Cultivated Fields Research Articles

Effects of weed management on soil metagenomic composition in cultivated chickpea fields

Abstract Non-chemical methods, including mechanical and manual weed management are important for improving crop yields and preserving soil microbial diversity. In Tunisia, chickpea cultivation uses a combination of these methods to suppress weeds. This study aimed to evaluate the impact of weeding practices on chickpea (Cicer arietinum L. cultivar REBHA) yield and soil microbial diversity. Field experiments were conducted at the Technical Center for Biological Agriculture in Essaida, Tunisia, using six plots with manual and no weeding treatments. Chickpea yield was measured, and soil samples were collected for metagenomic analysis. Floristic surveys identified 13 weed species, with Chenopodium album L., Rumex acetosa L., and Urtica dioica L. being the most dominant. Seed yield ranged from 23.2 to 26.2 qls/ha in non-weeded plots and from 25.1 to 30.1 qls/ha in weeded plots, showing an increase in yield (11.75%) with manual weeding.
Soil metagenomics revealed changes in bacterial community composition between the two treatments. The dominant phylum was Pseudomonadota, whose relative abundance increased from 24.88% in non-weeded plots to 34.76% in weeded plots. Alpha diversity indices showed lower species richness and diversity in weeded soils, with 62000 OTUs in weeded plots compared to 43202 OTUs in non-weeded plots. Betaproteobacteria and Alphaproteobacteria exhibited higher OTU counts in weeded soils. The Simpson diversity index was lower in non-weeded soils (0.025) than in weeded soils (0.075), indicating a more irregular microbial distribution in non-weeded plots. Thus, manual weeding improved chickpea yield and altered the soil bacterial community, increasing diversity in key microbial taxa. This study highlights the complex interaction between weed management practices and soil microbial ecosystems, which may influence crop productivity.

Experimental evidence of negative agricultural impacts and effectiveness of mitigation strategies of invasive green iguanas (Iguana iguana) in Puerto Rico

Losses in crop yield due to invasive insects, weeds, pathogens, and herbivores cost trillions of dollars per year globally. To prevent further spread of invasive agricultural pest species, continuous monitoring and prevention are crucial. Once introduced, however, assessing the impact of an invasive pest on agricultural production and testing management strategies are essential. The green iguana (Iguana iguana), a globally widespread invasive herbivore, is considered a possible agricultural pest although no quantitative data on its impact are available. In this study, we evaluated the impact of the invasive green iguana on cucumber (Cucumis sativus, var. Dasher II) and lettuce (Lactuca sativa, var. Black-seeded Simpson) yield by testing the efficacy of two management strategies – Neem-based pesticide and mesh fencing – compared to open field cultivation in Puerto Rico. Mesh fencing led to 20% more growth and doubled cucumber yield compared to open field cultivation, while spraying Neem led to an 18% increase in plant growth but no effect on cucumber yield. We found no difference in lettuce growth or yield among treatment and control plots. This study supports categorizing the green iguana as an invasive agricultural pest species and demonstrates the reptile’s potential to reduce crop yield. It also shows that Neem application at the manufacturer’s suggested concentration is not an effective mitigation technique for reducing crop loss due to green iguana herbivory. Government agencies in regions where the green iguana has the potential to be introduced should consider the species a threat to food production when developing monitoring programs and drafting regulations.

Abrasive Wear Characteristics of 30MnB5 Steel for High-Speed Plough Tip of Agricultural Machinery in Southern Xinjiang Region

