Design and Experiment of a Sowing-Layer Residual Film Recovery Machine Integrated with a Soil Preparation Function

Abstract

To address the issues of low efficiency and repeated soil compaction caused by segregated pre-sowing operations for residual film recovery and soil preparation in Xinjiang’s long-term film-mulched cotton fields, this study developed a sowing-layer residual film recovery machine integrated with soil preparation functionality. The modular machine sequentially performs harrowing, film-pickup, removal, collection, soil crushing, and leveling operations. An orthogonal experiment focusing on film-pickup rate and film-removal rate was conducted using forward speed, roller speed, and working depth as experimental factors to evaluate the residual film recovery performance. Simultaneously, the effectiveness of the soil preparation operation was quantitatively validated. The results indicated that the order of factor influence significance on the film-pickup rate was forward speed > working depth > rotational speed of the film-removal roller, while the film-removal rate was primarily affected by the rotational speed of the film-removal roller. The optimal parameter combination was identified as a forward speed of 4 km/h, a film-removal roller speed at 300 r/min, and a working depth of 120 mm. Validation tests under these conditions yielded a pickup rate of 71.23% and a removal rate of 95.06%. Regarding soil preparation, the surface evenness was maintained at 1.23 cm after operation, demonstrating significant performance improvement over previous machine prototypes. This study promises to deliver crucial advancements for combined pre-sowing operations, offering support for future agricultural machinery innovation.

1. Introduction

The widespread application of plastic film mulching in Xinjiang’s cotton fields has demonstrated significant agronomic benefits, including enhanced soil thermal retention, improved moisture conservation, effective weed suppression, and, consequently, increased crop productivity [1,2,3]. However, under long-term mulching cultivation patterns, the failure to efficiently and timely recover residual film has led to increasingly severe pollution. Regional surveys indicate a severe accumulation of residual film in Xinjiang’s farmland. The average residual film volume was reported as approximately 206.46 kg/ha in 2018 [4], and a large-scale survey found that 60.7% of the sampled sites exceeded the national standard limit of 75 kg/ha, with localized amounts reaching up to 502.2 kg/ha [5]. These residual film fragments form a physical barrier that hinders soil water infiltration and gas exchange, thus disrupting soil structure and exacerbating compaction [4,6]. The resulting degradation of soil environmental quality consequently leads to diminished soil fertility, reduced crop yield, and associated economic losses [7,8]. The residual film challenge in China presents unique characteristics. Unlike the thicker (0.015–0.250 mm), high-tensile-strength films used in developed countries that facilitate roll-collection [9,10], China has historically relied on thin films (≤0.008 mm) with low tensile strength [11]. Inadequate recovery of these fragile films has led to severe fragmentation and high soil residue. Current practices aim to curb future accumulation by recovering the current year’s surface film after the autumn harvest, and to reduce the existing stockpile by targeting fragmented film from past years during spring soil preparation [3]. This necessity creates a critical operational overlap between film recovery and soil preparation during the busy spring pre-sowing period, where both tasks are urgent. Performing these tasks in separate stages requires multiple passes of machinery, which not only increases energy consumption and reduces operational efficiency but also exacerbates soil compaction, damages soil structure, and subsequently adversely affects follow-up agricultural activities and crop growth [3,12]. Repeated machinery passages significantly increase soil bulk density and degrade the structural integrity of the seedbed [13]. This highlights the importance of limiting field passes through integrated soil-film recovery approaches.

To address residual film pollution in cotton fields and promote sustainable agricultural development, researchers have conducted extensive studies on tillage-layer residual film recovery technologies internationally, primarily focusing on machines such as the chain-tooth type, soil-throwing type, tine-air separation type, and shovel-screen type. Evaluating these technologies against the dual and measurable requirements for integrated pre-sowing operations, namely, effective film recovery coupled with the preservation or creation of a viable seedbed, reveals a common trade-off. Chain-tooth type machines employ a subsoil shovel to lift the film-soil mixture, followed by chain-driven teeth to pick up and convey the film. Zhang et al. [14] reported a film recovery rate of 81.12% with their design, while Zhao et al. [15] and Li et al. [16] reported rates greater than 90% and approximately 88%, respectively. However, this process involves deep soil excavation and aggressive mechanical action, causing severe soil disruption and providing no integrated soil preparation function, leaving the field in an unprepared state. Soil-throwing type machines use rotary tillage or similar mechanisms to excavate and throw the film-soil mixture for separation. Huang et al. [17] focused on optimizing the soil throwing device, achieving a soil throwing efficiency of 87.45% which is critical for film separation. Bench tests of a roll-type design by Shi et al. [18] showed a tillage gathering rate of 71.6% and a surface gathering rate of 83.4%. However, their rotary tillage mechanism fundamentally destroys the seedbed structure and lacks any leveling capability. Tine-lifting and air-stripping type machines utilize a tine roller for soil loosening and film lifting, followed by air suction for separation. This design minimizes soil mixing compared to more aggressive types. However, its film recovery performance can be limited, with Guo et al. [19] reporting a film-pickup cleanliness rate of 55.04%, and it offers no integrated soil preparation function. Shovel-screen type machines combine an excavating shovel with oscillating screens for separation. You et al. [20] reported a high film recovery rate of 91.26% for such a design, albeit with a film entanglement rate of 4.27%. To address the entanglement issue, Yan et al. [21] optimized the screen mechanism and achieved a significantly lower film-entanglement rate of 1.72%. Further structural improvements by Zhang et al. [22] yielded a film recovery rate of 85.72%. Nevertheless, the fundamental process of lifting and screening the soil incurs significant soil disturbance, and these designs omit any leveling mechanism. A critical distinction must be made here between tillage-layer and sowing-layer recovery. The aforementioned technologies are designed primarily for tillage-layer recovery, which aims to maximize the removal of fragmented film accumulated over years from a relatively deep (often > 150 mm) and already disturbed soil profile. In contrast, the objective of sowing-layer management during the pre-sowing window is fundamentally different: it must recover residual film from a shallower depth (typically 0–120 mm) while simultaneously creating a firm, level, and clean seedbed ready for immediate precision seeding. The high recovery rates of tillage-layer machines come at the cost of excessive soil disturbance and structure destruction, which is directly antagonistic to the agronomic requirements of the sowing layer. In summary, current tillage-layer residual film recovery technologies, while varied in focus and often achieving high film recovery rates ranging from approximately 70% to over 90%, uniformly fall short against the criteria for integrated pre-sowing operations precisely because their design paradigm conflicts with sowing-layer preparation goals. Their operation inherently causes significant soil disturbance, severely disrupting the seedbed structure, and they universally lack integrated soil preparation functionality. This necessitates separate, subsequent machinery passes for leveling, which increases operational time, cost, and fuel consumption, and, most detrimentally, compounds soil compaction. Therefore, a genuine integration of effective film recovery with simultaneous seedbed preparation in a single pass remains an unresolved challenge, creating a clear gap for the development of new machinery that balances and optimizes both performance metrics for the specific context of sowing-layer management.

