Effect Of Rotation Research Articles

Green Manure Rotation Combined with Biochar Application Improves Yield and Economic Stability of Continuous Cropping of Peppers in Southwest China

Crop rotation is widely recognized as a key strategy to mitigate the adverse effects associated with continuous cropping. Recent studies have demonstrated that biochar has a significant potential for preventing and controlling these challenges. However, the ameliorative effects of green manure rotation and biochar application on continuous pepper cultivation in the karst mountainous regions of Southwest China remain largely unexplored. To address this gap, a field experiment was conducted from 2020 to 2023 to investigate the effects of green manure rotation and biochar application on the continuous cropping of peppers. The experiment consisted of five treatments: CK (no green manure and no biochar), WP (winter fallow and conventional pepper production with chemical fertilization), GP (green manure and pepper rotation, the amount of fresh green manure returned to the field was about 15 t·ha−1), WP + B (winter fallow and pepper rotation with 1500 kg·ha−1 of biochar applied during the pepper season), and GP + B (green manure and pepper rotation with 1500 kg·ha−1 of biochar applied during the pepper season, the amount of fresh green manure returned to the field was about 15 t·ha−1). The results showed that all the improved measures (GP, WP + B, GP + B) increased the yield of fresh pepper and dry pepper by 26.97–72.98% and 20.96–65.70%, respectively, and the yield of dry pod pepper increased by 14.69–40.63% and 21.44–73.29% in 2021 to 2023, respectively, and significantly improved the yield stability and sustainability of continuous cropping of peppers compared with WP treatments. In addition, green manure rotation or biochar application alone or in combination enhanced the nutritional quality of pepper fruits by increasing the content of free amino acids (8.62–19.42%), reducing sugars (15.30–34.62%) and vitamin C (26.19–43.52), and decreasing the nitrate content (26.93–40.17%). Furthermore, the application of green manure rotation or biochar alone or in combination significantly improved the absorption of nitrogen (23.73–60.23%), phosphorus (18.12–61.71%), and potassium (20.57–61.48%) nutrients in the continuous cropping of peppers, which contributed to the improvement of fertilizer use efficiency. Notably, GP + B treatment not only improved the yield and quality of continuous cropping peppers but also resulted in higher production value and net income compared to the GP and WP + B treatments. In conclusion, the combination of green manure rotation and biochar application represents an effective strategy for mitigating the challenges of continuous cropping in pepper cultivation within the karst mountainous regions of Southwest China.

Post-traumatic osteoarthritic-mediated changes in condylar shape do not covary with changes in the internal microstructure of the bone

Post-traumatic osteoarthritis (PTOA) in the temporomandibular joint (TMJ) is associated with remodeling of the subchondral bone. This remodeling changes both the external appearance of the condylar bone and the internal bony microstructure. The external geometry can be quantified using shape, a multivariate mathematical measurement that contains all of the structure's geometric information with location, scale, and rotation effects removed. There is an important gap in knowledge related to how TMJ PTOA affects the shape of the mandible and if the external shape covaries with the internal bony microstructure. To evaluate these gaps, TMJ PTOA was induced in male and female skeletally mature mice using a surgical destabilization procedure. After four weeks, tissues were collected and characterized using a high-resolution μCT scanner. Shape was calculated from surface reconstructions of the mandibular condyle, and the internal bony microstructure was characterized by the region of interest including the subchondral trabeculae. The covariance of shape with and without corrections for allometric scaling and internal bony microstructure was calculated using a Procrustes ANOVA. The data illustrate that PTOA significantly alters the shape of the condyle in a sex-independent manner. PTOA does alter some aspects of the internal bony microstructure in a sex-dependent manner. Allometric scaling was a significant factor in the variance of shape. Shape including the effects of allometric scaling significantly covaries with some internal bony microstructure variables in both sexes. Shape scaled to remove the effects of allometric scaling does not covary with internal bony microstructure in either sex. These findings indicate that PTOA progression is associated with changes in the size and shape of the condyle but variance in trabecular bone remodeling is only associated with size related shape change. Thus, the allostatic response of subchondral bone is multimodal, coordinating two independent biological processes controlling size and shape. Since subchondral bone participates in and guides the progression of PTOA, these findings have implications for identifying select and specific mechanisms contributing to the progression and pathophysiology of the PTOA in the TMJ.

