Soil Microbial Parameters Research Articles

Changes in Soil Microbial Parameters after Herbicide Application in Soils under Conventional Tillage and Non-Tillage

Changes in Soil Microbial Parameters after Herbicide Application in Soils under Conventional Tillage and Non-Tillage

Immobilisation of anaerobic digestate supplied nitrogen into soil microbial biomass is dependent on lability of high organic carbon materials additives

Anaerobic digestate is a nutrient rich slurry by-product derived from biogas production, often used as a fertiliser due to its high nitrogen content. However, nitrogen losses from its application can lead to environmental pollution. In a laboratory experiment, the addition of high organic carbon materials to digestate-amended soil as a potential means to stimulate microbial immobilisation of digestate supplied nitrogen was investigated. Soil was incubated in pots for 5 months with digestate (equivalent to 250 kgN ha−1). The impact of adding carbon into the digestate (equivalent to 540 kgC ha−1) as either glycerol, straw, woodchip, or biochar on soil microbial and chemical parameters was quantified. Glycerol amended soils had significantly higher microbial biomass compared to digestate alone during the first month and at 30 days after application had a 4x higher on average microbial N. The digestate + straw treatment resulted in a 2.5x significantly greater nitrogen immobilisation compared to digestate alone after 3 months of incubation. The digestate + woodchip had a 2× higher mean microbial N after 5 months, whilst the biochar amendment did not stimulate significant nitrogen immobilisation at any time. These results suggest that mixing a labile to moderately labile organic carbon amendment, such as straw, with digestate has the greatest potential to reduce nitrogen losses following digestate application through microbial immobilisation.

Sustainable Restoration of Soil Functionality in PTE-Affected Environments: Biochar Impact on Soil Chemistry, Microbiology, Biochemistry, and Plant Growth

Biochar can be useful for the functional recovery of soils contaminated with potentially toxic elements (PTEs), even if its effectiveness is variable and sometimes limited, and conflicting results have been recently reported. To shed some light on this regard, softwood-derived biochar was added at 2.5 (2.5-Bio) and 5.0% w/w (5.0-Bio) rates to an acidic (pH 5.74) soil contaminated by Cd (28 mg kg−1), Pb (10,625 mg kg−1), and Zn (3407 mg kg−1). Biochar addition increased soil pH, available P and CEC, and reduced labile Cd, Pb, and Zn (e.g., by 27, 37, and 46% in 5.0-Bio vs. the unamended soil). The addition of biochar did not change the number of total heterotrophic bacteria, actinomycetes, and fungi, while it reduced the number of Pseudomonas spp. and soil microbial biomass. Dehydrogenase activity was reduced in amended soils (e.g., by ~60 and 75% in 2.5- and 5.0-Bio, respectively), while in the same soils, urease increased by 48 and 78%. Approximately 16S rRNA gene amplicon sequencing and the Biolog community-level physiological profile highlighted a significant biochar impact (especially at a 5% rate) on soil bacterial diversity. Tomato (but not triticale) yield increased in the amended soils, especially in 2.5-Bio. This biochar rate was also the most effective at reducing Cd and Pb concentrations in shoots. Overall, these results demonstrate that 2.5% (but not 5.0%) biochar can be useful to restore the soil chemical fertility of PTE-polluted soils with limited (or null) impact on soil microbial and biochemical parameters.

Soil microbial community parameters affected by microplastics and other plastic residues.