To overcome these challenges, our research team has conducted exploration and research in the field of pre-sowing residual film recovery management. To achieve integrated operation of residual film collection and land preparation, a spike-toothed roller residual film recovery device compatible with soil preparation machinery was designed [23]. However, issues such as soil accumulation, film entanglement on the spike-toothed roller device, and, critically, unverified soil preparation effectiveness emerged during application. To address the limitations of the spike-toothed roller device, including soil accumulation and film entanglement, the team further developed an arc-toothed roller residual film recovery machine [24]. This effectively resolved the problems of film entanglement and soil accumulation, though this model explicitly lacked integrated soil preparation functionality and thus did not fully achieve the goal of integrated “film recovery-soil preparation” operation.

Therefore, to resolve these specific limitations of our team’s prior research, the lack of verified, integrated soil preparation and the need for improved film recovery performance, this study builds upon the arc-toothed roller technology to develop a sowing-layer residual film recovery machine integrated with soil preparation functionality. We hypothesized that, building upon the performance of our previous prototypes [23,24] and meeting the agronomic requirement for surface evenness specified in the Chinese agricultural machinery extension appraisal standard DG/T 096-2021, the integrated machine would (1) achieve a film-pickup rate of >60% and a film-removal rate of >90%; (2) have its performance significantly influenced by forward speed, roller speed, and working depth; and (3) create a seedbed with soil surface evenness ≤ 2.5 cm. The objectives are to validate these hypotheses through component structural design, whole-machine dynamic analysis, orthogonal experiments, and field validation to investigate the influence patterns on residual film recovery performance indicators, determine the optimal operational parameter combination, and validate the soil preparation quality. Our study aims to lay a foundational theory and offer technical guidance for managing pollution from residual film before sowing, as well as for crafting integrated machinery.

2. Materials and Methods

2.1. Structure Composition and Working Principle

A schematic diagram of the machine is shown in Figure 1. The machine was designed based on a modular concept. It primarily consists of a traction device, spring-screw depth-limiting device, disc harrows, frame, transmission system, arc-toothed roller (hereafter referred to as the toothed roller), arc-shaped scraper film-removal device, dust-proof airflow guide cover, film collection device, hydraulic depth-limiting walking device, and a soil crushing and leveling device. The arc-toothed roller draws on our team’s previous research and is identical to the arc-toothed roller technology previously developed by the team. The disc harrow assembly is composed of notched disc harrows and full-edge disc harrows, while the soil crushing and leveling device comprises a serrated soil-crushing roller and a corrugated press roller. Based on functional configuration, the machine is divided into three core modules: the front-mounted disc harrow set, the central residual film recovery device, and the rear-mounted depth-limiting walking and leveling device. These modules are structurally integrated via U-bolts. Furthermore, by defining the operational sequence and designing the structural layout, several issues arising from modular integration were resolved. The operational sequence and depth consistency between the front-mounted disc harrow set and the central film recovery device were ensured to optimize soil loosening and film-pickup efficiency. During the design phase, the compact spatial arrangement between modules guaranteed structural integrity while preventing mechanical interference. Furthermore, the machine frame was fabricated from Q235 carbon steel. For the arc-shaped teeth, the tips were made of Q235 carbon steel for wear resistance, while the tooth bodies were constructed from ductile iron. The rubber scrapers were composed of wear-resistant nitrile rubber (NBR).

The machine was suitable for soil conditions after spring pre-sowing plowing operations and operates via tractor traction. During operation, the front-mounted disc harrow assembly cut into the soil, performing harrowing to break up soil clods and turn the soil. Subsequently, the arc-shaped teeth on the clockwise-rotating toothed roller penetrate the sowing-layer soil to pick up the residual film. When the film-laden teeth rotate to the position of the arc-shaped scraper film-removal device, the counter-rotating scrapers strip the film from the teeth and, through mechanical action, propel it into the collection bin. Finally, the rear-mounted soil crushing and leveling device levels and firms the loosened soil after film recovery, restoring the seedbed structure of the sowing layer. Through this operational sequence, the machine achieves continuous harrowing, residual film recovery, and soil crushing and leveling.

2.2. Design of Key Components

2.2.1. Arc-Shaped Scraper Film-Removal Device

The arc-shaped scraper film-removal device is a core component for achieving efficient residual film recovery. Its structural design and operational mode directly affect the film-removal efficiency and overall recovery performance. Its primary function is to reliably separate, scrape off, and convey the residual film picked up by the toothed roller into the film collection box. As shown in Figure 2, the device mainly consists of an arc-shaped film-removal scraper and a film-removal roller. The arc-shaped film-removal scraper includes a support baseplate, a rubber scraper, and a pressure plate, which are bolted together to clamp and secure the rubber scraper. The film-removal roller is composed of a central roller and scraper baseplates uniformly welded on its surface. The arc-shaped film-removal scraper is fastened to the baseplates via bolts, forming an integrated rotating scraping device.

During operation, the arc-shaped scraper film-removal device and the toothed roller film-picking device counter-rotate. The arc-shaped film-removal scraper acts upon the teeth on the toothed roller multiple times, thereby effectively scraping off the residual film entangled on them.

2.2.2. Structural Design of the Arc-Shaped Film-Removal Scraper

The arc-shaped film-removal scraper was designed to match the core dimensions and configuration of our team’s existing arc-toothed roller [25,26], which has a 1600 mm working width, a 475 mm roller radius, and features 18 rows of tooth bases (each with 12 or 13 teeth).

To ensure effective coordination between film-removal and film-picking operations and guarantee reliable performance, the arc-shaped film-removal scraper was designed according to the structural configuration and tooth arrangement of the toothed roller. As shown in Figure 3a, its width was determined to be 1600 mm. The rubber scraper features isosceles-triangular scraping notches with a horizontal spacing of 50 mm between adjacent notches. The supporting baseplate for the rubber scraper has isosceles-trapezoidal notches, which are larger than the corresponding notches on the rubber scraper. This design maintains the predetermined arc curvature and provides flexible deformation space for the rubber scraper, enabling effective film removal while ensuring only minimal contact with the teeth.

Based on the arc-shaped structure of the teeth, the film-removal scraper adopts a corresponding arc design to optimize film-removal performance. As illustrated in Figure 3b, the force exerted by the scraper to remove film adhered to teeth is denoted by F_m. This force can be decomposed into a tangential component F_mx along the detachment direction of the teeth and a normal component F_my. Here, F_mx represents the effective film-removal force, whose magnitude directly determines the film-removal effectiveness. According to the formula F_mx = F_m·cosα, analysis indicates that a smaller curvature radius r_s of the arc scraper (resulting in smaller α) causes the component force F_mx to approach closer to the maximum resultant force F_m, thereby enhancing the film-removal capability. However, an excessively small curvature radius r_s reduces the contact interaction distance between the scraper and the teeth, consequently diminishing the scraping efficiency. To balance maximizing the film-removal force and maintaining an adequate operational range for the scraper, ensuring effective removal of residual film from the teeth, the curvature radius of the arc scraper was determined to be 144 mm.

