physical and chemical weathering of the parent rocks to some extent. This is especially true for the chemical weathering of J2s. Structural equation model indicated that fertilizer application affects weathering through multiple pathways by affecting the chemical properties (pH, C:N and AP), specific bacterial genera (IMCC26256, Ramlibacter, and Nitrosospira), and bacterial community composition of weathered products.

Discussion

Our study links weathering characteristics with chemical properties and bacterial community changes of weathered products after fertilizer application, which plays a key role in controlling and predicting dynamic changes of rock weathering in space and time. It is helpful to further understand the law of human activities affecting the surface processes.

Composition and the predicted functions of fungal communities and the key drivers in acidic soils of Jiaodong Peninsula, China

Introduction

Soil acidification imperils soil health and hinders the agricultural sustainability. As being more tolerant than bacteria to soil acidification, so it would be more meaningful for agricultural management and crop yield to characterize fungal community in acidic soils and manifest its key drivers.

Method

This study investigated the composition and diversity of fungal communities and its key driving factors by collecting 90 soil samples from the acidic region of Jiaodong Peninsula China, spanning 3 × 104 km2.

Results

The results indicated that most soil pH values ranged from 5.01 to 6.42, and the exchangeable acidity (EA) content raised significantly (p < 0.01) along with soil acidic degree increasing. However, no significant differences were found in fungal community diversity and composition among various soil samples, which were all predominantly habited with the phyla of Ascomycota and Basidiomycota. Results of the linear discriminant analysis effect size (LEfSe) analysis revealed that saprophytic fungi were biomarkers of the slightly acidic soil (pH 6.0-6.5), including Nectriaceae, Thielavia, Nectria, Haematonectria, and unclassified Microascaceae, while plant pathogenic fungi, such as Didymellaceae, were biomarkers of the soils pH < 5.5. Similarly, the FUNGuild results also indicated that saprophytic fungi and pathogenic fungi were the dominant functional guilds in the investigated acidic soils, accounting for 66% of the total fungal communities. Redundancy analysis (RDA) revealed that soil pH as well as nitrate nitrogen (NO 3 - -N) and total nitrogen (TN) significantly associated with fungal community at the phylum level, whilst soil pH was the only factor significantly linked to individual fungal classes (p < 0.01 or 0.05). The further Mantel test analysis and structural equation modeling (SEM) suggested that, in contrast to the negative and directive driving of soil pH on fungal communities' variation, the specific plant pathogenic fungi, Gibberella and Didymellaceae, were significantly and positively associated with soil acidic characteristics (p < 0.05).

Discussion

These findings highlighted that, in addition to modulating the variation of soil fungal community, soil acidification might prime some plant pathogens development. So that, more attentions should be focused on impact of soil acidification on fungal ecology, as well as plant pathogenic fungi.

Changing patterns of global nitrogen deposition driven by socio-economic development

Advances in manufacturing and trade have reshaped global nitrogen deposition patterns, yet their dynamics and drivers remain unclear. Here, we compile a comprehensive global nitrogen deposition database spanning 1977-2021, aggregating 52,671 site-years of data from observation networks and published articles. This database show that global nitrogen deposition to land is 92.7 Tg N in 2020. Total nitrogen deposition increases initially, stabilizing after peaking in 2015. Developing countries at low and middle latitudes emerge as new hotspots. The gross domestic product per capita is found to be highly and non-linearly correlated with global nitrogen deposition dynamic evolution, and reduced nitrogen deposition peaks higher and earlier than oxidized nitrogen deposition. Our findings underscore the need for policies that align agricultural and industrial progress to facilitate the peak shift or reduction of nitrogen deposition in developing countries and to strengthen measures to address NH3 emission hotspots in developed countries.

