Ecoenzymatic Activities Research Articles

Decoupled fungal and bacterial functional responses to biochar amendment drive rhizosphere priming effect on soil organic carbon mineralization

The application of biochar to soil is widely recognized as a promising strategy for enhancing the accumulation and stability of soil organic carbon (SOC), which is crucial in mitigating climate change. However, the influence of interactions between plants and biochar on soil microbial communities and their involvement in SOC mineralization and stability remains unclear. This understanding is essential for optimizing carbon (C) sequestration in systems involving plants, soil, and biochar. In this study, employing a 13C natural abundance approach, we investigated the effect of biochar on the maize rhizosphere priming effect (RPE) in paddy soil. We also examined alterations in microbial communities and functional genes related to C degradation and fixation. Over the 99 days of maize growth, biochar application increased RPE and total SOC while decreasing dissolved organic C. It also elevated soil pH, resulting in shifts in fungal and bacterial community structure, favoring oligotrophic species. Fungal and bacterial assemblies were dominated by deterministic and stochastic processes, respectively. While the abundance of fungal guilds varied irregularly, bacterial guilds were uniformly enriched under biochar-plant interactions. Functional traits such as ecoenzymatic activities, bacterial guilds, and functional genes predominantly affected RPE under biochar application. Bacterial functional genes associated with C degradation and fixation were concurrently enhanced with biochar application. Our results indicate that interactions between plants and biochar can enhance native SOC mineralization and accumulation in a short timeframe by modulating functional traits of soil microorganisms, particularly the bacterial community involved in C degradation and fixation.Graphical

Ecosystem compartment stoichiometry drives the secondary succession processes of zokor‐disturbed grassland

AbstractIn terrestrial ecosystems, resource availability and soil microbial biomass are substantially changed with ecological recovery. However, the shifts in resource stoichiometry and microbial biomass stoichiometry often do not align, leading to stoichiometric imbalance that constrains microbial growth and, consequently, affects plant community succession. The mechanisms by which soil microbes acclimate to these imbalances and how such adjustments influence plant community dynamics remain largely unexplored in alpine grasslands. To address these processes, we examined ecological stoichiometry during the secondary succession of zokor‐disturbed grassland on the Qinghai–Tibet Plateau, China, utilizing a space‐for‐time substitution approach. Carbon (C), nitrogen (N) and phosphorus (P) contents across plant–soil–microbe and soil ecoenzymatic activities involved in soil microbial nutrient acquisition were measured. The results indicated that C:P and N:P imbalances between microbes and their plant resources intensified with the recovery of zokor‐disturbed grassland. This led to phosphorus limitation in microbial growth, as indicated by the mean vector angles exceeding 45° and decreased threshold element ratio of C:P. In response, soil microbes increased their production of P‐acquiring enzymes to mitigate P limitation. Through structural equation modelling (SEM), we found that the C:N:P ratios within the plant–soil–microbe systems explained 74.5% of the total variance in plant aboveground biomass. We concluded that maintaining balanced C:N:P stoichiometric ratios in plant–soil–microbe systems, facilitated by soil ecoenzymatic activities, enhances plant diversity and net primary productivity during the recovery of zokor‐disturbed grassland.

Effects of leguminous green manure-crop rotation on soil enzyme activities and stoichiometry

