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The optimization and sustainability of farming systems are essential. The use of biotechnologies, such as the increase in the density of arbuscular mycorrhizal fungi (AMF) propagules, can be an important technique to maximize the effects of fertilizers and benefit the plant and, consequently, increase the biomass and microbial activity in the soil. This study evaluated the effect of inoculation of native AMF on soil biochemical quality and the yield of different sugarcane (Saccharum species hybrids) cultivars. The experiment was conducted in the field following a randomized block experimental design in 6 × 2 factorial arrangements [sugarcane cultivars (CTC 1, CTC 7, CTC 9, CTC 16, SP89-1115, and RB925345) and inoculation of AMF], in two ratoon crops. The native AMF were inoculated through application of inoculum soil in the planting furrow at the time of sowing the crop. At the end of each ratoon crop, the following traits were evaluated: microbial biomass carbon and nitrogen, soil respiration, enzyme activities (β-glucosidase, urease, phosphatase, and fluorescein diacetate hydrolysis), mycorrhizal colonization and sugarcane yield. The increase in biomass and in microbial activities in relation to inoculation with native AMF led to increases in sugarcane yield, but the more prominent were CTC1, CTC7, and CTC9. The increase in the density of the native AMF by means of inoculation with inoculum soil favored soil biochemical quality and increased the yield of the sugarcane cultivars, regardless of the known yield potential of each cultivar, with reduction in production costs.

Flowering Sesbania sericea (Willd.) Link sampled from seasonally-flooded soils in the field displayed a 3-fold greater aerial biomass and root nodulation than individuals grown in nearby dry soils. Flooded plants (FP) showed high N2-fixation rates as apparent from their active leaf ureide catabolism and the high ureide content in nodules surrounded by an aerenchymatous phellem. Field-grown FP also exhibited high leaf Mn, P and chlorophyll but low carotenoid contents, suggesting non-stressful mineral nutrition and photosynthetic conditions. However, sufficient P in growing FP was not ascribed to an effective arbuscular mycorrhiza (AM) symbiosis. This was indicated by the age-related progressive decrease of root AM fungal colonization, and by the absence of AM arbuscules from the juvenile stages of growth. Aeration of flooded soils under greenhouse controlled conditions hindered growth, nodulation, leaf P content, and N2-fixation in rhizobia (Rh) and AM co-inoculated (Rh + AM) FP ruling out anoxia as the key factor underlying the inefficiency of the AM symbiosis in FP. Negative effects of aeration on FP were not counteracted by the addition of 2 mM KNO3 that inhibited nodulation, nor by the presence of the aerenchymatous phellem in the aerated roots. On the other hand, addition of 2 mM P enhanced the aerial mass of aerated and non-aerated FP, while inhibiting the colonization of root by AM. Analyses of rhizospheric fluorescein diacetate hydrolysis, urease, alkaline phosphatase and dehydrogenase enzymatic activities did not reveal marked differences in the soil microbial status between aerated and non-aerated FP, neither Rh + AM inoculated nor when fertilized by N and P. Overall results suggest a key role of AM only in seedling and juveniles providing sufficient P for the onset of N2-fixation.

Repeated applications and combination of glyphosate-containing herbicides (GCH) with other herbicides are two weed management practices (WMP) used to compensate for GCH decreasing efficiency impacts in field crops. These practices may have serious impacts on soil functions because GCH affect soil biota and soil biological activity (SBA). Two field experiments, one with corn and one with soybean crops, were conducted during one growing season. SBA indicators, soil respiration (SR) and fluorescein diacetate (FDA) hydrolysis, were measured at two sampling times following six WMP. These WMP included one or two GCH applications (GCH alone or combined with other herbicides), applications of other herbicides only and mechanical weeding. WMP did not affect FDA neither for corn or soybean at either sampling times. In contrast, WMP affected SR in corn fields at both sampling times and SR in soybean field at the first sampling time. Repeating GCH applications and combining different herbicides led to lower SR, suggesting that these practices decreased SBA, whilst one single GCH application presented higher SR, suggesting that this practice stimulated SBA. Our study demonstrates that using GCH in combination with other herbicides or in multiple applications affects SBA in field conditions. Affecting soil functions and carbon cycle do bear serious weed management implications, and the choice of WMP should be taken into consideration to minimize their impacts on SBA for field crops sustainability.

Made available in DSpace on 2021-06-25T12:33:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01. Added 1 bitstream(s) on 2021-07-15T14:36:31Z : No. of bitstreams: 1 S0006-87052020000400623.pdf: 197868 bytes, checksum: 5c72253dabd8ac9ce3daf0820f203157 (MD5) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Oxisols are important soils that have been converted from native vegetation to croplands, and can affect soil biological properties such as microbial biomass and enzyme activity. Thus, the aim of this study was to evaluate the changes on soil microbial biomass and enzyme activity when native vegetation (NV) was converted to cropland (CL), such as maize or sugarcane in six oxisols from Sao Paulo state, Brazil. Soil microbial biomass C (MBC) and N (MBN), and the activity of arylsulphatase, dehydrogenase and fluorescein diacetate hydrolysis (FDA) were assessed in samples collected at 0-0.20 m. In general, MBC was higher under NV than CL (about + 40%), while MBN and FDA did not show a consistent pattern between NV and CL. All soils showed higher values of arylsulfatase (increased from 101 to 717%) and dehydrogenase (increased 15 to 220%) under NV than CL. In conclusion, soil microbial biomass C is usually higher under native vegetation than cropland. Arylsulphatase and dehydrogenase were the attributes that presented better differentiation between native and cropped soils. Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Tecnol, Jaboticabal, SP, Brazil Univ Brasil, Programa Posgrad Prod Anim, Descalvado, SP, Brazil Univ Fed Piaui, Ctr Ciencias Agr, Dept Engn Agr & Solos, Teresina, PI, Brazil Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Ciencias Exatas, Jaboticabal, SP, Brazil Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Tecnol, Jaboticabal, SP, Brazil Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Ciencias Exatas, Jaboticabal, SP, Brazil