Effect of Gypsum, Cover Crop, and Crop Rotation on Bulk Density and Aggregate Properties of Soils

ABSTRACT Soybean production, worldwide, typically involves full tillage resulting in much less biomass than other crops, leading to decreased soil organic matter and increased soil degradation. The goal of this study was to evaluate the potential benefits of an innovative management system that includes the combinations of no-till, crop rotation, cover crop, and gypsum application on continuous soybean production. The response of soil physical properties, i.e. bulk density and water-stable aggregates, was evaluated across a range of soil types and climatic conditions. Treatments consisted of comparing (1) continuous soybean to a soybean-corn and corn-soybean rotation, (2) cereal rye [Secale cereale (L.)] cover crop to no cover crop, and (3) gypsum surface‐applied at 0, 1.1, and 2.2 Mg ha−1. The study was replicated at four different sites in the United States, including Shorter (AL), Farmland (IN), Hoytville (OH), and Piketon (OH). At the end of the 5-year study, soil bulk density and aggregate stability were determined. Soil bulk density and water-stable aggregates were unaffected by gypsum addition regardless of the location. Including cereal rye as a winter cover increased soil aggregation and bulk density at the Hoytville location only. Rotating the soybeans with corn (compared to continuous soybeans) resulted in soil aggregation and bulk density improvements at all research locations. Results indicated that soybean production that included crop rotation into management system improved soil aggregate stability, whereas cover crop benefits were less effective and amending the soil with gypsum did not significantly affect these soil properties.

Effects of crop rotation on plant- and microbial-derived carbon within particulate and mineral fractions in paddy soils

Paddy soil is an important soil organic carbon (SOC) sink, and particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) are distinct components of SOC concerning their formation and function. However, the contributions of plant- (lignin phenols) and microbial- (amino sugars) derived C within the POC and MAOC fractions of SOC under various paddy field rotation systems have not yet been documented. Thus, we conducted an 8-year field experiment encompassing four distinct crop rotation systems: wheat-rice (W-R), rapeseed-rice (R-R), Chinese milk vetch-rice (A-R), and A-R with a 20 % reduction in nitrogen fertilizer (A-R-N). From 2017–2023, crop rotation improved the concentration of amino sugars (AS) in POC and the lignin phenols (VSC) in MAOC. Compared to the beginning of the experiment, the W-R significantly improved the SOC stock at 0–20 cm by 84.1 % by promoting the formation of POC (69.5 %) and MAOC (101.5 %) in 2023. W-R increased the content and proportion of AS in POC, as well as the content of VSC compared with the other treatments. Nevertheless, rice yield does not increase synergistically with SOC. On average, W-R had the lowest rice yield and decreased rice yield by 9.2 %, 2.8 %, and 5.6 % compared to R-R, A-R, and A-R-N, respectively. However, the annual yield of W-R was 9.7 %, 62.6 %, and 57.9 % higher than that of R-R, A-R, and A-R-N, respectively. Our findings highlight that incorporating rapeseed and Chinese milk vetch can increase next-stubble rice yield slightly but is not conducive to carbon sequestration in rice fields, and wheat-rice is a promising cropping system for sustaining SOC sequestration and crop production.

Pengaruh E-learning, Knowledge Sharing, dan Job Rotation Terhadap Kinerja Karyawan dengan Pengembangan Diri sebagai Variabel Intervening [Studi pada Generasi Z di Kota Semarang

The study aims to analyze the effect of e-learning, knowledge sharing and job rotation on the performance of generation Z employees in Semarang City mediated by self-development. This research is quantitative type using PLS-SEM data analysis technique with SmartPLS 3.2.9 software. The results of this study prove that: (1) E-learning affects employee performance; (2) Knowledge sharing has no effect on employee performance; (3) Job rotation has no effect on employee performance; (4) Self-development affects employee performance; (5) E-learning affects self-development; (6) Knowledge sharing has no effect on self-development; (7) Job rotation affects self-development; (8) Self-development mediates e-learning on employee performance; (9) Self-development does not mediate knowledge sharing on employee performance; (10) Self-development does not mediate job rotation on employee performance.