The impact of plastics on terrestrial ecosystems is receiving increasing attention. Although of great importance to soil biogeochemical processes, how plastics influence soil microbes have yet to be systematically studied. The primary objectives of this study are to evaluate whether plastics lead to divergent responses of soil microbial community parameters, and explore the potential driving factors. We performed a meta-analysis of 710 paired observations from 48 published articles to quantify the impact of plastic on the diversity, biomass, and functionality of soil microbial communities. This study indicated that plastics accelerated soil organic carbon loss (effect size = -0.05, p = 0.004) and increased microbial functionality (effect size = 0.04, p = 0.003), but also reduced microbial biomass (effect size = -0.07, p < 0.001) and the stability of co-occurrence networks. Polyethylene significantly reduced microbial richness (effect size = -0.07, p < 0.001) while polypropylene significantly increased it (effect size = 0.17, p < 0.001). Degradable plastics always had an insignificant effect on the microbial community. The effect of the plastic amount on microbial functionality followed the "hormetic dose-response" model, the infection point was about 40 g/kg. Approximately 3564.78 μm was the size of the plastic at which the response of microbial functionality changed from positive to negative. Changes in soil pH, soil organic carbon, and total nitrogen were significantly positively correlated with soil microbial functionality, biomass, and richness (R2 = 0.04-0.73, p < 0.05). The changes in microbial diversity were decoupled from microbial community structure and functionality. We emphasize the negative impacts of plastics on soil microbial communities such as microbial abundance, essential to reducing the risk of ecological surprise in terrestrial ecosystems. Our comprehensive assessment of plastics on soil microbial community parameters deepens the understanding of environmental impacts and ecological risks from this emerging pollution.

Unlocking the secrets of soil microbes: How decades-long contamination and heavy metals accumulation from sewage water and industrial effluents shape soil biological health

Heavy metals contamination is posing severe threat to the soil health and environmental sustainability. Application of industrial and sewage waste as irrigation and growing urbanization and agricultural industry is the main reason for heavy metals pollution. Therefore, the present study was planned to assess the influence of different irrigation sources such as industrial effluents, sewage wastewater, tube well water, and canal water on the soil physio-chemical, soil biological, and enzymatic characteristics. Results showed that sewage waste and industrial effluents affect the soil pH, organic matter, total organic carbon, and cation exchange capacity. The highest total nickel (383.71 mg kg−1), lead (312.46 mg kg−1), cadmium (147.75 mg kg−1), and chromium (163.64 mg kg−1) were recorded with industrial effluents application. Whereas, industrial effluent greatly reduced the soil microbial biomass carbon (SMB-C), soil microbial biomass nitrogen (SMB-N), soil microbial biomass phosphorus (SMB-P), and soil microbial biomass sulphur (SMB-S) in the winter season at sowing time. Industrial effluent and sewage waste inhibited the soil enzymes activities. For instance, the minimum activity of amidase, urease, alkaline-phosphatase, β-glucosidase, arylsulphatase and dehydrogenase activity was noted with HMs contamination. The higher levels of metals accumulation was observed in vegetables grown in soil contaminated with untreated waste water and industrial effluent in comparison to soil irrigated with canal and tube well water. The mean increase in soil microbial parameters and enzyme activities was also observed in response to the change in season from winter to spring due to increase in soil mean temperature. The SMB-C, SMB-N, SMB-P and SMB-S showed significant positive correlation with soil enzymes (amidase, urease, alkaline-phosphatase, β-glucosidase, arylsulphatase and dehydrogenase). The heavy metals accumulation in soil is toxic to microorganisms and inhibits enzyme functions critical for nutrient cycling and organic matter decomposition and can disrupt the delicate balance of soil ecosystem and may lead to long-term damage of soil biological health.

Rapid response of soil GHG emissions and microbial parameters to the addition of biochar and the freeze-thaw cycle

Rapid response of soil GHG emissions and microbial parameters to the addition of biochar and the freeze-thaw cycle

Crop tillage, soil depth, and their influence on extracellular enzyme activities

Agricultural practices can alter both physicochemical properties and soil microbial parameters, modifying the dynamics of soil biochemical functioning and, consequently, nutrient cycling. This study evaluated the effect of land use on chemical and biochemical attributes, and relationships between environmental variables. We used a sampling design to collect soil samples at different depths in different agroecosystems. Soil samples from natural ecosystems (native Cerrado) and agroecosystems (cotton and sugarcane cultivation) were collected at 0–0.1 m, 0.1–0.2 m, 0.2–0.5 m, and 0.5–1.0 m from 12 areas in the State of Goiás, Brazil. Twelve chemical properties and two biochemical attributes (enzyme activity and microbial biomass carbon) were evaluated using a generalized linear model of variance and Tukey’s test with three factors: correlation between all soil attributes, multiple regression between soil attributes, and biochemical variables. Soil chemical and biochemical attributes were significantly affected by variable depth (p&lt;0.05). Most of the metabolic activity in the soil occurred at 0 to 0.2 m, independent of land use class. Seasonality also affected enzyme activity in the soil, with higher activity during the rainy season. In contrast, microbial biomass carbon, an attribute generally related to organic matter and carbon mineralization, did not vary significantly with different soil depths and seasons. Thus, enzyme activity is an important indicator of soil fertility variations and is more sensitive than chemical and microbial parameters