Abstract As a crucial strategy for sustainable agricultural production, green manure-crop rotation can regulate soil nutrient cycling and decrease the reliance on nitrogen fertilizers. However, we still lack a comprehensive understanding of the changes in soil eco-enzyme activities, microbial metabolism, and nutrient limitations caused by leguminous green manure crop rotation. Here, we conducted field experiments of leguminous green manure-crop rotation across China to analyze soil extracellular enzyme activities, specifically β-glucosidase (BG), N-acetyl-β-D-glucosaminidase (NAG), leucine aminopeptidase (LAP), and acid phosphatase (AP). The study revealed that long-term green manure-crop rotation increased carbon and nitrogen accumulation in farmland, with a significant average increase of 20.1% and 36.4% in BG, AP enzyme activities in topsoil, while showing a decrease in ln(NAG+LAP):ln(AP) ratios. The ratios of ln(BG):ln(NAG+LAP) and ln(NAG+LAP):ln(AP) in soil across various regions were typically below 1:1, indicating that soil microbial activity is more constrained by nitrogen and phosphorus nutrients rather than by carbon. Precipitation, temperature, soil total carbon, and total nitrogen were identified as key environmental factors for extracellular enzyme activities and stoichiometric ratios. Our study highlights that the green manure-crop rotation alleviates nitrogen limitation while enhancing phosphorus limitation, and is closely related to the accumulation of total carbon and nitrogen in the soil.

Green Infrastructure Microbial Community Response to Simulated Pulse Precipitation Events in the Semi-Arid Western United States

Processes driving nutrient retention in stormwater green infrastructure (SGI) are not well quantified in water-limited biomes. We examined the role of plant diversity and physiochemistry as drivers of microbial community physiology and soil N dynamics post precipitation pulses in a semi-arid region experiencing drought. We conducted our study in bioswales receiving experimental water additions and a montane meadow intercepting natural rainfall. Pulses of water generally elevated soil moisture and pH, stimulated ecoenzyme activity (EEA), and increased the concentration of organic matter, proteins, and N pools in both bioswale and meadow soils. Microbial community growth was static, and N assimilation into biomass was limited across pulse events. Unvegetated plots had greater soil moisture than vegetated plots at the bioswale site, yet we detected no clear effect of plant diversity on microbial C:N ratios, EEAs, organic matter content, and N pools. Differences in soil N concentrations in bioswales and the meadow were most directly correlated to changes in organic matter content mediated by ecoenzyme expression and the balance of C, N, and P resources available to microbial communities. Our results add to growing evidence that SGI ecological function is largely comparable to neighboring natural vegetated systems, particularly when soil media and water availability are similar.

Linking soil organic carbon characteristics, nutrient stoichiometry, and microbial community to eco-enzymatic stoichiometry within aggregates in different aged walnut plantations

Research on the variations of microbial attributes, C and nutrient properties, eco-enzymatic activities and their stoichiometry in different aged walnut orchards is essential for the sustainable development of walnut gardens. Here, four walnut orchards of various ages (0-, 7-, 14-, and 21-years) were selected in Hebei province, China, to evaluate the temporal changes in the above-mentioned indices within aggregates based on thermal gravimetric analysis, phospholipid fatty acid analysis and fluorometric assays. Results revealed that as the walnut plantation ages or aggregate sizes increased, the quantity and thermal stability of organic C exhibited increasing and decreasing trends, respectively. Long-term walnut plantation could increase C- and P- acquiring enzyme activities, and decrease N-acquiring enzyme activities in larger aggregates. Eco-enzymatic stoichiometry analyses demonstrated that the microbial C and P co-limitation increased with aggregate sizes or walnut plantation ages, although long-term walnut planting (14- and 21-years) and larger aggregates (>0.25 mm) provided more and easily available C resources for microbes. The aggravated C limitation (or P limitation) could be ascribed to the increased the ratio between microbial biomass C and organic carbon content (or the increased fungi/bacteria and soil N/P ratios) in the elder walnut plantations or larger aggregates. Overall, the study's results can provide several valuable insights (e.g., the old orchards can appropriately apply more P fertilizer) into the sustainable development of walnut gardens from the perspective of microbial nutrient demand.

