Soil Disturbance Characteristics Research Articles

Simulation of Draught Reduction Performance of Subsoiling with Upcutting Belt Motion Using Discrete Element Method

Conventional subsoiling has the problem of excessive draught resistance, which has long been a major concern. A great reduction in draught is urgently required to make better use of the subsoiling technique with many agronomic benefits. In this study, an attempt was made to test the draught reduction performance of a series of tools with continuous belt motions. Comparative simulations between regular tools and belt tools were carried out using the discrete element method (DEM) to investigate the effects of belt motion on tool force, soil disturbance characteristics, particle velocity distribution, and soil deformation and movement patterns. The results indicated that the belt motion reduced the draught force by 13.18%, 25.21%, 37.98%, and 44.64% for the rake angles of 30°, 45°, 60°, and 75°, respectively, and caused acceptable increases in downward vertical force. The changes in soil disturbance, particle velocity distribution, and soil deformation and movement patterns contributed to the reduction in draught force. Negative effects on soil disturbance were acceptable considering the 13.18% to 44.64% reductions in draught force. The present study suggests that the belt motion has a great application potential for draught reduction in subsoiling. Also, this can serve as a theoretical foundation for future studies.

An In Situ Videotaping Approach for Parameterizing Subsoiling-Induced Soil Disturbance

Subsoiling (SS) is an important technology in conservation tillage, but soil-disturbance characteristics in the SS are rarely described. Research on soil-disturbance characteristics during SS is conducive to the design and optimization of subsoilers, which provides a basis for reducing draft force and energy consumption. This study conducted SS experiments at five different tillage depths in the field with a specific field in situ test-rig facility, and in situ videotaping was made from five positions during SS. The microrelief test, draft force test, disturbance cross-section test and disturbance process analysis were conducted after SS. The results showed that draft force increased with tillage depth as a quadratic function. Soil displacement parameters and soil crack parameters extracted from the video of SS were significantly correlated with tillage depth, which could be used for a quantitative description of the paddy soil-disturbance characteristics. Cross-sectional area showed a trend of “increasing then decreasing” with increasing tillage depth, reaching a maximum at a tillage depth of 20 cm. When the tillage depth was greater than 20 cm, the bottom of the disturbing boundary formed a “mole cavity”. Fallback rate was used to describe the change in disturbed height or width during and after SS, which exceeded 100% at maximum. The surface roughness of microrelief and the size of the average clods reached the maximum at tillage depth of 20 cm. Considering the shallow cultivation layer of paddy soil in rice–wheat rotation, the recommended tillage depth of 20 cm could achieve maximum soil disturbance and minimum energy consumed.

Modelling of paddy soil using the CFD-DEM coupling method

Soil dynamics has been the core of studying the mechanism of soil-tool interaction. However, it is very challenging to study the dynamics of paddy soil that contains a significant amount of water. In this study, a paddy soil model, namely coupling model was developed using the CFD-DEM coupling method. In the coupling model, spherical particles with Johnson-Kendall-Roberts (JKR) surface energy were used to represent paddy soil. The Volume of Fluid (VOF) gas-liquid two-phase flow model was used to represent the characteristics of the water in paddy field. A test and a simulation of soil rotation were performed to calibrate the critical model parameter of soil particle, JKR surface energy. The calibrated value was 2.5 J·m−2, and the relative average error between the simulation and the test was 1.27 %. To verify the accuracy of the coupling model, an experiment of a fertilizer banding opener was conducted in a paddy soil in laboratory conditions. Also, the interaction of the opener with paddy soil was simulated using the coupling model. Then, soil disturbance characteristics and the soil resistance force of the opener were compared between the experiment and model prediction. When using the coupling model to predict, the relative errors were less than 10 % for soil disturbance characteristics and less than 15 % for soil resistance force. This suggests that the model developed using the CFD-DEM coupling method is able to predict the dynamics of soil-tool interaction in paddy fields with reasonably good accuracies.