How does land-use change alter soil microbial diversity, composition, and network in subtropical China?

Soil microbial communities play essential roles in degraded soil ecosystems. The “emergent trait” indices (e.g., microbial biomass C and N, and enzyme activity) and specific soil microbiota associations have been intensively studied, but the responses of soil microbial composition and network complexities to land-use changes remain unclear. Using amplicon sequencing of 16S rRNA genes and internal transcribed spacer (ITS) regions, we assessed the response ratio of soil microbial genomic diversity, community structure, and network parameters to primary evergreen broadleaved forest (control) conversion to conifer plantations, orchards, sloping tillage, and paddy fields. Agricultural lands had a higher soil bacterial and lower fungal diversity than primary forest. Overall, primary forest conversion reduced microbial network complexity, except in the sloping tillage. Moreover, land-use changes shifted the microbial community composition by either decreasing or increasing the relative abundance of dominant and putative keystone associations. The mean response ratio (indicator response percentage to primary forest conversion) of the microbial index to the land-use change varied depending on the soil microbial alpha diversity, network topological parameters, and dominant and putative keystone associations. Alterations in soil microbial diversity, composition, and network complexity were related to reduced soil resource availability following land-use change. Our study suggested that primary forest conversion to agricultural lands did not always negatively influences soil microbial diversity, composition, network complexity, and putative keystone associations. In addition, specific soil microbial associations showed highly sensitive to land-use change.

Residue and soil dissipation kinetics of chloroacetanilide herbicides on rice (Oryzae sativa L.) and assessing the impact on soil microbial parameters and enzyme activity.

The present investigation determines the persistence of herbicides like butachlor and pretilachlor in Indian soil, and their impact on soil biological properties including microbial biomass carbon (MBC), total microbial population numbers, and enzyme activities. Butachlor was degraded faster in autumn rice soil (t1/2 of 10-13days) than in winter rice soil (half-life of 16-18days). The t1/2 of pretilachlor in winter rice was 12-16days. Regardless of the seasons under cultivation, no pesticide residue was detected in rice at harvest. Herbicides induced an initial decline (0-14th days after application) in MBC (averages of 332.7-478.4gg-1 dry soil in autumn rice and 299.6-444.3gg-1 dry soil in winter rice), microbial populations (averages of 6.4cfug-1 in autumn rice and 4.6cfug-1 in winter rice), and phosphatase (averages of 242.6-269.3μg p-nitrophenol g-1 dry soil h-1 in autumn rice and 188.2-212.2μg p-nitrophenol g-1 dry soil h-1 in winter rice). The application of herbicides favored dehydrogenase (averages of 123.1-156.7g TPF g-1 dry soil in autumn and 126.7-151.1g TPF g-1 dry soil in winter) and urease activities (averages of 279.0-340.4g NH4 g-1 soil 2h-1 in autumn and 226.7-296.5g NH4 g-1 soil 2h-1 in winter) in rice soil at 0-14th DAA. The study suggests that applications of butachlor and pretilachlor at the rates of 1000gha-1 and 750gha-1, respectively, to control the weeds in the transplanted rice fields do not have any negative impact on the harvested rice and associated soil environment.

The Combined Applications of Microbial Inoculants and Organic Fertilizer Improve Plant Growth under Unfavorable Soil Conditions.

