Rice Field Soil Research Articles

Assessment of Boro Rice Areas of Meghalaya Using Geospatial Technology

Boro rice areas were delineated from Sentinel 2B images of March, 2021 by using standard visual interpretation technique. Soil fertility status of Boro rice feilds was evaluated by using soil sample analysis data collected from Soil Health Card dashboard and soil sampled collected from different rice fields in GIS environment. Soil sample location map was prepared from latitude and longitude information and soil analysis data was linked to it. The soil fertility maps were generated through Inverse Distance Weighted (IDW) interpolation technique using Spatial Analyst tools of Arc Toolbox. The study revealed that Boro rice is cultivated over 7647.9ha which is 15% of the total geographical area of the Selsella block. The soils of Boro rice fields are non-saline, slightly acidic, high to medium in organic carbon and sufficient in iron, manganese, zinc and copper content. The availability of phosphorus and potassium varies from medium to low and nitrogen availability is high to medium.

Comparative elemental analysis of soil of wheat, corn, rice, and okra cropped field using CF-LIBS

The food chain is responsible for harmful chemical poisoning due to land pollution. Heavy metal contamination of the food chain is regarded as one of the key environmental channels of human exposure leading to possible health risks. The purpose of this study was to investigate the toxic elements of soil samples of different cropped fields of the specific parts on the lower course of the river Indus in district Jamshoro, the southern Sindh province of Pakistan. We report the comparative elemental composition of the Soil at 3 and 6 in. depth of the wheat, rice, corn, and okra cropped field using Laser-Induced Breakdown Spectroscopy (LIBS). Soil plasma is generated using Q-Switched Nd: YAG laser (1064 nm), 5 ns pulse duration, and 10 Hz repetition rate. At laser energy of 25 mJ the estimated irradiance is 7.15 × 1010 W/cm2. In this experimentation we have detected the Fe, Si, Mg, Ca, Al, Ba, Hg, Cr, Ni, Mn, H, Cu, Li, Sr, K, Ti, Na, Pb, V, and C in soil plasma spectra at the depth of 3 in. and 6 in. of wheat, rice, corn, and okra cropped field. We have estimated the electron temperature and electron number density under the assumption of the local thermodynamic equilibrium. We have found electron temperature (Te) corn plasma (3 in. depth) in the range of (13768–7003) K and electron number density (Ne) in the range of (9.01–5.18) × 1016 cm−3. In addition, we have also estimated the weight percentage of the different soil samples using Calibration Free LIBS (CF–LIBS).

Root exudates with low C/N ratios accelerate CO2 emissions from paddy soil

AbstractRoot exudates can significantly modify microbial activity and soil organic matter (SOM) mineralization. However, how root exudates and their C/N stoichiometric ratios control rice field (paddy) soil C mineralization is poorly understood. This study used a mixture of glucose, oxalic acid, and alanine as root exudate mimics for three C/N stoichiometric ratios (CN6, CN10, and CN80) to explore the underlying mechanisms involved in SOM mineralization. The input of root exudates enhanced CO2 emissions by 1.8–2.3‐fold that of soil with only C additions (C‐only). Artificial root exudates with low C/N ratios (CN6 and CN10) increased the metabolic quotient (qCO2) by 12% over those with higher stoichiometric ratios (CN80 and C‐only), suggesting a relatively high energy demand for microorganisms to acquire organic N from SOM by increasing N‐hydrolase production. The increase of stoichiometric ratios of C‐ to N‐hydrolase [β‐1,4‐glucosidase to β‐1,4‐N‐acetyl glucosaminidase (NAG)] promoted SOM degradation compared to those involved in organic C‐ and N‐degradation, which had a significant positive correlation with qCO2. The stoichiometric ratios of microbial biomass were positively correlated with C use efficiency, indicating root exudates with higher C/N ratios provide an undersupply of N for microorganisms that trigger the release of N‐degrading extracellular enzymes. Our findings showed that the C/N stoichiometry of root exudates controlled SOM mineralization by affecting the specific response of the microbial biomass through the activity of C‐ and N‐releasing extracellular enzymes to adjust the microbial C/N ratio.