Enzyme activities and microbial nutrient limitations in response to digestate and compost additions in organic matter poor soils in the Marches, Italy

Digestate and its derived composts are valuable organic fertilizers for growing vegetables and field crops. However, the impacts on enzymatic activities and microbial resources acquisition pattern are not well addressed. This study investigated ecoenzymatic activities and microbial resource acquisition patterns following these organic fertilizations for sunflower cultivation. The experiment involved applying digestate, five compost types derived from digestate, and inorganic N fertilizer (NINORG), with a control plot having no treatment. Activities of nine enzymes related to C-, N-, P-, and S- acquiring were measured at three development stages: seedling, pre-blooming, and harvest. Across all treatments, resource allocations, especially for C-, N-, and P- acquisitions, increased with plant development, correlating positively with microbial biomass, soil organic carbon, and soil nutrients contents, showing the heightened energy and nutrient sources stimulated microbial growth, prompting increased resource allocation to meet elevated demands, particularly in later crop developmental stages. Stoichiometric analysis revealed greater investments in P compared to N and C, persisting throughout the study period, with P acquisitions at least four-fold greater than N and at least seven times greater than C. This pattern was greatly impacted at harvest for all treatments except NINORG and control, with a reduced investment rate for P- acquisition compared to that of C-, N-, albeit the C: N:P ratio was still far short of the global mean 1:1:1 ratio. The strong negative correlation between available P and vector angle (p<0.001) indicated that the addition of bioavailable P through organic amendments helped reduce the gap towards the ideal ratio. In summary, on soils with imbalanced microbial nutrient and energy demands, organic amendments intensified microbial growth, resulting in heightened nutrient acquisition. However, the declining trend in P acquisition rates compared to C and N over the cropping period suggests possible adjustments with the help of organic fertilizations. Organic fertilizers, by addressing energy-nutrient imbalances, can contribute to a healthier soil ecosystem under conventional farming systems.

Microbial Nutrient Limitation of Different Tea Cultivars: Evidence from Five Representative Cultivars

Soil microbial activity is generally limited by the availability of carbon (C), nitrogen (N), or phosphorus (P) in agricultural ecosystems. Soil ecoenzymatic activity (EEA), ecoenzymatic stoichiometry (EES), and vector characteristics were examined to assess microbial nutrient limitation. Investigating soil microbial nutrient limitation can provide insight into nutrient cycling in tea plantations with different tea cultivars. However, the dynamics of different tea cultivars on soil microbial nutrient limitations and their effect on tea quality remains poor. To address this issue, soil and plant samples were collected from a tea plantation cultivating five representative tea cultivars in Hunan Province, China. Baojing Huangjincha No. 1 (HJC1) and Huangjincha No. 2 (HJC2) were the extra early-sprouting cultivars, Zhuyeqi (ZYQ) and Zijuan (ZJ) were the middle-sprouting cultivars, and Zhenghedabai (ZHDB) was the late-sprouting cultivar, respectively. The results indicated that differences in EEA and EES were significant among five treatments. Notably, ZYQ and ZJ exhibited markedly lower activities of carbon (C), nitrogen (N), and phosphorus (P) acquiring enzymes compared to HJC1 and HJC2, whereas ZHDB showed significantly higher ecoenzymatic activities. Despite a general limitation in C and P for soil microorganisms across all cultivars (VL ranging from 1.42 to 1.59 and VA ranging from 58.70° to 62.66°), the degree of microbial nutrient limitation varied. Specifically, ZYQ experienced a pronounced P limitation (VA = 62.66°, N:P enzyme = 0.52), as evidenced by increased vector angles and decreased N:P enzyme values. Although C limitation was most pronounced in ZYQ (VL = 1.59), it did not significantly differ among the cultivars. These findings suggest that tea cultivars can influence the P limitation of microbial communities. Further analysis revealed that microbial nutrient limitations might adversely affect tea quality via impeding enzyme secretion. This study highlights the critical role of nutrient cycling within the soil-microorganism-plant ecosystem and emphasizes the influence of soil microbial nutrient limitations on tea quality within tea plantations. It is recommended that in the management of tea plantation fertilization, managers need to consider the influence of cultivars and develop specialized cultivar fertilizers.