The performance of two bio-inoculants either in single or in combined applications with organic fertilizer was tested to determine their effect on plant growth and yield under normal and unfavorable field conditions such as low pH value and low content of P. Arbuscular Mycorrhiza Fungi (AMF; three species of Glomus) and the plant-growth-promoting bacterial strain Kosakonia radicincitans DSM16656 were applied to barley in a two-year field experiment with different soil pH levels and available nutrients. Grain yield; contents of P, N, K, and Mg; and soil microbial parameters were measured. Grain yield and the content of nutrients were significantly increased by the applications of mineral fertilizer, organic fertilizer, AMF, and K. radicincitans, and the combined application of organic fertilizer with AMF and with K. radicincitans over the control under normal growth conditions. Under low-pH and low-P conditions, only the combined application of the organic fertilizer with K. radicincitans and organic fertilizer with AMF could increase the grain yield and content of nutrients of barley over the control.

Effect of microbial biofilm in the sustainable production of chrysanthemum

The study was undertaken to analyze the effect of cyanobacteria biofilm inoculants on plant growth, floral attributes, soil microbial and nutrient parameters of Chrysanthemum morifolium Ramat cvs. Pusa Sona and Pusa Chitraksha. Plant spread increased by 49% and 36.1% in Pusa Sona and Pusa Chitraksha over the control (T1). Treatment T7 (Anabaena-Trichoderma (An-Tz) two times drench plus 732:1406:375 mg NPK/Pot) showed 25.6% and 56.2% increase over the control for the number of flowers per plant in cvs. Pusa Sona and Pusa Chitraksha, respectively. Available soil nitrogen increased by 74.9% in Pusa Sona and 57.4% in Pusa Chitraksha with the treatment T6 (Anabaena-Nostoc (BF1-4) two times drench along with 732:1406:375 mg NPK/pot) as compared to the uninoculated control. Treatments T6 and T7 were particularly promising in most plant and soil-related parameters. In addition, applying biofertilizers saved 25% of nitrogen fertilizers, besides improving soil health.

Soil fertility, microbial dynamics and mustard yield potential mediated by addition of organic amendments under sodic irrigation water

ABSTRACT Use of saline-sodic irrigation water degrades soil health and reduced mustard yield, particularly in India’s low-rainfall regions. This research was conducted to assess the effect of sodic water and nitrogen sources on soil organic carbon (SOC), microbial biomass, soil enzymatic activities, and interaction effects on mustard seed yield. The experiment was laid out in split-plot design comprising four levels of sodium adsorption ratio (SAR) of water (6, 10, 20, and 30) and six nitrogen sources [(control, 125% recommended dose of nitrogen (RDN) through urea, 75% RDN+50% RDN through farm yard manure (FYM), 75% RDN through urea+50% RDN through vermicompost (VC), 50% RDN through urea+75% RDN through FYM, 50% RDN through urea+75% RDN through VC]. The use of high SAR irrigation water caused a significant reduction in soil fertility and microbial parameters. The combined use of chemical fertilizers, FYM, and vermicompost significantly increased microbial activities (64.9% SMB-C), SOC (23.5%), soil enzyme activity (dehydrogenase and alkaline phosphates), and mustard seed yield (49%). The use of 50% RDN via urea+75% RDN via VC was suggested as a better technology for minimizing the adverse effect of high SAR water on crop yield.

Effect of polyhalite on yield, nutrient uptake by wheat and soil properties

This experiment was conducted at the crop research farm of the ICAR, Indian Agricultural Research Institute, New Delhi during the rabi season of 2021–22. The research experiment was laid out in a randomized block design with three replications of twelve treatments. The nutrient uptake by grain and straw was significantly higher with the application of 100% K dose through polyhalite. The application of a 75% K dose through polyhalite results in significantly higher values of total K and S uptake over 50% K through MOP + 50% K through polyhalite, and 50% K through MOP + S (equivalent to T6). The treatment comprising 100% K dose through polyhalite depicted higher availability of soil available NPKS and organic carbon. The value of soil microbial parameters e.g. MBC and FDA were shown highest with the application of polyhalite treatments than with conventional fertilizer. Potassium and sulphur are two highly important elements for the production of high-quality, oil, crop, and protein, but most Indian farmers are unfamiliar with the advantages, which is why there aren't applying; in this circumstance, crops are taking soil nutrients, causing K and S deficiencies in Indian soils. Therefore use and awareness of polyhalite may be a beneficial option for improving soil health, addressing nutrient imbalances, and raising crop quality and productivity.

