Organic Farming Soil Research Articles

Molecular Characterization Reveals Biodiversity and Biopotential of Rhizobacterial Isolates of Bacillus Spp

Bacillus species appearas the most attractive plant growth-promoting rhizobacteria (PGPR) and alternative to synthetic chemical pesticides. The present study examined the antagonistic potential of spore forming-Bacilli isolated from organic farm soil samples of Allahabad, India. Eighty-seven Bacillus strains were isolated and characterized based on their morphological, plant growth promoting traits and molecular characteristics. The diversity analysis used 16S-rDNA, BOX-element, and enterobacterial repetitive intergenic consensus. Two strains, PR30 and PR32, later identified as Bacillus sp., exhibited potent in vitro antagonistic activity against Ralstonia solanaceorum. These isolates produced copious amounts of multiple PGP traits, such as indole-3-acetic acid (40.0 and 54.5 μg/mL), phosphate solubilization index (PSI) (4.4 and 5.3), ammonia, siderophore (3 and 4 cm), and 1-aminocyclopropane-1-carboxylate deaminase (8.1and 9.2 μM/mg//h) and hydrogen cyanide. These isolates were subjected to the antibiotic sensitivity test. The two potent isolates based on the higher antagonistic and the best plant growth-promoting ability were selected for plant growth-promoting response studies in tomatoe, broccoli, and chickpea. In the pot study, Bacillus subtilis (PR30 and PR31) showed significant improvement in seed germination (27–34%), root length (20–50%), shoot length (20–40%), vigor index (50–75%), carotenoid content (0.543–1.733), and lycopene content (2.333–2.646 mg/100 g) in tomato, broccoli, and chickpea. The present study demonstrated the production of multiple plant growth-promoting traits by the isolates and their potential as effective bioinoculants for plant growth promotion and biocontrol of phytopathogens.

Pristine and UV-aged polyethylene microplastics’ impact on gut microbiome and reproduction of earthworm Eisenia andrei

The impact of microplastics (MPs) on soil organisms is still a growing field, yet very little is known about the exposure of ultraviolet (UV) aging of MPs to soil organisms. In this study, we explored the response of the epigeic earthworm Eisenia andrei to pristine and UV-aged polyethylene (PE-MP) exposure at a wide range of environmentally relevant concentrations (0, 0.2, 2, 20, 200 and 2000 mg kg−1) in an organic farm soil for 56d and assessed changes in reproduction, ingestion, egestion and gut microbiome. Results showed that exposure to 20 mg kg−1 pristine PE-MP significantly increased earthworm reproduction by 39 % but the same concentration decreased reproduction by 29 % when they were exposed to UV-aged PE-MP. Ingestion of PE was verified by staining the whole worm body and their casts after 48h of starvation. The amounts of PE-MP found in the body and the casts were positively correlated with PE-MP concentrations in the soil, however only significantly so with pristine PE-MP. A decline in E. andrei gut microbiome alpha diversity and a significantly different community composition were observed in UV-aged PE-MP exposures compared to pristine PE-MP. Relative to the control treatments, Proteobacteria increased up to 135 %, Actinobacteria increased up to 35 %, and Firmicutes decreased up to 38 % under UV-aged PE-MP exposure, whereas Cyanobacteria increased up to 19 times in the pristine PE-MP treatments. These results confirm the negative effect of UV-aged PE-MP on earthworms even at low concentrations and could have important implications in the well-functioning of agricultural soils.

Extracting Insoluble Inorganic Phosphorus from Organic Farm Soils in Mountains: Identifying Effective Organic Acid Extractants

Phosphorus, among others, is quite a vital nutrient for the life of a plant. Because of the dominance of iron and aluminium oxides in acidic soils, they facilitate the fixation of phosphorus which results into phosphorus deficiency in large amounts. Hence, proper replenishment of the soil phosphorus (P) is very much important to cater the need of plant P requirement for better yield and development. The agricultural soils of Meghalaya (India) are by default rich in organic contents and organic P pool contributes 15-80% of the total plant P nutrition. Moreover, a different nature of nutrient pools is present in organic farming system compared to the conventional farming system. Lack of knowledge of these pools results in an imbalanced manuring plan, which hinders successful production system. The dynamic fraction of P cannot represent the correct status of phosphorus in soils under organic production systems, as the conventional soil testing protocols do not take into account the potentially available inorganic pools of phosphorus. Hence, a different extractant that can extract such potentially available P in an acidic soil under organic production system is highly required. The mineralization, solubilization and extraction (of the potentially available P pool) by using various organic acids produced through the beneficial soil microorganisms can serve this purpose. Therefore, the present research work was carried out to identify the best suitable P extractant to extract such potentially available inorganic P pool. The result of the present investigation revealed that out of 6 different extractants selected, 2% citric acid and double lactate extractants were found to be strongly correlated to the total P of the selected sites. Conventional Bray 1 extractant was taken as a check extractant. The outcome of the research is to develop a proper recommendation of fertilizer dose and an appropriate soil testing protocol for phosphorus being used in organic cultivation.