Background Soil respiration (SR) is a critical process for understanding the impact of climatic conditions and land degradation on the carbon cycle in terrestrial ecosystems. We measured the SR and soil environmental factors over 1 year in four land uses with varying levels of disturbance and different vegetation types viz., mixed forest cover (MFC), Prosopis juliflora (Sw.) forest cover (PFC), agricultural field (AF), and vegetable field (VF), in a semi-arid area of Delhi, India. Our primary aim was to assess the effects of soil moisture (SM), soil temperature (ST), and soil microbial activity (SMA) on the SR. Methods The SR was measured monthly using an LI-6400 with an infrared gas analyser and a soil chamber. The SM was measured using the gravimetric method. The ST (10 cm) was measured with a probe attached to the LI-6400. The SMA was determined by fluorescein diacetate hydrolysis. Results The SR showed seasonal variations, with the mean annual SR ranging from 3.22 to 5.78 μmol m−2 s−1 and higher SR rates of ~ 15–55% in the cultivated fields (AF, VF) than in the forest sites (MFC, PFC). The VF had significantly higher SR (P < 0.05) than the other land uses (AF, PFC, MFC), which did not vary significantly from one another in SR (P < 0.05). The repeated measures ANOVA evaluated the significant differences (P < 0.05) in the SR for high precipitation months (July, August, September, February). The SM as a single factor showed a strong significant relationship in all the land uses (R2 = 0.67–0.91, P < 0.001). The effect of the ST on the SR was found to be weak and non-significant in the PFC, MFC, and AF (R2 = 0.14–0.31; P > 0.05). Contrasting results were observed in the VF, which showed high SR during summer (May; 11.21 μmol m−2 s−1) and a significant exponential relationship with the ST (R2 = 0.52; P < 0.05). The SR was positively related to the SMA (R2 = 0.44–0.5; P < 0.001). The interactive equations based on the independent variables SM, ST, and SMA explained 91–95% of the seasonal variation in SR with better model performance in the cultivated land use sites (AF, VF). Conclusion SM was the key determining factor of the SR in semi-arid ecosystems and explained ~ 90% of the variation. Precipitation increased SR by optimizing the SM and microbial activity. The SMA, along with the other soil factors SM and ST, improved the correlation with SR. Furthermore, the degraded land uses will be more susceptible to temporal variations in SR under changing climatic scenarios, which may influence the carbon balance of these ecosystems.

Natural or anthropogenic disturbances in the forest ecosystem alter ecological conditions and lead to shifts in microbial diversity. We focused on the topsoil properties of specific sites in Tatra National Park (Slovakia) that were affected by windthrow, wildfire and wood extraction. We analyzed soil organic matter content (SOM), dry weight (DW), enzymatic activity including dehydrogenase activity (DHA), fluorescein diacetate hydrolysis (FDH) and phosphomonoesterase (PME). Bacterial community profiles were analyzed using the PCR-DGGE approach, and Ellenberg’s indicator values (EIV) were used as eco-indices of studied sites. Dystric Cambisol was sampled at sites distinguished by management approaches established after windthrow in 2004 and wildfire in 2005. We focused on the windthrow site where wooden debris was extracted (EXT); the site left for self-recovery with no intervention (NEX); the site affected by wildfire (FIR), a former reference site damaged by the windstorm in 2014 followed by the extraction of wooden debris (REX), and a non-affected reference spruce stand (REF). The windthrow sites with different management (EXT, NEX) showed relative similarities based on enzymatic activity, bacterial community profiling (85%) and EIV comparison. The FIR site exhibited no similarities (0%) with EXT and NEX in the bacterial community structure. The SOM content correlated only with PME (r2 = 0.42) and soil moisture (r2 = 0.64). Based on RDA analysis, certain EIVs seem to be suitable indicators of selected soil properties. The lack of differences between NEX and EXT could be caused by the diminishing of post-disturbance effects on microbial communities. The effect of wildfire on microbial activity and bacterial community structure seems to be longer than different management approach.

Brassica rupestris Raf. is a species native to South Italy, extremely rich in vitamins, fibers, and bioactive compounds with phytoterapic properties and may represent a resource for pharmaceutical and nutraceutical industries. Thus, our aim was to evaluate if and which soil properties affected the accumulation of secondary metabolites in B. rupestris. Knowledge of the causes of plant metabolism changes in a specific area may represent an important economic opportunity. We analyzed soils (physical and chemical parameters) in two different localities of B. rupestris growth and leaves (biocompounds and antioxidant activity) of B. rupestris grown over them to identify the soil factors that drove their phytochemical production and antioxidant power. Soil properties influenced the contents but not the types of the bioactive compounds in B. rupestris. No significant correlation was found between soil physical parameters and phytochemicals in Brassica leaves. Conversely, soil chemical and biochemical properties influenced the total antioxidant capacity and the synthesis of carotenoids and glucosinolates. Soil organic matter (SOM), dehydrogenase activity (DH), fluorescein diacetate hydrolysis (FDA), microbial biomass carbon (MBC), and humic acid/fulvic acid ratio (HA/FA) were the most important soil factors influencing the amount of phytochemicals in B. rupestris. A strict relationship between soil properties and metabolic profile of B. rupestris was found. The synthesis of specific classes of metabolites in B. rupestris is a direct response to soil biochemical conditions.

The aim of the study was to analyse the microbiological and biochemical activity of a reclaimed landfill produced during extraction and processing ozokerite and sown with Trifolium hybridum and Dactylis glomerata. The analyses were carried out in the third year after application of two doses of sewage sludge, spent mushroom substrate, sawdust, and manure to the landfill soil. The following parameters were determined: the total number of oligotrophic bacteria and filamentous fungi, the number of cellulolytic and lipolytic bacteria and fungi, respiratory activity, the activity of dehydrogenases, β-glucosidase, and lipase, and the activity of fluorescein diacetate hydrolysis. The results indicated that the wastes exerted a generally positive effect on the microbiological, biochemical, and enzymatic activities analysed in the reclaimed ground sown with both Trifolium hybridum and Dactylis glomerata. There was a negative effect on the total number of bacteria with low nutritional requirements, the number of cellulolytic bacteria, the number of lipolytic fungi, and the β-glucosidase and lipase activities only in some objects. The strength of the effects was dependent on the type and dose of the waste and on the plant species. The strongest impact on the analysed parameters was exerted by the manure, sewage sludge, and spent mushroom substrate, whereas the addition of sawdust was found to be the least beneficial. The higher dose of manure and the lower dose of spent mushroom substrate were the most beneficial doses of the wastes. The number of lipolytic bacteria and cellulolytic bacteria and fungi, as well as the fluorescein hydrolytic activity followed by the activity of dehydrogenases, β-glucosidase, and lipase were the most sensitive parameters.