2.2.3. Installation Position of the Film-Removal Device

Figure 4 illustrates the setup of an xy-coordinate system with its origin at point O, the pivot of the toothed roller. The pivot of the film-removal roller is denoted as point O₁ at coordinates (x, y). The notations R₁ and R₂ refer to the toothed roller’s and the arc-shaped scraper’s utmost rotation radii, measured in millimeters. Meanwhile, R₃ indicates the furthest radius at which the tooth mounting base can rotate, also in millimeters. The angle β describes the orientation of the line that joins the two pivot points relative to the horizontal x-axis. Lastly, L measures the separation between the centers of rotation, given in millimeters. Thus, the coordinates of O₁ can be expressed as (L·cosβ, L·sinβ). To avoid interference between the film-removal scraper and the tooth base during operation, the distance L must satisfy R₂ + R₃ < L < R₁ + R₂. S_m represents the effective operational area for film removal; a larger area indicates more significant film-removal effectiveness. Its expression, derived from the geometry of the intersecting circles (see Figure 4), is given by

$$S_m=\mathrm{arc}\cos \left({\displaystyle \frac{{R_1}^2+L^2-{R_2}^2}{2R_{1}L}}\right)\cdot {R_1}^2+\mathrm{arc}\cos \left({\displaystyle \frac{{R_2}^2+L^2-{R_1}^2}{2R_{2}L}}\right)\cdot {R_2}^2-\sqrt{\left[{\left(R_1+R_2\right)}^2-L^2\right]\cdot \left[L^2-{\left(R_1-R_2\right)}^2\right]}$$

(1)

where R₁ = 475 mm, R₂ = 360 mm, and R₃ = 370 mm.

To ensure a sufficiently large effective area S_m while satisfying the center distance L condition, L was set to 735 mm and β to 55°. Through calculation, the rotation center O₁ of the film-removal roller was determined to be (420, 600), thereby defining the installation position of the arc-shaped scraper film-removal device.

2.2.4. Device Disc Harrow Device

The disc harrow assembly, positioned at the front of the machine, is primarily used for harrowing operations after plowing. As a typical surface soil preparation device [27,28], it breaks soil clods and levels the ground surface through functions such as soil cutting, crushing, and turning. As shown in Figure 5, the device consists of a harrow frame, notched disc harrow set, full-edge disc harrow set, scrapers, and an angle adjustment mechanism. The overall dimensions of the device are 1212 mm in length, 1990 mm in width, and 720 mm in height, with a single harrow set working width of 850 mm. To ensure excellent traveling stability, the harrow sets are arranged in a compact double-row opposing configuration. Lightweight harrow discs with a diameter of 460 mm were selected based on the loam soil type. The angle adjustment mechanism is used to regulate the disc angles of both harrow sets to adapt to different soil conditions and harrowing depth requirements [29]. During operation, the discs roll forward under traction force and penetrate the soil to a certain depth under the combined action of the harrow set’s weight and soil resistance, thereby performing soil cutting and turning.

2.2.5. Soil Crushing and Leveling Device

The soil crushing and leveling device is located at the rear of the machine, comprising two symmetrically arranged sets with a working width that covers the film recovery operation width. Its function is to crush and level the surface soil, creating a “loose upper and compact lower” structure to improve soil preparation quality, reduce water evaporation, and facilitate seed germination. As shown in Figure 6, the device consists of a floating profiling frame, a soil-crushing roller, and a press roller [30]. The maximum dimensions of the device are 1055 mm in length, 2660 mm in width, and 945 mm in height. The soil-crushing roller features a serrated blade structure, offering advantages such as excellent soil penetration, low resistance, and high soil-crushing efficiency [31,32]. The press roller is composed of multiple spaced iron wheels with raised edges, featuring a corrugated pattern on their outer circumference that provides strong soil penetration capability [33].

The working principle of the soil crushing and leveling device is illustrated in Figure 7. The soil-crushing roller has 10 serrated blades uniformly distributed around its circumference, resulting in an angular spacing of 36° between adjacent blades. Based on agronomic requirements for a loose soil layer depth of 30–40 mm, the roller diameter must satisfy the following conditions:

$$\left\{\begin{array}{c}\cos 36°={\displaystyle \frac{D_S/2-Z}{D_S/2}}\\ 30⩽Z_S⩽40\end{array}\right.$$

(2)

where D_S is the soil-crushing roller diameter, mm. Z_S is the soil-crushing depth, mm. The solution yields a roller diameter range of 314 mm ≤ D_S ≤ 418 mm.

The compaction effect of the press roller on soil primarily depends on its ground contact weight and diameter [34]. The leveling depth is expressed as

$$Z_P\infty {G_P}^{{\displaystyle \frac{2}{3}}}{L}^{-{\displaystyle \frac{2}{3}}}{D_P}^{-{\displaystyle \frac{1}{3}}}$$

(3)

where Z_P is the leveling depth, mm; G_P is the ground contact weight of the press roller, kg; L is the working length of the press roller, mm; and D_P is the diameter of the press roller, mm.

2.3. Dynamics Analysis of the Machine’s Operational Process

During field operation, the machine sequentially performs harrowing, film picking, film removal, film collection, and soil crushing and leveling operations. A force analysis of the machine, as illustrated in Figure 8, yields the following equations:

$$\left\{\begin{array}{c}{\displaystyle \sum F_x=0},F-F_f=0\\ {\displaystyle \sum F_y=0},N_1+N_2+N_3+N_4-G=0\\ N_1=N_{11}+N_{12},N_4=N_{41}+N_{42}\end{array}\right.$$

(4)

where the traction force of the machine is designated as F, N, while the total resistance force is F_f, N. The total support force acting on the disc harrow is defined as N₁, N. N₂ is the support force on the arc-shaped teeth, N. N₃ is the support force on the walking wheel, N. N₄ is the support force on the soil crushing and leveling device, N. The gravitational force is represented by G, N. N₁₁ is the support force on the notched disc harrow set, N. N₁₂ is the support force on the full-edge disc harrow set, N. N₄₁ is the support force on the soil-crushing roller, N, and N₄₂ is the support force on the press roller, N.

During operation, the total resistance force F_f acting on the machine from the soil primarily originates from the harrowing, film picking, and soil crushing and leveling operations. Further analysis of this total resistance F_f yields

$$F_f=F_1+F_2+F_3+F_4$$

(5)

where F₁ is the soil resistance on the disc harrow blades, N; F₂ is the soil resistance on the arc-shaped teeth, N; F₃ is the soil resistance on the walking wheel, N; and F₄ is the soil resistance on the soil crushing and leveling device, N.

