Temperature Amplitude Research Articles

Temporal variability in water content, temperature, and electrical conductivity of sandy soil: Responses to soil-improving cropping systems (SICS)

There is little information on the effect of soil-improving cropping systems (SICS) on the temporal variability of soil volumetric water content (WC), temperature (T), soil temperature amplitude (A_T), and electrical conductivity (EC) in low-quality sandy soils although they are increasingly being used in agriculture. The objective of this study was to determine the effects of the following SICS: liming (L), leguminous catch crops for green manure (LU), farmyard manure (M), and liming + leguminous catch crops for green manure + farmyard manure together (LLUM), and the control (C) on temporal changes in the three properties simultaneously in a field experiment on sandy soil established in 2016 in Poland. The monitoring was performed using TEROS 12 sensors in the soil layers of 5–10, 20–25, and 30–35 cm from 25 April 2019–30 April 2020 with spring wheat as the main crop. The results showed that the average WC over the entire investigation period in the 5–10 cm layer was 0.206 m3 m–3 in the control and increased in the L, LU, M, and LLUM variants to 0.245, 0.219, 0.241, 0.262 m3 m–3, respectively. The highest WC was recorded in the LLUM system during most of the investigation period. The average T in the 5–10 cm layer increased in L, LU, and M by 0.221–0.262 °C and in LLUM by 0.052 °C. The average monthly soil temperature amplitudes in the soil layer 5–10 cm tended to be higher under all SICS vs. C except LLUM vs. C. The average EC in the 5–10 cm layer in variant C (0.066 mS cm–1) increased in the L, LU, M, and LLUM systems to 0.067, 0.090, 0.151, and 0.107 mS cm–1, respectively. The shapes of the temporal variability of WC and EC were similar in all SICSs, while the increase in the response to the combined effects of the SICSs and precipitation during the growing season was greater for the EC. The temporal variability of all soil properties in response to the SICSs and weather course and their averages declined with depth. The amplitudes of soil T in all treatments were lowest in the 30–35 cm layer. This study provides helpful information for the selection of the most suitable SICS in terms of soil properties influencing productivity and other soil functions.

Analyzing cutting force and vibration amplitude in high-speed milling of SKD11 steel with thermal assistance

In the realm of machining, the optimization of cutting conditions stands as a paramount pursuit for enhancing both efficiency and precision. This study embarks on a pioneering investigation delving into the intricate interplay among workpiece temperature, Thermal-Assisted High-Speed Machining (TA-HSM), cutting force dynamics, and vibration amplitudes during the milling process of SKD11 steel. Beyond a mere exploration, this research endeavors to unveil not only the impact of temperature and velocity on machining dynamics but also to delineate regions characterized by elevated temperature and velocity that exhibit the potential to mitigate cutting forces and vibrations, thereby refining machining methodologies. Experimental inquiries encompassing diverse temperature regimes, coupled with variations in cutting speeds, offer valuable insights into the nexus among temperature, cutting force and vibration amplitude. Of particular significance are the high-speed milling trials conducted under the most elevated admissible support temperature, which furnish elucidation on the ramifications of high speeds on cutting forces and vibrations. This inquiry constitutes a substantive contribution to the field by elucidating the correlation between cutting force and vibration amplitude under the thermal influence and high-speed milling within thermally demanding environments. Moreover, this study extends practical utility by proffering actionable insights into the optimal temperature range and cutting speeds requisite for effecting desired enhancements in machining productivity. By discerning and delineating these optimal parameters, this research endeavors to furnish tangible guidelines for practitioners seeking to optimize their machining processes, thus fostering advancements in both efficiency and precision within the machining domain.