Understanding the spatio-temporal variability of the microbial properties in soil with a different pedogenesis is crucial in evaluating their structure-function relationship and their influence on the functions of an ecosystem. The aims of the study were to determine the spatio-temporal variations in the selected microbial properties at the surface horizon in a conventionally managed arable field. The area selected for the research, which was mainly covered with typical Luvisols and Phaeozems, was a uniformly managed system that was considered to be homogenous in relation to texture. Winter rape was cultivated after winter wheat as the forecrop. A grid soil sampling (10 m × 10 m) was used to assess the spatial heterogeneity of the soil properties across a 0.4 ha field. Soil samples were collected from the upper 20 cm of both soils at 50 points in April and August 2008. The colony-forming units (CFUs) of bacteria, fungi and actinomycetes, soil basal respiration (BR), microbial biomass carbon (CMIC) as well as enzymatic activity were analyzed. The data were evaluated using classical statistical and geostatistical methods. In both soils, fungal CFUs were significantly lower than the bacterial CFUs with a B/F (bacteria/fungi) ratio of 68.4 in the Luvisols and 192.4 in the Phaeozems, while CFUs of the actinomycetes was similar in both soil types. Most of the studied properties were significantly higher in April than in August, while there was an opposite trend for dehydrogenase activity (DHA). In turn, fluorescein diacetate hydrolysis (FDAH) and CMIC did not show significant differences between the sampling months. Only some of the microbial properties had a significant spatial autocorrelation (Moran's I) and these were spatially dependent at the scale of the sampling grid. Most of the spatially correlated properties were in moderate and strong variability class, while the fungal CFUs in Luvisols (April), Phaeosems (August) and FDAH in Phaeosems (April) were in the weak variability class (a nugget effect >75%). Only the bacterial CFUs in Luvisols had a pure nugget effect. Most of the microbial-related properties did not exhibit a spatial structure at the examined scale, thus suggesting that changes in these properties would be detectable at a distance shorter than ten meters. More frequent seasonal sampling must be included in the sampling strategy in order to better understand whether the studied properties have any permanent spatial patterns in soil over time or whether they are more randomized.

The microbial community in the rhizosphere soil highly affects plant health and vice versa. However, the differences in soil microbial communities associated with different pathogenic statuses in the same field and their causes have not been comprehensively investigated. Here, we deciphered the dissimilarities in the rhizosphere soils of lisianthus (Eustoma grandiflorum) with different pathogenic statuses in a field under uniform management strategies at multiple scales. The rhizosphere soils of diseased plants harbored higher bacterial abundances and diversities compared to that of healthy plants. The relative abundances of three keystone operational taxonomic units (OTUs) and cumulative relative abundance of members in the central module (the largest module) of microbial network significantly decreased by 51.1%, 49.4%, 47.6%, and 42.0% in the rhizosphere soil of infected plants and by 64.3%, 58.8%, 63.4%, and 61.8% in that of dying plants, while the relative abundances of Flavobacteriales, Sphingobacteriales, and Xanthomonadales significantly increased to 4.89-, 1.88-, and 1.44-fold in the rhizosphere soil of infected plants and to 2.89-, 1.55-, and 1.66-fold in that of dying plants, respectively compared with that of healthy plants. Some human disease-related pathways and fluorescein diacetate hydrolysis were more prevalent in the rhizosphere soils of diseased plants. Stochastic processes contributed more than 50.6% and 86.4% to the assembly of different bacterial and fungal communities in these soils, and plants further shaped the bacterial communities, compared to fungal communities, probably by actively recruiting some potential suppressive agents in their rhizosphere when attacked by the pathogen. Overall, here, we firstly reported that the keystone taxa and members in the central module were enriched in the rhizosphere soil of healthy plants, which might be a potential indicator for the soil supporting plant health.

Lindane is a highly chlorinated and recalcitrant insecticide, capable to accumulate in soil and groundwater. Despite lindane has been banned in many countries, numerous sites still remain contaminated. The present work studies the bioremediation of soils of different textures contaminated with lindane by bioaugmentation with a quadruple Streptomyces consortium. In the three evaluated soils, silty loam soil (SLS), sandy soil (SS), and clayey soil (CS), heterotrophic microbial populations increased during the 14 days of the assay and CFU counts were higher in bioaugmented than in non-bioaugmented soils. Lindane removal was detected in all contaminated treatments, with higher removal percentages in the bioaugmented microcosms (SS 70.3%, SLS 36.3%, and CS 30.7%), than in non-bioaugmented ones (SS 40.4%, SLS 9.3%, and CS 12.2%). The pesticide half-life decreased by 77.3, 50.3, and 10.7 days, in bioaugmented SLS, CS, and SS, respectively. Lindane had an inhibitory effect on soil enzyme activities such as dehydrogenase, fluorescein diacetate hydrolysis, acid and alkaline phosphatases and increased the catalase activity, in non-bioaugmented controls; however, no effect on urease activity was observed. Bioaugmentation of soil microcosms with actinobacteria increased all enzymatic activities. Finally, the survival of the four strains of the consortium was demonstrated at the end of the bioremediation assay. Bioremediation using the Streptomyces sp. A2-A5-A11-M7 consortium represents a promising tool to restore different types of soils contaminated with organochlorine pesticides. Fil: Raimondo, Enzo Emanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Aparicio, Juan Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina Fil: Briceño Muñoz, Gabriela Elizabeth. Universidad de La Frontera; Chile Fil: Fuentes, María Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Benimeli, Claudia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Catamarca; Argentina