Effect of Mounting Angle on Bending Subsoiling Tool–Soil Interactions Using DEM Simulations

Mechanical subsoiling is an effective practice to promote better water infiltration and crop root development. The bending subsoiling tool (BST) is a primary subsoiling tool and is used to remove soil compaction and restore soil productivity. In this study, a discrete element model was developed and validated using laboratory soil bin tests to investigate the effects of the mounting angle of the BST (5°–33°) on soil disturbance behaviors and draft forces. The results show that the upheaval, failure and fragmentation of soil was achieved by successive shearing, uplifting, extrusion, tension and turning actions from the cutting share and cambered shank of the BST. Increasing soil depths gave smaller soil disturbance ranges in lateral, forward and upward directions. With an increase in mounting angle, both the draft force and soil rupture distance ratio initially decreased and then increased, whereas the soil loosening efficiency initially increased and then decreased. Overall, increasing the mounting angle of the BST from 5° to 33° gave a greater soil surface flatness that increased rapidly when the mounting angle increased from 26° to 33°. Appropriately increasing mounting angle of the BST from 5° to 26° could lift more moist soil from the deep seed and middle layers (5.0–15.5% increase) into the shallow seed layer (depth of <50 mm) without seriously affecting the mixing of the deep layer and other layers. Considering both the soil disturbance characteristics and draft forces, a mounting angle of 26° appeared to outperform the other angles.

Development of a dual sideway-share subsurface tillage implement: Part 2. Effect of tool geometry on tillage forces and soil disturbance characteristics

Simulation of tillage tool-soil interactions provides opportunities to accelerate new equipment design and evaluate its performance. The dual bent blade subsurface tillage implement which its performance has been evaluated in the field, is a new conservation tillage tool deserving its soil cutting efficiency to be improved by optimizing its geometry using discrete element method (DEM) modeling. In order to achieve this objective, the effect of share size (5.9, 7.6, 11.3, 16.8, 22.6 and 28.2 cm), rake angle (7.5°, 15°, 25°, 30°, 35° and 40°), tilt angle (10°, 20°, 25°, 30°, 35° and 40°), and shank rake angle (45°, 60°, 75°, 90° and 97.5°) of the tool plowing at 150 mm depth, on soil cutting forces and soil disturbance characteristics were investigated using the validated DEM model developed in part 1 of this study. Results showed that the draft and vertical forces increased with increasing share size, while the specific resistance (SR) decreased. With increasing share rake angle, the draft force, SR, upward vertical force and the degree of soil pulverization increased. The minimum SR of the tool was at the tilt angle of 20°. But at this tilt angle, the uniformity of the cutting-depth for a long share-size was low, due to greater lateral bending of the share. As the rake angle of the shank decreased, the draft and vertical upward forces decreased. DEM simulation results showed that an efficient non-inversion tillage implement design can be achieved by developing a dual sideway-share subsurface tillage tool having a total cutting width of 53 cm with the rake and tilt angles of 15° and 10°, respectively, and attached to a 75°-rake-angle shank and plowing 150 mm deep in a sandy clay loam soil.

Development of a dual sideway-share subsurface tillage implement: Part 1. Modeling tool interaction with soil using DEM

In this research, the interactions of a dual sideway-share subsurface tillage implement with soil were modeled by discrete element method (DEM) and evaluated in an indoor linear soil bin. Spherical particles with Hertz-Mindlin contact model and parallel bond between particles were used to simulate agricultural soil aggregates and their cohesive behaviors. In soil bin experiments, soil cutting resistance and soil disturbance characteristics resulting from the tillage tool operating at 0.25 m s−1 and 150 mm cutting depth, were measured. The calibration of bond stiffness was performed through comparing the draft forces of a simple soil engaging tool simulated with DEM and those estimated with an analytical tillage modeling results using a trial-and-error method. The ratio of soil bin measured vertical force to draft force was used in calibration of the most sensitive model parameter, particle shear modulus. Its calibrated value for a sandy clay loam soil was 50 MPa. The calibrated model was validated using the soil forces as well as the soil disturbance characteristics of the tool measured in the soil bin. When comparing the model to the experimental results, the relative error was −2.0% for the average draft force, 2.5% for the average vertical force, −7.7% for the average rupture distance, and 11.7% for the average disturbed area. Therefore, good correlations were achieved between the soil mechanical behaviors obtained by the experiments and the DEM simulations. It can be concluded that in DEM simulations of some tillage tools such as subsurface tillage implement, accurate predictions of the vertical forces as well as the draft forces, could be achieved by calibrating the particle shear modulus using the ratio of vertical force to the draft force applied to the tool.

