Soil Microbial Populations Research Articles

Utilisation of press mud for organic cultivation of Andrographis paniculata Wall. ex Nees in reclaimed sodic soil

ABSTRACT Andrographis paniculata is a medicinal plant used to treat many different ailments. The biomass of A. paniculata can be used safely either as fresh plant material, after decoction, or in pharmaceutical formulations. In the present study, different application rates of press mud were evaluated for organic cultivation of A. paniculata in the Indo-Gangetic Plains of Uttar Pradesh, India. The vegetative plant growth parameters were positively affected by increased application rates of press mud up to 7.5 and 10 t ha-1. Macro- and micro-nutrient (N, P, Ca, Fe, Zn, Cu, Mn, Mo and Ni) concentrations of the plant tissue increased with the application of press mud. Yields of active compounds in the A. paniculate, i.e. andrographolide, neo-andrographolide and wogonin, increased in line with the increased total plant biomass in response to increased press mud application rates. Soil microbial populations, total heterogeneous bacteria, fungi, actinomycetes and Azotobacter also increased with increased rates of press mud, as did soil enzyme activities, i.e. dehydrogenase, β-glucosidase, urease, protease and acid phosphatase. Soil pH and bulk density decreased with increased rates of press mud, which was seen as indications of improved soil properties. Furthermore, available macro- and micro-nutrient concentrations in the soil increased with increased rates of press mud. The present study demonstrated that in organic cultivation of A. paniculata, optimised application rates of press mud can be used not only to supplement soil nutrients but also to enhance yields of plant biomass and active constituents of A. paniculata.

Influence of Nano Urea on Growth and Microbial Population in Paddy Ecosystem

Chemical fertilizer usage has been a long-drawn criticism because of its harmful effects on the environment and on the quality of agricultural produce. Researchers are continually looking for more productive, better solutions while retaining societal wellbeing. Effective use of nano fertilizers in place of chemical fertilizers is essential in reducing fertilizer overuse and also contribute in lowering the pollution and leaching which in turn increase the effectiveness of nutrient consumption and also increase the yield of the crop. An experiment was carried out in paddy to study the influence of Nano urea applications on growth and microbial populations in soil. The field trial used a Randomized Block Design (RBD) with eight treatment combinations and three replications. Results showed that application of STCR based N as Urea (50%) and Nano Urea (2 sprays) and Recommended dosage of N as Urea (50%) and Nano Urea (2 sprays) recorded higher plant height, Leaf Area Index (LAI), Dry matter accumulation in paddy. In addition, applications of Nano urea increased the microbial population including bacteria, fungi and actinomycetes. Combining recommended dosage of fertilisers with nano urea spray at critical stages of paddy crop increases the crop growth and microbial activity.

Effect of indigenous bio-inoculants and commercial biological inputs on soil microbial population, soil health dynamics and pepper (capsicum annum L.) production

ABSTRACT Overusage of chemical fertilizers by farmers had adversely impacted soil fertility and agricultural ecosystem sustainability. To explore safer alternatives, six bio-treatments based on two Bacillus spp. consortium and three biological inputs were investigated. Assessments, carried out over two consecutive cropping years, were focused on their effects on soil microbial traits, pepper production and health status as measured by fungal and nematode infection levels. Rhizosphere microbial populations were more abundant at the second cropping year than at the first one, thus indicating their cumulative effects. The two Bacillus spp. strains applied individually, and Acadian input had induced significant increments in pepper production by 22–25% over control. No significant differences were recorded between two Bacillus spp. and their consortium on the severity of pepper-associated soil-borne diseases. B. amyloliquefaciens subsp. plantarum SV65 performed 39.7 and 59.6% better than Acadian and Trianum-P® in reducing nematode galling index and foliar severity index, respectively. Interestingly, single treatment using B. amyloliquefaciens subsp. plantarum SV65 performed better than the three biological inputs based on the majority of tested parameters. Thus, this strain used individually or in combination with B. subtilis SV41 is a promising eco-friendly alternative for the enhancement of pepper health and production.

Changes in soil microbial communities after exposure to neonicotinoids: A systematic review.