As the disc harrow blades roll forward and penetrate the soil to a certain depth under their weight and soil reaction, the soil resistance F₁ on the disc harrow blades, based on literature [35], is obtained as

$$F_1=k_{b}aB$$

(6)

where k_b is the specific resistance of disc harrowing, N/cm² (typically k_b = 3.5 N/cm² for uncultivated loam, k_b = 5.5 N/cm² for uncultivated heavy clay, k_b = 2.1 N/cm² for cultivated loam, and k_b = 2.8 N/cm² for cultivated heavy clay; k_b = 2.1 N/cm² is selected based on the operating environment). a is the soil penetration depth, mm, and B is the total working width of the disc harrow, cm.

During the film-picking operation, based on studies [36,37], the soil resistance F₂ on the arc-shaped teeth of the toothed roller is

$$F_2=n\left(f_0{N}_2+kab+\epsilon ab{v}^2\right)$$

(7)

where n is the number of arc-shaped teeth penetrating the soil during film picking. f₀ is the comprehensive friction coefficient (generally taken as f₀ = 0.35–0.5 according to literature [38]). k is the coefficient related to soil deformation and cutting resistance (typically k = 2 N/cm² for light soil, k = 4 N/cm² for medium soil, k = 6 N/cm² for heavy clay, and k = 6–10 N/cm² for very heavy soil; k = 2–4 N/cm² is selected based on the operating environment). ε is the coefficient related to penetration depth and actual working width (typically ε = 4000 N·s²/m⁴). a is the penetration depth, mm. b is the actual working width of a single arc-shaped tooth, mm, and v is the forward speed of the machine, m/s.

Comparable analyses of rotor-soil interaction demonstrate that transporting and loosening performance strongly depend on rotor geometry and soil resistance parameters [39]. These observations support the mechanical assumptions used in this study.

The resistance F₃ on the walking wheel is estimated as

$$F_3=f_1 N_3$$

(8)

where f₁ is the rolling friction coefficient between the soil and the walking wheel (i.e., the rolling friction coefficient between soil and rubber), generally taken as f₁ = 0.15–0.30 [40].

The soil crushing and leveling device consists of a soil-crushing roller and a press roller. The soil resistance on it can be composed of the resistances on these two components. The soil-crushing roller has spiral-arranged serrated soil-crushing bars. The soil resistance on it mainly comes from the serrated teeth penetrating the soil and shearing soil blocks, roller rolling friction, and kinetic energy consumption due to soil throwing by the rotating roller. Thus, the resistance on the soil-crushing roller consists of cutting and crushing resistance, rolling friction resistance, and soil-throwing dynamic resistance. The press roller has a corrugated surface, formed by multiple iron wheels with spaced protrusions arranged in a mesh structure. During operation, the protrusions compact the surface soil, and the soil resistance mainly comes from the rolling friction between the soil and the iron wheels. Based on the actual operation, the soil resistance on the soil crushing and leveling device is

$$\left\{\begin{array}{c}{F}_4=F_{41}+F_{42}\\ F_{41}=ika{b}_1+f_2{N}_{41}+i\epsilon a{b}_1{v}^2\\ F_{42}=f_2{N}_{42}\end{array}\right.$$

(9)

where F₄₁ is the total operational resistance on the soil-crushing roller, which comprises the cutting, rolling friction, and soil-throwing dynamic resistances as described, N; F₄₂ is the predominantly rolling friction resistance on the press roller, N; i is the number of serrated teeth penetrating the soil; b₁ is the working width of a single serrated tooth, mm; and f₂ is the rolling friction coefficient between the soil and the soil-crushing roller (i.e., the rolling friction coefficient between soil and steel), generally taken as f₂ = 0.13.

Combining Equations (5)–(9), the total soil resistance F_f acting on the machine is

$$F_f=a\left(k_{b}B+\left(k+\epsilon v^2\right)\cdot \left(nb+i{b}_1\right)\right)+n{f}_0{N}_2+f_1{N}_3+f_2{N}_4$$

(10)

The power required by the machine is mainly consumed in overcoming soil resistance, machine propulsion, machine transmission, and transmission system losses. It can be divided into traction power, transmission operational power, and transmission loss power:

$$W=W_1+W_2+W_3$$

(11)

where W is the total power required by the machine, kW. W₁ is the traction power of the machine, kW. W₂ is the transmission operational power of the machine, kW, and W₃ is the power lost in the transmission system of the machine, kW.

The traction power W₁ is

$$W_1={\displaystyle \frac{F_{f}v}{1000}}={\displaystyle \frac{1}{1000}}\left\{a\epsilon (nb+i{b}_1)v^3+v\left[a\left(k_{b}B+k(nb+i{b}_1)\right)\left.\left.+n{f}_0{N}_2+f_1{N}_3+f_2{N}_4\right]\right\}\right.\right.$$

(12)

The transmission operational power W₂ can be considered as the combined power of the film-picking power from the rotating toothed roller and the film-removal power from the rotating film-removal roller. The film-picking power can be regarded as the power generated to overcome soil resistance, while the film-removal power is determined by the product of the centrifugal force on the residual film and its relative sliding speed against the teeth:

$$\left\{\begin{array}{c}{W}_2=W_p+W_d\\ W_p={\displaystyle \frac{F_2{v}_p}{1000}}={\displaystyle \frac{F_2}{1000}}\cdot {\displaystyle \frac{2\pi n_p}{60}}{R}_p={\displaystyle \frac{1}{30000}}{F}_2\pi n_p{R}_p\\ W_d={\displaystyle \frac{m{v_m}^2}{1000r}}{v}_{pd}={\displaystyle \frac{m}{1000r}}{\left({\displaystyle \frac{2\pi n_d}{60}}{R}_d\right)}^2\left({\displaystyle \frac{2\pi n_p}{60}}{R}_p+{\displaystyle \frac{2\pi n_d}{60}}{R}_d\right)\\ ={\displaystyle \frac{{\pi }^3}{450000}}m{n_d}^2{R}_d\left(n_p{R}_p+n_d{R}_d\right)\end{array}\right.$$

(13)

where W_p is the rotational power of the toothed roller, kW. W_d is the rotational power of the film-removal roller, kW. n_p is the rotational speed of the toothed roller, r/min. R_p is the maximum rotation radius of the toothed roller, mm. m is the mass of the residual film on the teeth, g. v_m is the linear velocity of the residual film at the point of film-removal action, m/s. r is the rotation radius at the interaction point between the film-removal device and the residual film, usually taken as the maximum rotation radius of the film-removal roller R_d, mm. v_pd is the relative velocity between the two rollers at the interaction point, i.e., the relative sliding speed of the residual film leaving the teeth, m/s, and n_d is the rotational speed of the film-removal roller, r/min.