Freshwater mussels promote functional redundancy in sediment microbial communities under different nutrient regimes

Abstract Animals are a critical component of biogeochemical cycles. While animal mediated fluxes of nutrients and energy have received considerable attention, the impacts of these fluxes on microbial community structure and function are comparatively understudied. Here, we investigated if freshwater mussel influences on biogeochemical cycling in stream sediment are accompanied by changes in sediment microbial community composition and ecoenzymatic activity, and if these relationships change under different nutrient regimes. We predicted that mussel effects on ecosystem function are reflected by modified sediment microbial communities. We hypothesized that if changes in either sediment ecoenzymatic function or microbial community composition are driven by mussel‐derived nutrient amendments, we should see muted changes in microbial community assemblages or function when a given nutrient is abundant. However, if microbial communities and function are influenced by other mussel functions, then we should see uniform changes regardless of nutrient availability. We transplanted freshwater mussels and natural river sediment to flow‐through mesocosms and monitored changes in microbial community composition over 1 week. Our results indicate that mussels always changed sediment microbial community composition, but the way communities changed was dependent on ambient nutrient concentrations. On the final day we measured the activity of ecoenzymes known to correlate to microbial function and nutrient availability. Mussels homogenized the stoichiometric ratios of ecoenzyme activities, indicating a consistent function of sediment microbes associated with freshwater mussels. Our results suggest that mussels may promote functional redundancy in sediment microbial communities and highlight the importance of animals in controlling biogeochemical transformations under changing nutrient conditions. Read the free Plain Language Summary for this article on the Journal blog.

Exogenous nitrogen input skews estimates of microbial nitrogen use efficiency by ecoenzymatic stoichiometry

BackgroundEcoenzymatic stoichiometry models (EEST) are often used to evaluate microbial nutrient use efficiency, but the validity of these models under exogenous nitrogen (N) input has never been clarified. Here, we investigated the effects of long-term N addition (as urea) on microbial N use efficiency (NUE), compared EEST and 18O-labeling methods for determining NUE, and evaluated EEST’s theoretical assumption that the ratios of standard ecoenzymatic activities balance resource availability with microbial demand.ResultsWe found that NUE estimated by EEST ranged from 0.94 to 0.98. In contrast, estimates of NUE by the 18O-labeling method ranged from 0.07 to 0.30. The large differences in NUE values estimated by the two methods may be because the sum of β-N-acetylglucosaminidase and leucine aminopeptidase activities in the EEST model was not limited to microbial N acquisition under exogenous N inputs, resulting in an overestimation of microbial NUE by EEST. In addition, the acquisition of carbon by N-acquiring enzymes also likely interferes with the evaluation of NUE by EEST.ConclusionsOur results demonstrate that caution must be exercised when using EEST to evaluate NUE under exogenous N inputs that may skew standard enzyme assays.

Penggunaan Project-Based Learning (PBL) Eco-Enzim untuk Mengembangkan Kemampuan Menyimak dan Bicara Anak

This study aims to determine the effectiveness of the effect of learning the Problem Based Learning (PBL) model through Eco enzyme activities on the ability to listen and express language or speak in early childhood. This can be seen from various previous research results that the listening and speaking abilities of early childhood have not developed optimally. The learning which is assumed as an effort to improve listening and speaking skills for early childhood is by using the Problem Based Learning (PBL) learning model through Eco Enzim activities. This study used quantitative data collection techniques. The design used in this study is the Post test Only Control Design. The two groups were randomly selected and both groups were treated with PBL treatment. The post test was carried out on the experimental and control groups which arepreviously using solvin calculations. The results of the samples tested were 54 samples randomly. In the Kolmogrov-Smirnov normality test the speaking group obtained a result of 0.2, the listening group obtained a result of 0.054. In the Shapiro-Wilk normality test the speaking group obtained a result of 0.177, and the listening group obtained a result of 0.12. Then a homogeneous test was carried out with the Levene test, the result was 0.88, and in the independent sample t test, the result was 0.035, it can be concluded that HO was rejected and Ha was accepted. Therefore, there is an increase in the listening and speaking abilities of children in age group B in DKI Jakarta for the 2022-2023 school year on the effect of the eco enzyme project-based learning model. These results were obtained from data management of 118 children, through the solvin method the results obtained were 54 samples taken randomly. There is a standard deviation result looking at the distribution of data to the average, the result is 11,295 in the speaking variable, 7,808 in the listening variable. Thus that there is a significant (significant) difference between the average student learning outcomes in the listening group and the speaking group and the speaking group's results are superior to the listening group.