Neonicotinoids are a group of nicotine-related chemicals widely used as insecticides in agriculture. Several studies have shown measurable quantities of neonicotinoids in the environment but little is known regarding their impact on soil microbial populations. The purpose of this systematic review was to clarify the effects of neonicotinoids on soil microbiology and to highlight any knowledge gaps. A formal systematic review was performed following PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analyses) guidelines using keywords in PubMed, SCOPUS and Web of Science. This resulted in 29 peer-reviewed articles, whose findings diverged widely because of variable methodologies. Field-based studies were few (28%). Imidacloprid was the most widely used (66%) and soil microbial communities were most sensitive to it. Spray formulations were used in 83% of the studies and seed treatments in the rest. Diversity indices were the most frequently reported soil microbial parameter (62%). About 45% of the studies found that neonicotinoids had adverse impacts on soil microbial community structure, composition, diversity, functioning, enzymatic activity and nitrogen transformation. Interactions with soil physicochemical properties were poorly addressed in all studies. The need for more research, particularly field-based research on the effects of neonicotinoids on soil microorganisms was highlighted by this review.

Revitalizing sub-optimal drylands: Exploring the role of biofertilizers

Abstract Indonesia has a dry land area of 79.69%, with low soil productivity (physical, chemical, and biological), as well as uneven and unpredictable rainfall. The dryland potential is optimally utilized using biofertilizers that can produce microbes to increase soil fertility. This research aims to determine the effects of biofertilizers on dryland improvement and crop production. The study was conducted from February to May 2021 in Central Java, Indonesia. Using a randomized block design in peanut cultivation. Six biofertilizers (Controlled, Agrimeth, BioNutrient, Gliocompost, Agrimeth + BioNutrient, Agrimeth + BioNutrient + Gliocompost) were applied with four replications. The performance of each biofertilizer was assessed based on chemical soil parameters, soil microbe population, plant growth, and yields. The soil in the study area belonged to the Inceptisols group and exhibited moderately acidic pH, low organic carbon content, and low nitrogen levels. However, it had high potential and available phosphorus, as well as moderate potential and high available potassium. BioNutrient and Gliocompost increased available phosphate by 12 and 19%, respectively, due to the presence of Pseudomonas fluorescens and Aspergillus sp. Agrimeth influenced the population of Azospirillum (45–63%) and enhanced phosphate-solubilizing bacteria. Agrimeth + BioNutrient + Gliocompost promoted the growth of the Azospirillum and Trichoderma populations (17–18%), resulting in a 45.04% increase in profits. Biofertilizer inoculation positively affected peanut development, root nodule formation, and yield. This novelty showed the potential of biofertilizers in improving dryland conditions, increasing crop productivity, and contributing to sustainable agriculture in the long term.

Soil Microbial Biomass, Microbial Population and Diversity in Maize-Banana Based Agroforestry System in Kisii County, Kenya

Soil microbes are involved in many important ecosystem processes including nutrient acquisition, biogeochemical cycling and soil aggregation. Soil microbial diversity affects the soil belowground dynamics and fate of carbon and nutrients. Soil microbes are important for agricultural and plant production systems, hence understanding the effects of agroforestry systems on the soil microbes, is necessary in order to improve on soil health and fertility. The objective of the study was to determine the soil microbial biomass, microbial populations and microbial diversity in maize-banana based agroforestry system. The study was conducted at Kenya Agricultural and Livestock Research Organization farm in Kisii County. The experiment was laid out in a randomized complete block design with maize and banana intercropped with agroforestry trees. The treatments were; Maize, banana (MMBB), Maize-banana, Calliandra (MBCC), Maize (MM), banana (BB), Maize-banana, Leucaena (MBLL), Maize-banana, Sesbania (MBSS) and Maize, fertilizer (MMF). Soil samples were collected from the agroforestry fields using a soil auger. Soil microbial biomass was measured using the chloroform fumigation extraction. Fungi and bacteria were enumerated by serial dilution plate method.Shannon diversity index (H’) and Simpson diversity index (1 - D) were used for the calculation of species diversity. SAS (version 9) statistical software was used for analysis. The treatments with agroforestry tree species had significantly higher soil microbial biomass (MBSS-86.33, MBCC-52.66 and MBLL- 47.0MgC/Kg) populations of bacteria (MBSS-197, MBCC-128.0 and MBLL-111.25x108cfu g-1soil) and fungi (MBSS-50.83, MBCC-29.167 and MBLL-14.0x105cfu g-1 soil) and diversity of bacteria (MBSS- (H' =1.61, D = 1), MBCC- (H' =1.04, D = 0.83), MBLL (H' = 0.52, D = 0.5) and fungi MBSS (H' =1.39, D = 1) MBCC (H' =1.04, D= 0.83), MBLL (H' =1.56, D = 0.93). MBSS increased microbial biomass, microbial populations and microbial diversity significantly an indication of improved soil health and hence recommended for adoption by farmers.