Impact of irrigation, fertilizer, and pesticide management practices on groundwater and soil health in the rice-wheat cropping system-a comparison of conventional, resource conservation technologies and conservation agriculture

Agricultural intensification in the Northwestern Indo-Gangetic Plain (NWIGP), a critical food bowl supporting millions of people, is leading to groundwater depletion and soil health degradation. This is primarily driven by conventional cultivation practices in the rice-wheat (RW) cropping system, which dominates over 85% of the IGP. Therefore, this study presents a systematic literature review of input management in the RW system, analyzes district-wise trends, outlines the current status, identifies problems, and proposes sustainable management options to achieve development goals. Our district-wise analysis estimates potential water savings from 20 to 60% by transitioning from flood to drip, sprinkler, laser land leveling, or conservation agriculture (CA). Alongside integrating water-saving technologies with CA, crop switching and recharge infrastructure enhancements are needed for groundwater sustainability. Furthermore, non-adherence with recommended fertilizer and pesticide practices, coupled with residue burning, adversely affects soil health and water quality. CA practices have demonstrated substantial benefits, including increased soil permeability (up to 51%), improved organic carbon content (up to 38%), higher nitrifying bacteria populations (up to 73%), enhanced dehydrogenase activities (up to 70%), and increased arbuscular mycorrhizal fungi populations (up to 56%). The detection of multiple fertilizers and pesticides in groundwater underscores the need for legislative measures and the promotion of sustainable farming practices similar to European Union strategies. Lastly, emphasis should be placed on fostering shifts in farmers' perceptions toward optimizing input utilization. The policy implications of this study extend beyond the NWIGP region to the entire country, stressing the critical importance of proactive measures to increase environmental sustainability.

Impact of short-term soil disturbance on cadmium remobilization and associated risk in vulnerable regions

A comprehensive understanding of cadmium (Cd) migration in soils near contaminated hotspots is crucial for optimizing remediation efforts and ensuring crop health. This study investigates agricultural soils from four sites in mining and sewage-irrigation areas, assessing the impact of inorganic and organic fertilizer application on soil Cd remobilization. Results revealed that fertilization, particularly with mineral phosphorus, disrupts soil stability, substantially increases short-term Cd mobility in vulnerable regions. Random Forest analysis identified elevated dissolved organic matter and pH changes as key drivers of Cd remobilization. Monte Carlo simulation, integrating Michaelis-Menten reaction kinetics model, further accessed the potential risk of Cd remobilization. The model predicted that the probabilities of grain exceeding Cd thresholds ranged from 021.6 % for rice, 13.8 %100 % for wheat, and 084.2 % for maize in the absence of fertilizer use. Fertilization significantly increased these exceedance probabilities by 6.1 %87.4 %, with the highest risks observed in irrigation-contaminated soils, particularly under mineral phosphorus fertilization. Nevertheless, it recommended that while fertilization can elevate Cd remobilization risk in hotspots, remediation strategies might not always be necessary. This study highlights the potential of hybrid data-driven approaches, combining machine learning, mechanistic model and stochastic prediction to simplify the complex environmental process, allowing for integrated risk evaluations.

Enhanced Pb immobilization by CaO/MgO-modified soybean residue (okara) in phosphate mining wasteland soil: Mechanism and microbial community structure

Lead (Pb) contamination is an inevitable consequence of phosphate mining, necessitating the development of effective remediation strategies. This study investigated the use of CaO/MgO-modified okara (CMS) as an eco-friendly approach to remediate Pb-contaminated soils from phosphate mining wastelands. In the present study, following 30 d of CMS application, the exchangeable Pb content was significantly decreased to 10.46%, with the majority of Pb transforming into more stable forms: carbonate-bound Pb (56.44%), Fe/Mn oxide-bound Pb (11.03%), and organic-bound Pb (19.58%). Additionally, the treatment led to a substantial enhancement in total phosphorus, available phosphorus, ammonium, and soil organic matter, thereby improving soil fertility. The microbial community structure was also significantly influenced by CMS, with a notable increase in Firmicutes to 45%. Key genera within the microbial community included Azospirillum, Pseudoxanthomonas, Sphingomonas, and Microvirga, with Pseudoxanthomonas and Massilia being the main differential species. These genera were significantly positively correlated, contributing to the maintenance of microbial community homeostasis and promoting the production of CO32- and PO43-, which further accelerated Pb immobilization. The results indicate that CMS is an effective amendment for Pb immobilization in contaminated soils, enhancing soil fertility and modulating the microbial community to promote Pb stabilization. This provides valuable insights into the ecological remediation of Pb-contaminated soils and water bodies, highlighting the potential of waste reuse in environmental management.