Pengaruh Kegiatan Eco Enzyme Terhadap Keterampilan Proses Sains Anak Usia Dini Di Taman Kanak-Kanak Ananda Maek

The lack of science learning in an environment that supports the development of science process skills in early childhood is caused by a lack of teacher knowledge in introducing interesting science activities related to the environment. This study intends to demonstrate how eco enzyme activities at Ananda Maek Kindergarten affect young children's science process skills. In this study, a quantitative method and a quasi-experimental design are used. All pupils at Ananda Maek Kindergarten made up the study's population, and class B3 served as both the experimental group and class B4 served as the control group. Data analysis procedures employed normality tests, homogeneity tests, and hypothesis testing with the aid of the computerized SPSS 20. Data collection techniques used tests in the form of statements of 8 items. According to the study's findings, the pre-test sig (2-tailed) value was 0.118, and following treatment, there was a rise in both classes with a sig (2-tailed) of 0.000. However, the experimental class's average score was higher—28,400—than the control class's average of 25,80. Thus, it can be said that eco enzyme activities have a considerable impact on young children's science process skills at Ananda Maek Kindergarten.

Features and driving factors of microbial metabolic limitation in mountain ecosystems in arid areas: A case study on the Helan Mountains, Northwest China

Insights into what limits the growth of soil microorganisms in mountain ecosystems increase our understanding of microbial functions and processes. Although the distribution pattern of soil microorganisms in mountain ecosystems has been widely studied, their role in biogeochemical cycles along elevation gradients of mountain ecosystems in arid regions is poorly understood. In this study we analyzed the soil physicochemical properties, soil microbial community structure, extracellular enzymatic activities, ecoenzymatic stoichiometry, microbial metabolism, and their relationships along the 1,300–2,500 m elevational gradient of the Helan Mountains, northwest China. The results showed that the total microbial biomass and its components did not significantly vary with elevation. The GP:GN (gram-positive: gram-negative bacteria) ratios at low elevations were higher than those at the mid and high elevations, indicating enrichment of oligotrophic bacteria at low elevations. The five extracellular enzymes significantly differed with elevation gradient, while the levels of carbon (C)- and nitrogen (N)- acquiring enzymes first increased and then decreased with increasing elevations. Ecoenzymatic stoichiometry indicated that significant limitation of microbial growth by carbon (C) and phosphorus (P) levels occurred at high and medium elevations. Soil physicochemical characteristics, microbial community composition, and ecoenzymatic activities accounted for 43.94 and 22.21% of the microbial C and P restriction, respectively. Our study suggests that mountain ecosystems with high organic C storage possess abundant microbial populations limited by relative C and P. The study also provides important insights linking microbial metabolisms to the environmental gradients in arid mountain ecosystems.

New insights into the patterns of ecoenzymatic stoichiometry in soil and sediment