Risk factors associated with the prevalence of Listeria monocytogenes in manured soils on certified organic farms in four regions of the United States

IntroductionBiological soil amendments, including raw or untreated manure, are currently used to improve soil fertility, especially in organic operations that prohibit use of synthetic fertilizers. However, addition of untreated manure may pose a risk of contamination of fresh produce by pathogens of public health significance, including Listeria monocytogenes. Organic growers follow United States Department of Agriculture (USDA) National Organic Program regulations for raw manure use, which stipulate that harvest should commence no earlier than 90- or 120-days post-application, depending on direct contact between the edible portion of the produce and the soil. To inform the protection that such time-intervals provide, this study explored the farm-level risk factors associated with L. monocytogenes prevalence in USDA-certified organic farm soils amended with untreated manures.MethodsA longitudinal, multi-regional study was conducted on 19 farms in four states (California, Minnesota, Maine, and Maryland) over two growing seasons (2017 and 2018). Untreated manure, soil, irrigation water, and produce samples were collected and cultured for L. monocytogenes. Mixed effect logistic regression was used to investigate risk factors associated with L. monocytogenes prevalence in soil.Results and DiscussionResults showed that multiple factors influenced the odds of a soil-positive sample, including temporal [year (OR = 0.19), sampling day (OR = 0.09–0.48)] and weather-related [temperature range (OR = 0.48)] variables, manure characteristics [season of application (OR = 0.04, summer), presence of L. monocytogenes (OR = 2.89) and other pathogens in manure (OR = 5.24)], farm management factors [water source (OR = 2.73, mixed), number of year-round staff (OR = 0.02)], and soil characteristics [concentration of generic Escherichia coli (OR = 1.45), moisture (OR = 0.46), organic matter (OR = 7.30), nitrate (OR = 3.07), potassium (OR = 0.09) and calcium (OR = 2.48)]. This study highlights the complexity of L. monocytogenes prevalence in soil and contributes science-based metrics that may be used when determining risk-mitigation strategies for pathogen contamination.

Organic Farming Allows Balanced Fungal and Oomycetes Communities.

Conventional and organic farming systems affect soils differently, thereby influencing microbial diversity and composition. Organic farming, which relies on natural processes, biodiversity, and cycles adapted to local conditions, is generally known to improve soil texture and alleviate microbial diversity loss compared with that of conventional farming, which uses synthetic inputs such as chemical fertilisers, pesticides, and herbicides. Although they affect the health and productivity of host plants, the community dynamics of fungi and fungi-like oomycetes (under Chromista) in organic farmland are poorly understood. The present study aimed to determine the differences in the diversity and composition of fungi and oomycetes inhabiting organic and conventional farm soils using culture-based DNA barcoding and culture-independent environmental DNA (eDNA) metabarcoding. Four tomato farms with different farming practices were selected and investigated: mature pure organic (MPO) via non-pesticide and organic fertiliser, mature integrated organic (MIO) via non-pesticide and chemical fertiliser, mature conventional chemical (MCC) via both pesticide and chemical fertiliser, and young conventional chemical (YCC). Culture-based analysis revealed that different genera were dominant on the four farms: Linnemannia in MPO, Mucor in MIO, and Globisporangium in MCC and YCC. eDNA metabarcoding demonstrated that the fungal richness and diversity on the MPO farm were higher than that on other farms. Both conventional farms exhibited simpler fungal and oomycete network structures with lower phylogenetic diversity. Interestingly, a high richness of oomycetes was shown in YCC; in which, Globisporangium, a potential pathogenic group on tomato plants, was abundantly observed. Our findings indicate that organic farming enhances fungal and oomycete diversity, which may provide robust support for maintaining healthy and sustainable agricultural practices. This study contributes to our knowledge on the positive effects of organic farming on crop microbiomes and provides essential information for maintaining biological diversity.