EFFECTS OF DIFFERENT GEOMETRICAL STRUCTURES ON THE SOIL DISTURBANCES AND WORKING RESISTANCES OF VERY NARROW TINES APPLIED ON NATURAL GRASSLAND

Novel tillage tools with high working performance are desired in improving degraded natural grassland tillage system. This paper aimed to find the influence of various geometry structures of very narrow tines on related soil disturbance characteristics and tillage resistances. Four shank-type tillage tines with different cutting head shapes, and the test bench were designed and manufactured. Field experiments under different working depths were conducted. The working depth uniformity, soil over-turning rate, cross-section area of disturbed soil layer, and related forces were obtained, analysed, and compared. Results showed that, the working depth uniformities were above 70%, and soil overturning rates did not exceed 5%. Furrows with V-shaped cross-section were formed. The tine with an arc-shaped cutting edge (AT) obtained a lower draft force value, and the tine with chamfer structure (TTD) presented big differences on the draft force and soil disturbance compared to the tine with blunt cutting edge (TT). Both the draft force and the area of disturbed soil cross section had a good linear relationship with the working depth, and the specific draft force increased with the working depth increasing. Using a very narrow tine with chamfers to split and break the soil layer on the natural grassland without pulling or dragging the roots could be an appropriate tillage method applied for improving degraded natural grassland, but still need further surveys.

Effect of soil particle-size distribution (PSD) on soil-subsoiler interactions in the discrete element model

Aim of study: This work investigated the significance and mechanism for the effect of particle-size distribution (PSD) under different nominal radii using the discrete element method (DEM) and validated using the laboratory soil-bin results to accurately determine PSD.Area of study: Yangling, ChinaMaterial and methods: The experimental soil was Lou soil. Soil disturbance characteristics (soil rupture distance ratio, height of accumulated soil, soil density change rate) and cutting forces (draft and vertical) under different treatments were predicted and measured respectively.Main results: The ANOVA outputs showed that PSD significantly affected draft and vertical forces (p

Tillage force and disturbance characteristics of different geometric-shaped subsoilers via DEM

With the increased use of agricultural machinery in field operations, soil compaction has become increasingly severe, and the plough pan has become deeper. Subsoiling is an excellent way to address this problem. However, it is limited by high energy consumption, which is closely related to tillage force. To investigate the effect of the geometric shape of shanks and tines on tillage force and soil disturbance in loam, a layered soil model in accordance with the actual conditions was established and five different subsoilers were simulated via discrete element modeling. The results indicated that the shank impacted soil disturbance and tine impacted tillage force. The draft force of curved shank and chisel tine was 8% less than that of the straight shank and sweep tine. The straight shank and sweep tine produced a larger furrow profile and a higher furrow width. The subsoiler with curved shank and chisel tine (C-C) exhibited the lowest specific resistance (12.87, 17.52, 19.46 and 21.18 kN/m2 in the 30, 35, 40 and 45 cm tillage depth, respectively) considering the draft force and soil disturbance characteristics. Hence, these results will facilitate in the selection of a suitable subsoiler and design of new subsoilers with lower energy consumption requirements for loam areas worldwide.

The effect of various edge-curve types of plain-straight blades for strip tillage seeding on torque and soil disturbance using DEM

Strip tillage seeders have shown great advantages in seedbed preparation and residue handling in no and minimum tillage seeding. However, soil disturbance and torque requirements need to be further reduced. To address this issue, the simulation in this study used the discrete element method (DEM) to examine the effect of different edge-curve geometries on torque requirements and soil disturbance characteristics. Herein, the edge-curve geometries include three types of plain-straight blades (Archimedean spiral, logarithmic spiral, and sinusoidal-exponential spiral blades) with four slide-cutting angles of edge-curve tip (30°, 40°, 50°, and 60°). The model particle (i.e., ball-ball) stiffness kn was calibrated through a soil bin test, and the optimum value was 6 × 103 N/m. The results showed that the blade rotation angle varied with respect to the slide-cutting angle of the edge-curve tip when the soil cutting started and the peak value occurred: the larger the slide-cutting angle was, the earlier the soil cutting began and the peak value appeared. Among the three edge-curve types, the Archimedean spiral blade (which had the largest average slide-cutting angle) obtained the highest average torque and the largest number of soil particles thrown upward, whereas the sinusoidal-exponential spiral blade (which had the smallest average slide-cutting angle) obtained the lowest values in both metrics. As the slide-cutting angle of the edge-curve tip increased, the average torque requirement decreased and fewer soil particles were thrown upward, indicating that a larger slide-cutting angle was preferred when less soil disturbance was desired.

