## 1 Introduction  
In 2020, the area of land used to grow cereals in EU countries was 159 million ha. Wheat, spelt, barley, and triticale are grown in the EU, which are best adapted to the climatic conditions in Europe and provide a high straw mass. It is estimated that 144 million tons of wheat straw alone are produced annually in Europe [1]. The main chemical (elementally) components of straw are carbon (41.3-46.0%), hydrogen (5.33-6.07%), nitrogen (0.93-1.38%), oxygen (33.7-39.0%), and sulfur (0.10-0.15%) [2]. In addition, a significant portion of straw (about 80%) consists of nonnitrogenous organic compounds (lignin, 14-17%; cellulose, 32-34%; and hemicellulose, 33-45%); hot water soluble compounds, 7-19%; and ash, 5-12% [3]. Straw ash also consists of the internal and external microabrasive contamination of straw. Straw is the largest \"waste\" in grain harvesting. Straw is chopped or placed in windows, dried, and pressed at 15% moisture content. The pressed straw is used in livestock production for feed, bedding, and vegetable production. Straw biomass is being explored as a renewable resource with high potential and low emissions as a primary fuel in cogeneration plants (electricity and heat production) [4]. When straw is used for biofuel production, it is first chopped and then peltetized [5]. Straw is an important feedstock for biogas (methane) production. The lignocellulosic must be chopped to achieve rapid biomass degradation (biodegradation). Studies show that chopping increases the surface area and thus increases the speed and yield of methane production. The proper preparation of biomass increases the methane yield from 16% to 99.5% [6]. After harvesting, the straw is collected from the ground, which significantly damages the soil. Chopping and spreading straw is an effective method to reduce crop waste and improve soil quality. Straw plays an important role in the agroecosystem and directly and indirectly affects the physical, chemical, and biological processes in the soil [4]. Studies show that straw is rich in nitrogen, phosphorus, potassium, and other nutrients for plant growth. The addition of chopped straw to the soil increases the oxygen and humus content and the friability of the soil, which leads to a higher content of microorganisms [7]. Comminution of plant waste is complicated due to the heterogeneous and nonisotropic nature of these materials [8]. The choice of blades for the straw chopper of the combine harvester is crucial for the chopping quality. The benefit of straw to the soil depends on the fractions into which the straw is chopped and distributed. The length of the chopped straw is directly affected by the speed of the chopper shaft--as the speed increases, the size of the chopped straw decreases [8]. The speed of the shaft determines the speed at which the air velocity moves with the chopped straw in the chopper. The goal is to distribute the chopped straw mass evenly over the soil surface, but this is often difficult to achieve due to variations in wind speed and direction and terrain [9]. The shorter the straw, the more easily it is incorporated into the soil and the faster it decomposes. The optimum length of chopped straw for best incorporation/mixing with the soil is up to 30 mm [10]. The open blades of the chopper damage the straw less, and the decomposition (conversion to fertilizer) is longer and less efficient. After spreading the straw on the stubble, the straw is treated with fungicides to make it decompose faster and more evenly [11]. The classical structure of a straw chopper (straight blades) is shown in Figure 1. The blades are hinged in pairs to the axes mounted in the fastening loops. The fastening loops are generally arranged in four rows along the shaft and welded symmetrically to the chopper shaft axis. The loops can be arranged in a straight or spiral pattern. As the shaft rotates, the blades, under centrifugal force, are positioned parallel to the radius of the chopping drum under centrifugal force (Figure 1a).