针对玉米免耕播种时种子易被种沟内残膜包覆和秸秆架空,严重影响出苗率等问题,面向新疆免耕播种环境要求,提出了一种免耕种沟清理装置,采用侧抛弹齿和曲面滑铲协同清理方法,并对其作业过程和抛撒轨迹进行了分析,确定了影响种沟秸秆和残膜清理率的主要因素及取值范围,获得了秸秆和残膜在水平、垂直方向被抛撒的最大距离和高度分别为239.3～747.0 mm,141.7～442.2.0 mm.利用MATLAB 仿真,获取了120 r/min,150 r/min,和180 r/min不同转速下,相邻两弹齿端点的运动轨迹曲线变化规律,漏清区随弹齿转速增大而减小.以机具作业速度、弹齿转速和弹齿倾角为影响因子,种沟秸秆清理率和残膜清理率为评价指标进行了正交试验,结果表明,影响种沟秸秆清理率和残膜清理率显著性顺序依次为弹齿转速、机具作业速度和弹齿倾角,当作业速度为6 km/h,弹齿转速为180 r/min,弹齿倾角40°时,种沟秸秆清理率为88.27%,残膜清理率为84.31%,满足新疆玉米免耕播种的农艺要求,以期为适应新疆及西北地区的免耕播种装备研究提供参考.
Fine droplets with high adhesion can greatly improve the efficiency of atomization culture. Therefore, the development of a spray nozzle that can produce fine fog droplets with high adhesion is of great significance for aeroponics. Compared to piezoelectric ultrasonic atomizer, Hartmann resonator low-frequency ultrasonic electrostatic atomizer has the advantages of large atomization volume and constant liquid chemical structure, but the droplet size is larger. High-speed gas can generate low-frequency ultrasonic vibration sound waves in Hartmann resonator. The frequency and intensity of sound waves determine the atomization performance of supersonic atomizer nozzle. However, very few research literatures can be found on how the structure and operating parameters of Hartmann resonator affect the atomization performance. In order to improve the atomization performance of ultrasonic atomizer, a two-stage Hartmann resonator low-frequency ultrasonic electrostatic atomizer was designed. The shrinkage-type Laval tube was designed by fluid mechanics theory, and the design results were verified by fluent software. The virtual orthogonal test method was used to optimize the structure parameters of two-stage resonator and spray test was carried out. The results showed that when the included angle between the two stage resonators was 80 degrees, the diameter was 4.86 mm, the tube length ratio was 1.0 and the gas pressure was 0.5 MPa, the droplet size could reach 22.05 mu m. Additionally, compared with the traditional Hartmann cavity with 90 degrees included angle, the droplet size was decreased by 63%. The annular electrode was used as the charging electrode, and Comsol Multiphysics software was used to simulate and calculate the deformation and crushing process of electrostatic droplets and the influence of different voltage, surface tension and droplet diameter on the droplet deformation rate. The results showed that: (1) the optimum charge range of the electrode ring was within 20 mm of the axial distance along the electrode ring. (2) The higher the voltage U, the smaller the surface tension sigma the larger the droplet diameter d and the larger the droplet deformation rate. (3) The experimental results showed that the droplet size was inversely proportional to the gas pressure P-0, electrostatic voltage U and spray height h. When the gas pressure and electrostatic voltage were 0.4 MPa and 18 kV, 0.4 MPa and 18 kV, respectively, the droplet sizes were 7.8 mu m and 43.9 mu m respectively, the droplet size difference between the two conditions was 82.2%.
A comprehensive understanding of the distribution and water movement of the substrate in root areas is crucial to the design and management of drip irrigation systems, which is a significant step to maximizing crop water use efficiency by understanding the hydrodynamics in soilless substrates. In this study, an improved HYDRUS-2D model by the dynamic root growth model was used to simulate water movement under the condition of drip irrigation and the water uptake process of the root, and then, compared with the observed data. Substrate water content under drip irrigation was also measured with the calibrated ECH20-EC5 sensors. The situation of substrate water movement was analyzed under the conditions of different depths, different initial water content, and different irrigation amount. The substrate water movement under different drip irrigation conditions was explored. The results showed that incorporating the defined initial and boundary conditions and the hydraulic characteristics of the substrate into the model enabled HYDRUS model to predict the movement and position of water in unsaturated porous media by solving Richards equation. Under drip irrigation, the substrate wetting body was approximately a quarter ellipse, and the water would continue to move to the area where the wetting front did not reach within 1 h after irrigation. The simulation results of the improved HYDRUS-2D model agreed well with those observed by the ECH2O-EC5 sensors, and the model could provide a basis for precision irrigation of soilless substrate culture under drip irrigation.
Soil salinization is an issue of global concern. Despite recent evidence indicates that application of sediments into saline-alkali soil in Yellow River Delta as an additive can increase crop yield, its effects on soil structure and infiltration remain uncertain. In this study, the comprehensively analyses were conducted on the soil infiltration and microstructure of the soil treated with three sediment application layers (surface layer at 0-15 cm, lower layer at 15-30 cm, and plough layer at 0-30 cm) and four sediment incorporation rates (0, 2%, 5% and 10%), using soil column simulation experiment. Results indicated that the dredged Yellow River sediments can improve the infiltration capacity of saline-alkali soil; and the infiltration capacity increased with the rising sediment incorporation rate under the given application pattern. Compared with the control, applying dredged Yellow River sediments at 10% rate at lower layer and plough layer significantly facilitated the soil infiltration of the saline-alkali soil. Soil macro-porosity for T2, T5 and T10 was 26%, 52% and 158% more than that for the control, respectively. This phenomenon was attributed to the increased soil macro-porosity, due to the improved soil microstructure with the incorporation of sediment into the saline-alkali soil. Moreover, the cumulative infiltration was fitted better with Kostiakov infiltration model than Horton and Philip models.
: Precision agriculture (PA) through the use and utilization of innovative technologies is a concept in agricultural management that enables long-term efficiency gains, control of unforeseen changes, and a reduction of negative impacts on the environment. However, there are even more reasons and benefits to using precision agriculture technologies (PATs) on farms, but the actual use on small farms is often questionable. The main objective of this research was to evaluate and analyze the current state of PA and its potential on a set of small farms. In addition, a comparison was made between small farms located in less favored areas (LFAs) and more favored areas (MFAs) to find if specific characteristics of the surrounding environment affect the (non-) implementation of these technologies by farm owners, with respect to the given regional possibilities. The result shows that 57.5% of respondents on these farms have never implemented PATs before and 20% are beginners in their respective fields. It was found that there were no statistically significant differences in the integration between fewer LFAs and MFAs technologies and their use in this study. The majority of respondents believe that the main changes need to occur on the level of politics. The results show that the level of cost or initial investment is the main reason and the main obstacle in the implementation of PATs on the surveyed farms.