Mercury Pollution from Small Scale Gold Mines in Agricultural Lands

Abstract Small scale gold mines widely spread in developing countries, including Indonesia. Most miners use mercury (Hg) in an amalgamation process to separate gold from its ores. This process produces a waste as mercury-containing slurries which is eventually discharged to surrounding water streams, potentially creating ecosystem pollution. If the polluted water is used for irrigation to surrounding ricefields, mercury may stay and accumulate in streambed sediments and irrigated soils and enter the food chain, including human consumption. This research was aimed to assess pollution potential in stream water and ricefields surrounding small scale gold mines in Lebong District, Bengkulu, Indonesia. This research was conducted from November to December 2018. Field activities included collecting 9 water samples, 6 sediment samples, 3 soil samples, and 3 plant samples in different locations. Laboratory analysis were carried out at the Soil Science Laboratory, University of Bengkulu, Bengkulu and the Integrated Research and Testing Laboratory (LPPT) Gadjah Mada University, Yogyakarta, Indonesia. The results showed that all water, streambed sediment, soil, water, and plant tissue samples contained mercury and most of their concentrations exceeded the threshold values. The highest Hg concentrations were found 58.19, 16.85, and 15.44 ppm the streambed sediments, rice plants, and ricefield soils respectively, while a relatively lower Hg (0.044 ppm) was found in the stream water.

Amazonocrinis thailandica sp. nov. (Nostocales, Cyanobacteria), a novel species of the previously monotypic Amazonocrinis genus from Thailand

Cyanobacteria are distributed worldwide, and many new cyanobacterial species are discovered in tropical region. TheNostoc-like genus Amazonocrinis has been separated from the genus Nostoc based on polyphasic methods. However,species diversity within this genus remains poorly understood systematically because only one species (Amazonocrinisnigriterrae) has been described. In this study, two novel strains (NUACC02 and NUACC03) were isolated from moist ricefield soil in Thailand. These two strains were characterized using a polyphasic approach, based on morphology, 16S rRNAphylogenetic analysis, internal transcribed spacer secondary structure and ecology. Phylogenetic analyses based on 16SrRNA gene sequences confirmed that the two novel strains formed a monophyletic clade related to the genus Amazonocrinisand were distant from the type species A. nigriterrae. The 16S rRNA gene sequence similarity (<98.1%) betweennovel strains and all other closely related taxa including the Amazonocrinis members exceeded the cutoff for speciesdelimitation in bacteriology, reinforcing the presence of a new Amazonocrinis species. Furthermore, the novel strainspossessed unique phenotypic characteristics such as the presence of the sheath, necridia-like cells, larger cell dimensionand akinete cell arrangement in long-chains and the singularity of D1–D1′, Box-B, V2, and V3 secondary structures thatdistinguished them from other Amazonocrinis members. Considering all the results, we described our two strains as Amazonocrinisthailandica sp. nov. in accordance with the International Code of Nomenclature for Algae, Fungi and Plants.

Flooding and drainage induced abiotic reactions control metal solubility in soil of a contaminated industrial site

Intense industrialization has led to the increasing leaching risk of metals into groundwater at heavily polluted industrial sites. However, metal dissolution in polluted industrial soils has been neither fully investigated nor quantified before. In this study, the dissolution of Zn, Ni, and Cu in soil from a heavily contaminated industrial site during a flooding-drainage period was investigated by sequential extraction, geochemical modelling, and X-ray absorption near edge structure spectroscopy. The results showed a steady decrease in metal solubility during both reduction and oxidation stages. During reduction, with limited decrease in Eh (>100 mV), formation of carbonate precipitates rather than sulfide precipitates and adsorption on soil solids was responsible for Zn and Ni dissolution, whereas bound to soil organic matter (SOM) and iron oxides dominated Cu dissolution, due to its lower concentration and higher affinity to SOM and iron oxides compared to Zn and Ni. During oxidation, the acidity caused by ferrous oxidation was buffered by calcite dissolution, while metal precipitation ceased and adsorption on soil surface controlled metal solubility. The metal solubility and speciation during the flooding-drainage process were quantitatively predicted by geochemical model. The findings demonstrate that due to high metal concentrations and weak microbial effect in the industrial soil, metal release was largely regulated by abiotic reactions rather than biotic reactions, which is somehow different from that of the wetland or rice field soils.