Performance of Three DifferentSpades for Residual Plastic Film Recycling Machine

HighlightsEffectively separating the “white pollution” from agricultural soil.Three different spades for mechanical recycling residual film were tested.All spades had a similar draft requirement and soil disturbance trend.Spade A provided a higher residual film recovery rate.Abstract. Plastic film mulching cultivation provides important support for increasing the crop yield and ensuring food security, but residual plastic film pollution has become a prominent problem affecting the sustainable development of agriculture especially in northwest China. Recovery of thicker film by residual plastic film recycling machines may represent an effective way to solve this problem. In this study, a combined implement comprising three different spades (spades A, B, and C) were tested in a cotton field to compare their performance. All three types of spades were tested at a travel speed of 4.5 kmh-1 and a working depth of 40 mm. The residual plastic film recovery rate, soil draft force, soil disturbance characteristics (furrow profile), and cotton stubble uprooting were measured. Spade B had a higher draft force than the other spades. This trend was also observed for the soil disturbance area. Spades A and C produced stubble uprooting of approximately 5%, and spade B resulted in an approximately 5.7% larger degree of uprooting. Spade A had the largest recovery rate of residual film, while spade C had the smallest one. Overall, considering both recovery rate of residual film and draft force requirement, spade A showed better performance compared to spades B and C. Keywords: Draft force, Residual plastic film, Recovery rate, Soil disturbance, Spade.

Optimisation of installation parameters of subsoiler’ wing using the discrete element method

Optimisation of wing installation parameters of a subsoiler is essential for disrupting hardpans, avoiding excessive disturbance of top soil and improving soil loosening efficiency in conservation tillage. In this study, three key wing installation parameters (the upward angle φ, the mounting height h and the mounting angle β) were optimised using the discrete element method (DEM). Two objectives (soil loosening efficiency η and soil disturbance area ratio κ) were selected for the optimisation. The results showed that the φ affected the η the most, followed by the h, and the β. The significance for the influence of wing parameters on the κ followed the order: the h, the φ, and the β; the effect of φ and h interaction on κ was also significant. To maximise both the κ and the η, h and φ should be appropriately reduced and β should be increased appropriately. The optimal values concerning the η and κ maximization are −6.6°, 34.2° and 87.5 mm, respectively, for the φ, the β, and the h. The overall working performance of the subsoiler with optimal wing parameters was the best as indicated by greater η and κ. The model was able to predict soil disturbance characteristics resulting from the subsoiler with relative errors under 15%. The findings in the present study can have implications for optimising the winged subsoiler on aspects of water conservation and soil loosening efficiency.

Effect of soil particle size on soil-subsoiler interactions using the discrete element method simulations

The discrete element method (DEM) has been widely used as a modelling tool to investigate soil-tool interactions. Soil particle size has an important effect on soil disturbance behaviours and cutting forces in discrete element models. In this study, discrete element models were developed using the EDEM software and evaluated using laboratory tests to investigate the effect of varying modelled particle radii (ranging from 3 to 19 mm) on soil-subsoiler interactions in the models. Soil disturbance characteristics (soil rupture distance ratio, height of accumulated soil, soil disturbance area, soil density change rate, and fragmentation index), solution time of the computer, and soil cutting forces (draft and vertical) were measured. Based on the ANOVA outputs, all these variables were significantly affected by the treatments at p

DEM and soil bin study on a biomimetic disc furrow opener

To reduce the resistance and energy consumption of disc furrow openers, biomimetic coupling disc furrow openers (BCDFOs) that were inspired by digging animals (e.g., the convex hull of a dung beetle pronotum and the back-ridge scales of a pangolin) were designed as biomimetic coupling elements. The resistance of BCDFOs, analyzed by the discrete element method, was less than that of the common flat disc furrow opener (CFDFO). The effects of different structures on soil disturbances in the forward and lateral directions were analyzed. The soil swelling rate and soil disturbance coefficient were calculated to evaluate the soil disturbance characteristics. Three less resistant BCDFOs were manufactured and tested in soil bins with different working conditions (furrow speed = 0.6, 1 and 1.4 m/s; soil moisture contents = 18% and 22%). It was found that the furrow resistance of the BCDFOs was obviously less than that of the CFDFO under the same test conditions, thus indicating that the BCDFO concept was an efficient bioinspired design for efficient agriculture tillage.

