The implementation of Integrated Pest Management and use of Bt varieties has drastically reduced insecticide sprays on cotton farms. This enabled the industry to focus on agronomy, leading to continued growth in yields and profitability over the last 20 years. However, there are still ongoing challenges being faced by growers each season concerning sustainable pest management. Our research in this project focused on some of the more complex issues growers face that occur from the interactions between multiple biotic and abiotic factors that can be unique to each season. We aimed to generate new knowledge to support IPM adoption and potentially reduce the risk of IPM dis-adoption that we see as a growing threat to the future sustainability of cotton. What we achieved in this project included:

• • Further contributions to Table 4 of the Cotton Pest Management Guide, evaluating the effects of new pesticide compounds on non-target species (predators and parasitoids) and ranking them according to the standard that is now a well-known IPM resource.
• • We examined insecticides specifically aimed at controlling silverleaf whitefly (SLW) given the increased likelihood of resistance to some commonly used products. In both years the impacts of the insecticides were not significantly different from each other or the unsprayed control. However, our trials did show that predators and parasitoids, if not interfered with, can control pest numbers.
• • We tested an app that assessed SLW nymphs on leaves to make SLW monitoring more time efficient. The app captured about 51% of the variance of the nymphs on leaves. However, with refinement, these types of tools will become increasingly important for monitoring pest populations.
• • We conducted experiments to examine the effect of early season pest damage on yield of BGIII cotton and compensation for early fruit loss by plants. We simulated pest damage by tipping and removing fruit from the lower and mid-canopy fruiting branches. Tipping of cotton between nodes 5 and 7 or loss of fruit from the lower six fruiting branches (FB 1-6) in a portion of the crop (33%) did not result in significant yield loss or a delay in maturity. However, fruit loss from fruiting branches in mid- canopy (FB 7-12) and/or a higher proportion of the crop (100%) has the potential to incur greater yield loss and significantly delay maturity. The potential for loss was greater in higher yielding crops. Our results suggested that low levels of insect damage could be tolerated, which has implication for mirid management and future research.
• • There was no significant compensation for losses but the severity and timing of damage changed fruit development and contribution to yield within plants. In undamaged plants, the contribution to yield by bolls from the plant core (FB 1-12, Position 1&2 bolls) was 65%, contribution from bolls on vegetative branches was 21% and 14% from bolls on the remainder of the plant (FB 13+ and FB1-12 P3 bolls). This pattern remained when only every third plant was damaged (FB1-6 or FB 7-12) but damage to FB 7-12 or to more plants (100%) shifted yield contribution to vegetative branches and upper canopy in roughly equal proportions. The most extreme damage (FB1-12 x 100%) shifted 51% of fruit and yield production to the upper and outer canopy, and 33% to vegetative branches.
• • We conducted experiments to test the effect of cloudiness and mirid damage (both simulated and actual damage via mirids themselves) on cotton yield. Our findings showed that plants can compensate for both factors in this controlled environment, and there was no impact on bolls and lint weight at the end of the season.
• • We attempted to link changes in whole invertebrate communities to the cumulative application of multiple insecticide products across a season (via the BDI, beneficial disruption index). This exploratory approach showed that BDI is only one of many factors that influence community turnover and change and our experimental design could not unpick these interacting factors.
• • Endemic pest issues are further compounded by the continued threat of exotic incursions. During this project, we contributed to the Australia-wide response to the arrival of fall armyworm. This species has established in maize at ACRI and is already being attacked by parasitoids. We also contributed to the cotton industry plans to respond to future threats like blue disease.
• • An incentive-based approach to enhance IPM best practice that focussed on exploring the economic benefits of IPM to individual growers, especially long term; and encouraging realistic expectations of yield based on seasonal constraints. In consultation with Mr Ben Simpson (CRDC) and Ms Janine Powell (AgEcon) we developed a survey instrument to identify whether an IPM approach to growing cotton is costly (or whether there is no correlation in cost), however, the survey itself was not conducted