Temporal Stability of Soil Microbial Properties in Responses to Long-Term Application of Compost Obtained from Tannery Sludge

Successive applications of compost obtained from tannery sludge affected the soil microbial biomass and activity. However, the effect of this practice on the temporal stability of soil microbial properties is not known. This study evaluated the temporal stability of microbial biomass, respiration, and enzymes activities in soil with successive applications of compost obtained from tannery sludge. Soil samples (0–10 cm depth) were collected from sites with successive application of compost at the lowest (2.5 ton/ha) and highest (20 ton/ha) rates, including the control (0 ton/ha). Soil microbial biomass carbon (MBC) and nitrogen (MBN), respiration, dehydrogenase, and urease activities were evaluated at 0, 30-, 60-, 90-, and 150-days post-application. The soil microbial properties varied as per treatments and sampling time. The principal response curve showed higher variation of soil microbial properties in the treatment having highest rate of compost. This analysis showed dehydrogenase, urease, and MBC as the most responsive parameters. The temporal stability of soil microbial parameters showed highest values at the lowest rate of compost. This study showed that the successive application of compost contributed to a decrease in variation and increase in temporal stability of soil microbial properties at the lowest rate.

Characteristics and influencing factors of microbial function in soils around a typical mining smelter

Soil microorganisms were sensitive to heavy metal pollution, whose ecological effect on soil microbial community was impacted by the interaction of contaminated stresses and environmental factors. To explore the dominant factors governing those effects in heavy metal contaminated soil, field investigation was conducted for soil from different land use types in an area surrounding a typical mining smelter in Hunan Province. Soil microbial function parameters including microbial biomass carbon (MBC), basal respiration (BR), substrate-induced respiration (SIR) and nitrification potential (PNR) were used as measure endpoints for ecological effect to reflect soil carbon and nitrogen cycling. The results showed that the effect of land use on MBC, BR, and SIR was insignificant. The dominant impacting factors on microbial functions included CaCl2 extracted Pb (CaCl2-Pb) and soil organic matter (SOM) content. Results of multiple regression analysis showed that soil CaCl2-Pb and SOM together explained 39.8%-58.3% of the total variations of BR, SIR and PNR in soil, when CaCl2-Pb and SOM ranged in 0.004-13.14 mg·kg-1 and 0.24%-4.34%, respectively. Significantly quantitative exposure-effect equations were developed between the responses of soil BR, SIR and PNR and soil CaCl2-Pb and SOM when soil samples with medium contents (namely, SOM 1.70%～2.36% and CaCl2-Pb 0.004-12.98 mg·kg-1), which meant they could be used to quantitatively assess the ecological effect of heavy metals on microbial community function as measure endpoints.

Mesofauna as effective indicators of soil quality differences in the agricultural systems of central Cuba

Soil mesofauna play an essential role in soil functioning. However, in studies on the impact of agricultural management on soil quality, the overall abundance of soil mesofauna and specific groups thereof has not been widely used as an indicator in developing countries. Here, we used soil mesofauna as a soil quality indicator compared to more traditional soil chemical, physical, and microbial indicators, in a comparison of the impact of three diverse agricultural management systems in Central Cuba: state (CSt), conventional private (CPr), and organic private (OPr) farms. We sampled the top 20 cm of soil of 30 fields from 12 farms and 1 natural reference site (NR) and analysed a number of soil chemical, physical, and microbial soil parameters as well as mesofauna (Acari and Collembola, further subdivided into Mesostigmata–Prostigmata–Oribatida–Astigmata and Isotomidae–Entomobryidae, respectively). Differences in soil properties between agricultural fields and natural soil were observed (especially in the multivariate analysis), but no significant differences were observed between agricultural systems, probably due to a lack of differences in soil organic carbon (SOC) content. The mesofauna differed strongly between the NR and the two conventional management practices (CSt and CPr), both in total numbers and in group numbers for most groups and in both rainy and dry seasons, whereas there were almost no significant differences between NR and OPr. Principal component analysis based on mesofauna clearly distinguished NR from all farming systems and OPr from CSt and CPr. Differences in soil mesofauna were mainly attributed to the use of synthetic pesticides. We conclude that in this context, without clear differences in SOC content between agricultural fields, mesofauna is a superior soil quality indicator. Our results indicate that simple counts of total abundance are as useful as counts of specific mesofauna groups irrespective of the sampling period (dry or wet season).

