Quadratic Parabola Research Articles

Systematic-ecological estimation of seasonal activity of dehydrogenase in drained swamp soils of interstream of Ob and Tom

Drained peat soils (Histosols) were studied. In the mode of weak and moderate drainage, the trend of seasonal fluctuations (quadratic parabola) shows a weekly average increase in dehydrogenase activity with a weekly average deceleration, in the intensive mode – a weekly average deceleration with a weekly acceleration for June–October. A reliable nonlinear relationship of enzyme activity was revealed: positive – with redox potential and pH, multidirectional – with soil bulk moisture and soil temperature. According to canonical analysis, the discussed set cumulatively determines the seasonal dehydrogenase activity by 50–81%. The hydrological regime is statistically proved as a dominant factor. A negative conjugate interaction of dehydrogenase and peroxidase activity has been established, confirming their participation in the biochemical transformation of organic matter as a whole.

EHD simulation study on the influence of measured ICE compression piston ring profiles on the lubrication film formation

In this simulation-based research, the authors investigate the influence of the contacting profile and its tilting orientation of original compression piston rings on their hydrodynamic properties in internal combustion engines (ICEs). They employ a systematic approach, detailing the computational framework and simulation parameters. Three different original piston rings belonged to the same engine are used for the simulation and corresponding experimental validation in this publication. Results and discussions highlight the directional dependence of hydrodynamic conditions, with distinct differences for individual rings. Original smoothed profiles are compared with substitute geometries like quadratic parabola and circular arc fits. The research contributes insights into the complex dynamics of compression rings in ICEs, providing a foundation for optimizing ring profiles for enhanced hydrodynamic properties.

Experimental and Analytical Study on Shear Lag Effect of T-Shaped Reinforced Concrete Shear Walls

Because of the flanges on T-shaped shear walls (TSSWs), the shear force acting on such walls results in a shear lag effect, making it impossible to forecast with accuracy the normal stresses of the flanges using the Bernoulli–Euler assumption. Shear lag (SL) in flanged walls has, however, received less attention from researchers, particularly in experimental studies. Understanding the SL in T-shaped reinforced concrete shear walls under shear and axial force is the main goal of this work. First, a SL model is suggested for TSSWs. In this model, the SL deflection is considered to be the generalized displacement and the SL warping deformation, and it is assumed to be a quadratic nonlinear function. Then, experimental and numerical simulation studies are, respectively, conducted to investigate SL effect of TSSWs, and also to evaluate the accuracy of the SL method. Finally, the parameter analysis is conducted to investigate the influence of axial load, shear force, and flange length on the SL effect of TSSWs. The results show that the SL of the TSSW is significant, the normal stress distribution (NSD) of the flange is uneven, and the normal stresses near the web are higher, according to the results of the analytical, simulated, and experimental results. The SL model can accurately predict the normal stresses of the flange of TSSWs, and the quadratic parabola assumption of the SL warp displacement of TSSWs is reasonable. Parameter analysis shows that axial force has little effect on the SL effect of TSSWs. The TSSWs under larger shear force have the more obvious SL effect. A more obvious SL effect occurs in the TSSWs with longer flanges.

Experimental Study and Influencing Factors Analysis of the Electric Gear Urea Pump Supply Performance

Abstract An experimental study on four electric gear urea pumps was carried out, and the variation rules of supply flow rate, speed, and volumetric efficiency of the urea pumps were obtained. Test results show that the volumetric efficiency will be affected by the coupling of multiple factors simultaneously, showing complex nonlinearity. A simulation model whose accuracy was verified by test data was established for analyzing the influencing factors of supply performance. With the increase in speed, the variation of volumetric efficiency has a linear relationship with the change of radial clearance and a quadratic parabola relationship with the change of axial clearance. In the range of working speed, the influence of radial clearance on volumetric efficiency is more significant, while the influence of axial clearance on volumetric efficiency will be gradually enhanced with increasing speed. The radial tolerance range should be as small as possible to ensure the consistency of the urea pump’s volumetric efficiency.

