In agricultural machinery design and optimization, the discrete element method (DEM) has played a major role due to its ability to speed up the design and manufacturing process by reducing multiple prototyping, testing, and evaluation under experimental conditions. In the field of soil dynamics, DEM has been mainly applied in the design and optimization of soil-engaging tools, especially tillage tools and furrow openers. This numerical method is able to capture the dynamic and bulk behaviour of soils and soil–tool interactions. This review focused on the various aspects of the application of DEM in the simulation of tillage and furrow opening for tool design optimization. Different contact models, particle sizes and shapes, and calibration techniques for determining input parameters for tillage and furrow opening research have been reviewed. Discrete element method predictions of furrow profiles, disturbed soil surface profiles, soil failure, loosening, disturbance parameters, reaction forces, and the various types of soils modelled with DEM have also been highlighted. This pool of information consolidates existing working approaches used in prior studies and helps to identify knowledge gaps which, if addressed, will advance the current soil dynamics modelling capability.

Alternative fuels for diesel engines, such as biodiesel, have attracted much attention recently due to increasing fuel prices and the imperative to reduce emissions. The exhaust gas emissions from tractors and other agricultural machinery make a significant contribution to these emissions. The use of biodiesel in internal combustion engines (ICE) has been reported to give comparable performance to conventional diesel (CD), but with generally lower emissions. There is however, contradictory evidence of NO emissions being both higher and lower from the use of biodiesel. In this work, agriculture tractor engine performance and its emission using both CD and biodiesel from cotton seed oil (CSO-B20) mixed at a 20% blend ration has been evaluated and compared. The PTO test results showed comparable exhaust emissions between CD and CSO-B20. However, the use of CSO-B20 led to reductions in the thermal efficiency and exhaust temperature and an increase in the brake specific fuel consumption (BSFC), when compared to CD.

One of the limitations of using hobbyist remotely controlled aircraft with an attached digital camera is that a great number of images look alike and unless a large number of natural features or artificial targets are present at the location, it is hard to identify and orientate the images. This paper investigates the use of an unmanned aerial vehicle (UAV) for use in agricultural applications. Trials were conducted, in collaboration with researchers from the Australian Research Centre for Aerospace Automation and Queensland University of Technology, on the ability of a UAV autopilot to accurately trigger a two-camera sensor when at a desired location. The study area was located at Watts Bridge Memorial Airfield, near Toogoolawah (152.460°, -27.098°) in southeast Queensland, Australia. The airfield has dedicated areas for use of remotely controlled aircraft, with the mission being undertaken on 5 March 2008. The target and waypoints were arranged so that the UAV flew in an anticlockwise flight pattern. Three separate missions were flown with images being acquired when over target on each of the nine passes. Although capturing the target in the image was achieved on every flight, the accuracy of capturing the target in the middle of the image was variable. The offset from the centre of the image to the target (zero in the perfect system) ranged from just under 15% to just over 60% of the image extent. The misalignment was due to a combination of the predetermined offset value, cross-wind, global position system/autopilot error, the UAV not being level when the image was acquired, and/or inaccuracies in positioning the sensors in the hinged pod. The capacity to accurately acquire images over pre-determined points is essential to ensure coverage and to expedite mosaicing of the images. It will also expand the application of these technologies into the broader-scale applications, such as imaging in broadacre cereal cropping or imaging along transects.