# Applications of Water Jet Cutting Technology in Agricultural Engineering: A Review
## 3 Applications of Water Jet Cutting Technology on Different Agricultural Materials
### Stems
#### 3.5.1 Anti-Blocking  
No-tillage sowing in stalk mulching fields can effectively prevent soil erosion and improve soil [72]. However, the sowing operation cannot proceed smoothly because crop stems are on the soil surface, so the stems should be reduced in length or cut off to prevent the openers from blocking. When chopping the stem with a rotary blade or cutting the stem with a disc knife, tool wear occurs due to the direct contact between the tool and the stem, while water jet cutting technology has a non-contact way, which can avoid this problem [72].  
To deal with stems blockage, [PERSON] et al. [73] evaluated the cutting capacity of a pure water jet cutting device for a wheat straw internode stem under laboratory conditions (Figure 6). The results showed that the device delivered a cutting capacity of 10-35 Mg/ha of wheat straw stems across the range of nozzle diameters (0.15-0.3 mm) and traverse speeds (1.67-3.33 m/s) under a 380 MPa pressure. Moreover, when the wheat stem was wet and compressed, the water jet work efficiency was the highest. A full factorial design with 200 tests was implemented by [PERSON] et al. [74] to study the effect of different jet parameters on the cutting depth of one single corn stem. The experimental results showed that the cutting depth could increase with a high water jet pressure, a low traverse speed, and a short target distance. When the target distance was less than 10 mm and the water jet pressure was 280 MPa, all single corn stem samples could be completely cut off. Besides, they advised a 10-15 mm standoff distance to avoid the impact of soil and stubble on the nozzle when working in the field. Furthermore, [PERSON] et al. [22] found that the double-disc opener had a better performance than the hoe opener through field experiments assisted by pure ultrahigh water jet cutting (Figure 7). When the water jet pressure was 267-280 MPa, the jet angle was 80.2-90.0\({}^{\circ}\), and the traverse speed was 1.11-1.23 m/s, the overall performance of the double-disc opener reached the maximum. To study the damage process of water jet cutting a single corn stem, [PERSON] et al. [75] adopted an ALE-FEM (arbitrary Lagrangian Eulerian-finite element method) fluid-structure coupling numerical model (Figure 8). Compared with results captured by the high-speed camera, it was confirmed that the simulation model could predict the cutting depth of corn stalk under jet action. Besides, computational fluid dynamics (CFD) models could be used to simulate water jet diffusion inside or around the jet nozzle, and the discrete element method (EDM) could establish the corn stem model [76; 77].  
Figure 5: Cutting wood in an abrasive water jet (AWJ) system ([71], reproduced from “Influence of processing parameters on the surface roughness of solid wood cut by abrasive water jet” with permission from NC State University, 2022).  
Compared with pure water jet cutting, [PERSON] et al. [78] found that a number of garnet abrasives (3 kg/h) could improve the jet-cutting ability of wheat stems and reduce the maximum hydraulic power required by laboratory experiments. The cutting operation was estimated to require 5000-7500 W hydraulic power at 6-10 Mg/ha surface density. An average jet hydraulic power of 6400 W could guarantee a 90% cutting efficiency in the presence of heavy residue distribution. In addition, they advised that further research was needed to investigate the residual effects on soil physical properties after cutting.