Study of Structural Seismic Damage Considering Seasonal Frozen Soil–Structure Interaction

Frozen soil may cause structures to have different damage statuses, as revealed by earthquakes in northeastern China. ABAQUS (2019), a numerical simulation software application, was adopted to systematically and deeply study the structural seismic response, considering seasonal frozen soil–structure interaction under different ground motion intensities and soil ambient temperatures. The results showed firstly that the variation in soil ambient temperature had a great influence on the seismic response of the structure, as indicated by the damage status of the structure obtained through numerical simulation. Secondly, through further analysis of the numerical simulation results, the influence amplitude of different soil temperatures on the structural seismic response was quantitatively analyzed and systematically summarized. Finally, the structural seismic damage with negative ambient temperature could be significantly lower than that with positive temperature normally. Additionally, such an internal change mechanism was also objectively analyzed to verify the reliability of the conclusion.

Longevity of subtidal mussel beds (Mytilus edulis) in eutrophic coastal areas

Mussel populations (Mytilus edulis) around the coasts of Europe and the North Atlantic are often ephemeral and have notably experienced a large decline in abundance. Since 1993, annual blue mussel stock surveys have been carried out in the Limfjorden, Denmark. We used the stock survey data combined with electronic monitoring fishing data and Mechanistic Models for the Limfjorden, providing environmental data to investigate the impact of various stressors. Multiple factors were found to affect the longevity of subtidal mussel beds in Limfjorden. Predation by starfish, fishing activities, shell length of the mussels, amplitude in summer temperature and consecutive days of oxygen depletion decreased the longevity of the beds. Conversely, increased biomass, multiple cohorts and increasing water depth demonstrate stabilising effects. Water column stratification had both a negative and positive impact on bed longevity depending on the duration. These analyses can help inform environmental, conservation, and fisheries managers on the long-term trends of population dynamics and gain a deeper understanding of what factors can affect mussel bed longevity in the context of declining stocks.

Projection of mean and extreme precipitation and air temperature over India: a CMIP6 analysis

ABSTRACT This study used 15 Coupled Model Intercomparison Project Phase 6 (CMIP6) models to analyze the mean and extreme projection precipitation during the Indian summer monsoon (ISM) season, i.e., June to September (JJAS). A continuous rise in precipitation and its associated unpredictability were predicted by global climate models using the CMIP6. The extreme values are estimated on the basis of generalized extreme value (GEV) distribution. Four socioeconomic paths are used as SSP126, SSP245, SSP370 and SSP585 to understand the impact of low-emission to high-emission scenarios. In all the scenarios, it is seen that all the models predict a significant rise in JJAS mean and extreme precipitation. Moreover, a strong correlation is obtained between the historical (1995–2014) and near-emission future simulation (2021–2040), mid-emission future simulation (2041–2060), high-emission future simulations (2081–2100) of air temperature and precipitation. In extreme emission scenarios, ensemble mean of CMIP6 models shows an increasing amplitude in surface air temperature and precipitation over India in the near future (2021–2040), mid future (2041–2060) and the end of the century (2081–2100). The CMIP6 simulations mainly support the results of all models, but they also demonstrate improved robustness across models.

Non-uniformity of fluctuation characteristics inside an edge magnetic island in Heliotron J

Non-uniform fluctuation characteristics are observed within an edge magnetic island in Heliotron J. The island possesses a long connection length comparable to the confined region. These fluctuations are measured using a Langmuir probe. The island’s presence is confirmed through the plasma response, observed in the modulation amplitude of electron temperature and its phase delay relative to the heat source in a heat modulation experiment. Within the island, the electron density is notably high, accompanied by distinct profiles of electron temperature and electric field, likely attributable to the magnetic island. Contrary to expectations, density fluctuations within the edge magnetic island are not locally minimized, despite the reduced gradient of the profile within the island. Statistical analysis shows a suppression of intermittent transport inside the island, while intermittent fluctuations increase towards the exterior. A further analysis to segregate turbulence-driving and spreading factors reveals that both turbulence-driven and spreading contributions are comparably significant inside the island. Additionally, the non-uniform turbulence results in a spatially structured fluctuation-driven particle flux. Overall, the experimental findings indicate that fluctuation characteristics exhibit notable non-uniformity both inside and near the island. This non-uniformity potentially complicates heat transport and may lead to three-dimensional, asymmetric transport within and at the periphery of the islands.