Identification and Characterization of Key Genes for Nitrogen Utilization from Saccharum spontaneum Sub-Genome in Modern Sugarcane Cultivar

Sugarcane (Saccharum spp.) is globally considered an important crop for sugar and biofuel production. During sugarcane production, the heavy reliance on chemical nitrogen fertilizer has resulted in low nitrogen use efficiency (NUE) and high loss. Up until now, there has been extensive research on the transcriptomic dynamics during sugarcane response to low nitrogen (LN) stress. However, the specific contribution of S. spontaneum to the NUE of modern sugarcane remains unclear. In the present study, the comparative transcriptome analysis of two contrasting sugarcane cultivars in response to nitrogen deficiency was performed via the combination of genomes of S. spontaneum and S. officinarum. Sub-genome analysis indicated that S. spontaneum supports the high NUE of modern sugarcane by providing genes related to nitrogen and carbohydrate metabolism, photosynthesis, and amino acid metabolism. Additionally, the key genes involved in nitrogen metabolism from the S. spontaneum were successfully identified through weighted gene co-expression network analyses (WGCNA), and a high-affinity nitrate transporter named ScNRT2.3 was subsequently cloned. Heterogeneous expression of the ScNRT2.3, a cell membrane-localized protein, could enhance the growth of Arabidopsis under low nitrate conditions. Furthermore, a conserved protein module known as NAR2.1/NRT2.3 was shown to regulate the response to LN stress in sugarcane roots through molecular interaction. This work helps to clarify the contribution of S. spontaneum to the NUE in modern sugarcane, and the function of the ScNRT2.3 in sugarcane.

Soil type data provide new methods and insights for heavy metal pollution assessment and driving factors analysis

Assessing heavy metal pollution and understanding the driving factors are crucial for monitoring and managing soil pollution. This study developed two modified assessment methods (NIPIt and NECI) based on soil type-specific background values and pollution indices, and combined them with the receptor model to evaluate pollution status. Additionally, a structural equation model was used to analyze the driving factors of soil heavy metal pollution. Results showed that the average NIPIt and NECI were 1.48 and 0.92, respectively, indicating a low pollution risk level. In some areas, Cd and Hg were the primary heavy metals contributing to pollution risk, with their highest average concentrations exceeding soil type-specific background values by 2.06 and 2.04 times, respectively. Additionally, in black soils, meadow soils, and chernozems, heavy metals primarily originated from natural sources, accounting for 48.92 %, 45.98 %, and 45.58 %, respectively. In aeolian soils, agricultural sources were predominant, contributing 43.38 %. Soil pH and organic matter were key soil properties affecting NECI and NIPIt, with direct effects of 0.36 and -0.19, respectively. This study aims to provide new methods and insights for the comprehensive assessment and driving factors analysis of soil heavy metal pollution, with the goal of enhancing pollution monitoring and reducing risk.

Effects of bamboo biochar on soil physicochemical properties and microbial diversity in tea gardens