Soil Properties of Barley (Hordeum vulgare L.) Crop as Affected by Zinc-Based Fertilizers

The field experiment conducted during the Rabi seasons of 2021-22 at the Agricultural Research Sub-station in Vallabhnagar, Udaipur, Rajasthan, aimed to assess the influence of zinc-based fertilizers on soil properties including chemical and biological properties after harvest of barley (Hordeum vulgare L.) crop. The experimental design followed a split plot arrangement, with main plot treatments consisting of a control, 5 kg Zn per hectare as soil application, and seed treatment with zinc solubilizing bacteria (ZSB) at a rate of 5 ml per kg of seed. The sub plot treatments included a control and three foliar sprays of nano Zn at 5 ml per litre of water, applied at 15, 30, and 45 days after sowing. Each treatment was replicated three times. The soil application of zinc @ 5 kg Zn ha-1 along with foliar spray of nano Zn @ 5 ml per litre of water at 45 days after sowing had significantly influenced availability of macronutrients (N and K), micronutrients (Zn, Fe, Mn and Cu) as well as microbial population (bacteria, fungi and actinomycetes) in post-harvest soil of barley crop over control. The combined application of conventional zinc fertilizer and foliar spray of nano zinc offers a promising strategy to improve nutrient availability and enhance soil microbial population in soil after the harvest of barley crop.

Influence of fertigation and organic sources of nutrients on chlorophyll content and soil microbial population of Tuberose

Influence of fertigation and organic sources of nutrients on chlorophyll content and soil microbial population of Tuberose

Fertilizer technology based on optimized nitrogen release from urea‐loaded natural superabsorbent carriers

AbstractThere is a pressing need for advanced fertilizer application technologies that enhance crop yields, maintain soil health and reduce the environmental impact from agriculture. Here, we report on the optimization of nitrogen release profiles of urea‐loaded polysaccharide (starch) superabsorbent carriers, employing analytical techniques including UV–VIS, FTIR, EDX, SEM and GC‐FID for structural and phospholipid fatty acids PLFA analyses. We fitted existing kinetic models to the uptake and release profiles, providing a link between nitrogen release kinetics and carrier structural variables. The inclusion of zeolite microparticles in the starch‐based carriers accelerated the rate of nitrogen release and increasing the maximum amount released. Field tests of the technology on maize crops demonstrated improved plant parameters and enhanced the soil microbial population. These findings highlight the promise of urea‐loaded natural superabsorbent carriers as a sustainable alternative to core‐shell CRF fertilizers and urease inhibitors.

Impact of Pre and Post Emergence Herbicide Application on Soil Microbial Population Assessment in Direct Wet Seeded Rice

Impact of Pre and Post Emergence Herbicide Application on Soil Microbial Population Assessment in Direct Wet Seeded Rice

Effects of Bio- and Chemical Fertilizers on Growth and Soil Microbial Population of Cacao (Theobroma cacao L.) Seedlings