Ecoenzymatic stoichiometry connects the elemental stoichiometry of microbial biomass and detrital organic matter to microbial nutrient assimilation and growth, and thus has been proposed and developed to estimate microbial nutrient limitations. However, the theories and methods developed so far have not yet clearly explored the critical thresholds of ecoenzymatic stoichiometry that identify whether nutrient limitation occurs or not. Here, we developed methods quantifying critical thresholds for microbial carbon (C), nitrogen (N) and phosphorus (P) limitations by centering on the potential responses of microbial resource use efficiency to nutrient limitations. We also provided new insight into the relationships of bivariate regressions between C-, N- and P-acquiring ecoenzymatic activities by reconsidering the intercept of regressions as an index to initial nutrient limitations, and consequently distinguished six initial limitation scenarios based on the range of values for these intercepts. According to the empirical values of the regression intercepts, the overall frequency of primary nutrient limitations in microbial communities across a global suite of soils and sediments is P limitation > N limitation > C limitation. The result implies that P and N availabilities rather than that of C could be the most important limitations on microbial production and metabolism in terrestrial soils and freshwater sediments. Nutrient limitations in heterotrophic microbial communities are fundamental characteristics of both soil and sediment systems, which regulate organic matter decomposition and element cycles. Our perspective provides a foundational framework and avenue for understanding and quantifying microbial nutrient limitations in studies of terrestrial C cycling and microbial ecology.

Microbial nutrient limitation in rhizosphere soils of different food crop families: Evidence from ecoenzymatic stoichiometry

AbstractMicrobial metabolism directly participates in soil nutrient recycling and ecosystem stability. Although the rhizosphere soil is one of the most active habitats, information on how microorganisms acquire nutrients based on ecoenzymatic stoichiometry is lacking, especially for major food crops under field conditions. Thus, this study aimed to explore the soil nutrient properties and microbial biomass concentrations as well as extracellular enzymatic activities and focused on carbon (C), nitrogen (N), and phosphorus (P) cycling of different crop types, including potato (Solanaceae), maize (cereal), soybean (Leguminosae), and buckwheat (Polygonaceae) in the arid area of northern Shaanxi, China. Microorganisms in the rhizosphere soil of four crops were subjected to relative C and N limitation tests based on ecoenzymatic activities. Among the crops, potato and soybean exhibited the maximum limitations. Linear regression analysis of soil nutrients, microorganisms (stoichiometric homeostasis), and threshold elemental ratio synthetically supported microbial metabolic limitations. This finding coincided with the highest and lowest microbial carbon use efficiencies in soybean (0.58) and potato (0.51), illustrating the distinguishing physiological responses of microbes. Partial least squares path modeling further confirmed that the soil microbial nutrient limitations were significantly regulated by soil nutrient properties and extracellular enzyme activities. Taken together, soil microbial metabolism in agricultural ecosystems was co‐limited by relative C and N regardless of the main food crop families in this region in China (northern Loess Plateau). These observations clarified the nutrient cycling driven by soil elemental stoichiometry at the root–soil interface in arid and oligotrophic ecosystems.

Elevation gradient shapes microbial carbon and phosphorous limitations in the Helan Mountains, Northwest China

Soil extracellular ecoenzymatic activities (EEA) are major players in the biogeochemical cycles and are closely related to the metabolic demand and nutrient supply in microbes. However, their effects on biogeochemistry along the elevation gradient on mountain ecosystems in arid regions remain unclear. To address this, we investigated the variations of soil microbial resource limitation and the relative contributing factors along the elevation gradient of the Helan Mountains, northwest China. The results showed that the relative abundance of total microbial, bacterial, fungal, actinomycetes, and N-acquiring enzymatic activities (N-Acetyl-β-D-glucosaminidase and Leucine- α-aminopeptidase, that are NAG and LAP, respectively) in the soil first increased and then decreased with an increase in elevation. This variation pattern could be due to the changes in soil temperature and moisture along the elevation gradient. Soil enzyme stoichiometry and resource allocation further revealed that the microbial metabolism activity in the Helan Mountains was limited by carbon (C) and phosphorus (P). Furthermore, the two limited elements were significantly higher at the mid and high altitudes (2,139–2,438 m) than at low altitudes (1,380–1,650 m). Additionally, redundancy analysis revealed that the soil water content and bulk density played a crucial role in microbial community structures, while the soil pH had the most influence on soil EEA and ecoenzymatic stoichiometry. Our findings revealed the patterns of soil microbial community structure, extracellular enzyme activities, and microbial metabolism at various elevations, which will help in understanding the microbial resource limitation and nutrient cycling in mountain ecosystems in arid regions.