The high-speed plough tip is the core soil-touching component in southern Xinjiang field cultivation, but the interaction of the plough tip with the soil results in severe wear of the tip. The friction behaviour of sand and soil on plough tips was investigated with a homemade rotary abrasive wear tester in a one-factor multilevel test with three parameters: moisture content, velocity/rotational speed and friction distance. The objective was to study the friction behaviour of the sand soil and plough tip and analyse and characterise the wear amount, wear thickness and compressive stress distribution, three-dimensional wear morphology and microscopic wear morphology of the plough tips. The results show that with increasing speed, the wear amount changes more gently; with increasing soil water content, the soil adhesion force and lubricating water film increase so that the wear amount follows a second-order parabolic law; and with increasing friction distance, the wear amount gradually increases, and the wear rate also shows an upward trend when the plough tip is in the abrasive wear stage. The tip makes contact with the firmer soil with higher surface compressive stresses, causing the most wear. As the friction distance increases, sand particles become embedded in the contact surfaces, creating a groove effect along with spalling pits caused by fatigue wear. During the whole wear period, the groove effect is always accompanied by spalling pits appearing repeatedly. The analysis of the wear micromorphology of the plough tip shows that the number of flaking pits gradually decreases in the direction of soil movement, and the form of damage changes from impact wear to plough groove scratches. Abrasive wear interacts with corrosive wear to exacerbate plough tip wear.

Application of microorganisms in Panax ginseng: cultivation of plants, and biotransformation and bioactivity of key component ginsenosides.

Panax ginseng is a precious Chinese medicinal plant with a long growth cycle and high medicinal value. Therefore, it is of great significance to explore effective ways to increase its yield and main active substance content to reduce the cost of ginseng, which is widely used in food and clinical applications. Here, we review the key roles of microorganisms in the biological control of ginseng diseases, enhancement of ginseng yield, biotransformation of ginsenosides, and augmentation of ginsenoside bioactivity. The application of microorganisms in P. ginseng faces multiple challenges, including the need for further exploration of efficient microbial strain resources used in the cultivation of ginseng and biotransformation of ginsenosides, lack of microbial application in large-scale field cultivation of ginseng, and unclear mechanism of microbial transformation of ginsenosides. This review provides a deeper understanding of the applications of microorganisms in P. ginseng.

Tetranychus urticae Koch Biology on Apple Trees

The two-spotted spider mite (Tetranychus urticae Koch) is a polyphagous arthropod herbivore that consumes over 1,100 plant species from 140 distinct plant families, including those producing harmful chemicals in temperate and tropical climates. It is an important pest in greenhouse and field cultivation, causing damage to various crops such as citrus, apples, grapes, tomatoes, peppers, cucumbers, strawberries, maize, and soy. T. urticae ability to spread over agricultural fields and adapt to environmental stressors is linked to its high propensity for mutation, leading to the highest frequency of pesticide resistance among arthropods. The genetic diversity of T. urticae gathered from apple orchards throughout Poland has been studied to investigate potential correlations between molecular variations and the occurrence of resistance to METI-acaricides. Research has shown that an abundance of leaf pubescence on the abaxial leaf surface adversely affects the development of European red mite, two-spotted spider mite, and carmine spider mite. However, due to variations in leaf sizes, tree canopy, tree ages, and the existence of natural enemies, it is impossible to compare data gathered due to variations in leaf sizes, tree canopy, tree ages, and the presence of natural enemies. Pesticide treatments negatively impact fruit plantations' ecosystems, devastating biodiversity, altering the makeup and structure of arthropod populations, and promoting mass reproduction of phytophage mites by displacing certain species with others. The most extensive research has been done on the common spider mite's development of resistance to avermectin group preparations, with some studies showing resistance to multiple acaricides.

Peace Education through Agroecology and Organic Farming

In this paper, the challenge of peace education appears as an emergent cultural need in a context of conflictual relationships among human beings and between human beings and their life environment. All sectors of human activity, including agriculture, can potentially contribute to building a cultural barrier to a mounting wave of wars. The ecological approach to agriculture through the ecosystem concept is suitable for unveiling the power of cooperation in developing symbiotic relationships between and among agroecosystem components for attaining a balance of ecosystem services (supporting, provisioning, regulating, and cultural). Enhancement of biodiversity within and between cultivated fields is key for the maintenance of sustainable agriculture, land management, and viable rural community. Scaling up cooperation among hierarchical levels of agriculture organisation (field, farm, and regional, national, international landscapes) appears as the most promising solution for developing a coherent framework consistent with building a peaceful attitude for managing both land, food systems, and friendly relationships among human beings. Organic farming is already a certified and appreciated method of agriculture production that has a potential for improving a peaceful attitude when supported by the core principles of Agroecology.