A comparative study was done to determine the growth, microbial population, and physico- chemical properties on UF18 cacao (Theobroma cacao) seedlings when treated with chemical fertilizers and biofertilizers, either applied singly or in combination. The experimental design was randomized completely block design with five seedlings per treatment per block. Treatments used were: control, ½ recommended rate of chemical (RRC) fertilizer, RRC, MYKORICH®, MYKOCAP®, ½ RRC + MYKORICH®, ½ RRC + MYKOCAP®, RRC + MYKORICH®, and RRC + MYKOCAP®. MYKORICH® and MYKOCAP® contain 12 species of arbuscular mycorrhizal fungi isolated from stressed environments. The results showed that plant growth and physico-chemical properties were significantly improved by the application of biofertilizer than by chemical fertilizer. MYKORICH® treatment gave the highest spore count and is highly significant (p < 0.05) as compared to the other treatments with spore count ranging from 41–115.5/ 50 g soil. In terms of nitrogen-fixing bacteria count, ½ RRC treatment gave the highest (16.9 CFU x 10–5 g soil–1) bacterial count. RRC + MYKORICH® inoculation gave the highest values for most of the soil physico-chemical analysis (pH, P, K, and CEC). The positive response of cacao seedlings to mycorrhizal inoculation with or without chemical fertilizer provides a useful criterion in other agricultural lands throughout the country for crop production and sustainability.

Influence of alpine meadow deterioration on soil microbial communities in the Yangtze River source region

Introduction: Although soil microbial populations are a good predictor of soil texture, little is known about how they react to alpine meadow deterioration.Methods: This study utilized Illumina HiSeq sequencing to investigate the effects of alpine meadow degradation on soil microbial communities in the Yangtze River source basin at five different degradation levels [i.e., non–degraded (ND), slightly degraded (LD), moderately degraded (MD), severely degraded (SD), and very severely degraded (VD)].Results: The results indicated that bacterial and fungal α-diversity were not substantially different (p > 0.05) across the damaged alpine meadows, while β-diversity significantly differed (p < 0.01), indicating a higher variation in the microbial community due to alpine meadow degradation. Proteobacteria reduced considerably (p < 0.05) by 8.75%, 22.99%, and 24.65%, while Acidobacteria increased significantly (p < 0.05) by 41.67%, 85.20%, and 108.67%, in MD, SD, and VD compared with ND, respectively. Ascomycota declined significantly (p < 0.05) in the MD, whereas unclassified phyla rose significantly (p > 0.05) in the VD compared to the ND. The heatmaps of bacterial and fungal communities revealed two clusters: a ND, LD, and MD group and a SD and VD group, suggesting significant changes in soil microorganisms of alpine meadow in the SD and VD. Redundancy analysis (RDA) revealed that soil moisture, soil bulk density, soil organic carbon, total nitrogen, and plant biomass could explain 73.8% and 39.4% of the variance in bacterial and fungal community structure, respectively.Discussion: These findings imply that degradation of the alpine meadow impacts both plant and soil qualities, ultimately leading to changes in soil microbial populations in the Yangtze River’s source region.

Effect of Different Arsenic and Biochar Levels on Soil Microbial Population and Enzymatic Activity

Arsenic (As) poses a pervasive environmental contamination problem on a global scale. Human activities have significantly contributed to the extensive presence of arsenic (As) in soils. Recently, there has been growing interest in exploring the potential of biochar in addressing the issue of As-contaminated soils. This study focused on evaluating the effects of two types of biochar, namely straw biochar and iron-modified biochar, on the composition of soil microbial communities and enzymatic activity in soil contaminated with arsenic. After conducting a pot experiment for a duration of 9 months, the microbial communities and enzymatic activity were analyzed. Biochar refers to carbon-rich porous solids that are produced by heating biomasses under low oxygen conditions. These biochars are regarded as environmentally friendly sorbents that can be employed for the treatment of different types of arsenic contamination. The increased abundance of soil microbial populations and the enhanced enzymatic properties suggest that biochar fosters the richness and diversity of bacterial communities. Consequently, these improvements in the soil environment and biological quality highlight the potential of iron-modified biochar as an alternative agent for remediating arsenic-contaminated soils.