Evaluation Of Anti-Biofilm Activity Of Bacterial Amylase Against Human Pathogens

Global healthcare crisis has a significant impact on human health and economy because of antimicrobial resistance. Emergence of antibiotic resistance due to excessive antibiotic use results in resistant microbes. Biofilm shows integral resistance to antimicrobial agents and the host defense system. Microbes that exist in the biofilms, shows 10-1000 times resistance to antibiotics as compared to the free life style. The biofilms of bacteria serve as a great issue in not only environmental and industrial line but also play an important role in healthcare setting. The biofilm producing bacteria such as Vibrio cholerae and antibiotic resistant bacteria like methicillin resistant Staphylococcus aureus (MRSA) cause deadly infections. In present study, efficacy of bacterial amylase was tested against biofilm formation of pathogenic microbes. For this, Amylase producing bacterial isolates (isolated from a variety of sources, such as waste, rhizosphere of vegetable soil, rice field, potato, and sugarcane field soils sources (ArPs, ArDs, ArSs, ArVs and ArRs) were utilized to reduce the microbial biofilm development against pathogenic isolates of Staphylococcus aureus and Pseudomonas aeruginosa. Six bacterial isolates (SB, SW, SU, PB, PW, and PU) obtained from cancer patients of tertiary care hospitals. Amylase enzyme extracted from ArPs showed maximum growth inhibitory effect on SW pathogen, while ArRs showed minimum growth effect upon SB pathogens. However, amylase showed highest anti-biofilm activity against SW pathogen. In general, the highest biofilm inhibition was recorded at pH7 at 37°C as compared to rest of pHs and temperatures. The efficacy of bacterial amylase in biofilm inhibition of human pathogens, seem promising and having significant potential in health care systems.

Study of Potassium and Sodium content of Mahad-Raigad Tertiary Soil by Flame Photometry

The present study is devoted to determine the content of K, Na, pH of soil samples collected from Mahad tehsil territory. Elements leached from the deposits of the fertilizers have been accumulated in soil, thus constituting to soil pollution index. Focusing this study was carried out to compare out the nutrient contents of barren soil and Rice field soil in Mahad tehsil tertiary, by Flame photometry analysis.

Comparative Microbial Communities of Anode Associated Soils in Sediment Microbial Fuel Cells of Rice Field and Drainage Ditch Soils

Comparative Microbial Communities of Anode Associated Soils in Sediment Microbial Fuel Cells of Rice Field and Drainage Ditch Soils

Heavy Metal Accumulation in Soil and Water in Pilot Scale Rice Field Treated with Sewage Sludge

Widespread use of chemical fertilizers in agricultural activities poses a high risk of multi-micro metal contamination in soils and potentially causes health issues through consumption of contaminated foods. Bio-organic fertilizers from sewage sludge have been regarded as a suitable substitute for chemical fertilizer for rice farming. In this study, we investigated accumulation of heavy metals (Cu and Zn) in soil, water and rice plant in three pilot-scale rice paddy fields treated with different fertilization schemes. The control field was treated with conventional chemical fertilizers while the soil of two treatment fields was mixed with biological sewage sludge obtained from a local wastewater treatment system in Vietnam at different ratios (1% and 3%). Initial results showed that heavy metals accumulated in the soil, water, and rice plant at varying levels and most of the Cu and Zn contents found in soils, water and rice products exceeded permissible Vietnamese standards (QCVN 03: 2008) and US EPA 503. Notably, the rice field whose soil was treated with sludge at 3% ratio showed a significantly lower accumulation of heavy metals in soil, water and in rice plant. However, treatment of sludge at this level seemed to cause higher heavy metal retention in soil after one harvest. Semi-quantitative risk analysis revealed that the risk of metal contamination in soil and water of the control field ranged from medium (RQ index between 0.1 and 1) to high risk (RQ index higher than 1) and that fertilization methods would also affect the level of risk to the environment.