Toxicity bioassays measure the direct impacts of contaminants on aquatic environment. Sediment toxicity bioassay using resident species with analysis of priority chemicals accomplish the reliable risk assessment. Copepods are sensitive to environmental contaminants and widely applied for toxicity bioassays. Therefore, present study demonstrates sediment toxicity bioassay on meio-benthic harpacticoid copepod Tisbe furcata. Sediment quality parameters, metals, and total petroleum hydrocarbons (TPHs) are measured in the sediment. Pollution load index (PLI) and potential ecological risk index (PERI) are determined from metal concentration. Biological responses of copepod and sediment microbe are measured by hydrolysis of fluorescein diacetate (FDA). Sediment quality is assessed by the rate of FDA hydrolysis in comparison with sediment quality parameters. Absorbance of fluorescein in sediment extracts measured between 0.0437 and 0.0846 by copepods. Sediment toxicity response of copepods exhibited that the estuarine sediments are highly toxic with considerable ecological risk attributing higher PLI and PERI respectively. Interestingly, the toxicity bioassay exhibits moderate toxicity in the sediment samples of bar mouth and off-shore of the estuary. However, PLI and PERI reveal that these sediments are unpolluted with low ecological risk and even the impact from unknown emerging contaminants can be captured by sediment toxicity using copepod. High hydrolytic activities by sediment microbes at main stream of estuary and coastal sediments are attributed to sewage discharges. These assays are more environmentally relevant, reliable and cost-effective, and numerous tests can be conducted with basic laboratory equipments to regulate pollution.

International audience; Two 915-MHz microwave treatments (2 kW-8 min and 4 kW-4 min) were applied to soil and their effects were monitored just after treatments (T0) and 26 days (T26) in soil microcosms. Densities of culturable bacteria, fluorescent pseudomonads and nematodes, hydrolysis activity and soil DNA content declined by over 50% immediately after both microwave treatments (T0), excluding the total fungal 18S rRNA (-13 or -17%) and bacterial 16S rRNA copies (non-significant). A rapid shift in bacterial community composition occurred from T0 towards a large increase in the relative abundance of Firmicutes (+1650%) and a concomitant decrease in various phyla (e.g. Acidobacteria, Actinobacteria, Bacteroidetes, Proteobacteria) from -85 to -61%. At T26 and for both treatments, fluorescein diacetate hydrolysis, density of culturable bacteria, 18S rRNA gene numbers, Simpson diversity, relative abundances of Bacteroidetes and Proteobacteria regained levels similar to controls. Alpha, Delta and Gamma classes Proteobacteria also end up reaching a similar level. In contrast, fluorescent pseudomonad density, nematode diversity and abundance, soil DNA content and relative abundances of some phylum (Acidobacteria, Actinobacteria, Chloroflexi) did not increase in such proportions. Most of the soil biological properties have not been permanently impacted. Nevertheless, the recovery kinetics highly differed according properties, with resilience indices at T26 varying from -87 to +99%.

Novel green technologies for soil remediation have been focusing on altering soil properties and improving soil health. Hydrothermally-altered feldspar (HYP, HydroPotash), recently developed, is being related as both an efficient amendment to immobilize heavy metals in soils and a plant nutrients source, consisting in a promising technology for revegetation of contaminated sites. In order to evaluate the effectiveness of using HYP for phytostabilization programs, two different soils (Technosol and Oxisol) collected from a smelting site were amended with increasing doses of HYPs (HYP-1 and HYP-2): 15, 30, 60, and 120 Mg ha−1. For comparison, a control (soil without amendment) and a soil amended with zeolite (clinoptilolite) were also included as treatments. After 90 days of incubation, HYPs decreased up to 83.8 % of Cd availability and reduced exchangeable Al up to 100 %. HydroPotash increased pH, cation exchange capacity, and contents of potassium, calcium, and phosphorus, as well as microbial biomass carbon, and fluorescein diacetate hydrolysis of soils. Andropogon gayanus, Eucalyptus grandis, and Heterocondylus vitalbae started growing from the dose of 15 Mg ha−1 HYPs in the Oxisol and 60 Mg ha−1 HYPs in the Technosol. Principal component analysis indicates that plant shoot dry weight was negatively correlated with extractable Cd and Zn and positively with pH, CEC, and Ca content. Besides promoting plant growth, HYPs reduced heavy metals (Cd and Zn) absorption by plants, indicating that HYP has potential use as an amendment in phytostabilization programs.

Losses of microbial diversity in degraded ecosystems still have obscure consequences, especially when considering the interaction between arbuscular mycorrhizal fungi (AMF) and soil bacteria. This study investigates the effect of decreasing microbial biomass on mycorrhizal attributes and soil quality indicators. The dilution-to-extinction approach was applied in microcosms to search for associations among bacterial diversity, mycorrhizal attributes, and soil quality indicators. The experiment was conducted with four soil treatments (undiluted control 100 = D0, 10−3 = D3, 10−6 = D6, and 10−9 = D9) from a short-term (two years = 2Y) and a long-term (15 years = 15Y) coal mine revegetation area. Microcosms were inoculated with 300 spores of Acaulospora colombiana, Gigaspora albida, and Claroideoglomus etunicatum with millet as the host plant. Results included the total number of AMF spores, mycorrhizal colonization, soil aggregation, glomalin, fluorescein diacetate hydrolysis (FDA), basal soil respiration, microbial biomass, and soil bacterial microbiome. Larger differences were observed between areas than between dilution treatments within the sampling area. Attributes that presented differences in the dilutions compared to D0 2Y samples were mycorrhizal colonization (D0 = 85% and D9 = 43.3%), FDA (D0 = 77.2% and D9 = 55.5%), extractable glomalin-related soil protein (D0 = 0.09 and D9 = 0.11) and bacterial diversity (D0 = 7.3 and D6 = 5.3). D0 15Y samples presented differences in microbial biomass nitrogen (D0: 232.0) and bacterial diversity (D0: 7.9, D9: 5.6) compared to the dilutions. Bacterial microbiome present in the D0 samples formed distinct clusters as to other samples and correlated with soil aggregation and basal respiration attributes. Results suggest that AMF inoculation and dilution-to-extinction did not affect soil quality indicators preeminently, but the bacterial community is affected and can influence the process of environmental revegetation. A long-term revegetation period is substantial to improve quality indicators and establish the diversity of microorganisms and consequently revegetation in areas impacted by coal mining.