Simulation analysis of 3D stability of a landslide with a locking segment: a case study of the Tizicao landslide in Maoxian County, southwest China

Abstract. Rock bridges, also known as locking masses in landslides, affect the three-dimensional (3D) stability and deformation patterns of landslides. However, it is always difficult to simulate rock bridges with continuous grid models in 3D landslides due to their discontinuous deformations. Tizicao landslide, located in Maoxian County, southwest China, is a typical landslide with a super-large rock mass volume of about 1388.2 × 104 m3 and a locking segment. To explore a better rock bridge model used to simulate 3D stability and deformations of the Tizicao landslide, this study introduced three rock bridge models into the FLAC3D program, including the intact rock mass model (IRMM), the Jennings model (JM), and the contact surface model with high strength parameters (CSM-HSP). The CSM-HSP model was eventually used in the FLAC3D program to obtain the 3D deformation characteristics of the landslide. In addition, the two-dimensional (2D) stability of the Tizicao landslide was analyzed using the GeoStudio program. The simulation results indicate that the Tizicao landslide is generally stable under current conditions owing to the existence of the locking segment in its southern front. This inference is consistent with the field deformation and monitoring data. It was found that the general stability and local deformations of the landslide are influenced by the locking segment according to the comparison between the 2D and 3D stability. There was a linear relationship between the locking ratio and the factor of safety (Fos), which applied to the 2D stability analysis of the landslides with a locking segment each, while there existed an approximate quadratic parabola suitable for the 3D stability of the landslides. Finally, this study analyzed the laws of the 3D Fos varying with the locking ratio and strength parameters of the locking masses and the sliding surface. Furthermore, it explored the advantages and disadvantages of the three rock bridge models in the simulation of the 3D stability of landslides with a locking segment.

INCREASING THE LEVEL OF ENVIRONMENTAL SAFETY OF PUMPING UNITS BY ENERGY SAVING DURING REGULATION

The relevance of improving calculation methods for pumping units of hydraulic systems in order to save energy and correspondingly increase their level of environmental safety is substantiated. To speed up hydraulic calculations and increase their accuracy, it is proposed to approximate the existing characteristics of centrifugal pumps, which are usually presented in the equipment passport in graphic form, with a quadratic parabola. The general equations for the analytical determination of the working point parameters, the construction of the pressure characteristics of the pump at a new rotation frequency and the formula for the geometric location of the tops of the pressure characteristics for different rotation frequencies of the impeller were obtained. It has been proven that with frequency control, the pump characteristic shifts equidistantly along the parabola of proportionality. In a similar way, the characteristics of the pump are affected by the casing of the impeller. An equation has been obtained that allows, without resorting to the grapho-analytical method, to calculate the change in the characteristics of the pump with a proportional change in all its dimensions and a constant frequency of rotation and the equation of the curve of similar modes. This curve is proposed to be called the similarity curve. It is shown that the velocity coefficient is a constant value along the polynomial curve. On the basis of the obtained results, a method of comparative analysis of the energy efficiency of the regulation of the pumping unit by changing the rotation frequency and proportionally changing all dimensions of the impeller is proposed. The application of the method is demonstrated on concrete examples. Achieving the highest efficiency of the pumping unit ensures the lowest energy consumption, thus minimizing emissions of harmful substances into the atmosphere. Keywords: environmental safety, efficiency, centrifugal pumps, flow regulation, hydraulic resistances, change of rotation frequency, laws of similarity, laws of proportionality

Influence of Early Freezing on the Pore Structure Characteristics of Concrete and Its Correlation with Mechanical Properties