Shedding light on the functional role of the Ignavibacteria in Italian rice field soil: A meta-genomic/transcriptomic analysis

The Ignavibacteria are ubiquitously abundant in paddy soils, but their functional role is poorly known. Here, we applied a targeted meta-genomic/transcriptomic approach to elucidate genetic potential and functional activity of the Ignavibacteria in straw-amended paddy soils from Italy. Eight high-quality metagenome-assembled genomes (MAGs) were recovered, being the largest ones (∅ 4.8 Mbp) among all known Ignavibacteria genomes (∅ 3.7 Mbp). Functional annotation revealed that the Ignavibacteria in Italian paddy soil are facultative anaerobes, represent a novel lineage in the Ignavibacteriae phylum, and have the ability for aerobic-hybrid phenylacetate degradation. Their putative functional roles under anoxic and micro-oxic conditions were assessed by mapping environmental mRNA onto the MAGs. Transcript analysis showed that primary fermentation of sugars to acetate and hydrogen is a major energy-yielding pathway under anoxic conditions. Although the phenylacetate degradation pathway is widely distributed among taxonomically diverse paddy soil bacteria, Ignavibacteria almost exclusively expressed this pathway under micro-oxic conditions. In particular, the transcript level of the paaABCDE gene cluster increased significantly. It encodes a monooxygenase, which is the key enzyme of phenylacetate degradation. This was linked to a significant decrease in transcripts encoding fermentation pathways and oxygen-sensitive hydrogenases, but increase in transcripts encoding TCA cycle, respiratory chain, and proteins involved in oxygen stress response (SOD1, AhpC, Bfr). More than half of the carbohydrate-active enzymes (CAZymes) expressed under anoxic and micro-oxic conditions possessed signal peptides, thereby indicating that Ignavibacteria contribute to the decomposition of complex polymers, such as cellulose, hemicellulose, and chitin. In summary, the Ignavibacteria in rice field soil are metabolically versatile and particularly adapted to the varying oxygen conditions in this ecosystem.

Dissipation behaviour and safety risk assessment of a ready-mix formulation of clomazone and 2,4-D in rice field under tropical agro-climatic conditions of India

ABSTRACT This study portrays the dissipation behaviour of the herbicide mixture of clomazone and 2,4-D (clomazone 20% + 2,4-D ethyl ester 30% EC) in a rice field system. The combined formulation is widely used in India as it controls a broad spectrum of weeds, but its fate in tropical environment and the risks involved to the consumer as well as to the environment are still unexplored. Therefore, a supervised field trial was conducted following the post-emergence application of clomazone 20% + 2,4-D ethyl ester 30% EC at recommended (625 g a.i./ha) and double the recommended dose (1250 g a.i./ha) in rice in two consecutive seasons (Kharif and Rabi). The analytical methods for both clomazone and 2,4-D validated as per the SANTE guideline. The residues of clomazone were extracted by the modified QuEChERS method and analysed by GC-MS/MS, whereas the residues 2,4-D were extracted by classical partitioning method and analysed by LC-MS/MS. The recovery percentage of both the compounds ranged between 86–95% with LOQ 0.01 mg/kg for all matrices (rice grain, straw, husk, and field soil). The dissipation of both the compounds followed first-order kinetics. The half-life of clomazone and 2,4-D in soil ranged between 1.06–1.27 days and 4.74–6.24 days, respectively. The residues of clomazone and 2,4-D were below quantification level (BLOQ) in the harvested rice co-products (rice grain, husk and straw) and soil samples. Therefore, it can be summarised that the application of this herbicide mixture in rice cultivation will not pose any residual toxicity and the rice grains are safe for human consumption. Besides, the soil ecological risk assessment indicated that both the compounds possess low risk towards earthworm and soil arthropods. However, there was a concern about soil algal toxicity, which needs to be reconfirmed by further studies to establish a conclusive inference.

Ecological and human health risk evaluation of potential toxic metals in paddy soil, rice plants, and rice grains (Oryza sativa) of Omor Rice Field, Nigeria.