The present research was conducted to study the potential of cotton for the remediation of soils contaminated with Cd, to understand the biochemical basis of its tolerance to, and to investigate the plant-microbe interaction in the rhizosphere for enhancement of phytoextraction of Cd. Cotton (Bt RCH-2) was exposed to four Cd levels (0, 50, 100, and 200 mg/kg soil) in a completely randomised design and found that the plant could tolerate up to 200 mg/kg soil. Cd stress increased the total phenol, proline, and free amino acid contents in the plant leaf tissue compared with control but inhibited basal soil respiration, fluorescein diacetate hydrolysis, and activities of several enzymes viz. dehydrogenase, phosphatases, and β-glucosidase in the soil over control. The concentration of Cd in the shoot was less than the critical concentration of 100 µg/g dry weight, and bioconcentration and translocation factors were 100 µg g −1dw beyond 600 mg Cd/kg soil, the bioconcentration and translocation factors were

Soil microorganisms contribute significantly to terrestrial ecosystem functioning through their activities. Various methods exist to characterize soil microbial activity and functional diversity including those that focus on potential enzyme activities and the respiratory responses of microbes to different substrates. Here, we describe: (1) the fluorescein diacetate hydrolysis assay for total potential microbial enzyme activity; (2) measurement of beta-glucosidase activity using ρ-nitrophenyl (pNP); (3) multienzyme assay using 4-methylumbelliferone (MUB); and (4) MicroResp assays to measure the respiratory responses of microbes to different substrates and generate a community level physiological profile (CLPP).

espanolMuestras de suelo fueron colectadas en la provincia de Catamarca en lotes cultivados con topinambur (Helianthus tuberosus L.) al momento de implantacion y cosecha durante cuatro ciclos agricolas. Los tuberculos fueron tratados con Azospirillum brasilense, hongos micorricicos o ambos microorganismos. Tuberculos correspondientes a los testigos no se inocularon con estos microorganismos. Se determino la Actividad Biologica Total (ABT) por Hidrolisis del Diacetato de Fluoresceina a las muestras colectadas. La ABT del suelo fue afectada por los diferentes tratamientos del cultivo. La inoculacion microbiana elevo la ABT de los suelos estudiados, difiriendo estadisticamente con los testigos. Tambien se observaron diferencias signifi cativas entre la ABT de los suelos al inicio del cultivo con los valores registrados a la cosecha de los mismos. La inoculacion de tuberculos de topinambur con A. brasilense y hongos micorricicos afecta la ABT de los suelos cultivados. EnglishSoil samples were collected in the province of Catamarca in lots grown with topinambur (Helianthus tuberosus L.) at the time of implantation and harvest during four agricultural cycles. The tubers were treated with Azospirillum brasilense, mycorrhizal fungi or both microorganisms. Tubers corresponding to the controls were not inoculated with these microorganisms. Total Biological Activity (ABT) was determined by Fluorescein Diacetate Hydrolysis to the collected samples. The ABT of the soil was affected by the different treatments of the crop. Microbial inoculation raised the ABT of the studied soils, differing statistically with the controls. Signifi cant differences were also observed between the ABT of the soils at the beginning of the crop with the values recorded at their harvest. The inoculation of topinambur tubers with A. brasilense and mycorrhizal fungi affects the ABT of cultivated soils.

Microbes are vital components of atmospheric fine particle matter (PM2.5), and can have critical effects on human health (such as causing infectious diseases). Moreover, although China suffers from extensive concerns regarding human health issues related to air pollution, relatively few studies have focused on the characteristics of airborne microorganisms with respect to variations in air pollution, particularly under non-serious conditions. In this study, we used the modified fluorescein diacetate hydrolysis method to measure the seasonal microbial activity in PM2.5 during two levels of air pollution in Beijing. The mean microbial activity under excellent and good conditions (air quality index of < 100) was distinctly higher than that under slight and moderate conditions (101–200) during all four seasons. We further explored relationships between microbial activity and bacterial species richness and community diversity. The relative abundance of pathogenic bacteria was quite low overall, being highest in autumn (0.229%) and declining through winter (0.207%), summer (0.034%), and spring (0.022%), the same pattern observed for microbial activity. However, there was no statistical difference in the relative seasonal abundance of pathogens. Of the six types identified, streptococcus was most prevalent (0.23%). This study provides a reference and starting point for future research into the mostly unexplored field of pathogenic mechanisms during non-serious air pollution conditions.

Aim of study: This study evaluated the effect of the application of liquid aerobic treated manure (continuous liquid composting, CLC) on physical, chemical and biological soil properties, with the objective of monitoring changes induced by soil management with CLC as a biofertilizer.Area of study: Colonia, Uruguay (lat. 34,338164 S, long. 57,222630 W).Material and methods: Soil’s chemical properties, including nitrogen mineralization potential (NMP) and 15 microbiological properties (microbial biomass carbon, MBC; mesophylic aerobic bacteria; actinobacteria; filamentus fungi; fluorescein diacetate hydrolysis; dehydrogenase; with NMP; acid and alkaline phosphatase; cellulolose degraders; P-solubilizing bacteria; nitrifying; denitrifying and free-living N-fixing microorganisms; glomalin; and soil-pathogenicity index, SPI) were evaluated in two sites with similar cropping history, with one and three years of respective CLC application.Main results: CLC application had significant effects on soil microbial biomass (p