Effect of Cell Free Microbial Bio-Stimulant on Growth, Yield and the Microbial Activity of Tomato (Solanum lycopersicum L.) Grown in Vertisol

A field experiment was conducted to find out the effect of a cell-free microbial biostimulant on growth, yield, and the microbial activity of tomato (Solanum lycopersicum L.) grown in a field during the rabi season (December–April) of 2021–22 at the Instructional Cum Research Farm, College of Agriculture, IGKV, Raipur, Chhattisgarh, India. Pant-3 variety of tomato was used for the experiment, which was spaced in 45×60 cm. The experiment consists of seven treatments, viz., six levels of cell-free microbial bio-stimulant (control, 0.125 L ha-1, 0.25 L ha-1, 0.50 L ha-1, 0.63 L ha-1, 1.25 L ha-1, and 2.50 L ha-1), in combination with 100% Recommended dose of fertilizer (RDF), and was laid out in a randomised block design (RBD) with three replications. Data regarding the height of the plant, numbers of fruits (plant-1), yield (kg ha-1), dehydrogenase, and microbial activity were observed. The experimental result revealed that the application of a cell-free microbial bio-stimulant with a combination of 100% RDF was found to have a significant impact on the microbial population and dehydrogenase activity of soil, but that plant height, fruit number, and yield were not significantly affected. According to the performance of the crop and analysis of rhizosphere soil, it can be concluded that the cell-free microbial bio-stimulant @ 2.50 L ha-1 with soil application along with 100% RDF (120:80:80 kg ha-1 N:P:K) increases the soil microbial population, i.e., bacteria, actinomycetes, and fungi, and also improves the quality of the soil.

Triple-zero tillage and system intensification lead to enhanced productivity, micronutrient biofortification and moisture-stress tolerance ability in chickpea in a pearlmillet-chickpea cropping system of semi-arid climate

Pearlmillet-chickpea cropping system (PCCS) is emerging as an important sequence in semi-arid regions of south-Asia owing to less water-requirement. However, chickpea (dry-season crop) faces comparatively acute soil moisture-deficit over pearlmillet (wet-season crop), limiting overall sustainability of PCCS. Hence, moisture-management (specifically in chickpea) and system intensification is highly essential for sustaining the PCCS in holistic manner. Since, conservation agriculture (CA) has emerged is an important climate-smart strategy to combat moisture-stress alongwith other production-vulnerabilities. Hence, current study comprised of three tillage systems in main-plots viz., Complete-CA with residue retention (CAc), Partial-CA without residue-retention (CAp), and Conventional-tillage (ConvTill) under three cropping systems in sub-plots viz., conventionally grown pearlmillet-chickpea cropping system (PCCS) alongwith two intensified systems i.e. pearlmillet-chickpea-fodder pearlmillet cropping system (PCFCS) and pearlmillet-chickpea-mungbean cropping system (PCMCS) in split-plot design. The investigation outcomes mainly focused on chickpea (dry-season crop) revealed that, on an average, there was a significant increase in chickpea grain yield under CAc to the tune of 27, 23.5 and 28.5% under PCCS, PCFCS and PCMCS, respectively over ConvTill. NPK uptake and micronutrient (Fe and Zn) biofortification in chickpea grains were again significantly higher under triple zero-tilled CAc plots with residue-retention; which was followed by triple zero-tilled CAp plots without residue-retention and the ConvTill plots. Likewise, CAc under PCMCS led to an increase in relative leaf water (RLW) content in chickpea by ~ 20.8% over ConvTill under PCCS, hence, ameliorating the moisture-stress effects. Interestingly, CA-management and system-intensification significantly enhanced the plant biochemical properties in chickpea viz., super-oxide dismutase, ascorbate peroxidase, catalase and glutathione reductase; thus, indicating their prime role in inducing moisture-stress tolerance ability in moisture-starved chickpea. Triple zero-tilled CAc plots also reduced the N2O fluxes in chickpea but with slightly higher CO2 emissions, however, curtailed the net GHG-emissions. Triple zero-tilled cropping systems (PCFCS and PCMCS) both under CAc and Cap led to a significant improvement in soil microbial population and soil enzymes activities (alkaline phosphatase, fluorescein diacetate, dehydrogenase). Overall, the PCCS system-intensification with mungbean (PCMCS) alongwith triple zero-tillage with residue-retention (CAc) may amply enhance the productivity, micronutrient biofortification and moisture-stress tolerance ability in chickpea besides propelling the ecological benefits under semi-arid agro-ecologies. However, the farmers should preserve a balance while adopting CAc or CAp where livestock equally competes for quality fodder.

