When biochar is involved in rhizosphere dissipation and plant absorption of pesticides: A meta-analysis

Organic amendments restore soil biological properties under pesticides application

Pesticides are indispensable in modern agriculture, but they also affect soil biological properties and soil sustainability. Although organic amendments (OAs) have the potential to alleviate the negative effects of pesticides and restore soil biological properties, but results have been inconsistent. Here, we conducted a meta-analysis to study the overall effects of OAs on soil biological properties under pesticide application. Our results showed that sole pesticide application significantly decreased soil enzymatic activities (i.e., by -2.5 % for urease, -22 % for β-glucosidase, and - 10 % for dehydrogenase) and reduced microbial population size (e.g., by -6 % for microbial biomass, -10 % for actinomycetes population, -7 % for bacteria and - 12 % for fungi population). Noticeably, sole fungicide application did not significantly affect soil bacteria, fungi and actinomycetes populations as compared to sole herbicide and insecticide. In contrast, pesticide with OAs application significantly increased soil respiration (+60 %), activities of dehydrogenase (+73 %), urease (+80 %) and β-glucosidase (+65 %), microbial biomass (+79 %), bacterial (+65 %) and fungal (+13 %) population sizes than sole pesticide. However, soil acid phosphatase activity significantly decreased (-17 %) by using pesticide with OAs. Our results suggest that OAs in combination with pesticides can modify soil physicochemical properties and subsequently restore soil biological properties, but the magnitude of improvement of specific OAs in combination with individual pesticide classes remains unknown and should be studied in future research.

Global meta-analysis and machine learning reveal the critical role of soil properties in influencing biochar-pesticide interactions

Biochar application in soils is increasingly advocated globally for its dual benefits in enhancing agricultural productivity and sequestering carbon. However, lingering concerns persist regarding its environmental impact, particularly concerning its interactions with pesticide residues in soil. Previous research has fragmentarily indicated elevated pesticide residues and prolonged persistence in biochar-amended soil, suggesting a potential adverse consequence of biochar application on pesticide degradation. Yet, conclusive evidence and conditions for this phenomenon remain elusive. To address this gap, we conducted a comprehensive assessment using meta-analysis and machine learning techniques, synthesizing data from 58 studies comprising 386 observations worldwide. Contrary to initial concerns, our findings revealed no definitive increase in pesticide concentrations in soil following biochar application. Moreover, a significant reduction of 66 % in pesticide concentrations within soil organisms, such as plants and earthworms, was observed. The quantitative analysis identified soil organic matter content as a key factor influencing biochar-pesticide interactions, suggesting that applying biochar to soils rich in organic matter is less likely to increase pesticide persistence. This study provides a critical assessment of the environmental fate of pesticides under biochar application, offering valuable guidance for the optimal utilization of both pesticides and biochar in sustainable agricultural practices.

Oral Administration of Lactiplantibacillus plantarum CCFM8661 Alleviates Dichlorvos-Induced Toxicity in Mice

Dichlorvos (DDVP) is an organophosphorus pesticide commonly used in agriculture for pest control, which may enter the organism from the food chain and cause harm. This study aimed to investigate the mitigation effect of Lactiplantibacillus plantarum CCFM8661 (a strain of the bacteria) on DDVP toxicity. Sixty male mice were randomly divided into five groups including control (saline), model (DDVP), low-dose, medium-dose, and high-dose groups, and alleviating effect was evaluated by determining body weight, pesticide residues, oxidative stress, and inflammation, and by histological analysis. The results showed that compared with the model group, body weight and acetylcholinesterase activity, and SOD, CAT, T-AOC, and GSH levels significantly increased, and serum DDVP content, MDA level, IL-1β, and TNF-α significantly decreased after administration of the L. plantarum CCFM8661. The study demonstrated that L. plantarum CCFM8661 exhibited a significant detoxification effect on pesticide toxicity in mice, providing a theoretical basis for the application of probiotics in mitigating pesticide-induced damage.