Mining activities modify the landscape and may have severe environmental impacts. The degree of recovery or disturbance of these environments must be determined, and microbiological indicators are most sensitive for this evaluation. The aim of this study was to evaluate the soil microbiological attributes of an area rehabilitated after iron mining activities and evaluate the adjacent phytophysiognomies. Soil samples were collected in a rehabilitated area revegetated with grass (RA) and in the phytophysiognomies of ironstone outcrops (IO), of neotropical savanna (NS), and of Atlantic Forest (AF) in two climate seasons (dry and rainy). Microbial biomass carbon, soil respiration, and enzyme activities (β-glucosidase, acid and alkaline phosphatase, arylsulfatase, urease, fluorescein diacetate hydrolysis) were determined, and the metabolic quotient (qCO2), the microbial quotient (qMic), and specific enzyme activities were calculated. Analyses of variance, means testing, and principal component analysis between the soil microbiological and physicochemical attributes were carried out. The microbiological indicators differed according to the type of phytophysiognomy and the season. Enzyme activities, microbial biomass, qCO2, soil respiration, and qMic were sensitive in indicating differences among the phytophysiognomies, as well as organic carbon, total N, Fe, Cu, and Al3+ contents, pH, potential acidity, cation exchange capacity, and clay and sand contents. The IO and NS phytophysiognomies exhibited the highest organic carbon and total N contents, whereas AF, NS, and IO exhibited the highest values of microbial biomass carbon. In both climate seasons, the AF exhibited higher values of soil respiration and enzyme activities. The Ironstone Outcrops exhibited high microbial biomass that was active in the processes of nutrient cycling, shown by its enzyme activities, whereas lower values of microbial biomass carbon and enzymes and higher values of qCO2 were observed in RA. Nevertheless, RA exhibited higher specific enzyme activities and higher qMic, indicating that the process of revegetation with grass favors activity of the microbial community, and promotes recovery of this area.

World population growth has led to a rise in resource demands imposed on agricultural systems, generating an increased global use of natural resources. However, agroecology proposes self-regulation in order to achieve a sustainable agricultural balance. Therefore, considering the rapid responses of microbial communities to small changes in soil use, the objective of this study was to assess the response of soil microbial communities to agroecological vs. conventional systems of extensive agriculture. Soil sampling was carried out in 2016 and 2017 with three different treatments using the sequence soybean/maize (Glycine max L./Zea mays L.) as the main crop: Agroecological (AE), conventional with cover crops (CC) and conventional without cover crops (control). Species used as cover crops were wheat (Triticum aestivum), vetch (Vicia sativa L.), oat (Avena sativa L.) and radish (Raphanus sativus L.). Agroecological treatment showed the lowest total nitrogen (0.18 mg N g−1) and organic carbon (1.99 mg C g−1) content of soil, and CC treatment showed the highest value of fluorescein diacetate hydrolysis, with values 63.2% and 12.1% higher than AE and the control, respectively. However, AE treatment also produced the highest F:B ratio (44.8) and the lowest metabolic quotient (1.14), which indicates an improvement in metabolic efficiency and soil quality. No significant differences were recorded in the abundance of fungal and bacterial communities between treatments. Our results suggest that agroecological management is characterised by fungal dominance in soil microbial communities and a higher microbial metabolic efficiency compared to conventional management. These results demonstrate more efficient use of carbon substrates in agroecological systems, which could counteract the negative effect of the lack of synthetic fertilisation and reduced-tillage in the long term. The findings demonstrate that sustainable agricultural tools with adequate management can be effectively used to preserve soil quality. Fil: Chavarría, Diego Nicolás. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Perez Brandan, Carolina Gabriela. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Salta-Jujuy. Estación Experimental Agropecuaria Salta; Argentina Fil: Serri, Dannae. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina Fil: Meriles, Jose Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; Argentina Fil: Restovich, Silvina Beatriz. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; Argentina Fil: Andriulo, Adrian Enrique. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; Argentina Fil: Jacquelin, Luis. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; Argentina Fil: Vargas Gil, Silvina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

We conducted a pot experiment with biochar (BC), wood ash (WA), and humic substances (HS) to investigate their effect on As, Zn, Cu, Cd and Pb mobility in soil, as well as enzyme activities involved in C-, N-, and P-cycles, and Eisenia foetida toxicity in multi-contaminated soils. Amendments were dosed to increase еру soil pH from initial 6.0 to ∼6.5 and ∼7.0. Applying amendments has revealed, that WA significantly immobilized Cu, Zn and Pb, BC - Cu and Zn, and HS decreased solely Cu mobility in soil. The partition indices of Zn, Cu, and Pb, quantitatively describing the bioavailable species of elements in soil, were the lowest for WA. Changes in the water-soluble species of metals were more pronounced than in the exchangeable ones for all amendments. An opposite effect was observed on enzyme activity and earthworm toxicity for the WA and carbonaceous amendments. The BC and HS provided favourable soil conditions to dehydrogenase, β-glucosidase, urease activity and fluorescein diacetate hydrolysis, while WA significantly decreased the activity of all the mentioned enzymes in soil. The results are supported by an enzymes-based weighted mean index, being the highest for BC and HS and the lowest for WA (lower than in the control sample). At the same time, WA was suitable to eliminate the trace elements' stress to earthworms (biomass endpoints and cocoons production). Our data revealed that each amendment has its own advantages and disadvantages. The choice of the most suitable amendment therefore should always be made within an integral approach and based on the purpose of remediation.

A better understanding is required of the potential of soil biota in controlling the availability and mobility of heavy metals and ascertaining their toxicity. The objectives of this work are to assess, first, the modification of heavy metal speciation induced by earthworms Eisenia andrei and, second, the consequence of this metal speciation change on soil enzyme activities as an easy bioindicator of stress. The experiment was conducted on six sites from Jebel Ressas Mines, which are characterized by a gradient heavy metal contamination (Pb, Zn, and Cd). Earthworms E. andrei were introduced in these six soils for 60 days. We had performed heavy metal speciation both in the presence and absence of worms. Modifications of activities of seven enzymes implicated in C, N, and P biochemical cycles were used as a bioindicator of metal stress. We had used the co-inertia statistical method to evaluate the correlation between change in heavy metal speciation induced by earthworms and the enzyme activities in soils. Our results suggested that earthworms modified the heavy metal dynamic and speciation. They decrease the amount of metal associated with the most available fraction, such as exchangeable one, and increase the amount of metal bound to the more stable fraction, like Mn and Fe oxide ones. On the same hand, enzyme activities increased in majority of the soils, following earthworm activity, but this effect is dependent on the amount of soil contamination. Moreover, the co-inertia results denote that change in heavy metal speciation significantly influences the soil enzyme activities in Jebel Ressas soils, especially β-glucosidase, urease, deshydrogenase, and fluorescein diacetate hydrolysis (FDA), and can be considered as bioindicators of metal toxicity and biological quality in the contaminated area. By reducing the availability of heavy metals, the earthworms are useful in the bioremediation of heavy metal contaminated soils. Soil enzymes β- glucosidase, urease, deshydrogenase, and FDA can be used to assess the changes in metal speciation and can let us, therefore, predict if the soils are bioremediated.