Early freezing of concrete is common in the construction of water conservancy projects in northern China. Early freezing damage induces the deterioration of the mechanical properties of concrete structures, which seriously affects the safety, stability, and service life of engineering structures. Through a laboratory uniaxial compression test and a computed tomography (CT) test, the influence law of freezing time and freezing temperature on the mechanical properties of concrete is analyzed herein. The three-dimensional pore structure of concrete at different freezing times is reconstructed. The pore distribution and pore structure characteristic parameters of concrete at different freezing times are studied. The correlation between mechanical properties and the pore structure of early frozen concrete is determined. The results show that with the delay of freezing time, the porosity of concrete test blocks increases first and then decreases. The average pore surface area primarily decreases and then increases. The average pore diameter increases with the trend of a quadratic parabola. The average pore form factor primarily decreases, then increases, and then decreases. The average pore surface area has the best correlation with the compressive strength and elastic modulus of early frozen concrete. The outcomes suggest that the average pore surface area should be preferred when constructing the mesoscopic damage index of early frozen concrete. Relevant results provide support for revealing the macro and micro damage mechanisms of early frozen concrete.

Freeway crash risk prediction considering unobserved heterogeneity: A random effect negative binomial regression approach

Unobserved heterogeneity of crashes remains a significant issue for freeways that influence crash prediction, and therefore deserves much attention. Using a fusion data set of crash data, driving behavior data, and traffic flow data, this study explores the spatiotemporal heterogeneity of crash determinants for different freeway segments (e.g. Yixing section and Liyang section of Ning-Hang freeway of China) and then predict the crash probability. A random effect negative binomial regression model is built to investigate the contributing factors of the crashes. Remarkable differences are observed in the crash determinants for Yixing section (include average vehicle speed, hourly average traffic volume, average free speed, road segment length, and number of left lane-merging) and Liyang section (include average intensity of aggressive driving behavior, average kilometer traffic volume). The results found the traffic flow has a more significant impact on crashes than the driving behaviors. It is found that the crash probability is a monotone decreasing function when the predicted number of crash is 0. With the increase of the number of predicted crash, the crash probability gradually converges from a large value to 0. Then the probability of other predicted number of crashes (e.g. crash = 1, crash = 2, crash = 3) presents a quadratic parabola trends. The model comparison demonstrates that the proposed model outperforms conventional model, and the prediction performance for Liyang section is better than that of Yixing section. The research findings are interesting and important for preventing crashes.

Study on pore structure and the mechanical properties of sandstone-concrete binary under freeze–thaw environment

In China's cold region water conservancy and hydropower projects, the contact interface between the dam and the reservoir bank rock is prone to cracking under external loading and freeze–thaw action, which may lead to dam-bank failure and damage and cause engineering disasters. The NMR (Nuclear Magnetic Resonance) tests and uniaxial compression tests of concrete, sandstone, and sandstone-concrete composite after different numbers of freeze–thaw cycles were carried out to analyze the pore structure development and uniaxial compression mechanical properties of the three types of specimens under different numbers of freeze–thaw cycles. The results show that freeze–thaw cycling promotes the development of pores in sandstone and concrete, and sandstone is more sensitive to low-temperature freeze–thaw than concrete. The UCS (uniaxial compressive strength) of the sandstone-concrete binary changed in a V-shaped with the increase of the dip angle of the cemented interface, and the angle had no obvious effect on the microscopic pores. The freeze–thaw effect on the deterioration of the microscopic pore structure and mechanical properties of the sandstone-concrete binary has a similar effect pattern, in which the deterioration rate of porosity and compressive strength is faster in the early freeze–thaw period, slower in the middle period, and increases in the later period compared with the middle period, but the increase is smaller than that in the early period of freeze–thaw. In addition, the relationship between the porosity and UCS of the sandstone-concrete binary under the freeze–thaw cycle environment is a quadratic parabola.