Functional diversity and behavioral changes of microbial communities under salt affected soils

Salt-affected soils (SASs) are globally distributed especially in the arid and semi-arid regions of the world which highly affect the crop growth and productivity. The soil physico-chemical and biological properties largely vary with different types of SASs which trigger the crop yield, nutrient imbalance and soil quality. Therefore, to understand the changes in soil microbiology in relation to soil characteristics, a micro plot study was conducted to evaluate the impact of soil salinity/sodicity on physical, chemical properties at surface (0–15 cm) and subsurface (15–30 cm) soils in relation to soil microbial population, activities and functional diversity with focusing on community-level physiological profiling (CLPP) study. Five types of soils based on pH, electric conductivity (EC) and salt concentration maintained for last 25 years - highly saline, moderately saline, highly sodic, moderately sodic and normal were evaluated in micro plots to understand the changes in soil biological properties in relation to salt concentration. The results revealed that the highest value of pHs, ECe (EC of soil saturated paste extract), cation exchange capacity (CEC), exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR), anions and cations concentrations, bulk density (BD), infiltration rate (IR), penetration resistance (PR) were observed in highly saline and highly sodic soils at surface and subsurface soil layer. In surface and subsurface layers, organic carbon (0.67 and 0.52 %) and available N (110 and 195 kg ha−1) were found higher under normal soils than SASs (% OC: 0.20–0.34 and 0.17–0.38; available N: 75–80 and 47–77 kg ha−1), respectively. In relation to changes in soil physicochemical properties, average well color development (AWCD) was found highest with normal soils followed by moderately saline and moderately sodic soils and lowest was found in highly sodic soils at surface soils which indicates interference of salts in metabolic activities of microbes. The utilization of amino acids, amines, carboxylic acids, phenolic compounds and polymers was highest for normal soils followed by moderately saline and lowest was recorded for highly sodic soils. But AWCD for carbohydrates was highest in highly saline soils, followed by highly sodic soils in contrast to normal soil and lowest was found under moderately sodic soils. Shannon diversity index (H) and substrate richness (SR) were found higher (3.19 and 24.07) in normal soils than SASs. Similarly, effect of salt load was also reflected on less soil enzymatic activities such as dehydrogenase, aryl sulfatase, invertase, etc. under varying types of SASs. Thus, with the increasing salt load, chemical and physical properties of soils were found to deteriorate and directly affected the microbial population, activities and their diversity in soil. This study indicated that soil physico-chemical properties, functional diversity, population and community of microbes were highly influenced by nature of salts and their concentration that may affect the soil quality and crop yield.

A Study on Heavy Metal Sources and Pollution: Challenge to Biological and Ecosystem

The heavy metals pollution is a major environmental problem the modem world is facing today. These are major inorganic contaminants in the environment. Though a number of heavy metals are essential micronutrients for both plants and animals, but these are toxic at higher concentrations. The heavy metal ions of Al, Cr, Mn,Ca, Fe, Ni, Ca, Zn, Cd, Hg and Pb are major inorganic contaminants in the environment. These also affect soil microbial populations and their metabolic activities. These adversely affect the molecular mechanisms of life. The weathering of bedrock, volcanoes, forest fires and dust are natural sources of heavy metals to soils and ecosystems. The man made activities such as mining, smelting, printing, battery-manufacturing, electroplating, tanning etc. are resulting in high concentrations of these metals in the environments. This study described the different sources of heavy metals and their health hazards.

Lower soil nitrous oxide emissions by a high lipid genetically modified perennial ryegrass line compared to its wild type

AbstractWe describe an experiment where cattle urine was applied at a rate of 420 kg N ha−1, equivalent to 10 L m−2, to mesocosm swards of a high lipid genetically modified perennial ryegrass line (HME) and its wild type (WT). We measured N pools and fluxes in the plant and soil, soil microbial populations and N2O production. HME plants produced 21% greater biomass than WT (p = .02), resulting in greater N uptake (27% higher in HME, p = .05). Urine N recovery in total plant biomass during the experiment in HME and WT swards were 54.7% and 33.9% respectively. The nitrification potential of soil was significantly lower (p = .01) in HME than WT. Partial least square‐discriminant analysis using microbial gene abundance data indicated that HME and WT plant growth induced distinct microbial populations in the soil. These differences in plant soil microbial interactions between HME and WT swards resulted in significantly lower N2O emissions from the HME sward. Total N2O emissions over the 4 weeks after urine application was 38% lower (p < .03) in HME swards than in WT swards. The next step in this work is to identify the specific changes in HME traits that drive the reduction in N2O.