ИССЛЕДОВАНИЕ ПРОИЗВОДИТЕЛЬНОСТИ МАШИН ДЛЯ РАБОТЫ С ТЕПЛИЧНЫМ ГРУНТОМ

Hothouse plant growing based on the organic farming soil technology includes hothouse soil preparation, use, and removal from the hothouse upon the termination of the growing cycle. A complex of machines of new designs, consisting of a combined paver, a loader-mixer and a soil removal machine, is proposed to carry out these works. One of the main efficiency indicators of these machines is their performance Analytical expressions describing the influence of design and operating parameters on the performance of machines were obtained in the course of theoretical studies. The conveyor chain speed, the angular rate of the dosing drum, the number of conveyor scrapers, and drum bars have been determined to have the maximum impact on the performance of the combined stacker, while for the soil removing machine these parameters include the height of the removed soil layer and the machine travelling speed. A series of two-factor experiments have been carried out to define the optimal values of the above parameters. Based on the analysis of the experimental data, regression equations and respective 3D response surfaces have been obtained describing the impact of defined parameters on the performance. For the combined stacker, the following optimal parameter values have been determined, at which its performance reaches maximum value: 0.33-0.37 m/s chain speed, 7 to 8 conveyor scrapers (for the 2.5 m long conveyor); 6.0-6.5 rad/s angular rate and 6 dosing drum bars. The maximum performance of the soil-removing machine corresponds to the following parameters: 0.2-0.25 m/s travelling speed with the dump surface inclination of 22-24 degrees at the removed soil layer height of 0.18 m. Based on the obtained results, the performance of the hothouse soil preparation and removing machines has been determined.

Polycyclic aromatic hydrocarbons in diverse agricultural soils of central India: occurrence, sources, and potential risks

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds found ubiquitously in the environment and pose serious threat to the environment and humans. PAHs have received considerable attention due to their carcinogenic properties. In this study, the 16 EPA priority PAHs were determined in agricultural surface soils (0–5 cm) from diverse agricultural land use systems in central India. ∑16 PAHs of different agricultural soil samples ranged from ND–122.52 µg/kg. Total concentration of 7 carcinogenic PAHs ranged between ND and 101.64 µg/kg. The levels of PAHs in different agricultural soil samples varied widely. In general, we observed that ∑16 PAHs concentrations in agricultural soils have followed the order: sewage irrigated soil ≥ fly ash treated agricultural soil samples > horticulture land use soil > conservation agriculture soil > organic farming soil. PAH levels in fly ash-treated soils were 2–5 times higher than that in sewage-irrigated soils. PAHs containing four to five rings were the most common. Soil organic carbon (SOC) was positively correlated with ∑16 PAHs (p < 0.05). The principal sources of PAHs in these samples according to diagnostic ratios were biomass burning (grass, wood, crop residue) and coal combustion. In addition, it was found that agricultural soils treated with fly ash and sewage irrigated soils showed higher carcinogenic potential based on B[a]Peq TEQs. PAHs with higher carcinogenic potency in these contaminated soils indicate a higher level of health risk for humans.

Metagenomic Insights into the Gut Microbiota of Eudrilus eugeniae (Kinberg) and Its Potential Roles in Agroecosystem.