Biochar, a carbon-rich material that has attracted considerable interest in interdisciplinary research, is produced through a process known as pyrolysis, which involves the thermal decomposition of organic material in the absence of oxygen. Bamboo biochar is a specific type of biochar, manufactured from bamboo straw through carbonisation at 800 °C and subsequent filtration through a 100-mesh sieve. There is currently a lack of research into the potential benefits of bamboo biochar in improving soil quality in tea gardens. The aim of this study was to investigate the effect of bamboo biochar on the physicochemical properties, enzymatic activity, and microbial community structure of tea garden soils. The results demonstrate that the integration of bamboo biochar into the soil significantly enhanced the soil pH, total nitrogen, available nitrogen, total phosphorus, available phosphorus, available potassium, and slowly available potassium by 15.3%, 52.0%, 91.5%, 91%, 48.4%, 94.2%, and 107.7%, respectively. In addition, soil acid phosphatase activity decreased significantly by 52.5%. In contrast, the activities of sucrase, catalase, and β-glucosidase increased substantially by 54.0%, 68.7%, and 68.4%, respectively, when organic fertilizer and bamboo biochar were applied concurrently. Additionally, the Shannon, Simpson, and Pielou diversity indices of the microbial communities were significantly enhanced. Following the incorporation of bamboo biochar in the soil samples, the relative abundance of Proteobacteria increased significantly, whereas that of Acidobacteria decreased. Various concentrations of bamboo biochar markedly influenced microbial markers in the soil. The results of this study suggest that the application of bamboo biochar to soil may modestly improve its physicochemical properties, enzyme activity, and microbial community structure. These findings provide a foundation for future investigations on soil ecological restoration.

Human interventions have enhanced the net ecosystem productivity of farmland in China

Human interventions, such as farmland management, have long been considered crucial for soil carbon sequestration, but little is known about the exact impact of these interventions on the net carbon flux, represented by net ecosystem productivity (NEP). Here, using multiple long-term, large-scale data and statistical data, we reveal that 75.54% of farmland NEP in China experiences an increase, with northern regions showing the greatest potential for future farmland carbon sequestration. This growth is primarily attributed to the role of farmland management, especially the enhancement of no-tillage, land consolidation and multiple cropping level (17.02%, major grain-producing areas in 2020). Notably, the current unreasonable practices of mechanized straw returning and irrigation have a negative impact on farmland NEP. Our results show that it is imperative to acknowledge the crucial role of human interventions on farmland NEP to strike a balance between food security and farmland carbon sequestration.

Transcription factor SlSTOP1 regulates Small Auxin-Up RNA Genes for tomato root elongation under aluminum stress

Aluminum (Al) stress, a prevalent constraint in acidic soils, inhibits plant growth by inhibiting root elongation through restricted cell expansion. The molecular mechanisms of Al-induced root inhibition, however, are not fully understood. This study aimed to elucidate the role of Small Auxin-up RNAs (SlSAURs), which function downstream of the key Al stress-responsive transcription factor SENSITIVE TO PROTON RHIZOTOXICITY 1 (SlSTOP1) and its enhancer STOP1-INTERACTING ZINC-FINGER PROTEIN 1 (SlSZP1), in modulating root elongation under Al stress in tomato (Solanum lycopersicum). Our findings demonstrated that tomato lines with knocked-out SlSAURs exhibited shorter root lengths when subjected to Al stress. Further investigation into the underlying mechanisms revealed that SlSAURs interact with Type 2C Protein Phosphatases (SlPP2Cs), specifically D-clade Type 2C Protein Phosphatases (SlPP2C.Ds). This interaction was pivotal as it suppresses the phosphatase activity, leading to the degradation of SlPP2C.D's inhibitory effect on plasma membrane H+-ATPase. Consequently, this promoted cell expansion and root elongation under Al stress. These findings increase our understanding of the molecular mechanisms by which Al ions modulate root elongation. The discovery of the SlSAUR-SlPP2C.D interaction and its impact on H+-ATPase activity also provides a perspective on the adaptive strategies employed by plants to cope with Al toxicity, which may lead to the development of tomato cultivars with enhanced Al stress tolerance, thereby improving crop productivity in acidic soils.