Incremental Cost Benefit Ratio (ICBR) of Poly House and Open Field Conditions in Cabbage (Brassica oleracea var. capitata) after Chemical Intervention

This study evaluates the Incremental Cost Benefit Ratio (ICBR) between Poly house and Open field conditions in cabbage cultivation chemical intervention. The research aimed to compare the economic feasibility of adopting poly house technology over traditional open field methods, considering costs and benefits associated with chemical inputs. A comparative cost analysis was conducted to assess production expenses like costs for insecticidal treatments and labor charges. Yield data from both environments were collected to determine output differences and subsequent economic returns. Results indicate that Incremental cost benefit ratio of cabbage heads yields to the cost of treatments in poly house and open field presented as there was a significant superior difference in ICBR ratio of poly house with 1: 0.946 as compared to open field with 1: 0.639 of cabbage heads. The economic analysis revealed that the higher yields and quality achieved in poly house conditions due to less dissipation and undisturbed environmental factors on insecticide applied. Resulting in a favorable incremental Cost benefit ratio compared to open field cultivation.

Plant Factory Speed Breeding Significantly Shortens Rice Generation Time and Enhances Metabolic Diversity

Rice (Oryza sativa L.) plays a pivotal role in global food security, yet its breeding is constrained by its long generation time and seasonality. To enhance rice breeding efficiency and meet future food demands, we have developed a vertical hydroponic breeding system integrated with light-emitting diodes (LEDs) lighting in a closed plant factory (PF), which significantly accelerates rice growth and generation advancement. The results show that indica rice can be harvested as early as after 63 days of cultivation, a 50% reduction compared with field cultivation, enabling the annual harvesting of 5–6 generations within the PF. A hyperspectral imaging system (HSI) and attenuated total reflectance infrared (ATR-IR) spectroscopy were further employed to characterize the chemical composition of the PF- and field-cultivated rice. Metabolomics analysis with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) revealed that, compared with the field-cultivated rice, the PF-cultivated rice exhibited an up-regulation of total phenolic acids along with 68 non-volatile and 19 volatile metabolites, such as isovitexin, succinic acid, and methylillicinone F. Overall, this study reveals the unique metabolic profile of PF-cultivated rice and highlights the potential of PFs to accelerate the breeding of crops such as rice, offering an innovative agricultural strategy to support food security in the face of global population growth and climate change.

Maize crop residue cover mapping using Sentinel-2 MSI data and random forest algorithms

The return of crop residues to cultivated fields has numerous agronomic and soil quality benefits and, therefore, the areal extent of crop residue cover (CRC) could provide a rapid measure of the sustainability of agricultural production systems in a region. Recognizing the limitations of traditional CRC methods, a new method is proposed for estimating the spatial and temporal distribution of maize residue cover (MRC) in the Jilin Province, NE China. The method used random forest (RF) algorithms, 13 tillage indices and 9 textural feature indicators derived from Sentinel-2 data. The tillage indices with the best predictive performance were STI and NDTI (R2 of 0.85 and 0.84, respectively). Among the texture features, the best-fitting was Band8AMean-5*5 (R2 of 0.56 and 0.54 for the line-transect and photographic methods, respectively). Based on MSE and InNodePurity, the optimal combination of RF algorithm for the line-transect method was STI, NDTI, NDI7, NDRI5, SRNDI, NDRI6, NDRI7 and Band3Mean-3*3. Likewise, the optimal combination of RF algorithm for the photographic method was STI, NDTI, NDI7, SRNDI, NDRI6, NDRI5, NDRI9 and Band3Mean-3*3. Regional distribution of MRC in the Jilin Province, estimated using the RF prediction model, was higher in the central and southeast sections than in the northwest. That distribution was in line with the spatial heterogeneity of maize yield in the region. These findings showed that the RF algorithm can be used to map regional MRC and, therefore, represents a useful tool for monitoring regional-scale adoption of conservation agricultural practices.