The north Queensland region of Australia produces over 90% of Australia's bananas. However, to maintain its importance as a banana-growing region, producers are seeking innovative methods to manage their plantations in order to protect environmentally sensitive areas, reduce impacts from climatic events and suppress soil borne diseases. The development of a healthy soil is an aspiration sought to address these constraints, using indicators based on soil physical, chemical and biological parameters. From 2012 to 2015, 86 soil samples were received for analysis from different banana management scenarios; conventional (53), newly planted fields (15), and Ecoganic production (18). Ecoganics is a farmer certification program that combines environmental management systems with sustainable production practices. A stepwise-discriminate analysis was used to determine a minimum set of soil parameters required to discriminate between management systems. Ten soil parameters: fluorescein diacetate hydrolysis rate (FDA), nematode enrichment and channel indices, B/(B+F) ratio (bacterivorous nematodes relative to bacterivorous and fungivorous nematodes), nematode diversity, and abundance of Fu2 fungivorous nematodes, Om4 omnivorous nematodes, Ba1 and Ba3 bacterivorous nematodes and abundance of the plant-parasitic nematode Helicotylenchus multicinctus were required to separate the different banana management systems. However, the separation of banana management groups had a 19% error, with the leave-one-out validation model confusing Ecoganic bananas with conventional bananas 22% of the time. The results confirmed that crop management has considerable effects on soil biology. The use of soil indicators can guide farm management decisions to implement practices most likely to overcome banana production constraints.

In this study, we investigated the effects of one-off applications of glyphosate, glufosinate, paraquat, and paraquat-diquat on soil microbial diversity and function. All herbicides were added to soil as pure compounds at recommended dose and were incubated under laboratory conditions for 60 days. High-throughput phylogenetic marker gene sequencing revealed that none of the herbicides significantly influenced the richness, evenness and composition of bacterial and archaeal communities. Likewise, the diversity, composition and size of nematode communities were not significantly influenced by any of the herbicides. From a functional perspective, herbicides did not significantly affect fluorescein diacetate hydrolysis (FDA) and beta-glucosidase activities. Furthermore, the ability of soil organisms to utilise 15 substrates was generally unaffected by herbicide application. The only exception to this was a temporary impairment in the ability of soil organisms to utilise three organic acids and an amino acid. Given the global and frequent use of these herbicides, it is important that future studies evaluate their potential impacts on microbial communities in a wider-range of soils and environmental conditions.

Tidal flooding is an important control of nitrogen biogeochemistry in wetland ecosystems of Yellow River Delta, China. Variations in hydrology could change soil redox dynamics and conditions for microorganisms living. A tidal simulation experiment was designed to extract tidal flooding effect on nitrogen mineralization of salt marsh soil. Inorganic nitrogen and relevant enzyme were measured during the 20-day incubation period. Considering the variation of both inorganic N and enzymes, nitrogen mineralization process in tidal salt marsh could be divided into 2 phases of short term response and longtime adaption by around 12th incubation day as the inflection point. Soil ammonium nitrogen (NH 4 + -N) and volatilized ammonia (NH 3 ) occupied the mineralization process since nitrate nitrogen (NO 3 − -N) was not detected over whole incubation period. NH 4 + -N varied fluctuant and increased significantly after 12 day's incubation. Released NH 3 reached to peak value of 14.24 mg m −2 d −1 at the inflection point and declined thereafter. Inorganic nitrogen released according to net nitrogen mineralization rate (R M ) under the tidal flooding condition without plant uptake except first 2 days. However, during the transitional period of 6–12 days, R M decreased notably to almost 0 and increased again after inflection point with the value of 0.182 mg kg −1 d −1 . It might be due to the change of microbial composition and function when soil shifted from oxic to anoxic, which were reflected by arylamidase, urease and fluorescein diacetate. Fluorescein diacetate hydrolysis and arylamidase had the similar variation of U style with decreasing activities before 12 days' incubation. All the enzymes measured in this experiment increased after inflection point. Whereas, urease activity kept constant from 2 to 12 days. Alternant oxidation reduction condition would increase N loss through denitrification and ammonia volatilization during the transitional period, while more inorganic nitrogen would be available in reductive environment of long-term tidal flooding. Therefore, hydrological process regulation has great influence on nitrogen cycling and further influence on wetland productivity.

The wetland cultivation of rice is subjected to anaerobic and aerobic soil conditions causing substantial changes in the soil system. However, how long-term supplementation of organics with reduced chemical fertilizers affects microbial composition, their activities, and enzymatic activities in acid soil has not been sufficiently investigated. This research is focused on a rice-rice system after an ongoing field experiment set-up in 1977–78 at Assam Agricultural University, Jorhat, India, where 7 alternative nutrient management have been investigated to: (1) assess the effects on soil organic carbon (SOC), microbial biomass carbon, and enzymatic activity in acid soil; (2) identify and discuss the most suitable treatment combinations of organic and chemical fertilizers to enhance soil ecosystem services (SES). Accordingly, we analysed the soil microbiological properties as affected by the 32 years of continuous integrated nutrient management (INM) practices and also evaluated the INM treatments in terms of SES. Results revealed that the soil microbial biomass carbon significantly varied across the treatments from 129.4 to 412.1 µg g−1 which comprises 2.4 to 4.4% of the SOC. The highest bacterial count (8.95 log cfu g−1 soil) was recorded in RDF + Azolla treatment, whereas fungal count was the maximum (7.47 log cfu g−1 soil) in RDF + FYM treatment. All the enzymatic activities responded significantly to the INM practices, but the trend of response was different for different enzymes. The highest dehydrogenase (223.6 µg TTF g−1 soil 24 h−1) and urease (4.1 μg NH4-N g−1 soil 2 h−1) activities were recorded in RDF + Azolla, while phosphomonoeaterase (337.4 μg p-nitrophenol g−1 soil h−1) and fluorescein diacetate hydrolysis (10.0 μg fluorescein g−1 soil h−1) activities were found to be the maximum in RDF + FYM. The microbial and enzymatic activities decreased significantly in the control after 32 cycles of rice-rice cropping. In this study, a significant positive statistical correlation of all the microbiological properties with soil pH, soil organic carbon and grain yield of crops were recorded. Finally, the different soil properties under the different nutrient treatments have been discussed in terms of SES provision, highlighting that the most sustainable treatments have resulted in RDF + FYM, RDF + RS and RDF + Azolla.