The impact of Ricinus straw on tomato growth and soil microbial community

Returning straw can alter the soil microbial community, reduce the occurrence of soilborne diseases, and promote plant growth. In this study, we aimed to evaluate the effects of Ricinus straw on tomato growth and rhizosphere microbial community. We carried out microcosm experiments to investigate the effects of Ricinus straw with different dosages (0, 1, and 3%) on tomato dry biomass and rhizosphere bacterial and fungal communities. The results indicated that the dry biomass of tomato seedlings with 1% addition of Ricinus straw increased by 53.98%. In addition, Ricinus straw also changed the abundance, diversities, and composition of tomato rhizosphere microbial communities. In detail, the addition of 1% Ricinus straw increased the relative abundance of putative beneficial bacteria and fungi in straw decomposition, such as Ramlibacter sp., Azohydromonas sp., Schizothecium sp., and Acaulium sp., and decreased the relative abundance of Fusarium sp. Meanwhile, Ricinus straw inhibited the growth of putative pathogenic microorganisms. The correlation analysis showed that the changes in fungal community operational taxonomic units stimulated by the addition of Ricinus straw may play a crucial positive regulatory role in tomato growth. Finally, the representative fungal strain Fusarium oxysporum f. sp. Lycopersici (FOL), named TF25, was isolated and cultured. We found that Ricinus straw extract inhibited the growth of TF25 in an in vitro experiment with an inhibition rate of 34.95-51.91%. Collectively, Ricinus straw promoted plant growth by changing the rhizosphere microbial community composition and inhibiting FOL growth, which provides new evidence for understanding the improvement of key microorganism composition in improving crop growth and the sustainability of agriculture.

Microbial rrn copy number is associated with soil C: N ratio and pH under long-term fertilization

Soil microbial life-history strategies, as indicated by rRNA operon (rrn) copy numbers, strongly influence agro-ecosystem functioning. Long-term N fertilization causes strong and lasting changes in soil properties, yet its impact on microbial strategies remains largely unexplored. Using long-term field experiments across three agro-ecosystems, we consistently found that N fertilization strongly decreased soil C: N ratio and pH, further increasing the community-level rrn copy number, including both average rrn copy number and total 16S rRNA copy number. Soil C: N stoichiometry balanced by N supplement favored the growth of N-dependent copiotrophic species containing high rrn copy numbers (an average of 2.5) and increased their network connections, predominantly contributing to community-level rrn copy number increase. Decreased soil pH caused by N fertilization also favored the growth of some species whose abundances negatively correlated with pH, partially contributing to the community-level rrn copy number increase. By examining the genomes of two dominant species, we found that microorganisms with a higher rrn copy number (6), e.g., Streptomyces scabiei, possessed more genes related to C and N transport and metabolism. In contrast, the Mycobacterium simiae with a lower rrn copy number (1) has more genes associated with secondary metabolite biosynthesis and lipid transport and metabolism. Our finding challenges the concept of microbial life-strategy regulation solely by nutrient availability, highlighting the important contributions of soil stoichiometric balance and pH to microbial strategies in agro-ecosystems under long-term N inputs.

Light-driven nitrogen fixation routes for green ammonia production

The global goal for decarbonization of the energy sector and the chemical industry could become a reality by a massive increase in renewable-based technologies. For this clean energy transition, the versatile green ammonia may play a key role in the future as a fossil-free fertilizer, long-term energy storage medium, chemical feedstock, and clean burning fuel for transportation and decentralized power generation. The high energy-intensive industrial ammonia production has triggered researchers to look for a step change in new synthetic approaches powered by renewable energies. This review provides a comprehensive comparison of light-mediated N2 fixation technologies for green ammonia production, including photocatalytic, photoelectrocatalytic, PV-electrocatalytic and photothermocatalytic routes. Since these approaches are still at laboratory scale, we examine the most recent developments and discuss the open challenges for future improvements. Last, we offer a technoeconomic comparison of current and emerging ammonia production technologies, highlighting costs, barriers, recommendations, and potential opportunities for the real development of the next generation of green ammonia solutions.