Comparing greenhouse and field biocrust cultivation methods in the Sonoran Desert

Abstract Developing methods to use biocrusts in restoration is becoming more important as land use and climate change impact the health and intactness of high‐stress ecosystems. Methods of cultivation to maximize the production of biocrusts for use in restoration activities are necessary because salvage opportunities are limited. Our objective for this research was to determine an optimal method for scalable biocrust cultivation. We tested two Field and one Greenhouse cultivation methods. The Field cultivation methods had a base layer of weed cloth, soil and irrigation with either (1) shade cloth immediately over the surface (Quesadilla method) or (2) with shade cloth over a 1 m tall hoophouse (Hoophouse method). The Greenhouse method had nested basins with water wicking up to the soil surface and biocrust from below, with shade cloth attached to basins. We crossed these methods with the addition of native soil or sand and with and without a base of jute using salvaged biocrusts from the Sonoran Desert. All methods led to at least doubling biocrust cover in 11 weeks. The Greenhouse method led to the highest cover of cyanobacteria and mosses, whereas the field Quesadilla method and the addition of native soil in all cultivation methods led to higher abundance of lichens. There were interactions of cultivation method and soil type, with Greenhouse cultivation and native soil promoting the highest cyanobacteria cover and chlorophyll a. We measured exopolysaccharide sheaths (EPS) in native soil and all cultivation conditions, finding no differences for tightly bound sheath fractions, but higher quantities of the loosely bound EPS in the Greenhouse. We also quantified native and non‐native plants in cultivation, finding few plants in Greenhouse cultivation, but high abundance in both Field methods, and particularly with native soil and without jute for native plants. Practical implication: Together, these results demonstrate that all three cultivation methods are successful for bulking biocrust materials for restoration, and preference should be given to the method that is the easiest and most accessible for practitioners.

Towards an Inclusive Village: Literacy and Education for People with Disabilities Through the Development of Grape Planting Techniques (Vitis Vinifera L) Taman Ayu Village

People with disabilities are identical to people who are disabled, weak, stupid and backward. People with disabilities are no longer seen as problematic people, by providing equal access and being inclusive for everyone in their society (168 169). Equal roles for people with disabilities are an important issue for the government. Recognition of equal rights for groups with disabilities, both in terms of education, employment opportunities and others. Community service activities carried out by Herdiana, et al. in Taman Ayu village, in 2023 became the main basis for empowering people with disabilities and knowledge for people with disabilities, especially in the equality garden by involving groups with disabilities. Taman Ayu Village, Gerung District, West Lombok Regency, West Nusa Tenggara (NTB) in the "Equality Garden" group consisting of 15 people consisting of people with hearing and speech impairments which was carried out in June-December 2024 with the community service implementation team being a collaboration of 3 fields of science, namely agribusiness, accounting and agroecotechnology and involving 3 students from different study programs (fields of science). The purpose of this activity is to provide literacy and education about grape cultivation techniques, improve grape cultivation technique skills, financial management in business through ongoing training and mentoring. The forms of activities include literacy counseling and education for people with disabilities in grape cultivation techniques (Vitis Vinifera L), business management training and financial recording management, mentoring and coaching in marketing using digital marketing (marketplace: Facebook, Shopie, Tokopedia) and mentoring in submitting business legality. The hope of this activity is that groups with disabilities have skills in the field of grape cultivation, skills in management and financial recording of businesses so that from this activity a new business can be formed so that the goal of this activity is the independence of the disabled group's business. Collaboration between the service team (academics) and the village in the form of ongoing mentoring and coaching will be carried out until they have an independent business

Enhancing Capsicum Cultivation under Polyhouse, Shadenet House and Open Field Conditions with Drip Fertigation