Influence of Particle Rotation on the Shear Characteristics of Calcareous-Sand and Silica-Bead Granular Materials

The shear strength and resistance of granular materials are critical indicators in geotechnical engineering and infrastructure construction. Both sliding and rotation influence the energy evolution of soil granular motion during shear. To examine the effects of particle rotation on shear damage and energy evolution in granular systems, we first describe the transformation of irregularly shaped particles into regular shapes via geometrical parameters, ensuring the invariance of energy density and density. We then analyze the impact of particle rotation on shear-stress variation and energy dissipation through a shear energy evolution equation. Additionally, we establish the relationship between the shear-stress ratio and normal stress, considering particle rotation. Finally, we verify the influence of particle rotation on energy evolution and shear damage through shear tests on irregular calcareous sand and regular silica-bead particles. The results indicate that granular materials do not fully comply with the Coulomb strength criterion. In the initial shear stage, most of the external work is converted into granular rotational-shear energy, whereas in the later stage, it primarily shifts to granular sliding-shear energy. Notably, the sensitivity of the granular rotational energy to a vertical load is significantly greater than that of the granular sliding energy.

Analytic insight into the physics of standing accretion shock instability. I. Shock instability in a non-rotating stellar core

During the core collapse of a massive star, and immediately before its supernova explosion, there is amplification of asymmetric motions by the standing accretion shock instability (SASI). This imprints a frequency signature on the neutrino flux and the gravitational waves that carries direct information about the explosion process. The physical interpretation of this multi-messenger signature requires a detailed understanding of the instability mechanism. We carried out a perturbative analysis to characterise the properties of SASI and assess the effect of the region of neutronization above the surface of the proto-neutron star. We compared the eigenfrequencies of the most unstable modes to those obtained in an adiabatic approximation where neutrino interactions are neglected above the neutrinosphere. We solved the differential system analytically using a Wronskian method and approximated it asymptotically for a large shock radius. The oscillation period of SASI is well fitted with a simple analytic function of the shock radius, the radius of maximum deceleration, and the mass of the proto-neutron star. The oscillation period is weakly dependent on the parameterised cooling function, but this latter does affects the SASI growth rate. We describe the general properties of SASI eigenmodes using an adiabatic model. In this approximation, the eigenvalue problem is formulated as a self-forced oscillator. The forcing agent is the radial advection of baroclinic vorticity perturbations and entropy perturbations produced by the shock oscillation. We reduced the differential system defining the eigenfrequencies to a single integral equation. Its analytical approximation sheds light on the radially extended character of the region of advective-acoustic coupling. The simplicity of this adiabatic formalism opens new perspectives for the investigation of the effect of stellar rotation and non-adiabatic processes on SASI.

Design and Simulation of Flat Plate Collector With a Tube Rotation and Phase Change Materials Sn3N4‐LiNO3‐KNO3/Boron‐Arsenide for Enhanced Efficiency

ABSTRACTSolar thermal energy is crucial in our transition to renewable energy sources. Recent studies have focused on enhancing the efficiency of solar collectors by minimizing thermal energy loss during absorption. A promising approach involves an innovative design that integrates phase change materials (PCMs) and rotating tubes to capture thermal energy more effectively. Advanced nitride‐based salt hydrates, with boron‐arsenide additives, enhance thermal performance of the collector. In a flat plate collector using composite PCMs, radiative heat loss decreases from 250 to 210 W (a 6% reduction) with tube rotation, while convective heat loss drops from 225 to 195 W (a 4% decrease). The decomposition rate of the novel PCMs is low, measuring only 0.5% at a maximum temperature of 850°C, with a specific heat capacity of up to 4.50 W/m K. This unique blend, including the Sn₃N₄‐LiNO₃‐KNO₃/boron arsenide mixture, enhances thermal conductivity by 30%, significantly improving thermal absorption rates. The exergy efficiency achieved with the Nano‐enhanced phase change materials (NEPCM) and tube rotation reaches an impressive 90%. With tube rotation at 3 rad/min, the flat plate collector's efficiency improves by 22%, reaching an overall efficiency of 90% at a fluid flow rate of 25 kg/h. Simulations using Anaconda Jupyter Notebook and Python validate the effectiveness of both tube rotation and NEPCM in enhancing collector efficiency.