Green production of apples delivers environmental and economic benefits in China

Sustainable alternative farming systems are gaining popularity worldwide because of the negative effects of conventional agriculture on global climate change and the environmental degradation caused by intensive use of synthetic inputs. The green farming system in China is an integrated production strategy that focuses on reducing chemical fertilizer use while increasing organic manure inputs. Despite their rapid growth as more sustainable systems over the past decades, green farming systems have not been systematically evaluated to date. We used apple production as a representative case to assess the sustainability of green farming systems. Across major apple-producing regions in China, green farming reduced the application of chemical fertilizer nitrogen (N) by 46.8% (from 412 to 219 kg ha-1) and increased that of manure N by 33.1% (from 171 to 227 kg ha-1) on average compared with conventional systems enhancing N use efficiency by 7.27-20.27% and reducing N losses by 8.92%-11.56%. It also slightly lowered yield by 4.34%-13.8% in four provinces. Soil fertility was improved in green orchards through increases in soil organic matter, total N, and available major nutrients. Our cradle-to-farm-gate life-cycle assessment revealed that green farming helped to mitigate greenhouse gas emissions by an average of 12.6%, potentially contributing to a reduction of 165 239 t CO2 eq annually in major apple-producing areas. In addition, green farming achieved 39.3% higher profitability ($7180 ha-1 year-1) at the farmer level. Our study demonstrates the potential of green production of apples for the development of sustainable agriculture in China. These findings advance our understanding of sustainable alternative farming systems and offer perspectives for the sustainable development of global agriculture.

Flue-cured tobacco intercropping with insectary floral plants improves rhizosphere soil microbial communities and chemical properties of flue-cured tobacco

BACKGROUND

Continuous cropping of the same crop leads to land degradation. This is also called the continuous-cropping obstacle. Currently, intercropping tobacco with other crops can serve as an effective strategy to alleviate continuous cropping obstacles.

RESULTS

In this study, tobacco K326 and insectary floral plants were used as materials, and seven treatments of tobacco monoculture (CK), tobacco intercropped with Tagetes erecta, Vicia villosa, Fagopyrum esculentum, Lobularia maritima, Trifolium repens, and Argyranthemum frutescens respectively, were set up to study their effects on rhizosphere soil chemical properties and composition and structure of rhizosphere soil microbial community of tobacco. The 16 S rRNA gene and ITS amplicons were sequenced using Illumina high-throughput sequencing. tobacco/insectary floral plants intercropping can influence rhizosphere soil chemical properties, which also change rhizosphere microbial communities. The CK and treatment groups tobacco rhizosphere soil microorganisms had significantly different genera, such as tobacco intercropping with T. repens and A. frutescens significantly increased the number of Fusarium and intercropping T. erecta, V. villosa, L. maritima, T. repens, and A. frutescens significantly increased the number of Sphingomonas and unknown Gemmatimonadaceae. Additionally, intercropping T. erecta, V. villosa and L. maritima changed the rhizosphere fungal and bacteria community and composition of tobacco and the positive correlation between tobacco rhizosphere the genera of fungi and bacterial were greater than CK. The pathway of the carbohydrate metabolism, amino acid metabolism, and energy metabolism in rhizosphere bacteria were significantly decreased after continuous cropping. Fungal symbiotic trophic and saprophytic trophic were significantly increased after intercropping V. villosa, L. maritima and plant pathogen and animal pathogen were increased after intercropping T. repens and A. frutescens. Additionally, bacterial and fungal communities significantly correlated with soil chemical properties, respectively.

CONCLUSION

This study reveals that intercropping tobacco with insectary floral plants, particularly T. erecta, V. villosa, L. maritima and A. frutescens significantly affects soil chemical properties and alters rhizosphere microbial communities, increasing the abundance of certain microbial genera. Additionally, intercropping enhances pathways related to carbohydrate, amino acid, and energy metabolism in rhizosphere bacteria. These findings suggest that intercropping could provide a promising strategy to overcome challenges associated with continuous tobacco cropping by regulating the rhizosphere environment.