DEM simulation of bionic subsoilers (tillage depth >40 cm) with drag reduction and lower soil disturbance characteristics

Successive years of mechanical operations and conservation tillage in Northeast China have made subsoiling necessary, and the tillage depth can be no less than 40 cm. In this paper, a bionic design method was used to reduce subsoiler energy consumption and soil disturbance. The bionic structural elements, i.e., triangular prism (BTP) and partial circular column (BPCC), were inspired by the placoid scale rib structure of shark skin, which has low drag. These elements were then applied to the subsoiler to reduce energy consumption. Six types of bionic subsoilers were designed. Discrete element modeling (DEM) was used to simulate and analyze the interactions of the bionic subsoilers and an ordinary subsoiler (O-S) with the soil. The results showed that bionic subsoilers with a shank and BTP in the horizontal direction of motion (S-T-H) and tines with the BTP parallel to the centerline (T-T) had lower draft requirements and energy consumption than the other designs. The draft requirements and energy consumption of S-T-H subsoilers with different height-to-lateral-rib-spacing (h/s) ratios were then compared. The subsoiler with a bionic element h/s of 0.57 (S-T-H-0.57) had a lower draft requirement (1292.59 N) and a lower total energy requirement (23.48 J) than the other designs. A soil disturbance analysis demonstrated that S-T-H-0.57-T-T (bionic elements arranged in both the shank and tine) provided superior benefits in terms of root growth and improved crop stress resistance. The result is consistent with the mechanical analysis of the riblet, which will be helpful for designing new subsoilers with reduced drag and soil disturbance.

Modelling the interaction of a deep tillage tool with heterogeneous soil

Numerical simulation of soil-tool interactions is a cost-effective method to assess and gain insight into the tool performance as affected by working parameters. In this study, a discrete element model (DEM) was developed to simulate a deep tillage tool and its interaction with soil to address the stratified soil layers in agricultural fields using the Particle Flow Code in Three Dimensions (PFC3D). Sensitivity analysis was performed to determine the most critical set of model parameters which affected the soil dynamic behaviors. With test data, this set of model parameters was calibrated using a systematic scheme that featured response surface optimization and inverse solution technique to minimize the discrepancy between simulations and measurements. The model was validated and then utilized to investigate the effects and the optimal value of the working depth. The results showed that the particle stiffness and bond stiffness were the most influential model parameters and the calibrated values were 6.43×1 Nm−1 and 2.62×1 Pam−1, respectively. The calibrated model was capable of predicting soil cutting resistance and soil disturbance characteristics with relative errors ranging from 2.63 to 10.2%. Simulation results indicated that the when the deep tillage tool works at either 5 or 20mm deeper than the hardpan layer, the best performance for breaking the hardpan could be achieved. The proposed model can facilitate the investigation of interactions between soil engaging tools and heterogeneous soil.

Soil disturbance and cutting forces of four different sweeps for mechanical weeding

Sweeps are the most common tools for mechanical weeding for row-crops. However, how their soil disturbance characteristics are associated with the weeding performance has not been well documented in the literature. The main objective of this study was to evaluate the weeding performance of selected inter-row sweeps through laboratory tests. Four different sweeps, namely: Fin, Conventional, ¾-conventional, and Narrow-wing, were tested in an indoor soil bin at a working depth of 40mm and a travel speed of 8kmh−1 in a sandy loam soil. Soil disturbance characteristics (uprooting and cutting width, burial width, and burial depth), soil cutting forces (draft and vertical), and weeding rates were measured. Based on the ANOVA outputs, all these variables were significantly affected by the treatments at p<0.05, except for the draft force. The ¾-conventional and Conventional sweeps had higher vertical forces than the other sweeps. The Conventional and ¾-conventional sweeps produced an uprooting and cutting width of approximately 260mm, and the Fin and Narrow-wing sweeps resulted in an approximately 7.2% larger uprooting and cutting width. The Fin sweep had the smallest burial width (zero), while the ¾-conventional sweep had the largest burial width (308mm). This trend was also observed for the burial depth. In general, the burial depth decreased exponentially from the centre of the sweep path over the lateral distance. The Fin and ¾-conventional sweeps had over 70% weed kill and these two sweeps are recommended as the best choices for row-crop weed control.