Gut microbiomes, a consortium of microorganisms that live in the animal gut, are highly engineered microbial communities. It makes a major contribution to digestive health, metabolism management, and the development of a strong immune system in the host. The present study was taken up to answer the long-running question about the existence of truly indigenous microflora of the epigeic earthworm gut. This is due to the general difficulties of culturing many of the microorganisms found in soil or earthworms' gut. Keeping this fact in a view, the metagenomics approach using 16S rRNA marker gene incorporated with amplicon-based sequencing was used to explore microbiota of commercially overriding, diversely fed epigeic earthworm Eudrilus eugeniae (Kinberg) in three varied habitats viz., artificial soil (AS), organic agricultural farm soil (OAFS) and conventional agriculture farm soil (CAFS). There are predominant bacteria that belong to different phyla such as Proteobacteria (29.72-76.81%), Actinobacteria (11.06-34.42%), Firmicutes (6.02-19.81%), and Bacteroidetes (2.40-9.22%) present in the gut of E. eugeniae. The alpha diversity (Observed species, Chao1, ACE, Shannon, Simpson, and Fisher alpha) indices showed that OAFS had significantly higher alpha diversity than AS and CAFS groups. The core microbiota analysis showed that OAFS and AS groups had a relatively similar bacterial panel in comparison to the CAFS group. Various statistical tools i.e. MetagenomeSeq, LEfSe, and Random Forest analysis were performed and the findings demonstrated prevalence of the most significant bacterial genera; Aeromonas, Gaiella, and Burkholderia in CAFS group. Nonetheless, in AS and OAFS groups, the common existence of Anaerosporobacter and Aquihabitans were found respectively. Metagenomic functional prediction revealed that earthworms' gut microbial communities were actively involved in multiple organic and xenobiotics compound degradation-related pathways. This is the first research to use high-throughput 16S rRNA gene amplicon sequencing to show the gut microbiota of E. eugeniae in diverse agricultural systems. The findings suggest the configuration of the gut microbiota of earthworms and its potential role in the soil ecosystem depends on the microbial communities of the soil.

Water Deficit History Selects Plant Beneficial Soil Bacteria Differently Under Conventional and Organic Farming.

Water deficit tolerance is critical for plant fitness and survival, especially when successive drought events happen. Specific soil microorganisms are however able to improve plant tolerance to stresses, such as those displaying a 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. Microorganisms adapted to dry conditions can be selected by plants over time because of properties such as sporulation, substrate preference, or cell-wall thickness. However, the complexity and interconnection between abiotic factors, like drought or soil management, and biotic factors, like plant species identity, make it difficult to elucidate the general selection processes of such microorganisms. Using a pot experiment in which wheat and barley were grown on conventional and organic farming soils, we determined the effect of water deficit history on soil microorganisms by comparing single and successive events of water limitation. The analysis showed that water deficit strongly impacts the composition of both the total microbial community (16S rRNA genes) and one of ACC deaminase-positive (acdS+) microorganisms in the rhizosphere. In contrast, successive dry conditions moderately influence the abundance and diversity of both communities compared to a single dry event. We revealed interactive effects of the farming soil type and the water deficit conditioning treatment. Indeed, possibly due to better nutrient status, plants grown on soils from conventional farming showed higher growth and were able to select more adapted microbial taxa. Some of them are already known for their plant-beneficial properties like the Actinobacteria Streptomyces, but interestingly, some Proteobacteria were also enriched after a water deficit history under conventional farming. Our approach allowed us to identify key microbial taxa promoting drought adaptation of cereals, thus improving our understanding of drought effects on plant-microbe interactions.

Field mixtures of currently used pesticides in agricultural soil pose a risk to soil invertebrates

Massive use of pesticides in conventional agriculture leads to accumulation in soil of complex mixtures, triggering questions about their potential ecotoxicological risk. This study assessed cropland soils containing pesticide mixtures sampled from conventional and organic farming systems at La Cage and Mons, France. The conventional agricultural field soils contained more pesticide residues (11 and 17 versus 3 and 11, respectively) and at higher concentrations than soils from organic fields (mean 6.6 and 10.5 versus 0.2 and 0.6 μg kg−1, respectively), including systemic insecticides belonging to neonicotinoids, carbamate herbicides and broad-spectrum fungicides mostly from the azole family. A risk quotient (RQi) approach evaluated the toxicity of the pesticide mixtures in soil, assuming concentration addition. Based on measured concentrations, both conventional agricultural soils posed high risks to soil invertebrates, especially due to the presence of epoxiconazole and imidacloprid, whereas soils under organic farming showed negligible to medium risk. To confirm the outcome of the risk assessment, toxicity of the soils was determined in bioassays following standardized test guidelines with seven representative non-target invertebrates: earthworms (Eisenia andrei, Lumbricus rubellus, Aporrectodea caliginosa), enchytraeids (Enchytraeus crypticus), Collembola (Folsomia candida), oribatid mites (Oppia nitens), and snails (Cantareus aspersus). Collembola and enchytraeid survival and reproduction and land snail growth were significantly lower in soils from conventional compared to organic agriculture. The earthworms displayed different responses: L. rubellus showed higher mortality on soils from conventional agriculture and large body mass loss in all field soils, E. andrei showed considerable mass loss and strongly reduced reproduction, and A. caliginosa showed significantly reduced acetylcholinesterase activity in soils from conventional agriculture. The oribatid mites did not show consistent differences between organic and conventional farming soils. These results highlight that conventional agricultural practices pose a high risk for soil invertebrates and may threaten soil functionality, likely due to additive or synergistic “cocktail effects”.

