More attention has been paid to ubiquitous microplastics (MPs). As a major food producer, the situation of MPs in China’s farmland is of even greater concern. Spatial distributions, characteristics, ...and compositions of MPs in five types of agricultural lands with representative crops were investigated by collecting 477 soil samples from 109 cities in 31 administrative regions of mainland China. To better control MPs in farmland, nearly 400 field questionnaires were obtained, and meteorological conditions, soil properties, and other statistics were collected to quantify potential sources and determine influencing factors. The average abundances of MPs was 2462 ± 3767 items/kg in the agricultural soils, and MP abundance in the greenhouses, farmlands with film mulching, and blank farmlands from four integrated physical geographic regions were determined. The contributions of agricultural films, livestock and poultry manures, irrigation water, and air deposition to MPs in farmlands have been calculated. Influencing factors, such as recovery method, plowing frequency, meteorological conditions, and part of soil properties, were significantly correlated with the abundances of MPs in the agricultural soils (p < 0.05), while mulching age mainly affected MPs in the greenhouses (p < 0.05). This study provides basic scientific data for decision-making and further analysis.
The capacity of no-tillage and fertilization to promote soil organic carbon (SOC) accumulation and the impacts of occasional tillage on that SOC are topics of current debates. We quantified (i) the ...SOC and total nitrogen accumulations resulting from the adoption of long-term (23 years) no-tillage relative to conventional tillage by plowing, (ii) the impact of occasional chiseling every three years on SOC and total nitrogen stocks and (iii) the improvement in SOC and total nitrogen stocks due to normal fertilization relative to reduced fertilization (suppression of P and K application) in a subtropical Ferralsol of a field experiment in southern Brazil. After 23 years under normal fertilization, no-tilled soil stored significantly more carbon and nitrogen than conventional tillage soil, either to 30 cm depth (85.5 vs 71.3 Mg C ha‐1; and 6.12 vs 5.13 Mg N ha−1; P < 0.10) or to 100 cm depth (185.0 vs 163.2 Mg C ha−1; and 11.99 vs 10.32 Mg N ha−1; P < 0.10), which means that no-tillage significantly accumulated 0.60 Mg C ha−1 year−1 and 0.04 Mg N ha−1 year−1 compared to conventional tillage to 30 cm depth, and 0.93 Mg C ha−1 year−1 and 0.07 Mg N ha−1 year−1 to 100 cm depth. Those results indicate the capacity of no-tillage to promote SOC and total nitrogen accumulation in this Ferralsol, despite its aboveground residue being not significantly higher than that in conventional tillage (9.22±0.46 vs 8.47±0.44 Mg DM ha−1 year−1, normal fertilization), and also indicate that it might be useful to assess SOC and total nitrogen to 100 cm depth. Occasional chiseling did not significantly change SOC and total nitrogen stocks to 100 cm depth compared to no-tilled soil (180.4 vs 185.0 Mg C ha−1, and 11.02 vs 11.99 Mg N ha−1; P > 0.10), but this result should not serve as pretext to chiseling, a practice to be cautiously used only when and where needed. Across tillage systems, normal fertilization promoted SOC accumulation compared to reduced fertilization at rates of 0.04–0.25 Mg C ha−1 year−1 in the 0–100 cm, rates that were lower compared to those obtained with no-tillage relative to conventional. Overall, no-tillage system was efficient to accumulate SOC and total nitrogen, and therefore should continue to be encouraged, as well as the application of fertilizer; while occasional chiseling seemed not to change those stocks relative to no-tillage in this Ferralsol.
•C and N measured to 1 m depth in a Ferralsol under tillage and fertilization systems.•Over 23 years, no-tillage sequestered 0.93 Mg C ha−1 and 0.07 Mg N ha−1 annually.•Occasional chiseling did not significantly change C and N stocks compared to no-till•Fertilization sequestered 0.04–0.25 Mg C ha−1 year−1 compared to reduced fertilization.•It might be useful to assess C and N to 100 cm depth, not only to 30 cm.