Capsicum cultivation is a highly challenging task in open field conditions because of the extreme climatic conditions and poor input delivery system. Hence, the protected cultivation of capsicum is catching up. The present study evaluates the comparative performance of polyhouse, shadenet house and opens field conditions on the biometric, yield, fruit quality and economics of capsicum using drip and fertigation system. The study also determines the optimum dose of irrigation water and fertilizer application using drip irrigation methods under different protected cultivation structures. The study was conducted at Precision Farming Development Centre, IIT Kharagpur, for two consecutive years during 2022 and 2023. The irrigation water requirement of capsicum under polyhouse, shadenet house and open field conditions was estimated using FAO-56 Penman Monteith approach. When compared to open field cultivation, drip irrigated capsicum requires approximately 35.2% less water under polyhouse conditions and 25.5% less under shade net houses. The study also found that biometric parameters, yield and quality of capsicum are superior under polyhouse in comparison to the capsicum grown under shadenet and in open field conditions. Polyhouse treatments, particularly 100% RDF with 80% WR, demonstrated superior biometric parameters, quality metrics, and water productivity compared to other treatments. Capsicum grown under shadenet house conditions with 120% RDF with 80% WR also showed enhanced yield and quality over open field conditions. Economic analysis revealed that polyhouse cultivation, despite higher initial costs, yielded the highest net profit and benefit-cost ratio, followed by shadenet house and open field conditions. These findings underscore the importance of controlled environments in improving capsicum production and economic returns, highlighting the potential of polyhouses and shadenet houses in optimizing crop performance and resource use efficiency.

Estimating impacts of land cover change on erosion in a data-scarce catchment: Bot River, South Africa

ABSTRACT Rainfall intensity and land use changes and from natural vegetation to cultivated fields both impact on river streamflows and sediment dynamics. Assessing the magnitude of these flow and sediment changes is important for water management. However, many rivers are still under-studied/monitored and data sparse. Fully distributed rainfall–runoff models, such as the Jena Adaptable Modelling System (JAMS/J2000), allow for simulation of streamflow, its flow components and potential sediment yield given land use and hydrological changes. This study demonstrates the use of this method in the Bot River, a data-scarce catchment in South Africa. A hydrological model was implemented, and sediment yield was estimated under three land use and two hydrological flow component scenarios. The model reported Nash-Sutcliffe efficiencies (E2) of 0.64 and 0.32 (for streamflow) for model calibration and validation periods, respectively. Modelled mean annual sediment yield increased from 423 t/km2/year in 1990 to 490 t/km2/year in 2018, attributable to land use changes.

Effect of Land Cover Variations on the Fertility Status of Soils of Umuhu in Ngor-Okpala Area of Imo State

The study was conducted to ascertain the effect of four different land covers (cassava cultivated field (CCF), oil palm plantation (OPP), plantain plantation (PP) and forest land (FL)) on the fertility status of soils of Umuhu in Ngor-Okpala area of Imo State, Nigeria. Random sampling technique was used in the collection of soil samples from the four different land covers. The sampling was done at the beginning, middle and end of each land cover. Twelve (12) composite samples were collected from all the land cover types with 3 per land cover. The composite samples were prepared for routine laboratory analyses. Data generated were analyzed statistically using analysis of variance. The textural classes of all the sampled soils were of loamy sand. The soil which had plantain plantation as its cover had the highest pH (6.4), Total N (0.229 %), Soil organic matter 4.70%, Available P (27.05 mg kg-1), Exch. Ca (6.492 cmolc kg-1), Exch. Mg (3.942 cmolc kg-1), Exch. K (0.953 cmolc kg-1), Exch. Na (0.06 cmolc kg-1), Exch. H (1.2 cmolc kg-1) and CEC (28.4 cmolc kg-1) with its Exch. Al in trace amount (<0.001 cmolc kg-1). The soil under CCF, despite being under low cover, did not show much degeneration due to the shifting cultivation being practiced in the study location. However, the result obtained from the study indicated that the different land covers especially that under plantain plantation (PP) have affected the soils fertility at different rates. This observed factor is strongly controlled by high content of organic materials, a dense vegetative cover which mitigates erosion effects and the addition of ash as a means of fertilizing the soils under plantain plantation being practiced in the study area.