Conservation management practices can improve soil health while minimizing deleterious effects of agriculture on the environment. However, adoption of these practices, particularly cover crops, is not widespread, as they often reduce crop yields compared to traditional management practices. The purpose of the current study was to determine if a two-species cover crop treatment of rye (Secale cereale L.) and crimson clover (Trifolium incarnatum L.) could increase soil health parameters and maximize soybean (Glycine max L.) yield greater than rye only in tilled and no-till Mississippi field soils. Enhanced microbial biomass and organic matter input from cover crops increased the activities of β-glucosidase, cellobiohydrolase, fluorescein diacetate hydrolysis, N-acetylglucosaminidase, and phosphatase in surface soils. Rye plus clover tended to elicit higher activities than rye only in no-till plots. Both cover crop treatments inhibited soybean yield in tilled plots by 11–25%. These results indicate that tillage exacerbates yield inhibition by cover crops in soybean and that double-species cover crop treatments were more consistent in increasing activities linked to nutrient cycling. Further study examining different combinations of cover crops in no-till systems is necessary to gain a better understanding of how they can be implemented to enhance soil health while maximizing crop yield.

In most sandy soils with low organic matter content, nitrogen fertilizers are often applied to achieve desired crop yields, which may negatively affect microbial activity in the soil. We hypothesize that cover crops can mitigate the negative effects and balance the system via increased supply of carbon. The objective, therefore, was to evaluate the effect of cover crops (fallow, one grass species, two grass species, one grass species and legumes, and a mixture of three cover crops), nitrogen doses (70, 100, and 130 kg ha−1), and nitrogen sources (conventional urea and controlled-release urea) on soil microbial activity, glomalin content, and relationship of these parameters of soil quality with cotton fiber yield. Grass systems increased the soil dry matter supply. The carbon of the microbial biomass was 117% higher in the mixture and soil respiration and the metabolic quotient was 128% and 372% higher in the mixture compared to fallow. Fluorescein diacetate hydrolysis was (averaging two-year data) 60% higher in mixed cover crop systems than with fallow. Carbon from microbial biomass (grass + legume system) and glomalin content (all systems) were lower with the highest dose of N. Controlled-release urea can mitigate the negative effects of high nitrogen doses in environments with low dry matter input (as noted for enzyme β-glucosidase). Microbial biomass carbon, β-glucosidase, and qCO2 were the principal indicators of soil quality and were highly correlated with cotton yield. We recommend the use of a diversity of cover crops, moderate nitrogen doses, and controlled-release urea activate microbial and glomalin activity in sandy soil.

Soil material sampled from a reclamation experiment established in a former “Jeziorko” Sulphur Mine was analysed. The reclamation was carried out on a soil-less substrate with a particle size distribution of slightly loamy sand characterised by high acidity and poor sorption capacity. The different variants of the experiment consisted in the addition of post-flotation lime, mineral fertilisation, sewage sludge, and mineral wool to the reclaimed soil-less substrate. Next, the plots prepared in this way were sown with a mixture of grasses. A plot without any reclamation treatments served as a control. The analyses consisted in the determination of soil enzymatic parameters. The results obtained revealed a positive effect of the reclamation treatments on the analysed properties. All wastes and combinations thereof introduced into the degraded substrate stimulated catalase, protease, and urease activity. The activity of the other enzymes, i.e. dehydrogenases and acid phosphatase, as well as the level of fluorescein diacetate hydrolysis increased only in objects treated with sewage sludge. In turn, in objects receiving mineral fertilisation, a decline in the acid phosphatase activity was noted. In objects treated with mineral wool, the level of stimulation was dependent on the mode of application of this additive. In general, a mixture of 500 m3 ha−1 of mineral wool with the substrate proved more beneficial (with the exception of the acid phosphatase activity and fluorescein diacetate hydrolysis). A higher increase in the analysed enzymatic parameters was also found in objects treated with sewage sludge combined with post-flotation lime than in objects where sewage sludge was used alone.

Agricultural drainage ditches are conduits between production acreage and receiving aquatic systems. Often overlooked for their mitigation capabilities, agricultural drainage ditches provide an important role for nutrient transformation via microbial metabolism. Variations in ecoenzyme activities have been used to elucidate microbial metabolism and resource demand of microbial communities to better understand the relationship between altered nutrient ratios and microbial activity in aquatic ecosystems. Two agricultural drainage ditches, one in the northeast portion of the Arkansas Delta and the other in the lower Mississippi Delta, were monitored for a year. Sediment samples were collected prior to each ditch being dredged (cleaned), and subsequent post-dredging samples occurred as soon as access was available. Seasonal samples were then collected throughout a year to examine effects of dredging on selected nutrient concentrations and ecoenzymatic activity recovery in drainage ditch sediments. Phosphorus concentrations in sediments after dredging decreased 33–66%, depending on ditch and phosphorus extraction methodology. Additionally, ecoenzymatic activity was significantly decreased in most sediment samples after dredging. Fluorescein diacetate hydrolysis activity, an estimate of total microbial activity, decreased 56–67% after dredging in one of the two ditches. Many sample sites also had significant phosphorus and ecoenzymatic activity differences between the post-dredge samples and the year-long follow-up samples. Results indicate microbial metabolism in dredged drainage ditches may take up to a year or more to recover to pre-dredged levels. Likewise, while sediment nutrient concentrations may be decreased through dredging and removal, runoff and erosion events over time tend to quickly replenish nutrient concentrations in replaced sediments. Understanding nutrient dynamics and microbial metabolism within agricultural drainage ditches is a crucial step toward addressing issues of nutrient enrichment in aquatic receiving systems, especially those contributing to the Gulf of Mexico.