Portray rail head surface crack 3D contour through image analysis and morphology reconstruction

Rail head spalling and fractures are strongly correlated with fatigue crack propagation. Fatigue cracks typically form along evolving surfaces, but their propagation paths are not accurately described by idealized semi-elliptical crack morphology. This study aims to capture the true three-dimensional shape of fatigue cracks during initiation and propagation. New mathematical and physical models, based on reconstructed 3D cracks, are proposed to predict rail crack propagation at various service stages. The analysis reveals that the crack propagation path in the 2D lateral rail section approximates a quadratic parabola or circular curve, and the 3D crack morphology is similar to a partial spherical surface with a curvature radius of approximately 18.5 mm. The three-dimensional crack morphology remains consistent within a small rail range. The reconstruction model proposed in this study can predict internal crack propagation on the rail head surface, assisting in track inspection, maintenance, and repair.

Effects of alkaline concentration and saline contents on degradation of tensile properties, microstructure and chemical characterization of glass fiber reinforced polymer (GFRP) rebars

Glass fiber reinforced polymer (GFRP) rebar has attracted widespread attention in construction industries to mitigate steel corrosion problems which significantly affect the engineering sustainability. However, GFRP tensile strength may degrade under exposure to alkaline/saline environments, and the inherent quantitative relationship between tensile strength degradation and exposure conditions is still unclear. In this study, the tensile strength retention of GFRP rebars was found to drop to 45.9%, 47.2%, 44.2%, 41.1%, 27.6%, 30.3% and 31.9% in distilled water (DW, pH = 7), seawater (SW, pH = 8.2), sodium hydroxide solutions (NaOH, pH = 11, 12 or 13), simulated normal concrete (NC, pH = 13.6) and seawater sea-sand concrete pore solutions (SSC, pH = 13.6), respectively, after 12 months of exposure at 60 °C. Both the residual tensile strength retention and activation energy in the Arrhenius equation were found to decrease with pH in a descending quadratic parabola form. The underlying degradation mechanism was then revealed by relating the macroscopic tensile strength degradation to the water/ion diffusion and fiber/matrix deterioration at the microscopic level. The pH level rather than saline ions was uncovered to be the major influence factor for GFRP degradation. The findings of this study supply engineers with a comprehensive database on GFRP tensile strength degradation, suggesting that lowering the exposure pH rather than the saline content is critical for enhancing the durability of GFRP composites.

Tensile Fracture Property of Concrete Affected by Interfacial Transition Zone

As a weak link between aggregate and mortar in concrete, interfacial transition zone (ITZ) usually plays a key role in concrete fracture. To investigate the tensile fracture property of concrete affected by the mechanical properties of ITZ numerically, the geometrical models of heterogeneous concrete were established with the parameterization modeling. They include three phases, namely, mortar, ITZ, and randomly distributed aggregates with distinct sizes and orientations. The cracking behaviors of mortar and ITZ were characterized by the bilinear cohesive zone constitutive model. Based on the experiments, the mechanical properties of ITZ were mediated by changing the water–cement ratio of mortar, the aggregate surface roughness and the content of silica fume in interfacial agent. A series of numerical simulations were conducted on the concrete models in tension after the numerical modeling method was validated. The macroscopic tensile fracture properties of concrete were quantitatively connected with some microscopic variables, including the water–cement ratio of mortar, the aggregate surface roughness and the silica fume content in interfacial agent. It was found that the tensile fracture properties of concrete have negative linear correlations with the water–cement ratio of mortar, while the effects of the aggregate surface roughness and the silica fume content in interfacial agent are very complex. The tensile fracture mechanical properties of concrete have a bilinear relationship with the aggregate surface roughness and an approximate quadratic parabola relationship with the content of silica fume in the interfacial agent. This study is beneficial to improve the fracture resistance of concrete by some interface handling measures.