Soil health improvements from using a novel perennial grain during the transition to organic production

Organic crop production is a growing part of the agricultural economy. The transition from a conventional to an organic cropping system, while complying with certification guidelines, is financially and logistically challenging for growers. Therefore, it is important to develop strategies, perhaps using novel cropping systems, that can both mitigate economic challenges and quickly improve soil health. We evaluated the impact of perennial and annual cropping systems on soil health during the first two years of a three-year organic transition period at three research stations in Minnesota distinct in climate and soil conditions: Rosemount, St. Paul, and Lamberton. The sites were established in fall of 2017 by planting each of six cropping systems including 1) the novel perennial grain crop intermediate wheatgrass (IWG), 2) alfalfa, 3) an intermediate wheatgrass - alfalfa intercrop (IWGAlfalfa), 4) a winter wheat - red clover (WheatRC) rotation, 5) a corn – soybean (SoyCorn) rotation and 6) a corn - soybean rotation with a cereal rye cover crop (SoyCCorn). We measured root biomass and soil physical, chemical, and microbial parameters to evaluate soil health under the different cropping systems over time. IWG and IWGAlfalfa were consistently among the systems with greater root biomass and larger water stable soil aggregates, while SoyCorn systems had the least. Other soil health variables had site specific responses, with Lamberton and St. Paul the most influenced by cropping systems. At St. Paul and Lamberton soil pH increased in IWG and SoyCorn, and soil K decreased under WheatRC and alfalfa. Labile C and total C and N were not influenced by the different cropping systems. At Lamberton, increases in the biomass of microbial groups including bacteria, fungi, and actinomycetes were observed in IWGAlfalfa. The improvement in some health parameters at one or more sites by IWG and IWGAlfalfa after 2 years of the organic transition period could translate into building longer-term soil health for subsequent organically certified crops, but this is dependent on local soil and other characteristics. It will likely require more time for cropping systems to affect other important soil health parameters such as soil C in the C-enriched loamy soils of Southern Minnesota.

Development of a soil quality index for sequences with different levels of land occupation using soil chemical, physical and microbiological properties

The sustainable intensification of agricultural systems through crop rotations and/or the use of winter service crops can contribute to the diversification of the systems. This alteration of the surface layer creates conditions that favor an increase in the diversity of soil microbial communities, which improves the recovery capacity of the edaphic system, thereby contributing beneficial effects to plants, soil, and ecosystem. Our objectives were: 1) to evaluate the effect of crops sequences on soil chemical, physical and microbial parameters, and 2) to develop a soil quality index (SQI) from a minimum set of indicators for cropping sequences with different levels of land occupation. A long field experiment under no-tillage was established in 2006, where soil samples were collected during three agricultural seasons (2015, 2016, and 2017). We compared the effects of four different crop sequences that included soybean (S), maize (M) and wheat (W), and also incorporated wheat as a winter cover crop (CC), being S-S, CC/S, M-W/S, and W/S-CC/M. We found that sustainable management practices, crop rotation and inclusion of CC increased soil organic carbon. The highest basic infiltration rate and lowest penetration resistance values were found for double-cropped wheat/soybean-winter cover crop/maize (W/S-CC/M), the most intensified sequence. The average microbial biomass carbon level for soybean monoculture, was reduced by 32 % compared to maize-double-cropped wheat/soybean in the three agricultural seasons, while the metabolic coefficient in soybean monoculture and winter cover crop/soybean was significantly higher. In soybean monoculture, hydrolysis of fluorescein diacetate was decreased by 28.5 %, while dehydrogenase activity was increased by 43 % with respect to double-cropped wheat/soybean-winter cover crop/maize. The abundance of fungal and bacterial communities did not reveal significant variations between sequences by quantitative PCR analysis. The SQI was constructed by selecting a minimum set of indicators based on soil chemical, physical and microbial parameters. The parameters selected by the model were soil organic carbon, total organic nitrogen, basic infiltration rate, microbial respiration and hydrolysis of fluorescein diacetate, that revealed the differences among crop sequences in response to land occupation. The inclusion of different crops increased the SQI in comparison with soybean monoculture. The double-cropped wheat/soybean-winter cover crop/maize system improved the SQI by 73 % compared to soybean monoculture. Our findings show that crop sequences with high soil occupation improved their chemical and physical properties, as well as increasing the abundance and functionality of the microbial community, which is related to a better SQI.