Long-term effects of conventional cultivation on soil cation exchange capacity and base saturation in an arid desert region

Land reclamation and subsequent management affect soil condition, which is critical for sustainable agricultural production. Soil cation exchange capacity (CEC) and base saturation (BS%) play an important role in the assessment of soil fertility and buffering capacity. However, the variation of these indicators in the evolution of oasis farmland in arid desert areas remains unclear. Therefore, this study was carried out aiming to evaluate the effect of desert reclamation and following long-term conventional cultivation on the CEC and BS%. For the study, we investigated the CEC and exchangeable bases (ExBas) content in oasis farmlands along a chronosequence (0-100 years) of cultivation in arid region and identified the key factors affecting CEC and BS%. The results showed that soil CEC and ExBas significantly increased after desert reclamation, whereas the BS% dramatically decreased. However, all these changes were alleviated with the conventional cultivation age. Regression analysis showed that soil CEC, ExBas, and BS% all exponentially changed with cultivation years. Based on our findings, CEC and ExBas were closely related to soil particle size composition, total nitrogen (TN), soil organic matter (SOM) and soil water content (SWC). The multiple stepwise regression further indicated that the changes in CEC and ExBas after reclamation mainly depended on the silt content, SWC, SOM, and TN. Our findings highlight that although desert reclamation increases soil CEC and ExBas in arid area, this effect tends to disappear after about 100 years of conventional cultivation, and meanwhile, the decline in BS% due to increased acids should also be noted.

Biochar affects organic carbon composition and stability in highly acidic tea plantation soil

Biochar amendments are effective in stabilizing soil aggregates and improving soil organic carbon (SOC) content. However, the effects of biochar on highly acidic soil and their relation with soil SOC stability remain understudied. The study aimed to investigate the impact of biochar on changes of aggregate distribution and SOC stability in a highly acidic tea plantation soils over an eight-year period. Soil samples were collected from plots with varying biochar application amounts (0, 2.5 t ha-1, 5 t ha-1, 10 t ha-1, 20 t ha-1 and 40 t ha-1). The content of SOC, iron bound organic carbon (OC-Fe), particulate organic carbon (POC), mineral-associated organic carbon (MAOC) and the functional group composition of SOC was analyzed. The results indicated that in the biochar application treatments, the value of soil pH, SOC, POC and MAOC contents were increased from 3.92 to 4.28, 6.68%-187.02%, 8.31%-66.78% and 13.07%-236.47% respectively, compared with CK, while the content of macro-aggregate (particle size>0.25 mm) and soil aggregates mean weight diameter (MWD) significantly increased with higher biochar application amounts. But dissolved organic carbon (DOC) and OC-Fe content exhibited downward trend, decreased from 2.43% to 6.97% and 4.18%-19.91%. Furthermore, aromatic-C levels increased, with increased biochar application amounts. The integration of biochar not only bolstered soil aggregate stability but also amplified the presence of aromatic-C, thereby enhancing the resilience of organic carbon in highly acidic tea garden soil (BC40 > BC20 > BC5>BC2.5 > BC10 > CK), with increases ranging from 6% to 47%. The principal component analysis and structural equation modeling identified soil pH, TN, SOC, POC, MAOC, R > 0.25 and MWD as key factors of soil organic carbon stability. These findings provide crucial insights into the mechanism underlying biochar's efficiency in fortifying organic carbon stability, particularly in the context of highly acidic soil.

Towards sustainable use of acidic soils: Deciphering aluminum-resistant mechanisms in plants

The widespread occurrence of acidic soils presents a major challenge for agriculture, as it hampers productivity via a combination of mineral toxicity, nutrient deficiency, and poor water uptake. Conventional remediation methods, such as amending the soil with lime, magnesium, or calcium, are expensive and not environmentally friendly. The most effective method to mitigate soil acidity is the cultivation of acid-tolerant cultivars. The ability of plants to tolerate acidic soils varies significantly, and a key factor influencing this tolerance is aluminum (Al) toxicity. Therefore, understanding the physiological, molecular, and genetic underpinnings of Al tolerance is essential for the successful breeding of acid-tolerant crops. Different tolerance mechanisms are regulated by various genes and quantitative trait loci in various plant species, and molecular markers have been developed to facilitate gene cloning and to support marker-assisted selection for breeding Al-tolerant cultivars. This study provides a comprehensive review of the current developments in understanding the physiological and molecular mechanisms underlying Al resistance. Through the application of genome-wide association methods, it is expected that new Al-resistant genes can be identified and utilized to cultivate Al-resistant varieties through intercrossing, backcrossing, and molecular marker-assisted selection, promoting the sustainable use of acidic soils.