Experimental Study on Freezing Front Model of Alpine Tunnel under Wind Field

In order to study the freezing front characteristics of alpine tunnels under the condition of wind flow field and relying on the Osaka Mountain tunnel in Qinghai Province, the physical model test of an alpine tunnel was built. By using the Surfer software combined with the laboratory test data, the radial and longitudinal temperature variation trends of the tunnel were obtained, and the overall temperature vector graph of the tunnel was simulated; the radial and longitudinal evolutionary laws of a freezing front in an alpine tunnel under airflow conditions were systematically analyzed, and the radial and longitudinal governing equations of a freezing front in the tunnel model under airflow conditions were proposed. The results show that: With the decrease of the test air temperature, the thermonuclear area in the surrounding rock gradually shrinks, the frozen area of surrounding rock at the bottom of the arch gradually increases, and the frozen area of surrounding rock at the top of the arch gradually expands to the interior of the mountain. The influence degree of ventilation on the longitudinal and radial temperature distribution of the tunnel is obvious, and the greater the wind speed, the greater the influence degree. In particular, the fluctuation range of the longitudinal temperature distribution of the tunnel is more extensive under the influence of ventilation. The freezing front distance in the inverted arch area is the largest, and the expansion distance of the freezing front in the wall foot area is obviously higher than that in the vault; the variation of the longitudinal freezing front at different positions of the tunnel shows parabolic attenuation and with an increase in tunnel depth, the trend of freezing front gradually eases and becomes stable and disappears; the three radial regions of the freezing front and the longitudinal quadratic parabola governing equations can predict the specific distribution characteristics of the freezing front at different depths of the tunnel.

Shape optimization of inlet header of micro-channel heat sink using surrogate model combined with genetic algorithm

A lot of work has documented the significance of fluid-flow uniformity on the thermal-hydraulic performance of the micro-channel heat sink. The purpose of this work is to optimize the shape of inlet/outlet headers of a micro-channel heat sink to improve the flow distribution characteristics using the back propagation neural networks combined with the genetic algorithm as the surrogate model. The slanted edge of the inlet header is defined as the quadratic parabola instead of straight line. Meanwhile, the shape of the parabola is optimally designed for different flow rates. The 40 training sample points and six testing sample points on different geometry structures of inlet header are designed by the Latin hypercube sampling method. The 3-D CFD calculation is performed for all models. The objective function is defined as the non-uniformity of the fluid-flow. It is found that the prediction of the genetic algorithm back propagation for the fluid-flow distribution is capable of obtaining objective function values within the designed space. Through the optimizations, the non-uniformity of the optimal inlet header structure can be reduced by 52.43% to 33.17% for the inlet velocity of 0.05 m/s to 0.1 m/s, respectively, compared to that of the original design. The results demonstrate that the parabolic treatment for the slanted edge of the inlet header as well as structural optimization can greatly improve the flow uniformity of the micro-channel heat sink.

Experimental analysis of wet gas-liquid water mixture within the tank of water in glass evacuated tube solar water heater

ABSTRACT In this investigation, thermal performance characteristics of passive solar water heater with vacuum tube were experimentally studied by using the mixture of wet gas and liquid water. Five different outlet locations of the tank were used to produce five different proportions of wet gas-liquid water mixtures. Experimental results were proposed in the way of water temperature, gas temperature, thermal stratification number, temperature distribution zone and a correlation for thermal efficiency through wet gas proportion. It was concluded that the wet gas-liquid water mixture at a wet gas proportion of 70% ameliorates the water temperature and thermal stratification number by respectively 13.7°C and 10.33 times compared to the mixture at a wet gas proportion of 10%. For different wet gas-liquid water mixtures, temperature distribution zone shows a quadratic parabola. The correlation for thermal efficiency through different proportions of mixtures presents the regularity of linear regression equation. Also, the average R2 and average Root Mean Square Error (RMSE) of regression analysis correlation are calculated as 0.936 and 0.375, respectively. The novelty of this work is evaluating the effect of different proportions of wet gas-liquid water mixture on the thermal performance and thermal stratification of passive vacuum tube solar water heater, and develop a correlation for thermal efficiency through different proportions of mixture.