Environmental Safety Assessments of Lipid Nanoparticles Loaded with Lambda-Cyhalothrin.

Lipid nanoparticles (LN) composed of biodegradable lipids and produced by green methods are candidates for the encapsulation of pesticides, potentially contributing to decreasing their release in the environment. From a safety-by-design concept, this work proposes LN for the encapsulation of insecticide active ingredients (AI). However, given the complexity of nanoparticles, ecotoxicological studies are often controversial, and a detailed investigation of their effects on the environment is required. Accordingly, this work aimed to produce and characterize LN containing the insecticide lambda-cyhalothrin (LC) and evaluate their safety to crops (Solanum lycopersicum and Zea mays), soil invertebrates (Folsomia candida and Eisenia fetida), and soil microbial parameters. The average particle size for LN-loaded with LC (LN–LC) was 165.4 ± 2.34 nm, with narrow size distribution and negative charge (−38.7 ± 0.954 mV). LN were able to encapsulate LC with an entrapment efficacy of 98.44 ± 0.04%, maintaining the stability for at least 4 months. The LN–LC showed no risk to the growth of crops and reproduction of the invertebrates. The effect on microbial parameters showed that the activity of certain soil microbial parameters can be inhibited or stimulated by the presence of LN at highest concentrations, probably by changing the pH of soil or by the intrinsic properties of LN.

Plants, soil properties and microbes directly and positively drive ecosystem multifunctionality in a plantation chronosequence

AbstractChinese fir (Cunninghamia lanceolata) is the main plantation species in the subtropical region of China. However, the shift in ecosystem multifunctionality with stand development remains largely unexplored for these plantations. This study used a chronosequence to investigate the variations of ecosystem multifunctionality by employing individual functions and identified its driving factors in Chinese fir plantations. The findings provide strong evidence that the individual functions of carbon stocks, water regulation and wood production increased with stand ages, but the tradeoff of individual functions did not significantly increase ecosystem multifunctionality. Soil microbial parameters (the abundances of bacteria, fungi and actinomycete), soil properties (soil moisture, total carbon and total nitrogen), and plant parameters (the shrub layer cover and total understory cover) exhibited positive correlations with ecosystem multifunctionality. The structural equation model revealed that plants, soil properties and microbes pathways explained 83% of the total variance in ecosystem multifunctionality. Results showed that plants, soil microbes and properties directly and significantly affected ecosystem multifunctionality with path coefficients of 0.404, 0.487 and 0.334, respectively. Soil microbes were identified as the top direct predictor for ecosystem multifunctionality, while plant and soil properties had strong direct and positive effects on ecosystem multifunctionality. These results verified that soil microbes, plants and soil properties directly and positively regulated ecosystem multifunctionality. Our findings demonstrate that ecosystem multifunctionality should be considered as a comprehensive ecological indicator for ecosystem services and functions, and sustainable plantation management. This study highlights the importance of conserving soil microbes for maintaining multifunctionality in Chinese fir plantations.