A novel oscillatory thermal response test method for efficient characterization of ground thermal properties: Methodology and data analysis

This study presents a novel thermal response testing (TRT) approach to minimize test duration, labor, and associated costs. The proposed method, Oscillatory Thermal Response Test (OTRT), employs an oscillating heat flux using a sinusoidal wave with specific frequency and amplitude characteristics. A custom-designed TRT apparatus was developed to regulate the heating injection pattern for precise control. In Sapporo City, Hokkaido Prefecture, and Kai City, Yamanashi Prefecture, Japan, two in-situ OTRTs were conducted. The temperature profiles of the fluid and undisturbed soil were measured through optical fiber cables integrated within the U-tube legs. A novel analytical method was devised to filter, smooth, and fit the recorded data, enabling the determination of the response temperature amplitudes at the borehole inlet and outlet. Also, the temperature time derivative method calculates the effective thermal conductivity in the early 3 h. Comparative analysis with Normal Thermal Response Tests (NTRTs) demonstrated the accuracy and validity of the OTRT approach. Significant conclusions from this study include a remarkable reduction in TRT duration by over 95 %, with a high accuracy of 92 % achieved using only the first 3 h of testing. The proposed method exhibited a Root Mean Square Error (RMSE) of 0.1 W/(m·K) compared to NTRTs. To establish a strong correlation between the Amplitude Ratio and Effective Thermal Conductivity, further experimental studies are essential to address the limitations of the current study. These studies should explore a variety of geological and hydrological conditions, borehole diameters, type of heat exchanger, diameter of U-tubem grouting material, combined with numerical analysis, to enhance our understanding of this relationship.

Experimental study and multi‐scale refinement model of high damping acrylic polymer matrix VEDs for civil structural seismic retrofit

AbstractThe viscoelastic dampers (VEDs), which can provide both stiffness and damping, have been recently introduced into the field of structural vibration control for seismic enhancement of civil engineering structures. In this study, a kind of high damping acrylic polymer matrix VEDs (HDPVED) is developed independently, and this innovative HDPVED can solve the significant problem of service performance under medium‐high temperature environments, as well as low‐frequency vibration control under earthquake actions for civil engineering structures. To systematically investigate the influencing rules of frequency, temperature, and displacement amplitude on the mechanical properties and damping dissipation performance of HDPVEDs, a series of dynamic mechanical performance tests of the developed HDPVEDs are carried out at different frequencies, temperatures, and displacement amplitudes. The research results show that HDPVED exhibits excellent damping dissipation capability and adaptability under medium‐high temperature environments and low‐frequency excitations. The mechanical properties and energy dissipation performance present a strong correlation with frequency, temperature and displacement amplitude, and there is an obvious coupling effect between the three influencing factors. Based on the macroscopic mechanical property research of HDPVED, the microscopic damping mechanism and microscopic mechanical properties of HDPVED are then investigated. High‐order fractional derivative fraction Voigt and Maxwell model in parallel (FVMP) models are preferred to characterize the combined hyper‐elasticity and viscoelasticity owned by networked molecular chains and free molecular chains. The breaking and reconstruction theory of microphysical bonds is used to assess the effect of packing particles, and the time‐temperature equivalence principle is introduced to assess the effect of temperature. The multi‐scale refinement model is proposed, and the validity and accuracy of this model are verified by testing data of HDPVED. The study results show that the proposed model can accurately describe the effects of frequency, temperature, displacement amplitude, and microstructure on the multi‐scale mechanical properties of HDPVED. It provides a theoretical basis for the multi‐scale design and development of high damping VEDs.