Removal of environmental pollutants using biochar: current status and emerging opportunities

In recent times, biochar has emerged as a novel approach for environmental remediation due to its exceptional adsorption capacity, attributed to its porous structure formed by the pyrolysis of biomass at elevated temperatures in oxygen-restricted conditions. This characteristic has driven its widespread use in environmental remediation to remove pollutants. When biochar is introduced into ecosystems, it usually changes the makeup of microbial communities by offering a favorable habitat. Its porous structure creates a protective environment that shields them from external pressures. Consequently, microorganisms adhering to biochar surfaces exhibit increased resilience to environmental conditions, thereby enhancing their capacity to degrade pollutants. During this process, pollutants are broken down into smaller molecules through the collaborative efforts of biochar surface groups and microorganisms. Biochar is also often used in conjunction with composting techniques to enhance compost quality by improving aeration and serving as a carrier for slow-release fertilizers. The utilization of biochar to support sustainable agricultural practices and combat environmental contamination is a prominent area of current research. This study aims to examine the beneficial impacts of biochar application on the absorption and breakdown of contaminants in environmental and agricultural settings, offering insights into its optimization for enhanced efficacy.

Physiological and biochemical characteristics and microbial responses of Medicago sativa (Fabales: Fabaceae) varieties with different resistance to atrazine stress

Atrazine, a commonly employed herbicide for corn production, can leave residues in soil, resulting in photosynthetic toxicity and impeding growth in subsequent alfalfa (Medicago sativa L.) crops within alfalfa-corn rotation systems. The molecular regulatory mechanisms by which atrazine affects alfalfa growth and development, particularly its impact on the microbial communities of the alfalfa rhizosphere, are not well understood. This study carried out field experiments to explore the influence of atrazine stress on the biomass, chlorophyll content, antioxidant system, and rhizosphere microbial communities of the atrazine-sensitive alfalfa variety WL-363 and the atrazine-resistant variety JN5010. The results revealed that atrazine significantly reduced WL-363 growth, decreasing plant height by 8.58 cm and root length by 5.42 cm (p < 0.05). Conversely, JN5010 showed minimal reductions, with decreases of 1.96 cm in height and 1.26 cm in root length. Chlorophyll content in WL-363 decreased by 35% under atrazine stress, while in JN5010, it was reduced by only 10%. Reactive oxygen species (ROS) accumulation increased by 60% in WL-363, compared to a 20% increase in JN5010 (p < 0.05 for both). Antioxidant enzyme activities, such as superoxide dismutase (SOD) and catalase (CAT), were significantly elevated in JN5010 (p < 0.05), suggesting a more robust defense mechanism. Although the predominant bacterial and fungal abundances in rhizosphere soils remained generally unchanged under atrazine stress, specific microbial groups exhibited variable responses. Notably, Promicromonospora abundance declined in WL-363 but increased in JN5010. FAPROTAX functional predictions indicated shifts in the abundance of microorganisms associated with pesticide degradation, resistance, and microbial structure reconstruction under atrazine stress, displaying different patterns between the two varieties. This study provides insights into how atrazine residues affect alfalfa rhizosphere microorganisms and identifies differential microbial responses to atrazine stress, offering valuable reference data for screening and identifying atrazine-degrading bacteria.

The boom era of emerging contaminants: A review of remediating agricultural soils by biochar

Emerging contaminants (ECs) are widely sourced persistent pollutants that pose a significant threat to the environment and human health. Their footprint spans global ecosystems, making their remediation highly challenging. In recent years, a significant amount of literature has focused on the use of biochar for remediation of heavy metals and organic pollutants in soil and water environments. However, the use of biochar for the remediation of ECs in agricultural soils has not received as much attention, and as a result, there are limited reviews available on this topic. Thus, this review aims to provide an overview of the primary types, sources, and hazards of ECs in farmland, as well as the structure, functions, and preparation types of biochar. Furthermore, this paper emphasizes the importance and prospects of three remediation strategies for ECs in cropland: (i) employing activated, modified, and composite biochar for remediation, which exhibit superior pollutant removal compared to pure biochar; (ii) exploring the potential synergistic efficiency between biochar and compost, enhancing their effectiveness in soil improvement and pollution remediation; (iii) utilizing biochar as a shelter and nutrient source for microorganisms in biochar-mediated microbial remediation, positively impacting soil properties and microbial community structure. Given the increasing global prevalence of ECs, the remediation strategies provided in this paper aim to serve as a valuable reference for future remediation of ECs-contaminated agricultural lands.