Fruit growth, carbon allocation, and related enzymes in tomato under different irrigation and potassium application regimes

AbstractBackgroundThe increasing concentration of atmospheric CO2 not only affects the growing environment of crops but also aggravates the global greenhouse effect and further aggravates the problem of water shortage. The combined effect of water deficit and potassium (K) application has not been widely studied.AimsA pot experiment was conducted to investigate the effect of deficit irrigation (DI) and K application at different growth stages on carbon allocation and enzyme activities related to sugar metabolism.MethodsTomatoes were transplanted and planted on April 26, 2017 and harvested on August 15, 2017. Four irrigation regimes were implemented with two water levels (full irrigation‐W and DI‐W/2) in different growth stages, and each water treatment was equally divided into two subgroups: with K (K1) and without K (K0). Fruits from the first to fourth trusses of the tomato plants were sampled. Tomato growth, carbon allocation, and related enzyme activities were measured.ResultsThe fresh weight (FW), dry weight, and relative growth rate of dry mass were sensitive to irrigation amount under K fertilization, enhancing the promotion effect of irrigation on fruit. Meanwhile, carbon allocation was sensitive to irrigation amount under K regime. Sucrose synthase (SuSy), acid invertase (AI), and sucrose phosphate synthase (SPS) were also highly sensitive to irrigation amount under K application condition. Starch phosphorylase displayed a quadratic parabola for irrigation amount, and adenosine diphosphate glucose pyrophosphorylase (AGPase) was highly sensitive to irrigation amount without K fertilization. Carbon in the form of other carbohydrates, carbon in the form of soluble sugar (Csol), and fruit water content were the factors that had the greatest influence on the principal components. Classification by K‐means algorithm and canonical correlation analysis showed that FW, fructose, sucrose, and starch could be used as significant indicators of the dry matter components of the fruit for the treatment without K. In the case of K regime, SuSy, AGPase, AI, and Csol could be used as a significant indicator of the correlation analysis of carbon metabolism activity.ConclusionsThe factors related to the improvement of fruit quality and carbon allocation by deficient irrigation and K application were explored. Water stress changed the distribution of photosynthetic carbon between starch and soluble sugar. K application further changed the balance between soluble sugars and other compounds. In particular, it significantly increased the carbon content of soluble sugars and decreased that of other compounds. AI and SuSy are key enzymes affecting carbon metabolism under water‐deficient conditions.

Analysis of tooth contact for cylindrical gear with high-order topological modification and misalignment

The tooth contact analysis model is introduced for cylindrical gear with high-order topological modification and misalignment. According to the generation principle of gear, the tooth surface equation of double-crowned gear by using worm grinding wheel is derived. Based on the gear meshing theory, a tooth contact model of cylindrical gear considering errors and high-order topological modification is established. Taking helical gears as an example, the effects of errors and four different combinations of modification curves on the contact marks and transmission errors of tooth surface were analyzed. Results show that the paths of contact change dramatically with different combinations of modification curves. With the increasing of the order of modification curve, the contact path transitions smoothly in the middle of the tooth width, while the total length of the major axis of the contact ellipses increase significantly compared with taking the quadratic parabola modification. With proper parameters of the modification, the apex of transmission error function is flatter and its amplitude decreases which further reduces the vibration of gear transmission to installation error. The finite element method is applied to validate the proposed analysis model. The results are basically consistent and the maximum error is within 3.5 %.

Evaluation of the Effects of Nitrogen, Phosphorus, and Potassium Applications on the Growth, Yield, and Quality of Lettuce (Lactuca sativa L.)