Biochar decreases and nitrification inhibitor increases phosphorus limitation for microbial growth in a wheat-canola rotation

Agricultural management practices affect microbial populations and ecoenzymatic activities; however, the effect of these practices on ecological stoichiometry relating the elemental ratio of resources to microbial biomass is poorly understood. In a 2-year field study, we assessed the effects of biochar and nitrapyrin (a commonly used nitrification inhibitor (NI)) on the ecological stoichiometry and microbial nutrient limitation in a wheat (Triticum aestivum L.)-canola (Brassica juncea L.) rotation. This study used a 3 × 2 factorial design that included two treatments: (i) biochar with three levels: no biochar addition (BC0), and biochar added at 10 (BC10) and 20 t ha−1 (BC20), and (ii) NI with two levels: without (NI0) and with NI (NI1). Soil microbial biomass carbon (C), nitrogen (N) and phosphorus (P) were increased by biochar application, regardless of the application rate, but were not affected by NI application. Biochar increased and NI decreased β-1,4-glucosidase, β-1,4-N-acetyl glucosaminidase and acid phosphatase (P < 0.05) with subsequent changes in ecoenzymatic stoichiometry. Ecoenzymatic stoichiometry analysis showed microbial P limitation relative to N in the studied area irrespective of the treatment, with contrasting effects of biochar (decreasing) and NI (increasing) on the vector angle of ecoenzymatic stoichiometry (P = 0.037 and 0.043, respectively). Biochar applied at 20 t ha−1 decreased the threshold elemental ratio of C:P at which microbial growth switches between nutrient and C limitations, suggesting a shift towards C relative to nutrient (P) limitation. This study concludes that biochar produced from manure compost can be useful in increasing microbial growth by alleviating P limitations in a wheat-canola rotation.

Nitrogen addition may promote soil organic carbon storage and CO2 emission but reduce dissolved organic carbon in Zoige peatland

With the increase of nitrogen (N) deposition, N input can affect soil C cycling since microbes may trigger a series of activities to balance the supply and demand of nutrients. However, as one of the largest C sinks on earth, the role of extra N addition in affecting peatland soil C and its potential mechanism remains unclear and debated. Therefore, this study chose the largest peatland in China (i.e., Zoige, mostly N-limited) to systematically explore the potential changes of soil C, microbes, and ecoenzymes caused by extra N input at the lab scale incubation. Three different types of soils were collected and incubated with different levels of NH4NO3 solution for 45 days. After incubation, N input generally increased soil organic C (SOC) but decreased dissolved organic carbon (DOC) in Zoige peatland soils. Moreover, CO2 and CH4 emissions were significantly increased after high N input (equal to 5 mg NH4NO3 g−1 dry soils). Through a series of analyses, it was observed that microbial communities and ecoenzyme activities mainly influenced the changes of different C components. Collectively, this study implied that the increasing N deposition might help C sequestration in N-limited peatland soils; simultaneously, the risk of increased CO2 and CH4 by N input in global warming should not be ignored.

Assessment of soil enzymatic resilience in chlorpyrifos contaminated soils by biochar aided Pelargonium graveolens L. plantation.

