The effect of oscillation angle on the performance of oscillatory tillage

In established Australian vineyards compacted soil either created naturally or by trafficking prevents root growth to desirable depths and restricts root systems from getting water and nutrients. This can reduce the life span and productivity of grapevines considerably over a period of years. To break up these compacted soil layers using small tractors a deep working oscillatory ripper was developed at the University of South Australia which had two deep working oscillating tines. One of the most important factors for the performance of this oscillatory ripper is the oscillation angle of the tines. To find the optimum oscillation angle a series of field tests were conducted in a sand-loam soil at six different oscillation angles. The tines oscillated at a frequency of 4.9 Hz and with amplitudes of between ±60 and 69 mm, with a nominal forward speed of 3 km/h. The trial results were quantified as draft requirement, power saving, power ratio, loosened area and amount of vibration on tractor seat. The greatest draft reduction of 50% was achieved for negative oscillation angles, where power ratio was less than 1. Power saving was significantly affected by changing oscillation angle. In general, vibration of the driver seat was higher for negative angles. In terms of performance −22.5° oscillation angle was the optimum for draft reduction and power saving, whereas the least vibration was obtained at an oscillation angle of +16° which was equal to Australian Standard threshold for 8 h continuous work.

Analysis of effects of operating speed and depth on bentleg opener performance in cohesive soil using the discrete element method

High operating speeds are desirable, different seeding depths are required, and low soil disturbance is necessary for sowing in no-tillage farming. The effects of operating speed (8–16 km h−1) and depth (60–120 mm) on bentleg opener (four variations) performance were analysed in comparison to straight openers in a virtual soil bin using the discrete element method (DEM). Generally, increasing operating depth and speed resulted in increased soil disturbance and reaction forces. However, the bentleg openers loosened furrows down to the furrow bottom and caused less lateral soil throw at all operating depths and speeds. Bentleg openers, particularly without foot, increased furrow width by lower magnitudes compared with straight openers as operating speed was increased. The greatest lateral soil throw beyond furrow banks recorded for the bentleg openers at operating speed and depth of 16 km h−1 and 60 mm were less than the least for the straight openers, except for the footless bentleg with forward raked side leg. Backward raked side leg had the lowest impact on lateral soil throw and spill over distance with increasing operating speed. Increasing operating speed shifted the main ridge created by the bentleg openers above the furrow’s centre outward to the left. Furrow backfill of 97–100% was achieved with the bentleg openers. Bentleg openers with 45° foot rake angle required the lowest draught and vertical forces. Backward raked side leg resulted in the highest draught force among the bentleg openers and the greatest vertical (penetration) force among all the opener

Determination of discrete element model parameters for a cohesive soil and validation through narrow point opener performance analysis

The discrete element method (DEM) is a powerful tool that can be used to predict soil disturbance and soil cutting forces to assist design optimisation of soil cutting tools. In this study, DEM input parameters were calibrated to model a cohesive soil (Black Vertosol of southern Queensland, Australia) using the hysteretic spring contact model, coupled with linear cohesion model, and nominal particle radius of 5 mm. DEM simulations were validated using experimental results for the effects of opener rake angle and cutting edge chamfer, and bentleg opener shank offset on no-tillage narrow point opener performance. Overall, DEM results closely agreed with experimental results and exhibited similar trends. By using particle displacement analysis to predict loosened furrow boundary, most predictions of furrow parameters namely furrow cross-sectional area, furrow width, and critical depth had relative errors ranging from 1 % to 19 %. Lateral soil throw was predicted with relative errors of 0.2 %–9 %, except for the straight opener with 45° rake angle (-32 %). Ridge height was over predicted in all cases due to larger DEM particles than actual soil particles used. Relative errors of 20 %, 22 %, -31 %, and -5 % in draught were recorded for the straight openers with 90° (blunt), 90° (chamfered), and 45° rake angles, and the bentleg opener, respectively. These results show that DEM and the input parameters determined to model the cohesive soil of this study can be used to reliably assess furrow opener performance

No-tillage furrow opener performance: a review of tool geometry, settings and interactions with soil and crop residue

The primary features of an effective and efficient furrow opener include controlled soil disturbance and low draught and vertical force requirements. When integrated in a no-tillage seeding system, furrow openers should also have the ability to assist, and not hinder, the functions of seeding system components – such as maintaining adequate surface residue distribution, accurate and uniform placement of seeds and fertiliser, and regular inter-plant spacing. This review highlights how these goals are affected by opener type, geometry and settings, and soil and residue conditions. Typically, tine openers cause greater soil disturbance than disc openers whereas disc openers are likely to cause residue hairpinning. Winged tine openers reduce residue interference with seed placement and support greater lateral seed spread. Inverted-T openers can achieve subsurface soil shattering, which helps conserve moisture and provides good seed–soil contact. A tine opener with concave cutting edge reduces soil disturbance relative to straight and convex cutting edges. Increasing rake angle, tine width and operating depth increase degree of soil disturbance and draught requirement. Increasing forward speed reduces residue interference with sowing but might decrease the accuracy and uniformity of depth and separation of seed and fertiliser placement. Relative to common openers, bentleg openers have lower draught and penetration force requirements while combining minimal lateral soil throw with high furrow backfill, even at speeds of up to 16 km h–1. The performance of bentleg openers need to be evaluated under residue conditions and in cohesive and adhesive soils. Recommendations for future research are presented