Valorisation of hydrothermal liquefaction wastewater in agriculture: effects on tobacco plants and rhizosphere microbiota.

Industrial wastewater obtained from hydrothermal liquefaction (HTL-WW) of food wastes for biofuels production could represent a source of crop nutrients since it is characterized by a high amount of organic and inorganic compounds. In the present work, the potential use of HTL-WW as irrigation water for industrial crops was investigated. The composition of the HTL-WW was rich in nitrogen, phosphorus, and potassium with high level of organic carbon. A pot experiment with Nicotiana tabacum L. plants was conducted using diluted wastewater to reduce the concentration of some chemical elements below the official accepted threshold values. Plants were grown in the greenhouse under controlled conditions for 21 days and irrigated with diluted HTL-WW every 24 hours. Soils and plants were sampled every seven days to evaluate, over time, the effect of wastewater irrigation both on soil microbial populations, through high-throughput sequencing, and plant growth parameters, through the measurement of different biometric indices. Metagenomic results highlighted that, in the HTL-WW treated rhizosphere, the microbial populations shifted via their mechanisms of adaptation to the new environmental conditions, establishing a new balance among bacterial and fungal communities. Identification of microbial taxa occurring in the rhizosphere of tobacco plants during the experiment highlighted that the HTL-WW application improved the growth of Micrococcaceae, Nocardiaceae and Nectriaceae, which included key species for denitrification, organic compounds degradation and plant growth promotion. As a result, irrigation with HTL-WW improved the overall performance of tobacco plants which showed higher leaf greenness and increased number of flowers compared to irrigated control plants. Overall, these results demonstrate the potential feasibility of using of HTL-WW in irrigated agriculture.

Total Mikroba pada Tanah yang Dicemari Sludge Limbah Pabrik Kertas dengan Perlakuan Pupuk Guano

There are 83 paper mills in Indonesia recorded by the Indonesian Pulp and Paper Association (APKI) spread throughout the archipelago. These paper companies produce products in the form of tissues, various types of paper, and other fiber-based products. Efforts to meet the needs of this raw material produce innovations in the form of using waste paper by separating the ink from the fibers contained in the paper, this separation process is known as the deinking process. Paper mill solid waste can be in the form of sludge, pith, and biosludge. Sludge is a factory solid waste originating from the settling of WWTP which consists of 90% solid and 10% liquid. Paper mill waste in the form of solid waste from sludge contains heavy metals such as Cd, Cr, Pb, Ni, Cu, and Zn. These metals can be overcome by bioremediation using guano fertilizer which is an organic material derived from bat droppings which is rich in phosphate. The purpose of this study was to determine the microbial population in soil contaminated with paper mill sludge waste treated with guano fertilizer. The parameters observed in this study were the total number of bacteria and fungi that survive in soil contaminated with paper mill waste as an indication that the land can still be planted with certain plants. This research was conducted at the Laboratory of Soil Biology, Laboratory of Soil and Land Fertility Agrotechnopark – Faculty of Agriculture – University of Jember. This study used a 3x3 two factorial experimental design with the basic pattern of Randomized Block Design (RAK), namely between the concentration of paper mill effluent and the dose of guano fertilizer, each treatment was repeated three times. The microbial population can be determined by analyzing total bacteria, total fungi. Soil that had been contaminated with paper mill waste was incubated with guano fertilizer, each combination was analyzed at 15 hst and 30 hst for total bacterial and total fungal populations. During the incubation period, irrigation was carried out using a sprayer to maintain moisture in the incubation media. The results showed that the total population of bacteria and fungi in the growing media contaminated with paper mill sludge waste by administering different doses of guano showed results that were not significantly different, but the total population tended to increase. with increasing incubation period. Pollution of sludge waste in the planting medium has a significant effect on increasing the total Fungi Population when compared to the control. The relationship between paper mill effluent pollution and guano fertilization is very low with a coefficient of determination of less than 0.5.