Our work during this project supports the importance of early season crop management which can greatly impact on outcomes at the end of the season and beyond. The use of pesticides to control thrips, cutworm, wireworm and mirids is likely to increase the risks of resistance development and can negatively affect beneficial species. In some years that risk may be manageable and in others it may not. Furthermore, plants can compensate for certain levels of pest damage, even when combined with other factors (such as physiological fruit loss and cloudiness). Capacity-building of growers and consultants as well as a re-evaluation of what knowledge tools are required will help in these complex scenarios.

Our team faced many challenges throughout this project, beyond the risk of extreme seasonal weather events. Both the impacts of Covid-19, staff changes and personal crises influenced the timing and success of some experiments but we implemented contingency plans wherever possible. Furthermore, we see the need to better understand the complex interactions between the crop, insects and abiotic processes in order to answer pertinent industry questions and improve on current IPM practices.

Agriculture plays a vital role in the well-being of rural communities, food security, employment, and societal improvement. Adopting best management practices ensures socially responsible farming by safeguarding public health, promoting food safety, and supporting sustainable livelihoods for farmers and rural communities. These practices contribute to vibrant rural economies, enhance community resilience, and foster social cohesion, promoting a healthy and sustainable agricultural sector.

By embracing industry best management practices, farmers fulfil their social and environmental responsibilities, aligning their agricultural practices with broader goals of sustainable development, environmental stewardship, and community well-being. This primarily occurs through production-related practices and investment in natural capital improvements.

Through industry-led science-based practices and the adoption of precision agriculture methods and AgriTech, growers can:

• minimise soil erosion,
• enhance soil health and fertility,
• conserve water,
• reduce inputs.

Investments in wildlife corridors, habitat restoration, and collaborative projects with consumers and retailers.

• improve farm biodiversity,
• preserve essential species and ecosystems,
• protect soils from wind and water erosion,
• promoting on-farm biodiversity for future generations.

Globally, agriculture is both affected by and contributes to climate change. Embracing best management practices that promote climate-smart strategies helps reduce greenhouse gas emissions and increase soil carbon sequestration. Continuously improving practices enhance the resilience of agricultural systems by improving water management, soil health, and crop diversification, enabling farmers to adapt to changing climate conditions.

Adopting industry-led best management practices in agriculture ensures social responsibility, environmental sustainability, and community well-being. Farmers contribute to a more sustainable and resilient agricultural sector for present and future generations by minimising negative impacts, promoting biodiversity, and addressing climate change.

[1] Community Resilience, Wellbeing and Recovery Project Resources | Mental Health Commission of New South Wales

[2] Impact of Climate Change on Agriculture and Its Mitigation Strategies: A Review

International trade represents an important pathway for the accidental introductions of alien species that threaten primary industries’ (e.g., Australia’s cotton industry’s) resistance management program (RMP). This is especially important when the target pest is also a cosmopolitan species, and resistant genotypes selected elsewhere could rapidly spread across new geographic ranges. Recent high-profile introductions of noctuid pests into the Americas (i.e., Helicoverpa armigera) and the Old World/Oceania (i.e., Spodoptera frugiperda), are examples highlighting the importance of trade-assisted pest spread. Helicoverpa armigera also represents a significant biosecurity threat to Australia’s cotton industry because of endemic Australian populations, and of known resistance to different Bacillus thuringiensis (Bt) toxins, including dominant resistances to the Cry1Ac toxin reported from northern Chinese populations.  

To understand threats posed by foreign H. armigera via global trade pathways, it is necessary to first assess the frequency and species status of specimens from Australia’s pre-border inspections of imported agricultural/live-plant commodities, and to develop the best practice for detecting known resistance alleles. Various scenarios addressing the implications to industry of accidental introductions of a dominant resistant allele and appropriate management strategies can be assessed by modelling and computer simulations. Finally, the relevant RMP should be reviewed and compared with other countries’ RMP, especially from where the dominant resistant genes originated from. To date, these aspects remained unexplored by Australia’s cotton industry. 