Impact of spanwise rotation on flow separation and recovery behind a bulge in channel flows

Direct numerical simulations of spanwise-rotating turbulent channel flow with a parabolic bump on the bottom wall are employed to investigate the effects of rotation on flow separation. Four rotation rates, $Ro_b := 2\varOmega H/U_b = \pm 0.42$ , $\pm$ 1.0, are compared with the non-rotating scenario. The mild adverse pressure gradient induced by the lee side of the bump allows for a variable pressure-induced separation. The separation region is reduced (increased) when the bump is on the anti-cyclonic (cyclonic) side of the channel, compared with the non-rotating separation. The total drag is reduced in all rotating cases. Through several mechanisms, rotation alters the onset of separation, reattachment and wake recovery. The mean momentum deficit is found to be the key. A physical interpretation of the ratio between the system rotation and mean shear vorticity, $S:=\varOmega /\varOmega _s$ , provides the mechanisms regarding stability thresholds $S=-0.5$ and $-$ 1. The rotation effects are explained accordingly, with reference to the dynamics of several flow structures. For anti-cyclonic separation, particularly, the interaction between the Taylor–Görtler vortices and hairpin vortices of wall-bounded turbulence is proven to be responsible for the breakdown of the separating shear layer. A generalized argument is made regarding the essential role of near-wall deceleration and resultant ejection of enhanced hairpin vortices in destabilizing an anti-cyclonic flow. This mechanism is anticipated to have broad impacts on other applications in analogy to rotating shear flows, such as thermal convection and boundary layers over concave walls.

The Effect of U-Bend Zone, Rotation, and Corrugation on Two-Pass Channel Flow

Abstract Further consideration on the two-pass channel flow is still necessary due to the complexity of 180-deg turn, rotation, and wall ribs. Numerical investigations have repeatedly revealed differences from experiments, with the primary focus of the smooth walls. Thus, this work deals with newly added ribs and three-equation variant of the shear stress transport (SST) k–ω model to the current fluid flow and heat transfer depending on an existing experiment as a reference. The adapted turbulence model thought to be more susceptible to U-bend zone, rotation, and wall corrugation is applied using comsolmultiphysics program. A two-pass profile with leafy characteristics, derived from a prior work by the first author, is implemented for the first time and contrasted against alternative corrugation designs. The findings demonstrated that applying the suggested model reduces the percentage error between the computational and experimental data to less than 20%. The Nusselt numbers computed at different leafy-corrugated channel divisions are augmented to 30% with 70% surface temperature reduction; however, the friction penalty rises too.

