The Spatial Variation Mechanism of Size, Velocity, and the Landing Angle of Throughfall Droplets under Maize Canopy

Zhongrui Zhu,Maosheng Ge,Delan Zhu

doi:10.3390/w13152083

Abstract

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.

Highlights

Sprinkler irrigation technology, as a high degree of mechanization and more modern irrigation mode, can significantly improve the utilization rate of water and fertilizer, irrigation efficiency, and crop yield and quality, and has been widely promoted and applied in the world [1]
When the landing angle was 81.69◦, 71.33◦, 60.58◦, and 42.04◦, the variation ranges of D50 of throughfall droplets under the maize canopy and their percentages to uncrowned were 1.64–3.40 mm (49.10–101.80%), 1.68–3.25 mm
Since there were almost no differences in the physical parameters of sprinkler irrigation droplets and plant canopy morphological parameters under different treatments during experimenting, with treatment 1 (81.69◦ ) as the control group, the influence of variations in the landing angle of sprinkler irrigation droplets was analyzed in this paper

Summary

Introduction

As a high degree of mechanization and more modern irrigation mode, can significantly improve the utilization rate of water and fertilizer, irrigation efficiency, and crop yield and quality, and has been widely promoted and applied in the world [1]. Sprinkler droplets have different landing angles, in addition to specific drop size and velocity [1,2]. When the sprinkler droplets impact the soil surface, soil splash detachment is more likely to be caused [3]. Soil surface crust formation and soil infiltration rate decrease, and runoff generation will begin to occur gradually [4,5,6]. The above phenomenon becomes more serious as the sprinkler droplets’ landing angle decreases [7,8,9]

Methods

Results

Conclusion