Potential toxic metals from natural and anthropogenic sources accumulate in soil and plants, and represent important environmental contamination challenges. The ecological and human health risks of the potential toxic metals in rice grain, paddy soil, and rice plants of Omor rice field were assessed. The total metal concentration from the four sampling sections (mg/kg) were soil-Zn (29.51 ± 2.23), Mn (55.27 ± 8.10), Cd (5.49 ± 2.24), Cu (2.94 ± 1.47), Pb (14.35 ± 6.54), and Cr (27.06 ± 8.31); rice grain-Zn (21.70 ± 5.44), Mn (3.30 ± 0.21), Cd (00.14 ± 0.11), Cu (2.80 ± 0.34), Pb (11.98 ± 0.58), and Cr (15.86 ± 2.79); and for rice plant-Zn (5.24 ± 1.93), Mn (4.68 ± 1.91), Cd (0.21 ± 0.11), Cu (4.88 ± 0.61), Pb (15.24 ± 6.16), and Cr (46.5 ± 6.05). The estimated daily intakes for adult showed that Cd and Pb exceeded the safe limit by 1% and 93%, respectively. The metal hazard quotients (Zn-0.0007, Mn-0.00019, Cd-0.16, Cu-0.19, and Cr-0.0000077) were less than 1 indicating no probable health risk originating from their exposure. The total hazard index (0.35) also suggests no probable health risk connected with the rice consumption. The metals' ecological risk indices of the soil showed low-risk (< 40), except Cd in some sections of the rice field which indicated moderate potential ecological risk (40-80).

OXIDATION-REDUCTION PROCESSES IN THE SOILS OF RICE AGROCENOSES OF THE KUBAN REGION (RUSSIA)

Background: The studies were carried out on the Maryano-Cheburgolsky irrigation array in the Krasnoarmeisky district of the Krasnodar Territory. Aim: This work aims to study the oxidation-reduction processes and activity of iron compounds in meadow-chernozem and meadow-boggy soils of rice agrocenoses of the Kuban region. Methods: Soil samples were taken from paddy fields occupied by rice and perennial grasses, in which the pH value, redox potential (Eh, mV), magnetic susceptibility (χ×10-3 S.I. units), and the content of active iron compounds (FeO and Fe2O3, mg/100 g) were determined. Results and Discussion: The reductive processes created in the soils of rice fields after flooding led to the transformation of poorly soluble Fe2O3 compounds into more active reaction forms of FeO. The maximum content of FeO and the minimum amount of Fe2O3 were recorded during the period of negative Eh values. The maximum reduction of iron in meadow-boggy and meadow-chernozem soils was achieved by the phase of flowering of rice plants at Eh = -127, pH = 7.36 units, rH2 = 10 and Eh = -152...-167 mV, pH = 6.89-7.10 units, rH2 = 9, respectively. Conclusions: In the soil of permanent rice cultivation, the dynamics of Eh and iron compounds are similar to the fields of rice crop rotation. In non-flooded soils of rice fields under perennial grasses, the oxidative regime prevails, and the transformation of iron compounds is not expressed. The minimum values of χ coincide with the maximum content of ferrous iron in soils at negative Eh values, which corresponds to the rice flowering phase. Correlation coefficients of χ with Eh, FeO, and Fe2O3 equal from +0.66 to +0.75, from -0.69 to -0.84, and from +0.74 to +0.77, respectively. The χ value increases in the soil under crops of perennial grasses with a predominance of oxidative processes. The correlation coefficient between χ and Fe2O3 equals from +0.83 to +0.90.

Characterization and mosquitocidal potency of a Bacillus thuringiensis strain of rice field soil of Burdwan, West Bengal, India

Bacillus thuringiensis is the most popular mosquitocidal bacteria, strains of which are effective against almost all mosquito larvae. It has host specificity and thus, has no adverse effect on non-target species of the ecosystem. Culex tritaeniorhynchus, a vector of Japanese encephalitis (JE), breeds in vast area of rice fields in Burdwan district of West Bengal, India, which has already confronted JE epidemic.Entomological investigation and ecological studies on this vector mosquito showed that JE epidemic may reoccur anytime in the area. A strain of Bt (BU55) was isolated from rice field soil, efficacy was tested against Cx. tritaeniorhynchus and mosquitocidal role was confirmed against Cx. quinquefascistus also. The LC50 of Bacillus thuringiensis BU55 against Cx. tritaeniorhynchus and Cx. quinquefascistus after 72 h was 8.59 ml (final dose 2.49 x107 CFU/ml) and 7.52 ml (final dose 2.20 x 107 CFU/ml), respectively. Insecticidal crystal protein profile of BU55 produced 136.89, 64.80, 43.45, 33.65 and 26.98 kDa bands. Among them 136.89, 64.29, 26.98 kDa proteins are comparable to actual toxins viz. Cry1Ac (138.3 kDa, Lepidoptera specific), Cry4D (68.0 kDa, Diptera specific) and Cyt (27.4 kDa, Diptera specific). The results clearly showed that the Bt strain is a potent dipteran larvicide and can be used against the JE vectors to control the disease.