Divergent controlling factors of freeze–thaw-induced changes in dissolved organic carbon and microbial biomass carbon between topsoil and subsoil of cold alpine grasslands

Freeze-thaw (FT) processes in cold regions significantly influence the mineralization and sequestration of soil organic carbon (SOC), particularly in its active pools, such as dissolved organic carbon (DOC) and microbial biomass carbon (MBC). However, manipulation experiments often amplify the effects of natural FT processes and overlook soils below 20 cm depth. To investigate carbon responses to seasonal FT events across soil depths (0–80 cm) and identify controlling factors, field sampling was conducted before freezing and after thawing in alpine grassland soils on the Qinghai-Tibet Plateau. Results are as follows: 1) After soil thawing, the entire soil profile showed insignificant changes in SOC (−4.46%) and MBC (3.21%), but DOC (45.27%) and DOC/SOC (160.08%) increased significantly, and strong associations were observed in DOC changes between adjacent soil layers. 2) FT indicators (number and temperature amplitude of daily FT cycles, frozen temperature, and frozen days) influenced SOC changes differently in the topsoil (0–10 cm) and subsoil (20–30 cm). Contrary to the impact of frozen temperature, other FT indicators largely facilitated the production of DOC0–10 and DOC20–30. The effects of FT indicators on MBC were nonlinear. 3) Structural equation models indicated that average soil water governed FT-induced changes in both DOC0–10 and DOC20–30. The varying effects of porosity and pH from topsoil to subsoil, along with the weakening relationship between changes in DOC and MBC, favored a stronger increase in DOC20–30. Increases in soil water and DOC after thawing stimulated the increment of MBC0–10, while porosity (positively) and sand content (negatively) regulated the MBC20–30 change. It indicates that, influenced by soil structure and biogeochemical environment, DOC and MBC in grassland soils are more sensitive to natural FT processes than SOC. Nevertheless, changes in FT patterns due to long-term climate change may cumulatively affect SOC.

Consistency assessment of latent heat flux and observational datasets over the Amazon basin

The Amazon basin plays a crucial role in the global hydrological cycle and the climate system. Removal of latent heat from the surface covered by the tropical forest through evapotranspiration is a key process that still requires further research due to the complex nature of the involved processes, lack of observations and different model assumptions. Here we present an assessment of the consistency between different latent heat fluxes datasets through an indirect comparison against the daily amplitude of surface temperature and vegetation status estimated from satellite observations. Our study is based on the hypothesis that the observational satellite data can be used to provide hints on how realistically fluxes are represented in different datasets. Results evidence that datasets diverge inside the basin in both space and time, but it is possible to figure out areas under water-limited conditions, especially around the borders of the basin and some regions over eastern/southeastern Amazonia. In despite of these differences, a clear link between daily amplitude of surface temperature, leaf area index and latent heat flux can be observed over particular areas and seasons, where also correlations reach values closer to −0.98 (0.94) for surface temperature (leaf area index) indicating that satellite observations are suitable for assessing the representation of the partitioning of energy fluxes in models and widely used datasets.

The quest for CMB signatures of conformal cyclic cosmology

Circles of low-variance and Hawking points in the Cosmic Microwave Background (CMB), resulting from black hole mergers and black hole evaporation, respectively, in a previous cycle of the universe, have been predicted as possible evidence for the Conformal Cyclic Cosmology model (CCC) introduced by R. Penrose. We present a high-resolution search for such low-variance circles in the Planck and WMAP CMB data, and introduce HawkingNet, our machine learning open-source software based on a ResNet18 algorithm, to search for Hawking points in the CMB.We find that spots consisting of a few unusually bright (high-temperature) or dark (low-temperature) pixels, erroneously lead to regions with many low-variance circles, and consequently sets of near-concentric low-variance circles, when applying the search criteria used in previous work [1]. After removing those spots from the data, no statistically significant low-variance circles can be found.Concerning Hawking points, also no statistically significant evidence is found when using a Gaussian temperature amplitude model over ∼ 1° opening angle and after accounting for spots of unusual brightness.That the unusual spots in the data are themselves remnants of Hawking points is not supported by low-variance and/or low-temperature circles around them.The absence of such statistically-significant distinct features in the currently available CMB data does not disprove the CCC model, but implies that higher resolution CMB data and/or refined CCC based predictions are needed to pursue the search for CCC signatures further.