Effect of rotation on wake vortices in stratified flow

Stratified wakes past an isolated conical seamount are simulated at a Froude number of $Fr = 0.15$ and Rossby numbers of $Ro = 0.15$ , 0.75 and $\infty$ . The wakes exhibit a Kármán vortex street, unlike their unstratified, non-rotating counterpart. Vortex structures are studied in terms of large-scale global modes, as well as spatially localised vortex evolution, with a focus on rotation effects. The global modes are extracted by spectral proper orthogonal decomposition (SPOD). For all three studied $Ro$ ranging from mesoscale, submesoscale and non-rotating cases, the frequency of the SPOD modes at different heights remains coupled as a global constant. However, the shape of the SPOD modes changes from slanted ‘tongues’ at zero rotation ( $Ro=\infty$ ) to tall hill-height columns at strong rotation ( $Ro=0.15$ ). A novel method for vortex centre tracking shows that, in all three cases, the vortices at different heights advect uniformly at approximately $0.9U_{\infty }$ beyond the near wake, consistent with the lack of variability of the global modes. Under system rotation, cyclonic vortices and anticyclonic vortices (AVs) present considerable asymmetry, especially at $Ro = 0.75$ . The vorticity distribution as well as the stability of AVs are tracked downstream using statistics conditioned to the identified vortex centres. At $Ro=0.75$ , intense AVs with relative vorticity up to $\omega _z/f_{c}=-2.4$ (where $\omega_z$ is the vertical vorticity and $f_c$ is the Coriolis frequency) are seen with small regions of instability and they maintain large $\omega _z/f_{c}$ magnitude in the far wake. Recent stability analysis that accounts for stratification and viscosity is found to improve on earlier criteria and show that these intense AVs are stable.

Effects of cotton peanut rotation on crop yield soil nutrients and microbial diversity

Background and Aims Cotton-peanut rotation is a sustainable farming practice that enhances land utilization and promotes the sustainable development of agriculture. Crop rotation can reduce the occurrence of pests and diseases, as different crops have varying levels of resistance to such threats. Additionally, by alternating the types of crops grown, the soil environment is changed, which can lead to the elimination of favorable conditions for pathogens and pests, thereby alleviating the impact of these issues. Furthermore, cotton-peanut rotation can improve soil fertility.To investigate the effects of different crop rotation systems on crop yield, soil nutrients, and soil microbial communities. Methods: Using high-throughput sequencing technology, investigate the soil microbial diversity in the root zone after cotton-peanut rotation.Various planting patterns, including cotton continuous cropping (MC), peanut continuous cropping (HC), peanut-cotton-peanut rotation (HR), and fallow (X), were established to assess variations in crop yield, soil nutrients, and soil microbial diversity. Results: Significant differences were observed in crop yield, soil nutrients, and soil microbial community structure among different planting patterns. The HR system significantly increased the output compared with the HC and MC systems. Additionally, HR exhibited significantly lower total nitrogen (N) and basic nitrogen (BN) contents than HC and MC, whereas MC showed lower total potassium (K) and available potassium (AK) contents. HR led to a decrease in soil bacterial diversity but an increase in fungal diversity, with Ascomycota and Mortierellomycota being dominant. Various bacteria (Chloroflexi, Bacteroidota, and Actinobacteriota) associated with organic matter degradation and nutrient cycling were found across different planting systems, enhancing material cycling efficiency. Furthermore, Planctomycetota bacteria related to crop nutrient synthesis and Glomeromycota bacteria aiding plant nutrient absorption were significantly higher in the MC system than in the HR or HC systems. Redundancy analysis indicated a significant negative correlation between crop rotation and soil fungal community, whereas Ascomycota exhibited a significant negative correlation with organic matter.Conclusion: Peanut-cotton rotation can mitigate soil nutrient loss, enhance beneficial microorganism diversity, suppress harmful bacterial populations, stabilize ecosystems, and boost crop yield.

Agroecological estimation of the effect of crop rotation and mineral fertilizers on productivity and quality of spring barley grain in the Central Blackearth region of Russia