Cost Economics Study of Tomato Production under Poly House and Open Field Cultivation

The studies was performed by conducting the field experiments under polyhouse and open field at the Instructional Farm of Department of Irrigation and Drainage Engineering, Dr.Annasaheb Shinde College of Agricultural Engineering and Technology, Mahatma Phule Krishi Vidyapeeth, Rahuri during rabi seasons of 2013-14.These experiments state that the best practice found in different environmental conditions (Polyhouse and open field cultivation.) can be adopted for maximum economic returns from tomato cultivation. Polyhouse tomato cultivation was found best alternative tomato cultivation during rabi season to obtain maximum yield, net return and benefit:cost ratio. The combitation of 0.95ETc x 125 % RD (I1x F1) recorded maximum yield (437.98 tha-1) under polyhouse cultivation and (149.98 tha-1)under open field cultivation. The maximum net income was found due to T1 (0.95ETc x 125 %RD) treatment i.e. ₹ 2,95,210/- under polyhouse cultivation and in case of open field cultivation the maximum net income was found ₹ 5,527/- and benefit:cost ratio was found 3.29 under polyhouse and 1.13 under open field cultivation.

Analysis of the Causes and Countermeasures of Classroom Silence Phenomenon among Students in Contemporary Chinese Colleges and Universities

The college classroom is an important field for talent cultivation and student development in colleges and universities. However, in actual teaching, only a relatively small number of Chinese college students are able to actively participate in classroom activities and speak positively. Most students often choose to remain silent in response to teachers' questions. Classroom silence is generally categorized into negative silence and positive silence. Negative silence has become a major obstacle to improving the efficiency of classroom teaching, which to some extent affects the effectiveness and function of classroom teaching. By analyzing classroom silence, a common phenomenon in Chinese university classrooms, and analyzing the phenomenon of classroom silence and its causes from the perspectives of teachers' teaching and students' learning, we can better understand the characteristics of college students' classroom participation, reveal the deficiencies of teachers' classroom teaching, further propose strategies to improve classroom teaching and reduce the phenomenon of negative silence in college classrooms, and improve the effectiveness of college classroom teaching.

Mixed cropping of Medicago ruthenica-Bromus inermis exhibits higher yield and quality advantages in the Longxi loess plateau region of Northwest China

Medicago ruthenica is a promising leguminous forage crop due to its lack of saponins, which prevents bloat in livestock from excessive consumption. Legume/grass mixed cropping is an effective forage planting method widely used in agricultural and pastoral regions. However, there is a lack of research on using legume-grass mixed cropping to establish perennial, high-yield, and high-quality cultivated grasslands in the Longxi Loess Plateau. This study conducted a legume/grass intercropping experiment in the Longxi Loess Plateau region of northwestern China, using Medicago ruthenica and Bromus inermis. Experimental plots were established in 2021, with field sampling and laboratory analysis starting in 2022 and 2023, respectively. The research aimed to investigate the effects of intercropping Medicago ruthenica with Bromus inermis on forage yield and quality, and to determine the optimal intercropping ratios. The experiment tested various intercropping ratios of Medicago ruthenica and Bromus inermis in the fall (2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2), with sole crops of each species serving as controls. Results showed that, in the second and third years of mixed cropping, the forage yield under mixed cropping treatments was significantly higher than that of Medicago ruthenica and Bromus inermis monoculture, with increases of 40.89–70.88% and 13.97–38.22% in the second year, and 131.91–199.13% and 44.06–85.82% in the third year. When the legume proportion in the mixed cropping system was around 30%, competition between the two forages reached equilibrium, demonstrating the benefits of mixed cropping. The crude protein and ether extract content of mixed forage were significantly higher than those of monoculture, while the neutral detergent fiber and acid detergent fiber contents were significantly lower, indicating a higher feeding value for the mixed forage. The legume proportion was a key factor influencing the yield of mixed forage. In conclusion, a mixed planting ratio of Medicago ruthenica and Bromus inermis at 3:7 resulted in higher yield and nutritional quality, making it an optimal ratio for establishing cultivated forage fields in the Longxi Loess Plateau.