Identification of basmati rice (Oryza sativa L.) rhizobacteria and their effect on plant growth traits for sustainable development in agriculture

Plant growth-promoting rhizobacteria (PGPR) play an important role to support the plant growth on sustainable basis. The present study was undertaken to identify the potential PGPR associated with the rhizosphere of basmati rice and in vivo screen for their effect on morphological traits. It also investigates the combined study of PGPR with synthetic fertilizers on basmati rice production. A total of 617 bacterial isolates were selected randomly from the rhizosphere, endorhizosphere and bulk soil of different rice fields. The preliminary characterization of bacteria for different plant growth promoting (PGP) traits led to the selection of PGPR for further studies. The 16S rRNA sequencing of the isolates classified the PGPR into nine different genera i.e. Bacillus, Pseudomonas, Streptomyces, Exiguobacterium, Aeromonas, Chryseobacterium, Enterobacter and Stenotrophonomonas. Overall, 18 most promising native strains of PGPR were applied alone or in combination with 50% recommended dosage of NPK fertilizers (RDF) to study their role in morphological growth parameters of rice. All the PGPR isolates showed an increase in plant growth compared to the control but in combination with 50% RDF, more significant growth was observed. Pseudomonas otitidis sp. SB 5 (T5) along with dose of fertilizers exhibited highest increase in root length (37 cm/plant) compared to the control and individual treatment of PGPR. Enterobacter sp. (T4 + NPK) showed highest shoot length (109.75 cm/plant) with significant increases (p < 0.5) over the uninoculated control. Chryseobacterium sp. (T18 + NPK) gave significant increase in fresh and dry weight of root and shoot, compared to T18 and control plant. This is the first report for identification of PGPR in basmati growing area under Geographical Indicator (GI) and their effect on plant growth `promotion. Thus, their use can improve the yield and profit of rice crop with reduced synthetic fertilization.

Profile of microbial community of organic and conventional rice field using metagenomic analysis

Organic farming can increase the diversity of soil bacterial. This research aimed to compare the profile of microbial community of organic and conventional rice fields in early (0 Day After Planting/DAP), mid (15 DAP), and late (45 DAP) fertilizer application period. The total DNA genome from the soil sample was extracted then analyzed metagenomically using Next Generation Sequencing (NGS). There was nine genus of bacteria found in high relative abundance, 95.28%, while 4.72% included in Domain of Archaea (genus Methanosaeta). Phylum of Firmicutes (genus Clostridium has 24.50% relative abundance, Bacillus 11.90%, Lactobacillus 9.69%); Proteobacteria (genus Defluviicoccus 12.10%, Buchnera 18.46%, Rosenbergiella 2.46%); and Actinobacteria (genus Nocardioides 12.21%, and Streptomyces 3.96%). Meanwhile, the average plant height of organic rice fields was shorter than conventional rice fields got directly measured coincided with soil sampled. Based on alpha and beta diversity analysis, the highest community diversity and abundance were found in organic rice field soil samples taken at 45 DAP, i.e., at the end of the fertilizer application period. However, in both organic and conventional rice field soils, there was almost no significant difference in the bacterial community, so it impacts that organic and conventional systems do not make a real difference in the total N, P available, CEC, and pH values. It makes a significant difference in organic C and organic matters.