We address these issues through: (i) analysis of historical pre-border pest interception data to identify patterns and species status, and to identify potential factors that limited the use of interception data to bolster our primary industry’s biosecurity plans; (ii) apply molecular approaches to confirm the species status, and to characterise known Cry1Ac dominant resistance genes; (iii) using a computer simulation approach to provide a preliminary understanding of the speed of resistance allele fixation in the Australian cropping landscape with different refugia and dominance scenarios, thereby enabling policy makers to better comprehend and identify potential difficulties associated with the current RMP, and (iv) undertaking a comprehensive review comparing Australia’s and China’s cotton industries’ Bt RMP to enable recommendations to be made to prepare for the accidental introduction of dominant Cry1Ac resistance genes. This work will contribute to Australia’s cotton industry biosecurity preparedness, and protect growers’ income and the transgene Bt technology. 

Analyses of historical interceptions and trade data identified challenges relating to species identification (Appendix I). Molecular diagnostics via DNA-barcoding (Appendix II) delivered a comprehensive DNA database for global H. armigera populations (Appendix III) to accurately identify and assist with differentiating between endemic and non-native individuals of this high priority agricultural pest including from imported live plant-related commodities (Appendix IV). The whole genome sequencing approach represents a valuable tool-set to obtain large volume genome data and enabled surveys of the Tetraspanin and E-cadherin genes of intercepted H. armigera for known dominant Cry1Ac resistance-associated mutations (Appendix V). A review of current Bt RMP practice and simulation modelling assessments enabled six recommendations to prepare the cotton industry to the dominant Cry1Ac resistant genes (Appendix VI). 

This PhD project forms a significant, embedded part of the project, “Novel insecticides and synergists from endemic and exotic flora”, funded by the Cotton Research and Development Corporation (CRDC), 2015-2018. I aimed to identify and develop new tools for integrated pest management (IPM) in cotton (Gossypium hirsutum). While adoption of transgenic cotton has resulted in reduced synthetic insecticide use against the cotton bollworms Helicoverpa spp., secondary pests such as two-spotted spider mite, cotton aphid, green mirid, and silverleaf whitefly continue to be of concern. Thus, there is an urgent need to investigate and develop novel options, such as biopesticides and semiochemicals for insect pest management.

My proof-of-concept study employed two insect cell lines and evaluated three pyrethroid insecticides by combining three in vitro methods, absorbance spectrometry, confocal scanning laser microscopy (CSLM) and microelectrode ion flux estimation (MIFE) to assist in elucidating possible mode of action, which could be adopted to evaluate insecticidal activity of complex, unknown, or multi-constituent formulations. I observed that the two cell lines produced distinctly different responses. Drosophila melanogaster D.mel-S2 cell line was a useful model to monitor ion flux changes, resulting from insecticides with neural toxicity; however, it was less useful to determine some metabolic pathway indicators of toxic stress. Conversely, the Spodoptera frugiperda Sf9 cell line produced acute reactive oxygen species (ROS) in response to insecticide treatments, but was not highly responsive in electrophysiological experiments. I also showed that the natural, multi-constituent botanical extract of pyrethrum elicited different Na+, Cl- and Ca2+ ion fluxes than its synthetic, single constituent analogues, α-cypermethrin and esfenvalerate. These two methods used in combination with absorbance spectrometry measuring cell growth inhibition plus cell mortality assays shed some light on cytotoxic responses in differing model cell lines. The study highlights the importance of utilising multiple cell types and interdisciplinary methods to provide a better insight into mode of insecticidal action. This is especially pertinent to novel biopesticide discovery, as the underlying mechanisms for toxicity in initial screening processes are likely to be unknown.