The purpose of the current study was to determine the effect of crop rotations and doses of mineral fertilizers on productivity, grain quality of spring barley and fertility of typical chernozem in the Central Сhernozem Region (CBR). The study was conducted in a multifactorial trial located on the watershed plateau of the research and production department No. 2 of the Federal Agricultural Kursk Research Center in 2018 and 2022. The soil of the experimental plot was typical medium-loamy chernozem, with 5.9 % of humus. There have been studied such factors as grain-fallow-row and grain-grass-row crop rotations; with fertilizer doses and no fertilizers, N30Р30К30, N60Р60К60. The highest biological productivity of spring barley up to 5.99 t/ha was identified in the grain-fallow-row crop rotation with the dose of N60Р60К60. However, the presence of perennial leguminous grasses in the grain-grass-row crop rotation contributed to a smaller decrease in humus, the maximum loss of which in it was 0.14 %, which was 0.02 % lower than in the grain-fallow-row crop rotation. The trends of agroecological effect of crop rotations and mineral fertilizers on the indicators of spring barley grain production were estimated with a digital method, namely the Harrington desirability function. There has been established an “acceptable, satisfactory” effect of crop rotations and mineral fertilizers on the studied indicators (di = 0.50), but in relation to individual indicators of grain production, the level of effect of crop rotations varies significantly from di = 0.12 “completely unacceptable” to di = 0.83 “most acceptable”. The ecological properties of crop rotation are manifested in the estimation of its effect on the humus content in the soil: “acceptable, satisfactory” (di = 0.38–0.52). The comprehensive estimation of the effect of mineral fertilizers for most indicators has increased proportionally to their dose, reaching di = 0.49–0.65, which indicates their “acceptable, satisfactory” effect.

CFD analysis of rotation effect on flow patterns and heat transfer enhancement in a horizontal spiral tube heat exchanger

This study explores the enhanced thermal performance of heat exchangers utilizing spirally coiled tubes, particularly in applications such as heating saltwater in solar desalination plants, which require elevated heat transfer coefficients. A numerical investigation is conducted to assess the impact of mechanically rotating horizontal spiral tubes on flow patterns and temperature profiles along their length. A detailed physical model was developed using COMSOL Multiphysics software. The findings from computational fluid dynamics simulations indicate that mechanical rotation significantly modifies both velocity and temperature gradients at each cross-section of the tube. This rotation effectively reduces the formation of thermal hotspots in the outer regions, thereby improving and accelerating heat dispersion. Notably, substantial variations in velocity and temperature profiles occur at rotation speeds up to 4 rpm; however, these changes diminish beyond this speed threshold. The study reveals that rotation increases the Nusselt number of the heated flow within the tube by over 145 %. Furthermore, the effects of rotation are more pronounced in smaller diameter tubes compared to larger ones. Ultimately, the performance factor indicates that the benefits of enhanced heat transfer outweigh the increased pressure drops associated with tube rotation, validating the effectiveness of the proposed heating system.

Turbulent convection in rotating slender cells

Turbulent convection in the interiors of the Sun and the Earth occurs at high Rayleigh numbers $Ra$ , low Prandtl numbers $Pr$ , and different levels of rotation rates. To understand the combined effects better, we study rotating turbulent convection for $Pr = 0.021$ (for which some laboratory data corresponding to liquid metals are available), and varying Rossby numbers $Ro$ , using direct numerical simulations in a slender cylinder of aspect ratio 0.1; this confinement allows us to attain high enough Rayleigh numbers. We are motivated by the earlier finding in the absence of rotation that heat transport at high enough $Ra$ is similar between confined and extended domains. We make comparisons with higher aspect ratio data where possible. We study the effects of rotation on the global transport of heat and momentum as well as flow structures (a) for increasing rotation at a few fixed values of $Ra$ , and (b) for increasing $Ra$ (up to $10^{10}$ ) at the fixed, low Ekman number $1.45 \times 10^{-6}$ . We compare the results with those from unity $Pr$ simulations for the same range of $Ra$ and $Ro$ , and with the non-rotating case over the same range of $Ra$ and low $Pr$ . We find that the effects of rotation diminish with increasing $Ra$ . These results and comparison studies suggest that for high enough $Ra$ , rotation alters convective flows in a similar manner for small and large aspect ratios, so useful insights on the effects of high thermal forcing on convection can be obtained by considering slender domains.