Mitophagy Regulates the Circadian Rhythms by Degrading NR1D1 in Simulated Microgravity and Isolation Environments.

Long-term spaceflight is known to induce disruptions in circadian rhythms, which are driven by a central pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus, but the underlying molecular mechanisms remain unclear. Here, we developed a rat model that simulated microgravity and isolation environments through tail suspension and isolation (TSI). We found that the TSI environment imposed circadian disruptions to the core body temperature, heart rate, and locomotor-activity rhythms of rats, especially in the amplitude of these rhythms. In TSI model rats' SCNs, the core circadian gene NR1D1 showed higher protein but not mRNA levels along with decreased BMAL1 levels, which indicated that NR1D1 could be regulated through post-translational regulation. The autophagosome marker LC3 could directly bind to NR1D1 via the LC3-interacting region (LIR) motifs and induce the degradation of NR1D1 in a mitophagy-dependent manner. Defects in mitophagy led to the reversal of NR1D1 degradation, thereby suppressing the expression of BMAL1. Mitophagy deficiency and subsequent mitochondrial dysfunction were observed in the SCN of TSI models. Urolithin A (UA), a mitophagy activator, demonstrated an ability to enhance the amplitude of core body temperature, heart rate, and locomotor-activity rhythms by prompting mitophagy induction to degrade NR1D1. Cumulatively, our results demonstrate that mitophagy exerts circadian control by regulating NR1D1 degradation, revealing mitophagy as a potential target for long-term spaceflight as well as diseases with SCN circadian disruption.

A century-long tendency of change in surface air temperature on the territory of Ukraine

A century-long tendency of change in surface air temperature on the territory of Ukraine

Green Roofs on Shipping Containers: How Substrate Thickness Affects Thermal Performance

Green roofs have become a popular sustainable solution in urban areas, and in recent years, shipping containers have gained popularity as a sustainable alternative for housing. A promising proposal is to combine these two solutions. This research aims to analyze the thermal behavior of experimental modules of scale constructions. Four modules were constructed with different substrate thicknesses (4, 6, 8, and 12 cm) to verify the impact on thermal behavior and provide guidance for this technology. Additionally, another module was built without a green roof for control purposes. The indoor and outdoor air temperatures and humidities, soil moistures, and temperatures between green roof layers were recorded in a tropical climate in summer. The behavior was similar between the different thicknesses for the whole period but with significant differences in the indoor temperature amplitudes (13.8 °C for the thinner substrate, 9.7 °C for the thicker one, and 38.7 °C for the bare roof). This study also revealed considerable heat conduction between the side walls and the slab, which resulted in an upward heat flow to the substrate during a day with a clear sky, which is the opposite of what is observed in conventional roofs. During the night and rainy periods, temperatures tend to become closer between the roof’s layers when the substrate dissipates the energy absorbed throughout the day.

Model-based prediction of frost formation inside frozen food packages under temperature fluctuations

Abstract Frozen storage of food products is widely accepted not only in the industry but also by households. Frost formation during long-term storage is recognized as a phenomenon that causes changes in product characteristics and quality losses. However, quantitative prediction and control of frost formation remains a challenge. In this study, a mathematical model was developed to predict frost formation inside frozen food products (i.e., frozen minced meat packed in a polyvinylidene chloride (PVDC) film) under fluctuating temperature conditions in a domestic refrigerator. The proposed model is based on heat transfer and energy balance equations, and the amount of frost formation is estimated from the heat generated by condensation. The heat transfer coefficients were experimentally obtained and applied to the developed model. The interactions between the amplitude and frequency of temperature fluctuations and the corresponding amount of frost formation were visualized using contour plots. Both the amplitude and frequency were found to increase frost formation. For the range of fluctuations tested (temperature amplitudes of 0.5–2.5 K and cooling rates of 0.0125–0.2 K/min when connected to the compressor), the simulation predicted that the amount of frost in the packages varied up to approximately 4.5 times (0.48–2.18 g/month for packages containing 300 g of minced meat) depending on the different temperature fluctuation settings.