Neglecting the power loss in the transmission system W₃, the total power W of the machine can be considered as the sum of the traction power W₁ and the transmission operational power W₁. Combining Equations (12) and (13), the total power required by the machine W is

$$\begin{array}{ll}W& ={\displaystyle \frac{1}{1000}}\left[a\epsilon (nb+i{b}_1)v^3+v\left(a{k}_{b}B+ak(nb+i{b}_1)+n{f}_0{N}_2+f_1{N}_3+f_2{N}_4\right)\right]\\ & +{\displaystyle \frac{\pi n_p{R}_{p}n}{30000}}\left(f_0{N}_2+kab+\epsilon ab{v}^2\right)\hspace{0.33em}\hspace{0.33em}+{\displaystyle \frac{{\pi }^3}{450000}}m{n}_d^2{R}_d\left(n_p{R}_p+n_d{R}_d\right)\hspace{0.33em}\end{array}$$

(14)

Analysis shows that under constant structural parameters such as the actual working width b of a single arc-shaped tooth, the total working width B of the disc harrow, the working width b₁ of a single serrated tooth, the radius R_p of the toothed roller, and the radius R_d of the film-removal roller, the total power required by the machine depends on the following operational parameters: forward speed v, rotational speed of the toothed roller n_p, rotational speed of the film-removal roller n_d, and working depth a (penetration depth of the disc harrow and teeth).

Based on the corresponding parameters, the calculated maximum total power required by the machine is approximately W ≈ 82 kW, and the required transmission operational power is approximately W₂ ≈ 57 kW. Considering power redundancy, and according to the literature [41], the tractor efficiency η ranges from 0.8 to 0.9. Thus, the required tractor engine power for traction and driving the machine is W_T ≥ 103 kW, and the required PTO output power is W_PTO ≥ 71 kW. These calculated power requirements directly determined the selection of a tractor with commensurate power specifications for the field experiment.

2.4. Field Performance Experiment

2.4.1. Test Conditions and Instruments

To investigate the influence of operational parameters on residual film recovery performance, identify the optimal parameter combination, and evaluate the soil preparation functionality, a field performance test was conducted on a cotton farm in Shihezi City, Xinjiang (approximately 44.45° N, 85.96° E) in mid-April 2025. The test field was a cotton field that had been plowed and was awaiting harrowing and soil preparation. The field had been continuously used for film-mulched cotton cultivation for over 15 years, covering an area of approximately 5.3 hm², with a film thickness ranging from 0.008 to 0.01 mm. The soil was identified as loam with a mean compaction of 218.23 kPa and an average moisture content of 14.86% in the 0–150 mm depth profile and had a surface evenness of 7.35 cm. The testing process is illustrated in Figure 9.

The vehicles, instruments, and tools used in the experiment included a Tiantuo wheeled tractor (model: TNP1604; manufacturer: Tianjin Tractor Manufacturing Co., Ltd., Tianjin, China; rated engine power: 118 kW; PTO power: 100.3 kW; PTO speed: 540 r/min), a measuring tape (range: 50 m; accuracy: 0.001 m), a roll tape (range: 5 m; accuracy: 0.0001 m), a digital electronic scale (range: 3 kg; accuracy: 0.01 g), a sampling frame (1 m × 1 m, custom-made), a protractor, a stopwatch, adhesive tape, a shovel, a marker pen, sealing bags, a notebook, marker flags, etc.

2.4.2. Test Methods

Based on the analysis results from Section 2.3 and in accordance with the relevant requirements of the Chinese national standard GB/T 25412-2021—“Residual Plastic Film Recovery Machines”, which governs the test methodology for machine performance, and GB/T 25413-2010—“Limit and Determination of Residual Plastic Film in Farmland” [42,43], which stipulates the sampling and measurement protocols for residual film, a three-factor orthogonal experiment was conducted. The factors selected were the forward speed, the rotational speed of the film-removal roller, and the working depth, aiming to determine the order of influence of these factors on the performance indicators and to identify the optimal parameter combination. Additionally, the surface evenness after operation was measured following the evenness quantification method defined by the Chinese agricultural machinery extension appraisal outline DG/T 096-2021—“Combined Soil Preparation Machines”, where evenness is evaluated as the standard deviation of surface height measurements with a compliance threshold of ≤2.5 cm, to assess whether the soil preparation quality met the standard for leveling operations [44].

The test field was divided into four plots along the midlines of its length and width. Two diagonal plots were randomly selected as measurement areas. The positions of five measurement points were determined using the five-point sampling method, with each point covering a 1 m × 1 m area. This sampling protocol was designed to comply with the Chinese national standard GB/T 25413-2010 [43], ensuring a representative assessment of residual film mass across the field for performance evaluation. Before machine operation, the residual film was collected from all five points in each of the two measurement areas. After operation, the remaining residual film in the randomly selected points and the film remaining on the arc-shaped teeth of the film-removal roller were collected. The collected film was rinsed with clean water, air-dried in the shade, and weighed using an electronic scale to calculate the film-pickup rate and the film-removal rate, using the following formulae:

$$\left\{\begin{array}{c}{H}_1={\displaystyle \frac{C_0-C_1}{C_0}}\times 100\%\\ H_2=\left(1-{\displaystyle \frac{C_2}{C_2+C_3}}\right)\times 100\%\end{array}\right.$$

(15)

where H₁ is the film-pickup rate, %. C₀ is the mass of residual film at the measurement point before operation, g. C₁ is the mass of residual film remaining at the measurement point after operation, g. H₂ is the film-removal rate, %. C₂ is the mass of residual film remaining entangled on the film-removal roller after operation, g, and C₃ is the mass of residual film in the collection box after operation, g.

After machine operation, measurement points were randomly selected in the worked area. A horizontal line through the highest point on the ground surface within each point served as the datum line. Multiple equidistant points were set within the measurement area, and the vertical distance from each point to the datum line was measured. The average value and the standard deviation of these measured heights were calculated, with the standard deviation representing the surface evenness. The calculation formulae are as follows:

$$\left\{\begin{array}{c}\overline{X}={\displaystyle \frac{\Sigma X}{n_x}}\\ S=\sqrt{{\displaystyle \frac{\Sigma {\left(X-\overline{X}\right)}^2}{n_x-1}}}\end{array}\right.$$

(16)

where $\stackrel{-}{X}$ is the average measured height, cm. X is each measured vertical distance, cm. n_x is the number of vertical distance measurements within the measurement point (n_x = 20). S is the surface evenness, cm.