Dietary Shift in a Barn Owl (Tyto alba) Population Following Partial Abandonment of Cultivated Fields (Central Apennine Hills, Italy).

While most studies focused on the impact of intensive agriculture on the barn owl's diet, little is known about the effect of cropland abandonment. We compared the taxon composition/evenness and feeding guild structure of small mammal prey identified in pellets collected before (2004) and after (2012) the abandonment of 9% of cultivated fields within a cultural landscape. Data on prey abundance per pellet were analysed through non-metric multidimensional scaling and permutational, paired tests. Prey taxon evenness in 2012 was significantly lower than in 2004. That induced a shift in prey taxon composition as indicated by the significantly lower dietary similarity compared with the random expectation. The increasing and declining abundance of Murinae and Crocidurinae, respectively, had the largest contribution to the differentiation of the diet spectrum. Insectivorous prey was significantly more abundant in 2004 compared to 2012, while the opposite was true for omnivorous prey. Our results suggest that even a small fraction of abandoned crops in the landscape might induce a detectable shift in the barn owl's food niche. The dietary effects are similar to those observed after agricultural intensification, that is, an increase in the abundance of generalists to the detriment of specialist mammal prey.

Isolation of Monocrotophos degrading bacterial consortium from agricultural soil for in vivo analysis of pesticide degradation.

Extensive Monocrotophos (MCP) application in agricultural soils has led to its ubiquitous accumulation in the environment. Human health can be adversely affected by chronic exposure to produce and water from such areas, causing endocrine dysfunction, birth defects, blood and nervous disorders. This study investigated the possibility of detecting Monocrotophos-degrading bacteria in soil samples taken from a cotton cultivation field in a local area. We isolated a consortium that could tolerate and neutralize Monocrotophos upto a concentration of 2000 ppm. The consortium on 16S rRNA sequencing were identified as Micrococcus luteus SBR2, Rhodococcus SBR5, Bacillus aryabhattai SBR8, Ochrobactrum intermedium SBK2. Significant tolerance of individual strains in the range of 500-5000 ppm was observed when incubating them in vitro with Monocrotophos in minimal salt medium. An analysis of the degrading genes opdA, mpd, and opd revealed plasmid borne opdA and mpd in the O.intermedium strain and B.aryabhattai strain. All the strains indicated genomic opdA and mpd whereas opd was not detected in plasmid or genomic DNA. The HPLC showed no peak at 2.5min, when individual strains were incubated with Monocrotophos. The HPLC analysis of soil samples incubated with the consortium for two weeks showed complete degradation of Monocrotophos. GC-MS analysis confirmed that Monocrotophos and its solvent cyclohexamide were degraded into non-toxic compounds such as cyclotrisiloxane compounds, acetic acid, and others. This study indicates that the expression of organophosphate hydrolyzing enzymes in the consortium can greatly contribute to the neutralization of organophosphorus compounds and also serve as a bioremediation method for agricultural soils.

Transient dispersion of settling gyrotactic microorganisms in an open channel flow

Dispersion of microorganisms is a key issue in bio-physics and has many applications in the fields of algae cultivation, biomass energy, and wetland ecology. However, there has been limited exploration of the effects of settling behavior and initial release conditions on the transient dispersion of gyrotactic microorganisms. This paper explores the transient dispersion of settling gyrotactic microorganisms in an open channel flow. The moment equations derived from the Smoluchowski equation are solved by the biorthogonal expansion method, and the results are compared with random walk simulations, showing good agreement. The time variations of concentration distribution, drift velocity, and dispersivity of settling gyrotactic microorganism suspension are explored in detail under typical initial release conditions. As illustrated and characterized, settlement weakens the gravitactic focusing of microorganisms near the free surface, leads to accumulation at the bottom, and increases the dispersivity; from a line source release, the relaxation time is shortest, and the microorganisms scatter fastest in the longitudinal direction, while the point source at the water surface leads to the most concentrated longitudinal distribution and the highest drift velocity; furthermore, the initial release condition assumes an important role in shaping the concentration distribution and drift velocity.