Flow structure and cooling effect of seeping gas film in supersonic turbulent boundary layer

Seeping gas film cooling is an active cooling method that involves injecting a cooling gas film into the boundary layer through porous media. In this study, a sintered wire mesh porous material is used to generate the gas film through seepage flow. The flow of the gas film in the supersonic turbulent boundary layer is observed using nanometer particle plane laser scattering technology, while the temperature distribution of the porous wall surface is measured by infrared thermometry. It is observed that as the injection rate of the gas film exceeds 0.2 %, the supersonic turbulent boundary layer thickens significantly. The rate of thickness growth is promoted from 5.5 % to 17.1 % as the injection rate increases from 0.3 % to 0.8 %. Additionally, the injection of the gas film induces an oblique shock wave, and the shock angle increases with the enhancement of the injection rate, resulting in an uneven cooling effect along the injector length. The transient cooling efficiency of the seeping gas film under thermal non-equilibrium conditions is analyzed. The results indicate that the temperature amplitude on the porous wall surface decreases significantly when the injection rate is promoted from 0.2 % to 0.3 %. However, continuing to increase the coolant injection rate does not lead to a more significant improvement in cooling efficiency. When the injection rate reaches 0.5 %, the relative cooling efficiency reaches 50 %–60 %, which is much lower than the predicted values of the thin film theory.

Daily temperature fluctuation interacts with the mean temperature to increase the toxicity of a pyrethroid insecticide in a moth

Climate change complicates ecotoxicology studies because species responses to pesticides depend on temperature. Classically illustrated by the effect of constant laboratory temperatures, a recent review revealed that the toxicity of pesticides is also often increased by daily temperature fluctuations. Here, we investigated the combined effects of daily temperature fluctuation and mean temperature on the toxicity of two insecticides in the moth Spodoptera littoralis. Our study tested the toxicity of chlorpyrifos and deltamethrin on larvae of six experimental groups that crossed three treatments of daily temperature fluctuations (0, 5 or 10 °C) and two treatments of mean temperatures (25 or 33 °C). We showed that daily temperature fluctuation increased larval mortality induced by chlorpyrifos and deltamethrin. However, the response differed between the organophosphorus insecticide chlorpyrifos and the pyrethroid insecticide deltamethrin. The increase in chlorpyrifos toxicity by daily temperature fluctuation did not differ between mean temperatures of 25 and 33 °C. Remarkably, the increase in deltamethrin toxicity by daily temperature fluctuation was dependent on the crossed effects of the amplitude of daily fluctuation and mean temperature. This increase in deltamethrin toxicity occurred with a daily fluctuation of only 5 °C for larvae reared at 25 °C and a daily fluctuation of 10 °C in larvae reared at 33 °C. To confidently quantify the responses of insecticide toxicity to temperature, future ecotoxicology studies will have to evaluate the generality of the interaction between the effects of daily temperature fluctuation and mean temperature.

Distribution patterns and driving factors of mixed-ploidy Actinidia species in China

Polyploidization is an important driver for species formation and adaptive evolution, which results in mixed-ploidy species in the nature, i.e., one species contains at least two cytotypes. Understanding the driving factors of mixed-ploidy species offer unique insights into unraveling the evolutionary mechanisms of polyploid species. Here we investigated the distribution patterns and driving factors of 40 Actinidia species in China. Polyploid Actinidia species formed from whole-genome duplication (WGD). Actinidia species showed a mosaic geographic pattern. The potential range of mixed-ploidy Actinidia species is significantly larger than diploid and polyploid species, with higher ecological amplitude of longitude, latitude and elevation. Mixed-ploidy species showed wider temperature and water niches than diploid and polyploid species, and the tolerate capacity of mixed-ploidy species to climate extremes increased with ploidy diversity. Polyploid Actinidia species occupied niches of high altitude, low temperature and drought, supporting the niche shift hypothesis to explain the survival of polyploids. Ploidy diversity and mixed-ploidy effect was positively correlated with the ecological amplitude of temperature. Our results support that the formation and distribution of polyploidy species are associated with climate factors and adaptation capacity to abiotic stresses, and highlight the importance of mixed-ploidy species in the species formation and adaptive evolution.