Rice Production and Nitrogen Use Efficiency by Diverse Forms of Fertilization in Rice-Based Crop Rotation Systems

The rising demand for climate change mitigation has brought attention to agricultural systems focused on carbon farming and reducing emissions. Composting food wastes and livestock manure not only mitigates environmental concerns but also boosts soil fertility and crop yields as an alternative fertilizer. In this experiment, we investigated the effects of different fertilizer types (chemical and organic waste compost) and crop rotations (rice–fallow, rice–Italian ryegrass, and rice–potato) on rice production, nitrogen use efficiency, and soil carbon stocks. In this experiment, soil carbon and nitrogen retention were more influenced by compost nutrient levels than by crop rotation types. Overall, as the nitrogen levels increased, the rice yields improved with both chemical and organic waste fertilizers. Among the crop rotations, the rice–Italian ryegrass rotation showed a higher nitrogen use efficiency. Optimal fertility levels, balancing nitrogen use efficiency, yield, and soil carbon were observed between 523 and 582 kg N ha−1 when combined with specific crop rotations. Moreover, soil total carbon and soil total nitrogen varied among crop rotation systems. Our results indicate that organic waste compost can be a potential alternative to chemical fertilizers, while crop rotations offer a viable approach for maximizing the environmental benefits.

Crop rotation and fungicides impact microbial biomass, diversity and enzyme activities in the wheat rhizosphere

Sustainable crop production systems should promote large and diverse soil microbial communities to enhance biological soil processes rather than depend solely on chemical interventions that include pesticide applications. Crop rotation increases above-ground temporal diversity which, relative to monoculture, usually increases soil microbial diversity. But comparisons between short and long crop rotations that also include pesticide effects are rare. A 5-yr (2013-2017) field study was conducted to investigate crop rotation and fungicide effects on the soil microbiome and activity. There were nine rotations, with or without fungicide applications, that included four 2-yr rotations (wheat preceded by canola, barley, pea, or flax), four 3-yr rotations where barley or canola were added to the 2-yr rotations, and one rotation where canola and wheat were stacked (canola-canola-wheat-wheat). In 2017, soil microbial biomass, composition, diversity and enzyme activities were measured in the rhizosphere of the final wheat crop in each rotation. Fungicides reduced fungal richness (the number of different fungal taxa) in the wheat rhizosphere (e.g., Chao1 indices of 64.0 vs. 79.9) especially in 2-yr rotations, but rotation length/type and the crops that preceded wheat had different effects on different taxa. Two of the three most predominant prokaryotic phyla, Proteobacteriota and Actinobacteriota, responded differently to rotation length: 3-yr rotations enriched the former (27.4% vs. 20.1% relative abundances), but 2-yr rotations enriched the latter (19.9% vs. 28.3% relative abundances). Relative to oilseed crops preceding the sampled wheat, a field pea preceding crop enriched Actinobacteriota (31.7% vs. 24.8% relative abundances) and the most abundant fungal class, Sordariomycetes (39.1% vs. 22.1% relative abundances), in addition to increasing microbial biomass carbon (MBC) and arylsulphatase activity by 33% and 57%, respectively. Correlations of the relative abundances of fungal or prokaryotic genera with β-glucosidase and arylsulphatase activities were similar (both positive or negative), but they were the opposite of correlations with acid phosphomonoesterase, suggesting a close link between C and S cycling. Besides the nutrient cycling implications of these soil microbial characteristics, there is need to study their biological disease control significance.

Effects of rotation and chemical reactions on an electroconvection in Maxwell dielectric nanofluids within anisotropic porous media

ABSTRACT This study explores the complex interactions between rotation, chemical reactions, and electroconvection in Maxwell dielectric nanofluids within anisotropic porous media. The research aims to elucidate how these factors influence the heat transfer efficiency and fluid dynamics under the influence of external alternating current (AC) electric fields. The normal mode method is employed to analyse the stability of the system, allowing for the examination of oscillatory modes and their growth rates. By introducing perturbations in the physical parameters, the study derives a set of ordinary linear differential equations that characterize the system's response to external influences. The coupled differential equations were solved using the Galerkin approach for first approximation while meeting the necessary boundary conditions. Analytical solution of the representative equation for stress-free boundary states yields Rayleigh number formulas for nonoscillatory and oscillatory mode occur. Oscillatory modes are seen for both bottom and top-heavy nanoparticle distributions. The electric Rayleigh number, thermal Prandtl number, and stress relaxation parameter increases, whereas the Brinkman-Darcy number delays the onset of stationary and oscillatory convection. The study finds that positive concentration Rayleigh numbers stabilize the system, while negative ones lead to instability. Additionally, it demonstrates that external alternating current electric fields influence convection behavior and provides formulas for critical Rayleigh numbers, enhancing our understanding of fluid interactions in various engineering and technological applications.