2.4.3. Experimental Factors and Levels

A field experiment on residual film recovery performance was conducted by selecting the forward speed, the rotational speed of the film-removal roller, and the working depth as experimental factors. A three-level orthogonal experimental design was adopted to sufficiently capture the main effects and interactions of these factors with a practical number of experimental runs. Based on the operational speeds of residual film recovery and soil preparation, as well as the theoretical gear speeds of the tractor, the forward speed was set to 3–5 km/h. According to the structural parameters of the film-removal device and the number of actions of the arc-shaped scrapers on each row of teeth, the rotational speed of the film-removal roller was set to 150–450 r/min. The working depth range of 80–120 mm was selected based on the structural parameters and theoretical penetration depth of the disc harrow and the previously studied toothed roller. The factors and levels for the field experiment are shown in

Table 1. Factors and levels of the field experiment.

Level	Experimental Factor
	A/km·h−1	B/r·min−1	C/mm
Lower level (−1)	3	150	80
Center level (0)	4	300	100
Upper level (1)	5	450	120

.

3. Results

3.1. Analysis of Residual Film Recovery Performance

3.1.1. Range Analysis and Variance Analysis

To investigate the influence of operational parameters on the residual film recovery performance of the machine, this study selected forward speed (A), rotational speed of the film-removal roller (B), and working depth (C) as experimental factors. The performance indicators evaluated were the film-pickup rate (H₁) and the film-removal rate (H₂). A three-factor, three-level orthogonal experimental design was established using Design-Expert 13 software, resulting in nine test groups, each replicated three times with averaged results. The experimental scheme and results are presented in

Table 2. Orthogonal experimental scheme and results for film-pickup rate (H₁) and film-removal rate (H₂).

Test Number	Factors			Indicators
	A/km·h−1	B/r·min−1	C/mm	H1/%	H2/%
1	3	150	80	39.47	81.12
2	3	300	100	56.68	98.17
3	3	450	120	58.82	100.00
4	4	150	100	60.75	85.20
5	4	300	120	71.98	96.20
6	4	450	80	58.61	100.00
7	5	150	120	48.45	84.63
8	5	300	80	47.17	91.69
9	5	450	100	53.26	100.00

Note: A—forward speed; B—rotational speed of the film-removal roller; C—working depth.

.

As presented in Table 2, the film-pickup rate H₁ ranged from 39.47% to 71.98%, and the film-removal rate H₂ ranged from 81.12% to 100.00%. The 100% removal rates recorded in Tests 3, 6, and 9 were attributed to the high rotational speed of the film-removal roller (450 r/min), which, in synergy with the counter-rotating scrapers, ensured complete mechanical stripping of the collected film. The removal rate reached 100% at the maximum roller speed (450 r/min) due to maximized centrifugal force and scraping action. Conversely, the lower values (e.g., 81.12%) occurred at the minimum speed (150 r/min), indicating that the force applied was insufficient to fully detach the film from the teeth on the toothed roller. The corresponding range analysis is presented in

Table 3. Range analysis of the effects on film-pickup rate (H₁) and film-removal rate (H₂).

Experimental Index	Items	A/km·h−1	B/r·min−1	C/mm
H1	k1	51.66	49.56	48.42
	k2	63.78	58.61	56.90
	k3	49.63	56.90	59.75
	R	14.15	9.05	11.33
	Order of significance: A > C > B
	Optimal combination: A2B2C3
H2	k1	93.10	83.65	90.94
	k2	93.80	95.35	94.46
	k3	92.11	100.00	93.61
	R	1.69	16.35	3.52
	Order of significance: B > C > A
	Optimal combination: A2B3C2

.

Based on the range analysis results presented in Table 3, comparing the mean k values and range R values for different levels of each factor, the optimal combination of factor levels affecting the film-pickup rate H₁ was determined to be A₂B₂C₃. The order of influencing factors, primary to secondary, was A > C > B. Similarly, for the film-removal rate H₂, the optimal combination was A₂B₃C₂, and the order of factor significance was B > C > A.

To determine the statistical significance of each experimental factor’s effects and to validate the optimal combinations and their order of significance, an analysis of variance (ANOVA) was conducted. The ANOVA results are presented in

Table 4. Analysis of variance.

Experimental Index	Source	Sum of Squares	Degrees of Freedom	Mean Square	F-Value	p-Value
H1	Model	695.08	6	115.85	141.52	0.0070 **
	A	347.24	2	173.62	212.09	0.0047 **
	B	139.20	2	69.60	85.02	0.0116 *
	C	208.65	2	104.32	127.44	0.0078 **
	Residual	1.64	2	0.8186
	Cor Total	696.72	8
H2	Model	450.48	6	75.08	20.75	0.0467 *
	A	4.34	2	2.17	0.5999	0.6250
	B	425.88	2	212.94	58.84	0.0167 *
	C	20.25	2	10.13	2.80	0.2633
	Residual	7.24	2	3.62
	Cor Total	457.72	8

Note: “*” indicates significant difference (p < 0.05); “**” indicates highly significant difference (p < 0.01).

.

The ANOVA results demonstrate the significance of the factors for both response variables. To further quantify their effects and enable prediction, the final equations in terms of coded factors were derived as follows:

For the film-pickup rate (H₁):

$$H_1=55.02-3.33A_1+8.70A_2-5.47B_1+3.61B_2-6.61C_1+1.90C_2$$

(17)

For the film-removal rate (H₂):

$$H_2=93-9.35B_1+2.35B_2$$

(18)

The validity of the statistical models and the ANOVAs is contingent upon several assumptions, which were rigorously checked. Normal probability plots of the residuals showed points closely adhering to a straight line, and plots of residuals versus predicted values showed points randomly scattered without discernible patterns. This confirms that the assumptions of normality and homoscedasticity (homogeneity of variance) were not violated for either model. Additionally, key model comparison statistics were evaluated to assess each model’s quality. For H₁, the predicted R² (R²_Pred) was 95.24%, and for H₂, it was 84.35%, both indicating good predictive capability.

According to the ANOVA results presented in Table 4, for the film-pickup rate H₁, both forward speed A and working depth C exerted a highly significant influence (p < 0.01), while the rotational speed of the film-removal roller B exerted a significant influence (p < 0.05). For the film-removal rate H₂, the rotational speed of the film-removal roller B showed a significant effect (p < 0.05), whereas neither forward speed A nor working depth C demonstrated significant effects. The order of factor influence significance was A > C > B for H₁ and B > C > A for H₂, which is consistent with the range analysis results shown in Table 3.

3.1.2. Analysis of Single-Factor Influence Patterns

To further elucidate the influence patterns of A, B, and C on H₁ and H₂, the analysis model was configured with each factor set to its center level (0) to isolate and determine their individual effects on the performance indicators.

As depicted in Figure 10a, H₁ exhibited significant variations with changes in the level of forward speed A. As shown in Figure 10b, when the rotational speed of the film-removal roller B increased from 300 r/min to 450 r/min, H₁ showed a slight increase. Figure 10c indicates that the influence of forward speed A on H₁ was higher than that of working depth C, and H₁ changed significantly when the forward speed increased from 3 km/h to 4 km/h. In summary, the order of factor influence on H₁ was A > C > B, which is consistent with the order of significance obtained from both the range analysis and ANOVA.

