Larger diameter and velocity and smaller landing angle of sprinkler irrigation droplets are more likely to cause soil splash and erosion. However, the mechanism of crop canopy influence on the physical parameters of sprinkler droplets is unknown. In this study, with the landing angle of sprinkler irrigation droplets as the independent variable and maize plants (Zea mays L.) as the research object, an indoor sprinkler irrigation experiment was carried out. The effects of maize canopy and variation in sprinkler irrigation droplets landing angle on the value and spatial distribution pattern of size, the velocity, and the landing angle of throughfall droplets was analyzed. In addition, the spatial variation patterns of throughfall droplets size, velocities’ distribution, and individual droplet’s speed, kinetic energy were also explored. The results showed that maize canopy and the decreasing of the sprinkler irrigation droplet landing angle had a positive and obvious effect on reducing the size and velocity of penetrating rain droplets. However, the throughfall droplets’ landing angles were only small variations. When the landing angle of sprinkler irrigation droplets was >45°, the spatial distribution of throughfall droplets size and velocity corresponded well with the canopy structure and leaf projection area of maize, i.e., the further away from the maize stalk, the larger the size and velocity of throughfall droplets. Nevertheless, if the landing angle of sprinkler irrigation droplets was <45°, the spatial distribution mentioned above was mainly affected by droplets landing angle. The spatial variation of throughfall droplets’ size and velocities at different measurement points was attributed to the change of the larger droplets’ volume proportion and the equivalent velocity. Although the maize leaves had a certain degree of perturbation effect on the velocities and kinetic energy of the larger kinetic energy droplets, the flight path of these drops did not alter significantly. The results of this research will be of practical value in guiding the development of a new sprayer and the optimum selection of sprinkler heads.

中文翻译：

---

玉米冠层下直落液滴大小、速度和着陆角的空间变化机制

喷灌液滴的直径和速度越大，降落角度越小，越容易引起土壤飞溅和侵蚀。然而，作物冠层对喷洒水滴物理参数的影响机制尚不清楚。本研究以喷灌水滴降落角度为自变量，玉米植株（Zea maysL.)作为研究对象，进行了室内喷灌实验。分析了玉米冠层和喷灌液滴降落角度变化对直通液滴尺寸、速度和降落角度的值和空间分布格局的影响。此外，还探讨了通过液滴尺寸、速度分布和单个液滴的速度、动能的空间变化模式。结果表明，玉米冠层和喷灌液滴着陆角的减小对减小穿透雨滴的尺寸和速度具有积极而明显的作用。然而，直通液滴的着陆角度只是很小的变化。当喷灌液滴降落角度>45°时，直射液滴大小和速度的空间分布与玉米的冠层结构和叶片投影面积有很好的对应关系，即离玉米茎越远，直射液滴的大小和速度越大。然而，如果喷灌液滴的着陆角度<45°，则上述空间分布主要受液滴着陆角度的影响。不同测量点处通过液滴尺寸和速度的空间变化归因于较大液滴的体积比例和等效速度的变化。尽管玉米叶片对较大动能液滴的速度和动能有一定程度的扰动作用，但这些液滴的飞行路径并没有明显改变。