Microbial Basis for Suppression of Soil-Borne Disease in Crop Rotation.

The effect of crop rotation on soil-borne diseases is a representative case of plant-soil feedback in the sense that plant disease resistance is influenced by soils with different cultivation histories. This study examined the microbial mechanisms inducing the differences in the clubroot (caused by Plasmodiophora brassicae pathogen) damage of Chinese cabbage (Brassica rapa subsp. pekinensis) after the cultivation of different preceding crops. It addresses two key questions in crop rotation: changes in the soil bacterial community induced by the cultivation of different plants and the microbial mechanisms responsible for the disease-suppressive capacity of Chinese cabbage. Twenty preceding crops from different plant families showed significant differences in the disease damage, pathogen density, and bacterial community composition of the host plant. Structural equation modelling revealed that the relative abundance of four key bacterial orders in Chinese cabbage roots can explain 85% and 70% of the total variation in pathogen density and disease damage, respectively. Notably, the relative dominance of Bacillales and Rhizobiales, which have a trade-off relationship, exhibited predominant effects on pathogen density and disease damage. The disease-suppressive soil legacy effects of preceding crops are reflected in compositional changes in key bacterial orders, which are intensified by the bacterial community network.

Modeling the Effect of Milk Vetch-Rice Rotation on N Runoff Loss in the Middle and Lower Reaches of the Yangtze River.

The winter planting of green manure (GM) is widely used in South China to reduce chemical nitrogen (N) fertilizer use, improve soil fertility, and maintain rice yields, but its effect on N runoff loss in paddy fields remains unclear. This study combines multi-site field experiments with a process model (WHCNS-Rice) to assess how GM with reduced N fertilizer impacts N runoff loss and its forms in the Yangtze River's middle and lower reaches, considering different rainfall years. The network field experiments included four treatments: conventional fertilization (FR), conventional fertilization plus straw return (FRS), GM with a 40% N reduction (MR), and GM-straw combined return with a 40% N reduction (MRS). Monitoring the results showed that compared to the winter fallow treatment, the GM treatments reduced the peak and average total N (TN) concentrations by 11.1-57.9% (average 26.9%) and 17.1-27.3% (average 22.3%), respectively. The TN runoff loss under the GM treatment decreased by 3.50-10.61 kg N ha-1 (22.5-42.1%). GM primarily reduced the runoff loss of dissolved inorganic N (DIN), with reductions at different sites ranging from 0.22 to 9.66 kg N ha-1 (8.4-43.4%), indicating GM effectively decreases N runoff by reducing DIN. Model simulations of ponding water depth, runoff, TN concentration in surface water, and TN loss in paddy fields produced the consistency indices and simulation efficiencies of 0.738-0.985, 0.737-0.986, 0.912-0.986, and 0.674-0.972, respectively, indicating that the model can be used to evaluate water consumption and N runoff loss in the GM-paddy system. The simulations showed that GM with a 40% N fertilizer significantly reduced N runoff loss under all rainfall conditions, with the greatest reductions in wet years. Under wet, normal, and dry conditions, the GM treatments significantly reduced average TN loss by 0.37-5.53 kg N ha-1 (12.77-29.17%), 0.21-5.32 kg N ha-1 (9.95-24.51%), and 0.02-3.2 kg N ha-1 (1.78-23.19%), respectively, compared to the winter fallow treatment. These results indicate that the combination of GM and a 40% reduction in N fertilizer can significantly reduce N runoff loss from paddy fields, demonstrating good effectiveness under various rainfall conditions, making it a green production model worth promoting.