Evaluation of Inter-Row Sweeps with Different Working Widths

Abstract. Little information is available on the performance of inter-row sweeps. The aim of this study was to evaluate the potential of inter-row sweeps for mechanical weed control. Sweeps with different working widths (153, 280, and 330 mm) were tested at different working speeds (0.70, 1.53, and 2.22 m s-1) and a constant working depth (50 mm) in an indoor soil bin with a sandy loam soil. Measurements included soil disturbance characteristics: distance of soil throw (L), width of disturbed soil (W), mass of soil throw (M), height of soil ridge (H), and draft force (Fd). Results showed that L increased linearly with the working speed, but L was not affected by the working width of the sweeps. In contrast, W was slightly affected by the speed, but it was significantly increased if a wider sweep was used. Effects of working speed on M and H depended on the sweep width, and the smallest sweep traveling at 2.22 m s-1 resulted in the highest M and H. Draft force was higher for a wider sweep and a higher working speed. Considering the potential weeding efficiency (defined as the ratio of W and Fd), the width of sweep would not make any differences, and a lower working speed would result in better performance. Keywords: Draft force, Inter-row, Soil disturbance, Speed, Sweep, Weeding.

Minimising soil disturbance and reaction forces for high speed sowing using bentleg furrow openers

Australian no-till farmers often use narrow point openers to create furrows for seed and fertilizer placement. However, operational speeds are limited due to excessive lateral soil throw reducing furrow backfill and causing interactions between adjacent furrows. This study measured the effects of speed (8, 12 and 16 km h−1) on soil disturbance and tillage forces for five different openers, aiming to evaluate suitable options for high speed seeding. Three straight shank openers, 90° (blunt and chamfered face) and 53° rake angles were compared to two bentleg geometries (45 and 95 mm offsets), in a dry silt-loam field soil. The 53° straight opener showed the largest response to speed, reducing furrow backfill and increasing lateral soil throw (from furrow center). The addition of a double sided chamfer reduced lateral soil throw and maintained 100% backfill at 8 km h−1 but soil disturbance increased at 12 and 16 km h−1. Both bentleg openers maintained 100% backfill and operated with a lateral soil throw less than half the straight openers at 8 km h−1. However, the 45 mm offset bentleg opener had more soil throw at speed. This resulted in reduced furrow backfill and increased lateral soil throw at 16 km h−1 (reaching similar to the straight shank openers). The 95 mm offset bentleg was able to maintain its low soil disturbance characteristics at speeds up to 16 km h−1. The findings show potential for new opener technology to increase operating speeds of no-till seeding operations by minimising soil disturbance and draft, therefore improving work-rate and timeliness of sowing.

Modeling of soil–claw interaction using the discrete element method (DEM)

Bionics can be applied in the area of designing soil engaging tools in agriculture to minimize power requirement and optimize soil conditions for crop growth. In this study, a bear claw was investigated with the objective of mimicking it for the future design of subsoiling tools. A numerical model was developed using the discrete element method (DEM) to simulate the interaction of the bear claw with soil. During the simulations, soil cutting forces were recorded and soil disturbance of the claw was monitored. The most critical model parameter, particle stiffness, was calibrated through comparing the soil cutting forces and disturbance width of a blade between the simulations and the predictions by the universal earthmoving equation from the literature. Then the calibrated model was used to examine effects of the working depths and rake angles of the claw on the soil cutting forces and soil disturbance characteristics. The results showed that draft and vertical forces varied linearly and nonlinearly, respectively with the rake angle of the claw; however, number of particles dislodged and soil porosity changes varied only slightly with the change of rake angle. All these dynamic attributes significantly increased as the working depth of the claw increased. Considering draft force and soil disturbance, the best performance of the claw was at the rake angle of 30°.