► In spite of extensive research on no-till in northern Europe uptake by farmers is negligible. ► In southern Europe improved soil and water conservation are increasing uptake of no-till. ► ...Environmental benefits from no-till, especially net climate forcing, need further evaluation. ► Weed control is critical with no-till, especially if restrictions in herbicide use are introduced. ► Greater practical understanding and financial assistance would increase the uptake of no-till.
Recent literature on no-till is reviewed with particular emphasis on research on commercial uptake and environmental concerns in northern, western and south-western Europe. Increased interest in no-till, and minimum or reduced tillage, results from changes in the economic circumstances of crop production, the opportunity to increase the area of more profitable autumn-sown crops and increased concern about environmental damage associated with soil inversion by ploughing. Highly contrasting soil and climate types within and between these regions exert a strong influence on the success of no-till. While no-till may often result in crop yields which equal or exceed those obtained after ploughing, modest reductions in yield may be tolerated if production costs are lower than with ploughing. The relative costs of fuel and herbicides have changed appreciably in recent years making no-till more attractive commercially. While effective weed control is an essential aspect of no-till, current herbicide technology may not yet fully achieve this.
In northern regions no-till usually allows earlier drilling of winter-sown crops but will give lower soil temperature and higher moisture content in spring, causing delayed drilling of spring-sown crops. No-till soils have greater bulk density and bearing capacity than ploughed soils with a pronounced vertical orientation of macroporosity allowing penetration of roots and water, especially in view of the increased population of deep-burrowing earthworms. Particular care must be taken with no-till to minimise soil damage at harvest and to ensure the even distribution of crop residues prior to drilling.
Reduced erosion and runoff after adoption of no-till are widely observed and are of particular importance in southwestern Europe. No-till reduces losses of phosphorus in runoff and, in some cases, reduces the loss of nitrate through leaching. Emissions of greenhouse gases CO
2 and N
2O from no-till soils are highly variable and depend on complex interactions of soil properties. Emission of CO
2 from fuel during machinery usage is always appreciably reduced with no-till. Increased soil organic carbon in surface layers of no-till soils is widely found but may not be associated with increased carbon sequestration throughout the profile. The evaluation of the relative carbon balance for no-till and ploughing depends upon complex inter-relationships between soil and climate factors which are as yet poorly understood. Adoption of no-till could be encouraged by government financial assistance in recognition of environmental benefits, although future restrictions on the use of herbicides may be a deterrent. Opportunities for further research on no-till are outlined.
•Challenges in the current generation of mobile network and the need for 5G in agricultural sector.•5G based UAV navigation beyond line of sight for real time monitoring for agricultural ...applications.•Application of 5G in AI driven robots and cloud-based processing.•AR and VR takes precision farming to the next level with 5G network.
Over the next decade, the superfast 5G network will play a critical role in farming industries to improve the yields and quality of crops while using minimal labor. Smart and precision farming allows farmers to be more informed and productive. The advent of 5G will considerably change the nature of jobs in farming and agriculture. The internet of things (IoT)-based cloud computing service in the 5G network provides flexible and efficient solutions for smart farming. This will allow the automated operation of various unmanned agricultural machines for the plowing, planting, and management phases of crop farming and will ultimately achieve secure, reliable, environmentally friendly, and energy-efficient operations and enable unmanned farms. This paper provides a complete survey on 5G technology in the agricultural sector and discusses the need for and role of smart and precision farming; benefits of 5G; applications of 5G in precision farming such as real-time monitoring, virtual consultation and predictive maintenance, data analytics and cloud repositories; and future prospects.