Furthermore, as each factor varied from its lower level (−1) to upper level (1), the trend of H₁ showed that it initially increased and then decreased with increasing forward speed A and rotational speed of the film-removal roller B. In contrast, H₁ consistently increased with greater working depth C. The maximum H₁ was achieved at a forward speed of 4 km/h, a film-removal roller rotational speed of 300 r/min, and a working depth of 120 mm. This optimal parameter combination is consistent with the results from the range analysis.

Based on Figure 11a, the film-removal rate H₂ showed no significant change with variations in forward speed A but changed significantly with the rotational speed of the film-removal roller B. Figure 11b demonstrates that H₂ increased significantly when the rotational speed of the film-removal roller B increased from 150 r/min to 300 r/min, while the influence of working depth C on H₂ was not significant. According to Figure 11c, neither forward speed A nor working depth C had a significant effect on H₂, although H₂ showed a slight increase when the working depth increased from 80 mm to 100 mm. In conclusion, the order of factor influence on H₂ was B > C > A, which aligns with the results from both the range analysis and ANOVA.

Additionally, as each factor varied from its lower level (−1) to upper level (1), the trend of H₂ initially increased and then decreased with increasing forward speed A and working depth C. In contrast, H₂ consistently increased with a higher rotational speed of the film-removal roller B. The maximum H₂ was achieved at a forward speed of 4 km/h, a film-removal roller rotational speed of 450 r/min, and a working depth of 100 mm. This optimal parameter combination is consistent with the results from the range analysis.

3.1.3. Determination of Optimal Parameter Combination

The comprehensive analysis results indicate that the optimal combination for maximizing the film-pickup rate H₁ is A₂B₂C₃, while that for maximizing the film-removal rate H₂ is A₂B₃C₂.

Considering that factors A and C exhibited highly significant effects on H₁ but did not reach statistical significance for H₂, as shown in Figure 12, factors A and C were fixed at their optimal levels. Specifically, with factor A fixed at level 2 (4 km/h) and factor C fixed at level 3 (120 mm), increasing factor B from level 2 (300 r/min) to level 3 (450 r/min) resulted in only a 3.24% improvement in H₂. Given that factor B ranked last in the order of influence on H₁ (A > C > B), the limited gain in H₂ achieved by increasing factor B level, and the need to balance both the film-pickup rate H₁ and overall operational efficiency, the optimal parameter combination for field operation was ultimately determined to be A₂B₂C₃. This corresponds to a forward speed of 4 km/h, a film-removal roller rotational speed of 300 r/min, and a working depth of 120 mm. Under these conditions, the model predicts a film-pickup rate H₁ of 72.05% and a film-removal rate H₂ of 96.76%.

To further validate the robustness of this compromise optimal combination (A₂B₂C₃), a sensitivity evaluation was performed by examining the performance of adjacent experimental runs in the orthogonal array. For instance, Test 5 (A₂B₂C₃) itself yielded a high H₁ of 71.98% and H₂ of 96.20%. More importantly, nearby combinations such as Test 2 (A₂B₂C₂) and Test 6 (A₂B₃C₃) maintained H₁ at 56.68% and 58.82%, respectively, while H₂ remained above 98%. This indicates that the system performance, particularly the critical film-removal rate, is not highly sensitive to minor deviations in working depth or roller speed around the chosen optimum. The stability of performance within this operational neighborhood confirms the practical robustness of the selected parameter combination (A₂B₂C₃) for field applications where precise control can be challenging.

3.2. Analysis of Soil Preparation Performance

To evaluate the soil preparation performance of the machine, surface evenness measurements were conducted in all test areas following the residual film recovery performance tests. The results are presented in Figure 13. The surface evenness values measured in all test groups were below 2.5 cm, meeting the performance requirements for surface evenness specified in the Chinese agricultural machinery extension appraisal outline DG/T 096-2021 [44]. Minimal variation in surface evenness was observed across different operational parameter combinations, indicating that the soil preparation quality was primarily determined by the soil crushing and leveling device at the rear of the machine, while showing minimal sensitivity to variations in film recovery operational parameters. These results demonstrate that the machine can consistently meet the evenness requirements for field soil preparation operations while maintaining efficient residual film recovery performance.

3.3. Validation Test

To verify the operational performance and reliability of the optimal parameter combination, validation tests were conducted using the same experimental methodology, with the forward speed set at 4 km/h, the rotational speed of the film-removal roller at 300 r/min, and the working depth at 120 mm. Each test was repeated five times, and the average values of all performance indicators were calculated. The detailed field validation test results are presented in

Table 5. Results of validation test.

Test Number	H1/%	H2/%
1	70.50	97.72
2	71.21	94.11
3	70.23	95.26
4	73.11	95.10
5	71.09	93.11
Average	71.23	95.06
Predicted value	72.05	96.76
Relative error	1.15%	1.79%

.

The validation test results demonstrate that, under the optimal parameter combination, the machine achieved a film-pickup rate of 71.23% and a film-removal rate of 95.06%. The minor variations observed across the five replicates (H₁: 70.23–73.11%; H₂: 93.11–97.72%) are attributed to normal field heterogeneities, such as local variations in soil moisture, compaction, and the distribution and size of residual film fragments. The relative errors between the predicted and validated values were 1.14% and 1.76%, respectively, indicating good agreement between predicted and experimental values and confirming the high prediction accuracy and reliability of the model. The surface evenness after operation was 1.23 cm, which is below the standard limit. Overall, the machine met the expected design requirements.

4. Discussion

The optimal parameter combination—forward speed of 4 km/h, roller speed of 300 r/min, and working depth of 120 mm—reflects a balance between the competing goals of high film-pickup rate and high film-removal rate. Forward speed exerted the strongest influence on pickup performance, as it directly governs material throughput and the kinetic energy available for film-soil separation. At insufficient speeds, the toothed roller operates below capacity, resulting in inadequate energy for overcoming film-soil adhesion. Conversely, excessive speed leads to overloading of the roller, reducing the effectiveness of tooth penetration and film scraping, thereby decreasing both pickup and removal efficiency. The strong effect of working depth on pickup rate is attributable to the depth distribution of the residual film. As shown in prior studies [45], the 0–12 cm soil layer in Xinjiang’s cotton fields contains the highest concentration of residual film. Setting the working depth to 120 mm allows the arc-shaped teeth to directly engage this high-density zone, significantly improving the efficiency of film separation and recovery.

The differential effects of parameters on pickup versus removal rates highlight the distinct mechanisms involved. Pickup performance is governed mainly by soil engagement parameters (forward speed and working depth), whereas removal efficiency depends primarily on the mechanical interaction between the arc-shaped teeth and the scrapers. This explains the dominant role of roller speed in removal performance, as optimal rotation is essential for effective film stripping and transport without re-entanglement. These findings align with those reported by Huang et al. [17] and Shi et al. [18], who also underscored the importance of rotational dynamics in film-soil separation. Furthermore, the observed performance gap, wherein the film-pickup rate (39.47–71.98%) consistently lags behind the film-removal rate (81.12–100%), can be attributed to this fundamental mechanistic distinction. The initial pickup process must overcome the strong, variable adhesion between the soil and fragmented film, which is inherently less efficient than the subsequent, well-controlled mechanical stripping of the film from the roller by the scrapers.