Effects of Organic Agriculture in Structure and Organic Carbon Adsorption at Colloidal Scale in Marginal Olive Groves, Characterized by the Extended DLVO Model

Relationship between macroscopic and microscopic behavior of soils is a difficult issue, especially when dealing with complex properties such as structure or carbon sequestration, but it is necessary for a suitable understanding of the agricultural soil quality. In this work, we used the extended-DLVO theory to compute total energy of interaction between particles (kT), of three soils over granodiorites. This parameter allows predicting the tendency to aggregate formation at the colloidal scale, being the basis of soil structure. Furthermore, we characterized the mechanism and adsorption capacity of humic molecules on mineral surfaces, and its influence in the interaction energy, by means of the adsorption isotherms. The aim was to compare first the effects of organic farming on conventionally managed soils and, second, to compare these with a non-cultivated forest soil under Mediterranean climate. When total energies are negative (particle attraction), or positive (particle repulsion) but near 0 kT (&amp;lt;100 kT), then particle flocculation occurs and the structure at colloidal scale can be developed. Total energy was less in the forest sample and greater in the soil of conventional groves, with intermediate values in organic farming soil. This indicates a tendency toward particle flocculation and more stability of the structure at colloidal scale in less disturbed soils, agreeing with other soil physical properties such as the total porosity (50, 41 and 37% in forest, organic and conventional plots, respectively) or the aggregate stability index (0.94, 0.73 and 0.66, respectively), which followed the same trend. Of the three components of the total energy of interaction, the acid-base force was a key factor. This component, related with the electron-donor component of surface free energy, γ−, yielded a strong attractive force (−150 kT at 3 nm) when calcium solutions were analyzed for the forest soil. This indicates a clear hydrophobic character of this sample. Because the mineralogical composition of the samples is quite similar, hydrophobicity should be attributed to the organic carbon content of the forest soil, which is much higher than that of the cultivated ones (12.03 vs. 1.44% and 0.88% in organic and conventional farms, respectively), proving to be an essential element for the development of the structure at the colloidal level.

Understanding rice growth-promoting potential of Enterobacter spp. isolated from long-term organic farming soil in India through a supervised learning approach.

This study addresses the plant beneficial enterobacteria present in rice rhizosphere and their efficiency for enhancing nitrogen uptake in rice plant. Using culturable approaches, the population of total diazotrophs present in rhizosphere samples collected from different organic rice fields of Sikkim were studied and recorded in the range between 4.62 to 4.97 log 10 CFU/g soil. All the isolated commonly occurred diazotrophic bacterial isolates were screened based on their ability to fix nitrogen in milligram per gram of sugar consumed under in-vitro condition with the reference check. In addition to nitrogen fixation, plant growth promoting traits such as production of indole-3-acetic acid and gibberellic acid were estimated using spectrophotometric approaches and compared against Bacillus subtilis as reference multi-potent plant growth promoting strain. In-vivo evaluation of these diazotrophic species in rice found improvement in both above and below ground responses in rice plant evaluated by estimating changes in chlorophyll concentration, plant biomass, root architecture, nitrogen uptake, microbial biomass and associated biochemical activity of soil. Further, the selected isolates were identified through DNA targeted analysis of 16S rRNA gene present in diazotrophs and which identified that the isolates belonged to the Enterobacter genus. Statistical models were prepared for deciphering the dynamics of plant growth improvement due to selective enrichment of rhizosphere bacteria and found significant (p<0.05) correlation between soil and plant parameters. This study concludes that Enterobacter spp. present in organic paddy soils of Sikkim having good nitrogen fixing abilities and whose selective enrichment in rhizosphere improved nitrogen uptake and plant growth promotion in rice plant.

