The 2020-21 year marked the third year under the CRDC Strategic RD&E Plan 2018–23. The strategic RD&E investments that CRDC made in 2020-21 under this plan are helping to continue to drive the Australian cotton industry towards a future of innovation, increased commercialisation and digital transformation.

In 2020-21, Australian cotton growers and the Australian Government co-invested $16.9 million through CRDC into cotton RD&E, across 188 projects and in collaboration with 85 research partners. The investments were made in the five key areas identified in the Strategic RD&E Plan: increasing productivity and profitability on Australian cotton farms; improving cotton farming sustainability and value chain competitiveness; building the adaptive capacity of the Australian cotton industry; strengthening partnerships and adoption; and driving RD&E impact.

In the Annual Report, we bring you an update on our progress towards our strategic goals – our investments, our innovations, and our intended impacts – three years into our Strategic RD&E Plan 2018–23.

Research was undertaken to develop a machine vision-based weed spot sprayer for the Australian sugar and cotton industries. Competition from weeds causes significant loss in production that is estimated at $70M annually to the Australian sugar industry. Commercially-available weed spot sprayers have ability to control weeds growing between the rows. However, weeds growing in the row cannot be easily controlled as the current technologies do not discriminate weeds from sugarcane. Machine vision-based weed detection has potential to reduce herbicide use and runoff by selectively spraying weeds.

This project aimed to integrate machine vision-based weed discrimination algorithms with commercial spray control systems from a spray equipment manufacturer, to develop a field-ready, optimised, precision weed detection system. The project followed from SRA project NCA011 (2010/011) in which proof-of-concept algorithms for discriminating Guinea Grass from sugarcane were developed.

The video data set of sugarcane and Guinea Grass was extended in the current project using a dedicated over-the-row data collection unit, consisting of colour and colour/depth cameras. The data collection device was sent to Cairns in 2016 where video imagery was recorded across nine field trials. Collected video was used to refine and optimise Guinea Grass detection under a range of conditions. Evaluations indicated that colour cameras were more robust and cost-effective than colour/depth cameras.

A commercialisation agreement was developed with the aim of making this technology commercially available to the sugar industry, and a generic sensor module compatible with the commercial partner was developed. An SRA sprayer instrumented with generic sensor modules was evaluated in field trials at Cairns in 2018. Agronomic field trials consisted of recording hit and miss rates during a real-time detect and spray operation using the machine vision-based weed spot sprayer. The machine vision-based spot sprayer achieved average hit rates of 96%, 88% and 67% with less than 1% false triggers on big, medium and small Guinea Grass, respectively, in agronomic field trials for large cane. The spot sprayer was inconsistent in agronomic trials for low cane; however, weed detection accuracy of 89% accuracy was achieved during post-processing analysis that involved image analysis parameter adjustment and recorded field images being replayed through the spot sprayer equipment in a desktop study.

Simultaneous to research in the sugar industry, development of the machine vision-based spot sprayer also occurred for application in the cotton industry. Volunteer cotton is an emerging weed problem in the Australian cotton industry, and there are currently six grasses and two broadleaf weeds with herbicide resistance in Australian cotton systems.

Initially, the project focussed on weed discrimination algorithms using a colour/depth camera, leading to development of novel algorithms. However, the colour/depth camera was limited in application given it required a shade hood and controlled lighting. Subsequently, algorithm development focussed on colour cameras that could operate in daylight and on a free-standing boom that was consistent with industry use cases. The algorithms were implemented on the generic sensor module and a ute-mounted spot spray boom was designed and manufactured for data collection using the generic sensor module to validate developed algorithms.

Video imagery of weeds was collected at six cotton field sites using the ute-mounted spot spray boom, a Phantom drone and a handheld phone/gimbal apparatus. Post-processing analysis was applied to video data collected at five of the cotton farm sites to evaluate weed management strategies using the machine vision-based weed spot sprayer.

Traditional practices of broadacre weed management and the use of the machine vision-based spot spray system were compared by calculating the volumes of herbicide used for both potential approaches. The volume of herbicide required was significantly reduced using the machine vision-based weed spot sprayer. Potential herbicide cost savings were calculated as up to $8 per hectare for a glyphosate-based strategy, and $30 to $40 per hectare for alternate modes of action.

Commercial trials will be required to continue during 2019 for extended field trials including spray efficacy, for both sugar and cotton industries.

Newer export destinations for Australian cotton have demanded larger volumes of traditionally ‘lower’ grade, i.e., shorter staple Middling and Strict Middling types for bulk knit fabrics that like higher grades are still required to dye brightly and consistently. In order to demonstrate the suitability of Australian cotton the CRDC sponsored a small project to demonstrate the yarn quality, dyeing ability and knitted fabric appearance of Australian cotton measured against competing growths in these markets.

The project was proposed after interactions with Bangladeshi spinners in 2016 and 2017; where comparisons were drawn between the dyeing-ability of Australian cotton and other growths used by Bangladeshi mills. A controlled mill trial was proposed to provide a comparison of ‘lower grade’ Australian cotton with other export growths, with which it might compete in this market.