The comparative evaluation against our team’s previously developed prototypes confirms the substantial advancements of the present integrated design. This internal comparison demonstrates a clear improvement, with the new machine achieving a 7.75 percentage point higher film-pickup rate than the arc-toothed roller machine [24] and surpassing the spike-toothed roller device by 2.67 and 15.10 percentage points in pickup and removal rates, respectively [23]. To situate these results within the broader technological context, we compare them with the performance spectrum of dedicated spring tillage-layer recovery mechanisms reported in the literature, such as chain-tooth, soil-throwing, and shovel-screen types [14,15,16,17,18,19,20,21,22]. These established, dedicated machines exhibit a wide range of film-pickup or recovery rates, from approximately 55% to over 90%. However, they share a fundamental and operationally critical limitation: the lack of integrated soil preparation functionality. Consequently, their use typically leaves the field in an unprepared state, necessitating separate subsequent operations and failing to resolve the core pre-sowing operational conflict. In contrast, this study introduces a distinct design paradigm aimed at combined operational efficacy. The developed machine achieves a film-pickup rate of 71.23% and a removal rate of 95.06%, performance levels that are competitive with and fall within the effective range of dedicated recovery machines. The key differentiator is that it simultaneously delivers concurrent soil leveling, preparing a seedbed that meets the ready-to-plant standard (surface evenness ≤ 2.5 cm) in the same pass. This holistic integration of recovery and preparation directly addresses the challenge highlighted in the introduction and represents the principal innovation of this work.

The integrated mechanical approach developed herein addresses a distinct operational challenge compared to perception-based technologies, such as UAV imaging and deep learning for film detection [46,47,48]. These sensing methods provide efficient, non-contact assessment of surface pollution, supplying valuable data for monitoring. However, they do not execute physical field operations. Our machine, conversely, is designed to solve the immediate fieldwork bottleneck of pre-sowing preparation by directly performing physical recovery and simultaneous soil conditioning. This functional distinction highlights that the present work delivers a tangible field-operational solution, which complements the pollution-assessment capabilities provided by remote sensing.

Field studies confirm that minimizing the number of tillage passes reduces soil compaction and results in more uniform seedbed conditions [13]. This supports the advantages of integrating film recovery and soil preparation operations into a single pass. The principal benefit of the developed machine lies in its integration of three critical pre-sowing operations—harrowing, residual film recovery, and soil leveling—into a single, sequential process. This integration delivers clear advantages over the conventional practice of employing separate, dedicated machines for each task. Firstly, it confers major gains in operational efficiency. By reducing the required number of machinery passes across the field from three to one, it directly translates to substantial savings in total field operation time, labor, and fuel consumption. Secondly, it offers significant agronomic and soil health benefits. The single-pass design eliminates the repeated soil compaction that inevitably occurs when multiple heavy machines traverse the field in succession, a key limitation of the segregated approach highlighted in the Introduction. This preservation of soil structure is vital for moisture infiltration, root development, and sustainable soil management. Finally, the machine provides a decisive practical advantage in timeliness. It effectively resolves the core scheduling conflict between the two urgent spring tasks, allowing farmers to achieve both complete film recovery and a ready-to-plant seedbed in a single operation, thereby securing crucial planting windows. These combined benefits underscore the practical relevance and potential impact of the integrated design for sustainable farming systems.

Several limitations should be acknowledged. First, the study was conducted under soil conditions specific to Xinjiang; performance should be verified across other soil types and film-mulching histories. Second, although short-term performance is excellent, long-term durability—particularly the wear arising from the scraper-tooth interaction—requires further evaluation. Third, the power consumption model, while used successfully for tractor selection and parameter screening, lacks validation from in-field measurements (e.g., PTO torque, fuel use). Future work should include such empirical data to fully assess the machine‘s energy efficiency. Future work should include multi-regional trials to enhance adaptability and a comprehensive economic analysis to assess cost-effectiveness compared to conventional separate operations. Furthermore, future iterations could focus on optimizing components such as the soil crushing and leveling roller to mitigate potential film wrapping. Collectively, these limitations highlight that, while the integrated machine is technically viable under Xinjiang conditions, its practical application in diverse regions requires further validation of adaptability, durability, and economic performance, which will be the focus of future work.

In a broader context, this study provides both a technical solution and a methodological framework for addressing agricultural plastic pollution. The optimization strategy combining orthogonal experimental design and analysis may also be applicable to other agricultural machinery development challenges requiring multi-objective optimization.

5. Conclusions

(1)

This study successfully developed and validated a sowing-layer residual film recovery machine integrated with soil preparation functionality. The modular design, incorporating “harrowing–film picking–film removal–soil leveling” in a single pass, effectively resolves the operational conflict between pre-sowing residual film recovery and soil preparation in Xinjiang’s cotton fields. This integration delivers substantial field benefits by reducing the required machinery passes from three to one, thereby saving time, labor, and fuel, while crucially eliminating the repeated soil compaction inherent in conventional segregated operations. Consequently, the machine provides a technically effective and agronomically superior solution for combined pre-sowing operations.

(2)

Through dynamic analysis and orthogonal experimental design with subsequent analysis, the influence patterns of operational parameters on film recovery performance were systematically investigated. The results indicate that forward speed, the rotational speed of the film-removal roller, and working depth significantly affect the film-pickup rate, with the order of influence being forward speed > working depth > rotational speed of the film-removal roller. The film-removal rate is primarily influenced by the rotational speed of the film-removal roller, with the order of influence being rotational speed of the film-removal roller > working depth > forward speed. The optimal parameter combination was determined as a forward speed of 4 km/h, a rotational speed of the film-removal roller at 300 r/min, and a working depth of 120 mm.

(3)

Validation test results under the optimal parameters showed that the film-pickup rate reached 71.23%, the film-removal rate reached 95.06%, and the surface evenness was stabilized at 1.23 cm after operation. All the indicators met the design requirements and showed good agreement with the predicted values (relative error < 2%). Compared to the previously developed arc-toothed roller and spike-toothed roller residual film recovery devices by our team, the current machine achieved significant improvements of 7.75 and 15.10 percentage points in the film-pickup rate and film-removal rate.

(4)

Looking forward, this integrated machine presents a promising solution for regions facing similar challenges of residual film pollution and tight farming schedules. Future work will focus on its adaptability across different soil types and film-mulching histories, along with a comprehensive assessment of scaling potential and cost-effectiveness to facilitate broader adoption.