Soil carbon pool under organic and conventional crop production system of semi arid tropics

Regardless of land use, the results indicated significant differences in all the studied parameters. Total % SOC ranged from 0.52 to 0.72 for conventional farm samples (mean 0.62%) and 0.63 to 1.59 for the organic samples (mean 1.19). Bulk density (g/cc) ranged from 0.43 to 0.81 (mean 0. 62) for conventional and 0.17 to 0.28 (mean 0.20) organic farm soils. Organic manures increased microbial biomass carbon by 117% and dissolved organic carbon (DOC) concentration by 181% over conventional farming. The results suggested that organic matter is better protected in organic soils and are consequently less vulnerable to mineralization.

Bacteriocin production by Leuconostoc citreum ST110LD isolated from organic farm soil, a promising biopreservative.

The objective of this study was to isolate a bacteriocin-producing strain and to characterize the expressed bacteriocin for the control of Listeria monocytogenes with aim of biopreservation application. Soil samples from a Korean organic farm were subjected to microbiological analysis for isolation of potential bacteriocinogenic LAB, based on a three-level approach, using L. monocytogenes ATCC 15313 as an indicator test micro-organism. From a total of 17 isolates with inhibitory potential, seven were confirmed to be bacteriocin producers. The selected isolates were differentiated based on their morphology, catalase reaction, sugar fermentation profile obtained by API50CHL and by RAPD-PCR generating two unique profiles. One of the isolates, ST110LD, a specific strong producer of anti-Listeria bacteriocins (12800AUml-1 ) was identified as Leuconostoc citreum. The proteinaceous nature of the inhibitory compound produced by Leuc. citreum ST110LD was confirmed through treatment with pepsin and α-chymotrypsin. Bacteriocin activity was observed to be not affected by the presence of milk, NaCl, SDS, Tween 80 or glycerol. Bacteriocin ST110LD effectively inhibited the growth of exponentially growing L. monocytogenes ATCC 15313 during a 10-h incubation period in BHI at 37°C. In addition, this bacteriocin showed specific inhibition of only Listeria spp., but did not inhibit the growth of beneficial cultures included in the microbial test panel for assessment of the spectrum of activity. Leuconostoc citreum ST110LD was evaluated as safe bacterium strain, producing bacteriocin with high specificity against listerial and enterococcal species. Specificity of producer strain and expressed bacteriocin can be explored in biopreservation of different fermented food products or applied in biotherapy of antibiotic resistant listerial or enterococcal infections. To the best of our knowledge, this is the first report of bacteriocin produced by Leuc. citreum strain with highly specific antimicrobial activity against Listeria sp. and Enterococcus sp.

AKTIVITAS EFFECTIVE MICROORGANISMS (EM) DALAM TANAH PERTANIAN ORGANIK YANG TERPAPAR KLORPIRIFOS

One way to restore soil fertility exposed to pesticides such as chlorpyrifos is by bioremediation using Effective Microorganisms (EM). The purpose of this study was to determine EM microbial resistance and chlorpyrifos degrading enzyme activity in organic farming soil sample.The organic farming soil sample used previously has been exposed to EM for a long time. This soil sample was divided into two treatments, namely sterilized by autoclaving and not sterilized (thus indigenous microbes remain alive). The next two soil samples were with and without addition of EM with incubation time of 3, 5, and 7 days. The results of this study indicated that EM microbes could withstand exposure to chlorpyrifos to a concentration of 56 ppm. The phenomenon of chlorpyrifos degrading enzyme activity was found in sterile soil samples with EM addition of 0.017 U/mL during 7-day incubation with a decrease in chlorpyrifos levels of 16.65%. The highest activity of chlorpyrifos degrading enzyme was found in unsterile soil sample, which amounted to 0.039 U/mL during the 3-day incubation period with a decrease in chlorpyrifos levels of 74.11%. The highest decrease in chlorpyrifos was found in unsterile soil sample by 80.04% with an incubation time of 5 days.&#x0D; Keywords: chlorpyrifos, bioremediation, microbial EM (Effective Microorganisms)

KARAKTERISASI BAKTERI TANAH PERTANIAN ORGANIK DAN TANAH PERTANIAN ANORGANIK DAN UJI ANTAGONIS TERHADAP JAMUR AKAR PUTIH (Rigidoporus microporus)