Funiculitis causing sepsis-associated laminitis in a Mangalarga Marcha-dor gelding

Castration is one of the most common surgical procedures performed in equine practice, and potential complications may range from mild to life-threatening condi-tions. This paper aims to report clinical and la-boratory features, treatment, and long-term follow-up infor-mation in a case of fu-niculitis causing sepsis-associated laminitis and acute renal failure (ARF) in a Mangalarga Marchador gelding. A 5-years-old Mangalarga Marchador gelding was referred for hospital care after seven days of an open orchiectomy approach on farm-setting. Physical exami-nation revealed hypere-mic mucous mem-branes, dehydration, tachycardia, scrotal swelling with a foul-smelling serousangui-nous discharge, in-creased hoof tempera-ture and digital pulse amplitude, and lame-ness. Laboratory find-ings included leukocy-tosis by neutrophilia, hypoalbuminemia, high creatinine, and urea levels, and an increased number of bacteria, leukocytes, and hyaline cylinders on urine anal-ysis. After three days of intensive care, the horse underwent gen-eral anesthesia for scro-tal ablation and resec-tion of the infected spermatic cord stumps. Microbiological assays revealed Streptococcus spp. and a multi-resistant Escherichia coli. This report high-lights uncommon post-castration complications in a Mangalarga Marchador gelding as a consequence of septic funiculitis. Further-more, the microbiologi-cal isolation of a multi-resistant E. coli strain raises concerns about the indiscriminate use of antibiotics in equine practice.

Elucidating waterhemp (Amaranthus tuberculatus) suppression from cereal rye cover crop biomass

AbstractCereal rye (Secale cereale L.) as a cover crop can be an effective nonchemical tool for waterhemp [Amaranthus tuberculatus (Moq.) Sauer] suppression in crop production. Previous studies have evaluated A. tuberculatus suppression by cereal rye as part of weed management programs but have not investigated the underlying mechanism of suppression by the cover crop. This study aimed to investigate the effect of cereal rye biomass on A. tuberculatus emergence and development, and on soil environmental parameters (temperature, moisture, and light transmittance) that are key triggers of A. tuberculatus germination to elucidate the mechanism of suppression by the cover crop. A dose–response study was conducted under field conditions in Brooklyn and Janesville, WI, from 2021 to 2023. Cereal rye biomass from a fall-planted field was harvested at anthesis in the spring and dried to constant weight at 60 C to provide 0.0, 0.6, 1.2, 2.4, 4.8, 7.2, 9.6, and 12.0 Mg ha−1 of dry biomass that was evenly distributed over 1.9 m−2 plots. Increasing cereal rye biomass reduced A. tuberculatus height, biomass, and density. An average ED50 of 5.2 Mg ha−1 of biomass was needed to reduce A. tuberculatus density by 50%. Low levels of biomass (≤2.38 Mg ha−1) augmented A. tuberculatus density due to an increase in soil moisture underneath the mulch compared with bare soil. Cereal rye biomass decreased the amount of sunlight reaching the soil, which resulted in lower mean soil temperature and temperature amplitude throughout the day (9.3 and 2.7 C temperature amplitude at 0 and 12.0 Mg ha−1, respectively). Prevention of A. tuberculatus germination by this thermal effect is likely the main mechanism of A. tuberculatus suppression from the cereal rye cover crop. Our results support biomass from cereal rye cover crop effectively suppressing A. tuberculatus and contributing to the integrated management of A. tuberculatus.