Lettuce (Lactuca sativa L.), a popular edible vegetable, is highly responsive to mineral fertilizers. A two-year field trial was carried out to determine how nitrogen (N), phosphorous (P), and potassium (K) application ratios affected lettuce growth, yield, and quality. Within a certain range of nutrient application rate, the plant height, stem diameter, yield, and the concentrations of vitamin C and soluble sugar were higher than those without fertilization. Compared with no fertilization condition, the yield increased approximately 13.56–22.03%, 15.15–42.42% and 7.14–10.32% under increased N, P, and K application conditions, respectively. Furthermore, substantial quadratic parabola relationships were observed between lettuce yield and fertilizer application amounts as well as most quality traits. The nitrate concentration was proportional to the N fertilization rate, while the concentrations of soluble sugar and vitamin C positively correlated with N and P application ratios, respectively. The lettuce leaves had the largest N (60.59%) and K (52.25%) accumulations, whereas the lettuce stem had the highest P (46.33%) accumulation. Above all, the optimal N, P, and K application amounts for lettuce were 315 kg N ha−1, 210 kg P2O5 ha−1, and 285 kg K2O ha−1, respectively.

Trace elements apportionment in forage, soil, and livestock in rangeland ecosystems along climatic gradients

BackgroundAlpine meadows, typical steppes, and deserts are among the globally important rangeland types that are generally distributed along temperature and precipitation gradients. Mineral losses caused by grazing are one of the key factors that can lead to instability or even degradation of these rangeland ecosystems. MethodsWe examined the concentrations of Cu, Fe, Mn, and Zn in soil, forage, and livestock dungs from diverse rangeland types in northwest China, to determine the relationships between these trace elements (TEs) concentrations and climatic factors (i.e., temperature, precipitation, and humidity), and to evaluate the potential risks of TEs deficiencies or excesses in these rangeland ecosystems. ResultsForage Zn concentrations in forage of all three types of rangeland, and Cu concentrations in forage of the alpine meadow did not meet the growth requirements of grazing livestock. Concentrations of Cu, Fe, and Mn in forage and Fe, Mn, and Zn in livestock dungs had quadratic parabola relationships with temperature, precipitation, and humidity, but the relationships between climate factors and Cu, Fe, and Mn concentrations in soil were not significant. In addition, the abilities of the plant to absorb Cu, Fe, and Zn from soil were stronger in the typical steppe than that in the alpine meadows and desert. Also, the abilities of livestock to return TEs to soil were stronger in the alpine meadow than that in the typical steppe and desert. ConclusionWe derived a conceptual mode that the ratio of TE concentrations of the plant to soil and of livestock dung to forage represents the abilities of plants to absorb TEs from the soil matrix and livestock to return TEs to soil or to absorb TEs from forage, respectively. Results indicate potentially more serious risks of TEs deficiencies, especially that of Zn than previously considered in typical steppes and desert rangelands.

Effects of Different Mulching Materials on the Grain Yield and Water Use Efficiency of Maize in the North China Plain

Mulches combined with drip irrigation techniques have been widely applied in China for higher yield and water use efficiency (WUE). To develop an efficient strategy that can improve maize yield and save water in the North China Plain (NCP), we conducted a two-year field experiment, using transparent plastic film mulching (T), black plastic film mulching (B), and straw mulching (S) and non-mulching (N) for spring maize in 2019 and summer maize in 2020, and high drip irrigation amount (H) and low drip irrigation amount (L) were also considered in 2019. We mainly studied the effects of mulches on soil water content, soil temperature, crop growth rate, grain yield, and water use efficiency (WUE). The results indicated that T and B treatment increased soil water content (SWC) and topsoil temperature. The T treatment promoted the growth rate significantly more than N treatment, by 27.7–43.4% at the early stage in two years. The grain yield under TH treatment was significantly (p < 0.05) higher than that of other treatments, by 9.8–17.4% for spring maize in 2019, and significantly (p < 0.05) higher under both TH and BH than under NH, by 8.9% and 4.7% for summer maize in 2020. There was a significant quadratic parabola relationship between ET and grain yield in 2019, and the correlation between SEAT of 0–10 cm soil depth with grain yield or with biomass was positive. These results indicate that the transparent plastic film with high drip irrigation amount treatment (TH) can be recommended for spring maize, and both transparent and black film mulch treatments (TH and BH) can be recommended for summer maize in the NCP.