Research on the Characterization and Antagonist Test of Organic Soil Bacteria and Inorganic Farm Soils Against White Root Fungi (Rigidoporus microporus), was studied at the USU FMIPA Microbiology Laboratory, Medan, in May 2018. The method used was the characterization of agricultural soil bacteria with scatter plates and Yeast media. Extract 1%, obtained 3 soil bacterial isolates namely Sp01, Sp02 and Sp03 and 3 isolates from the inorganic agricultural soils Spa1, Spa2, and Spa3 which were characterized by shape, color, elevation edge and edge of the colony. Sp02 and Sp03 bacteria have greater ability to inhibit the growth of Rigidoporus microporus than Sp01 with inhibition zones of 2.5 and 3.5 mm. Sp a1 bacterium has the highest inhibitory ability of 30 mm against Rigidoporus microporus compared to Spa2 and Spa3. Keywords: Bacteria, Rigidoporus microporus, Faarm soils

Antagonistic and plant-growth promoting novel Bacillus species from long-term organic farming soils from Sikkim, India.

Three bacteria namely Bacillus luciferensis K2, Bacillus amyloliquefaciens K12 and Bacillus subtilis BioCWB possessing plant growth promotion and biocontrol potential against phytopathogens and rice leaf folder were identified from organic soils of Sikkim, India. The results revealed significant higher production of phytohormones IAA (97.1μgmL-1) and GA3 (10.6μgmL-1) was found in K2, whereas BioCWB had higher phosphate solubilization (570.0μgmL-1) efficacy and also possessed nitrogen fixation ability (5.34 log copy number mL-1 culture). All these bacteria had higher antagonistic activities against phytopathogens viz. Rhizoctonia solani, Fusarium proliferatum, Athelia rolfsii and Colletotrichum gloeosporioides and also had higher larvicidal activity against rice leaf folder Cnaphalocrocis medinalis (Guenne) under in vitro conditions. Molecular insights into the antagonistic mechanisms of Bacillus strains deciphered the presence of several antimicrobial peptides (ericin, subtilin, surfactin, iturin, bacilysin, subtilosin, fengycin and bacillomycin), volatiles (dimethyl disulphide, methyl-Furan, acetic acid, Z-1,3-pentadiene and 3-hexyn-2-ol) and soluble metabolites (9-octadecenamide, E-15-heptadecenal, E-3-eicosene and 5-octadecene). Furthermore, liquid microbial inoculum prepared using the bacterial strains (K2, K12 and BioCWB) were evaluated under glass house (rice) and field condition (capsicum), which significantly enhanced plant growth in rice and yield in capsicum compared to control. The present study revealed the combination of Bacillus spp. (K2, K12 and BioCWB) can be used as bio-inoculants for improving agricultural production in Sikkim. Moreover, for the first time, we demonstrated plant growth promoting (PGP) traits, antifungal and insecticidal properties of B. luciferensis.

Soil Enzyme Activities and Their Relationship with Soil Physico-Chemical Properties and Oxide Minerals in Coastal Agroecosystem of Puducherry

The objectives of our research were to assess the soil enzyme activities in relation with soil physicochemical and oxide minerals in the coastal agroecosystem of Puducherry region, India. Soils from nine farms in organic (ORG), sustainable (SUS), and conventional (CON) farming were sampled. Organically managed farming system soils contain significantly higher amounts of soil total N, organic carbon, and a higher level of microbial biomass C and N. Urease, protease, β-glucosidase, cellulose, saccharase, xylanase, and alkaline phosphatase enzyme activities were higher in organic farming system soils compared to sustainable and conventional farming soils. In addition, silt, clay, Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O, and P2O5 oxides were higher in organic farming soil and they showed a significant positive correlation with soil enzyme activities. Our study revealed that soil enzyme activities and soil minerals were significantly affected by farm management practices. The organic farming system had improved the soil health, enzyme activities, and plant available nutrients in coastal agro-ecosystem.

有機栽培野菜畑土壌における施用有機物の窒素無機化特性 II. 有機・慣行栽培の土壌における窒素無機化量の資材間の比較

有機栽培野菜畑土壌における施用有機物の窒素無機化特性 II. 有機・慣行栽培の土壌における窒素無機化量の資材間の比較

有機栽培野菜畑土壌における施用有機物の窒素無機化特性 I. 有機栽培・転換中・慣行栽培の土壌に添加した米ぬかからの窒素無機化量の違い

有機栽培野菜畑土壌における施用有機物の窒素無機化特性 I. 有機栽培・転換中・慣行栽培の土壌に添加した米ぬかからの窒素無機化量の違い