Predicting the bioavailability of polycyclic aromatic hydrocarbons in rhizosphere soil using a new novel in situ solid-phase microextraction technique

In situ measurement of the bioavailability of organic pollutants in soil is crucial for understanding their environmental behavior and assessing health risks. Due to the high heterogeneity of soil, microscale determination is crucial for achieving high accuracy, but few methods are available. In this study, microsized probes coated with polydimethylsiloxane (PDMS) were used to measure the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in soil in situ. The concentrations of PAHs enriched by the PDMS-coated probes correlated well with the results of bioassays using earthworms (R2 = 0.92-0.99) and ryegrass roots (R2 = 0.92-0.99). Compared with other chemical extraction methods, such as n-butanol extraction, the proposed method has advantages such as in situ operation, microvolume analysis, and negligible interference to the soil environment. In the soil rhizosphere zone, PAHs bioavailability decreased in the following order: rhizosphere > near-rhizosphere > far-rhizosphere. The bioavailability of PAHs in soil amended with biochar was also successfully characterized by the proposed method. Thus, this study developed an in situ and microscale method to predict the bioavailability of organic pollutants in contaminated soils and provides new insight into migration and transformation processes in rhizosphere soil.

Exploring the influence of invasive weed biochar on the sorption and dissipation dynamics of imazethapyr in sandy loam soil

The management of invasive weeds on both arable and non-arable land is a vast challenge. Converting these invasive weeds into biochar and using them to control the fate of herbicides in soil could be an effective strategy within the concept of turning waste into a wealth product. In this study, the fate of imazethapyr (IMZ), a commonly used herbicide in various crops, was investigated by introducing such weeds as biochar, i.e., Parthenium hysterophorus (PB) and Lantana camara (LB) in sandy loam soil. In terms of kinetics, the pseudo-second order (PSO) model provided the best fit for both biochar-mixed soils. More IMZ was sorbed onto LB-mixed soil compared to PB-mixed soil. When compared to the control (no biochar), both PB and LB biochars (at concentrations of 0.2% and 0.5%) increased IMZ adsorption, although the extent of this effect varied depending on the dosage and type of biochar. The Freundlich adsorption isotherm provided a satisfactory explanation for IMZ adsorption in soil/soil mixed with biochar, with the adsorption process exhibiting high nonlinearity. The values of Gibb's free energy change (ΔG) were negative for both adsorption and desorption in soil/soil mixed with biochar, indicating that sorption was exothermic and spontaneous. Both types of biochar significantly affect IMZ dissipation, with higher degradation observed in LB-amended soil compared to PB-amended soil. Hence, the findings suggest that the preparation of biochar from invasive weeds and its utilization for managing the fate of herbicides can effectively reduce the residual toxicity of IMZ in treated agroecosystems in tropical and subtropical regions.

Research progress on remediation of organochlorine pesticide contamination in soil

Deteriorated soil pollution has grown into a worldwide environmental concern over the years. Organochlorine pesticide (OCP) residues, featured with ubiquity, persistence and refractoriness, are one of the main pollution sources, causing soil degradation, fertility decline and nutritional imbalance, and severely impacting soil ecology. Furthermore, residual OCPs in soil may enter the human body along with food chain accumulation and pose a serious health threat. To date, many remediation technologies including physicochemical and biological ways for organochlorine pollution have been developed at home and abroad, but none of them is a panacea suitable for all occasions. Rational selection and scientific decision-making are grounded in in-depth knowledge of various restoration techniques. However, soil pollution treatment often encounters the interference of multiple factors (climate, soil properties, cost, restoration efficiency, etc.) in complex environments, and there is still a lack of systematic summary and comparative analysis of different soil OCP removal methods. Thus, to better guide the remediation of contaminated soil, this review summarized the most commonly used strategies for OCP removal, evaluated their merits and limitations and discussed the application scenarios of different methods. It will facilitate the development of efficient, inexpensive and environmentally friendly soil remediation strategies for sustainable agricultural and ecological development.