Exploration and isolation of cyanobacteria cultures from the soils of rice fields of the republic of Kazakhstan)

The species diversity of the microalgae of two rice fields in Kazakhstan, located on the territory of the Almaty and Kyzylorda regions with different types of landscape was studied. The objects of the study were fields located in the Almaty region, Balkhash district of the village of Birlik and the Kyzylorda region of the village of Karaultobe. In the Birlik village the soil microalgae was studied for the first time. The purpose of this work was to study the microalgae of soils that were exposed to anthropogenic impact due to the cultivation of agricultural crops in them to identify and isolate cyanobacteria cultures. The above-mentioned objects are important for agriculture, as well as economic importance for the population of these areas. Therefore, the biological assessment of the soil of these objects is the most relevant. The analysis of the algological composition of the soils of rice fields identified an extensive species diversity of cyanobacteria in the studied objects. The greatest quantitative and qualitative composition in the soils revealed cyanobacteria of such types as: unicellular, colonial and filamentous forms. The scientific importance of the research is to study the species diversity of cyanobacteria of these objects. The practical importance of research is established in the fact that the results of the conducted analyses and experiments can be used in predicting the ecological state, and can also be necessary in creating recommendations for the conservation and functioning of environmental objects. According to the results of studies on obtaining algologically pure cultures from samples taken from the soils of rice fields in Almaty and Kyzylorda regions, such algological cultures of cyanobacteria as: Oscillitoria subbreris, Oscillitoria pseudogeminate, Osillitoria geitleriana, Phormidium purpurascens. Key words: microalgae of rice fields, cyanobacteria, algologically pure cultures. &nbsp;

Characterization of Effective Microorganism (Phosphate Solubilizing Bacteria) Isolated from Rice-Field Soils

Phosphate solubilizing bacteria (PSB) is included in one of the effective organisms for plant growth-promoting rhizobacteria (PGPR) and considered as promising biofertilizers. This study is focused on identifying with inoculations PSB will give effects to the solubilization of phosphorus in soil and become available for plant uptake. To address this, four treatments are set up which are Merlimau soil (T0), Merlimau soil with Phosphate Solubilizing Bacteria (PSB) (T1), Tanjong Karang soil (T2), and Tanjong Karang soil with PSB (T3). Available P for the treatments and the value of soil pH is being taken as the parameter. Besides, the growth performance of rice plants was also recorded with the measurement of plant height, the number of tillers, and the number of leaves on weekly for five weeks. The soil analysis for available P and the soil pH was found to have a significant increase when treated with PSB as shown for the results of T1 and T3. The plant analysis for the growth performance of rice plants also shows that better growth of plants for the soils that have been treated with PSB. Thus, the application of PSB to the rice-field soil can increase P availability and reduce the acidity of the soil. In addition, it gives effect to the performance of the rice growth where this study shows results in increasing plant height, higher development of tillers, and plant leaves compared to the soils that do not treated with PSB.

Lignocellulolytic bacteria isolated from organic rice field soils for enzyme production using agricultural wastes: Screening, medium optimization, and co-culture

Lignocellulolytic bacteria can degrade agricultural biomass and fungal cell walls. Organic agriculture intensively employs these microbes as biofertilizers and biocontrol agents. This study focused on isolating, screening, identifying, and optimizing enzyme production of the lignocellulolytic bacteria obtained from organic rice field soils for utilizing in organic farming. Here we have shown that the farming periods can alter the bacterial biodiversity in organic rice field soil by providing different nutrients. Paenibacillus polymyxa BTK01 and Bacillus subtilis BTK07, which were isolated from the preharvest soil, exhibited a high activity of mannanase (MNN) and xylanase (XLN). By optimizing the enzyme production, BTK01 and BTK07 were specifically productive in xylanase and mannanase, respectively, because of the induction of substrate-like carbon sources. Varying the type and concentration of nitrogen source revealed that mannanase production positively correlated to bacterial growth of both strains. Throughout the study, we used soybean meal as a nitrogen source with the nitrogen concentration of 0.144% (w/v), BTK01 was productive in xylanase when cultured in the medium comprised of 1.5% (w/v) rice straw (0.905 ± 0.016 U/mL), and BTK07 was efficient in mannanase production when cultured in the medium consisted of 1.0% (w/v) copra meal (0.440 ± 0.000 U/mL). The co-culture of BTK01 and BTK07 using the volume ratio of 1:10 could yield MNN and XLN to be 2.470 ± 0.013 and 0.906 ± 0.015 U/mL, respectively. This result demonstrates that Paenibacillus polymyxa BTK01 and Bacillus subtilis BTK07 can be useful and applicable for organic agriculture as biocontrol agents and biofertilizers.