A novel model of the vibration plowing effect (VPE) is proposed for the first time to reveal hitherto not well-understood ultrasonic cutting mechanics and provide a theoretical basis for controlling ...the tool wear and machining quality of longitudinal ultrasonic vibration-assisted drilling (LUAD). The new model includes a condition model to judge the occurrence of the VPE on the whole flank of the drill and a volume model to calculate the vibration plowing force caused by the VPE of LUAD. For one thing, a condition model is proposed to distinguish the plowing effect of conventional machining and the VPE of LUAD by comprehensively analyzing the relationship between the clearance angle of the main cutting edge and the drill's path. For another, an analytical model of the vibration plowing volume (VPV) of LUAD is derived by integrating the plowing volume of the main cutting-edge element to improve the tool wear and machining quality. Finally, a series of comparative experiments between conventional drilling (CD) and LUAD is carried out. The validity of the proposed VPE's condition model and the VPV's analytical model is verified by the chip's micromorphology and the specific plowing force of the workpiece, respectively. The experimental results show that the fine and regular textures caused by the VPE can be observed on the chip surface and side micromorphology of LUAD. However, the coarse and irregular textures are displayed in CD, which shows that the proposed conditional model is adequate. Moreover, it is calculated by the deduced VPV's analytical model that when the ultrasonic amplitude is 3.8 and 8.3 μm, the average value of the specific plowing force of Al 6061-T6 determined in this paper is 1.399 × 105 N/mm3 and 1.274 × 105 N/mm3, respectively. These results agree with the value reported in other literature, that is 1.31 × 105 N/mm3, which proves the validity of the proposed model of the VPV. The validated analysis model is then used to conduct predictive analysis on the VPE and vibration plowing force of LUAD under a series of process parameters. The above research results clarify the mechanism of vibration plowing under ultrasonic action and provide a theoretical basis for controlling the tool wear and machining quality of LUAD.
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•A vibration plowing effect's judgment model of LUAD is proposed for the first time.•An analytical model of the vibration plowing volume under ultrasonic action is established.•The vibration plowing force of LUAD can be obtained by the derived VPV's model•Evidence of vibration plowing effect is observed on the chip side and surface.•The vibration plowing condition and volume models are general in ultrasonic cutting.
The first full greenhouse gas (GHG) flux budget of an intensively managed grassland in Switzerland (Chamau) is presented. The three major trace gases, carbon dioxide (CO₂), methane (CH₄), and nitrous ...oxide (N₂O) were measured with the eddy covariance (EC) technique. For CO₂ concentrations, an open‐path infrared gas analyzer was used, while N₂O and CH₄ concentrations were measured with a recently developed continuous‐wave quantum cascade laser absorption spectrometer (QCLAS). We investigated the magnitude of these trace gas emissions after grassland restoration, including ploughing, harrowing, sowing, and fertilization with inorganic and organic fertilizers in 2012. Large peaks of N₂O fluxes (20–50 nmol m⁻² s⁻¹ compared with a <5 nmol m⁻² s⁻¹ background) were observed during thawing of the soil after the winter period and after mineral fertilizer application followed by re‐sowing in the beginning of the summer season. Nitrous oxide (N₂O) fluxes were controlled by nitrogen input, plant productivity, soil water content and temperature. Management activities led to increased variations of N₂O fluxes up to 14 days after the management event as compared with background fluxes measured during periods without management (<5 nmol m⁻² s⁻¹). Fluxes of CO₂ remained small until full plant development in early summer 2012. In contrast, methane emissions showed only minor variations over time. The annual GHG flux budget was dominated by N₂O (48% contribution) and CO₂ emissions (44%). CH₄ flux contribution to the annual budget was only minor (8%). We conclude that recently developed multi‐species QCLAS in an EC system open new opportunities to determine the temporal variation of N₂O and CH₄ fluxes, which further allow to quantify annual emissions. With respect to grassland restoration, our study emphasizes the key role of N₂O and CO₂ losses after ploughing, changing a permanent grassland from a carbon sink to a significant carbon source.
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