Bales of shorter staple, Strict Middling type cotton from seven countries (Australia, USA, Brazil, China, Uzbekistan, West Africa and India) were supplied by the Australian Cotton Shippers Association (ACSA). Each bale was spun at CSIRO’s industry-scale pilot mill into carded and combed medium-fine count yarn for evaluation. Bales were assessed on fibre and yarn properties, spinning performance, dyed colour and fabric pilling properties.

The results showed Australian cotton was best overall in terms of fibre, yarn and fabric properties. The Australian cotton was whiter (brighter) and produced relatively cleaner, more even and stronger yarn. These fibre and yarn properties translated into a bright, clean fabric with good (bright) dyed colour and better pilling resistance than the other growths. Whilst not representative in a proper sampling sense, the trial highlighted the widely accepted consistency of Australian cotton quality and the excellent efficacy with which it can be transformed into higher quality dyed yarn and fabric.

The presence, compatibility and biodegradability in the environment of pervasive textile materials microfibers shed during laundering or use has been increasingly recognized as an important environmental issue. Textile materials that biodegrade are greatly advantageous relative to those that are not. In this research, the influence of typical textile finishes on the persistence of cotton fibers in aquatic environment has been assessed in aerobic conditions using an RSA PF-8000 respirometer (ISO 14851) using an inoculum of activated sludge at low concentration (30 ppm of total suspended solids). The presence of the finishes alters the surface chemistry of the fibers and their biodegradation rate in aquatic environments. Fibers and fragments of the same cotton knitted fabrics (interlock) without a finish and with different finishes such as durable press, silicone softener, C6 based fluorinated (Non-PFOA) water repellent, and a dye (blue 19) were tracked and fit to kinetic biodegradation models. relative to cotton fabrics without treatments. The biodegradation of fabrics with some levels of crosslinking in the finishing treatment was more affected than other finishes. Cotton fibers with water repellent finish have the longest lag-phase (λ) in which the biodegradation is delayed initially, whereas cotton fabrics with durable press finish had the lowest degradation rate (R) and degraded the least among the samples. Despite the differences in rate, all the cotton samples reached more than 60% biodegradation in 102 days; in fact, the cotton fibers with silicone softener degraded by 90%. The biodegradation rates extents with respect to the different samples are in agreement with the observed trends of the same samples for cellulase hydrolysis and cellulase adsorption experiments (Cellulclast, a cellulase mixture from Trichoderma reesi). This indicates that the finishes decrease the adsorption of enzymes excreted by the microorganisms and the initial rates of biodegradation relative to untreated cotton but that the cellulosic material maintains its biodegradability.

Evaporation of water from open storages is a national problem impacting water security. This is particularly a problem for farmers where evaporation losses are estimated to be above 1,320 GL/year. Cotton industry research shows that these evaporation losses contribute significantly to the amount of water consumed by farmers, estimated between 20-40 %. Monolayer technology has been explored as an alternative to mechanical structures which are limited to small storages (<10 ha) due to their high capital and maintenance costs. Ultra-thin monolayers spread out across the water forming a thin layer which reduces evaporative losses. They have little to no capital costs, can be used only when needed, and can be used on storages of all shapes and sizes, as well as irrigation channels. They are therefore a potentially cost-effective method of reducing this evaporative loss. However, current commercial products have low performance, are readily disrupted by wind and need to be frequently reapplied.

The research team at The University of Melbourne (UniMelb) has previously developed new technology for monolayers to reduce evaporation losses. Testing in the laboratory and small-scale field trials demonstrated savings of up to 40-60% could be obtained under favourable conditions. However, larger scale trials on cotton farm dams identified that there is a critical wind speed threshold for monolayer performance. On storages of ~10 hectares this threshold was identified as 3 m/s: below this threshold the monolayer could achieve evaporation savings of up to 20%. Above this threshold the monolayer failed. This project aimed to understand the mechanism behind the failure of the monolayer at elevated wind speeds and investigate methods to increase the ability of the monolayer to maintain performance at higher wind speeds.

The project has developed a new approach to reduce the impact of wind which causes wind shear and waves, reducing the performance of the monolayer. The new approach was designed and their impacts on monolayer performance were tested.

A series of trials was conducted in a 15 m wind/wave facility in the Michell Hydrodynamics Laboratory at the University of Melbourne. These trials used mechanically produced waves to investigate the separate effects of wind and waves on monolayer behaviour and as such lead to an improved understanding of the monolayer failure mechanism. This information was then used to develop strategies to improve monolayer performance, with prototypes of the new approach tested in the wind/wave facility. It was demonstrated that the negative impact of wind and waves could be reduced, leading to the potential for improved monolayer performance.

For more information please contact Professor Greg Qiao, Department of Chemical Engineering, The University of Melbourne, gregghq@unimelb.edu.au, Ph: (03) 8344 8665

This document provides a brief outline of the projects CRDC has invested in for 2021-22 (current as of May 2021).