Chlorpyrifos (CP), a broad-spectrum organophosphorus insecticide, is known for deleterious effects on soil enzymatic activities. Hence, the present study aims to examine the resilience effect of biochar (BC) aided Pelargonium graveolens L. plantation on enzymatic activities of chlorpyrifos contaminated soil. The two chlorpyrifos contaminated agriculture soils (with concentrations: S1: 46.1 and S2: 95.5mgkg-1) were taken for the pot experiment. The plant biomass, plant growth parameters, soil microbial biomass, and enzymatic activities such as alkaline phosphatase, N-acetyl glucosaminidase, aryl sulphatase, cellulase, β-glucosidase, dehydrogenase, phenoloxidase, and peroxidase enzymes were examined. Ecoenzyme activities and their stoichiometry were used to enumerate the different indices including geometric mean, weighted mean, biochemical activity indices, integrated biological response, treated-soil quality index, and vector analysis in all treatments. The results of the study demonstrated that the biochar incorporation enhanced the tolerance of P. graveolens (from 42-45% to 55-67%) in chlorpyrifos contaminated soil and reduced the CP accumulation in plants. A reduction in the inhibitory effect of chlorpyrifos on soil enzymatic activities and plant growth by BC incorporation was observed along with an increase in the activities of ecoenzymes (16.7-18.6%) in soil. The investigation indicated more microbial investments in C and P than that in N acquisition under CP stress. The BC amendment catalyzed the activities of lignin and cellulose-degrading enzymes and enhanced nutrition acquisition. The CP contamination and BC amendment have no significant effect on the oil quality of P. graveolens. The study demonstrated that BC-aided P. graveolens plantation offers sustainable phytotechnology for CP contaminated soil with an economic return.

The eco enzyme application to reduce nitrite in wastewater as the sustainability alternative solution in garbage and wastewater problems

The increasing population growth has an impact on increasing problems in wastewater quality and garbage volume. It is a need to develop a sustainability solution for both problems. In this research, the papaya fruit and spinach vegetable garbage were used as raw organic materials and fermented for six months. This study objective was to determine whether eco enzymes can be used to reduce nitrite concentration in wastewater. The research method was conducted on a laboratory scale with the artificial samples in a batch system. The result showed that eco enzyme made from a mixture of papaya and spinach can reduce the nitrite concentration in the water sample. The t-test showed that the effect of eco enzyme application in reducing nitrite in water samples was significant. The application of eco enzyme 0%, 2%, 4%, and 6% respectively during 10 hours exposure showed the nitrite removal were 0.3 %, 20%, 29%, and 35 %. It can be seen that the reduction of nitrite concentration in samples added by eco enzyme was caused by eco enzyme activity. The application at a higher concentration of 10%, 15%, and 20% showed that nitrite removal efficiencies were 35.7%, 36.7%, 46.7%, 49.4% respectively during 7 hours exposure. It can be concluded that a longer time exposure, and also the more eco enzyme concentration, showed the more result in the effect of nitrite reduction concentration in water. 4. By this study it is proven that application of eco enzyme made from organic garbage can be an alternative solution for garbage and wastewater quality problem.

Increased microbial carbon and nitrogen use efficiencies under drought stress in a poplar plantation

Drought has been observed to decrease the accumulation of carbon (C) and nitrogen (N) in forest ecosystems. The microbial C use efficiency (CUE) and N use efficiency (NUE) are critical to elemental cycling in terrestrial ecosystems, which can be calculated by the C:N stoichiometry of soils, microbial biomass, and extracellular enzyme activities. However, little is known about how drought affects microbial CUE and NUE. We extracted soil samples at different depths (0–15 cm, 15–30 cm, and 30–45 cm) in forest stands that were subjected to 30% and 50% throughfall reduction manipulation experiments, in contrast to those obtained from stands that were left undisturbed from July 2019 to April 2020 in a poplar plantation of Eastern China. Under drought conditions, we found that the soil moisture, soil C:N ratio, and C- and N-acquiring enzyme activities decreased; however, the soil pH, microbial biomass C:N ratio, ecoenzymatic activity C:N ratio, and fungi:bacteria ratio increased. Microbial CUE and NUE, which were calculated based on these C:N stoichiometric ratios, also increased. These responses were similar at different soil depths across sampling dates. Our structural equation models indicated that drought-induced increases in CUE and NUE were driven by changes in the soil moisture, fungi:bacteria ratio, and ecoenzymatic activity C:N ratio. Our results suggested that decreases in soil moisture and increases in the ecoenzymatic activity C:N and fungi:bacteria ratios could stimulate microbial CUE and NUE.