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.

Sugar transporter modulates nitrogen-determined tillering and yield formation in rice

Nitrogen (N) fertilizer application ensures crop production and food security worldwide. N-controlled boosting of shoot branching that is also referred as tillering can improve planting density for increasing grain yield of cereals. Here, we report that Sugar Transporter Protein 28 (OsSTP28) as a key regulator of N-responsive tillering and yield formation in rice. N supply inhibits the expression of OsSTP28, resulting in glucose accumulation in the apoplast of tiller buds, which in turn suppresses the expression of a transcriptional inhibitor ORYZA SATIVA HOMEOBOX 15 (OSH15) via an epigenetic mechanism to activate gibberellin 2-oxidases (GA2oxs)-facilitated gibberellin catabolism in shoot base. Thereby, OsSTP28-OSH15-GA2oxs module reduces the level of bioactive gibberellin in shoot base upon increased N supply, and consequently promotes tillering and grain yield. Moreover, we identify an elite allele of OsSTP28 that can effectively promote N-responsive tillering and yield formation, thus representing a valuable breeding target of N use efficiency improvement for agricultural sustainability.

Polymer-Modified Fertilizers for Mitigating Strawberry Root Burn

Polymer-modified fertilizers (PMFs) with prolonged nutrient release present a promising solution to address the challenges associated with conventional fertilization practices, particularly for sensitive crops such as strawberries. This study investigates the effectiveness of biodegradable PMFs in maintaining nutrient availability at optimal levels while minimizing root burn and nutrient losses. In a factorial field experiment, we obtaineda total of 3780 sets of parallel measured time series for soil EC, moisture, and temperature as well as two sets of harvest data to evaluate the impact of varying concentrations of polyvinyl alcohol (PVA) on the nutrient release rates from complex NPK fertilizer and monoammonium phosphate. Results indicate that polymer modifications significantly slow down nutrient release, leading to optimal salt levels and maximizing yield while remaining low enough to prevent the risk of root burn (EC of soil solution below 1 mS/cm). Consequently, the application of PMFs enhances strawberry yield surplus (on average 2.8 times in the second harvest) by ensuring a steady supply of nutrients throughout the growing season without inducing stress, which reduces the yield by nearly half. This research provides valuable insights into the development of more effective fertilization strategies for strawberry cultivation and other sensitive crops using PMFs.

Potential to Ensure Safe Production of Water Spinach in Heavy Metals-Contaminated Soil by Substituting Chemical Fertilizer with Organic Fertilizer

Organic fertilizers are widely used to improve soil quality. However, their potential for ensuring the safe production of vegetables in soils with varying levels of heavy metals pollution remains inadequately explored. Here, we conducted a pot experiment to investigate the effects of substituting chemical fertilizers with organic fertilizer on the HMs accumulation in water spinach by simulating soils with different levels of HMs pollution. The results showed that the organic fertilizer significantly increased the soil pH, cation exchange capacity (CEC), and organic matter (OM). Furthermore, it led to a reduction in the soil DTPA-Cd and DTPA-Pb levels by 3.3-20.6% and 22.4-47.3%, respectively, whereas the DTPA-As levels increased by 0.07-7.7 times. The organic fertilizer effectively reduced the Cd and Pb content in water spinach below the safety limits when the added Cd content in the soil was less than 2 mg/kg and the Pb content was equal to or less than 90 mg/kg. However, its efficacy in reducing As accumulation in water spinach was limited, emphasizing the need for caution when using organic fertilizers in As-contaminated soils. Our results provide valuable insights for the scientific and precise utilization of organic fertilizers, thereby contributing to the safe production of vegetables.