A laboratory direct application insect bioassay utilising a Potter precision spray tower was employed during the initial foundation project to screen over 400 plant extracts for their efficacy on a selection of cotton insects, after which I identified 20 extracts for further experimentation. I have investigated the insecticidal mode/s of action from a physiological, cellular and genetic standpoint with a focus primarily on three major cotton pests, one model species and two insect cell lines. A combination of insect bioassays, absorbance spectrometry, CSLM, and MIFE have been employed to provide insight into potential target sites for these novel botanical pesticides. Ion channels are the major target sites of action in many insecticides. I found novel physiological responses of two model insect cell lines, D.mel-S2 and Sf9 and a selection of insects to some of the novel botanical extracts using cytotoxicity assay, cell-stress response and ion flux, which provide greater insight for understanding multiple toxicity responses. Moreover, a combination of insect bioassays, RT-qPCR and RNA- sequencing were employed to provide insight into potential molecular targets for these novel botanical pesticides. I identified a large number of differentially expressed genes (DEGs) especially in the categories of membrane transport and oxidative stress that are relevant for the understanding of mode of action (MOA) of these novel extracts on cotton insects. Moreover, I found that, in comparison to the susceptibility of Aphis gossypii to the novel botanical extract 68N.M, the DEGs encoding such as chemoreceptors and Ca2+ channels may equip D. melanogaster with superior capacity to sense and tolerate 68N.M. Many of these key DEGs should be considered for more detailed functional analysis in both D. melanogaster and A. gossypii to elucidate the gene function in insecticidal MOA in the future.

In summary, by targeting ion transport, ROS production, chemoreceptors and their associated genes in insect cells and insects, there is a great potential to develop reliable laboratory screening methods to identify novel and environmental friendly botanical pesticides for Australian and global agricultural industry in the future.

1) to study the effects of exogenous BR on cotton growth and tolerance to water, salt and pathogen stresses;  

2) to characterise in detail CBP60-related genes in cotton for gene structure, phylogenetic relationships, their transcriptional responses to exogenous BR, drought, salinity and pathogen challenge, as well as their tissue/organ-specific expression;  

This report presents and summarizes the outcomes of five years of research into enhancing integrated pest management (IPM) in cotton production systems. Multi-year field and laboratory experiments aimed to answer pest management related questions developed with industry input and relevant across the different cotton growing regions. Analysis and synthesis of experiments have shown a number of important outcomes:

1. We have further unravelled the myriad factors influencing the effect of insect honeydew on fibre quality and factors that contribute to its reduction in the field. The presence of insect honeydew in cotton is complex and problematic since the remedial rainfall that reduces stickiness in cotton, has the potential, under some circumnstances, to increase the risk of sooty mould development, another factor that diminishes cotton quality and can lead to penalties.
2. The host range of SLW was further confirmed and key hosts identified which is critical when considering management strategies to reduce overwinter survival and predict risks from outbreaks.
3. Studies on the retention of SLW DNA in the gut of key predators wers completed and will be used to identify the most significant predators.
4. Several new weed hosts of this disease were confirmed, potentially improving prediction of seasons with higher risks from CBT.
5. Seed treatments such as Cruiser would not be effective in preventing transmission of CBT but Cruiser Extreme could reduce the infection rate by 50%. Application of folair sprays against aphids just after aphids entered the crop, or 24 hours after they entered the crop would not be effective at preventing initial transmission but may retard secondary transmission..
6. We found in the central and southern cotton areas, the currently employed SLW sampling methodology inadequately predicts populations, potentially reducing the timeframe for optimal management decisions. The groundwork for development of new strategies was completed and will be developed in a subsequent project.
7. The IPM fit of new insecticides was assessed and a number of new IPM compatible insecticides have been added to Table 3: “Impact of insecticides and miticides on predators, parasitoids and bees in cotton” in the Cotton Pest Management Guide.
8. Fipronil and clothianidin were compared as management options for Green vegetable bug (GVB) and mirids. Both compounds were effective against target pests and improved yeild, but both also had negative impact on some predators (including Coccinellids) and one had high potential to flare mites. The complexity of these experiments highlighted the challenges involved in pest management decisions.
9. Thrips control with alternative seed treatment options to neonicotinoids was poor, indicating that these biologicals could not replace currently used chemicals. In new cooler regions thrips larvae were controlled by neonicotinoid seed treatments but benefits to yield did not occur probably due to low thrips abundance.
10. Assessing the relationship between boll age and susceptibility to GVB damage. GVB nymphs and adults inflicted most damage on five day old cotton bolls which usually aborted within days of being damaged, while older bolls continued to develop but exhibited staining and tightlocking.
11. Evaluating various insecticides used to manage SLW to understand their different modes of action We were unable to assess the effects of SLW insecticides as low whitefly numbers precluded conclusions resulting from a single application of whitefly insecticides, though our efforts will be continued in the future.
12. Providing expert advice to consultants and growers throughout the season and rapid responses to critical pest problems Expert advice was provided to growers and consultants throughout the year via phonecalls, e-mails and personal interactions. Support was given particularly in 2016/17, a high pest year that threw up many questions about occasional pests and their management.
13. Investigating the simulated effects of early and late flower damage by thrips and mirids on yield and maturity With respect to simulated thrips damage, the removal of one weeks’ worth of flowers at peak flower or cut-out was generally not severe enough to cause yield loss. More extreme, early season flower removal that simulated mirid damage had variable results on yield and maturity depending on the severity of the treatment and the regional climatic conditions, with higher risk of yield loss in southern areas. These experiments will be repeated across regions for verification.

The outcomes of this project have added to the current understanding of cotton pests, their assessment and impact on plants as well as their management and control options. They have also contributed to the better understanding of plant responses to pests which may potentially change management practices of some pests. Further, they have highlighted the interactions between plants, insects and other organisms, and the climatic factors that affect these interactions. What has become clear through the regional experiments is, that insect management decisions in the different cotton growing areas are governed by season length, and that the wrong decision in a short season area can have great consequences with respect to yield loss. These outcomes reinforce the importance of IPM in the cotton system and, once published and extended to the industry, will guide growers and consultants to make more informed decisions and perhaps influence the degree to which some pests are managed and tolerated.

The Objectives of this project were to undertake research to enable:

1. Cotton businesses to understand the value of improving the capability of their workforce.
2. CRDC to be able to assess and objectively report on the impacts of its investments in developing human capacity, via an appropriate monitoring and evaluation system.
3. The Australian cotton industry to make informed investment decisions about how best to produce the skilled, knowledgeable and progressive workforce required into the future.

In other words, the Purpose was to support the cotton industry to make more informed assessments of the return on investment or impact of capacity building projects and activities at a strategic level.

The project outcomes can be summarised as:

• An overall Monitoring, Evaluation and Reporting (MER) Framework and measuring system was developed – to allow assessment of the level of success of industry funded social research and capacity building projects funded by industry;
• A personnel management process to support cotton growers in better managing and understanding the value of skill development, training and professional development – via an adapted and further developed Cotton myBMP system (supports Level 3 HR practices in a revised module). This includes checklists supporting increased capacity for training and professional development in leadership and higher-level personnel management; using personnel performance metrics, to gauge business and industry improvements over time;
• A series of frameworks, mapping data/schematics and findings/recommendations from the project – to support thinking and action in the industry around higher-level Personnel Management and how to create a culture of learning in the industry;
• Increased overall industry awareness (including a recommendation to create a Cotton Industry Personnel Roundtable) that supports a strategic and on ground thinking activity to ensure implementation of project outputs, within a framework of a longer-term strategic plan of attack. The purpose is to support the critical contribution of higher level personnel and their management in industry adaptation to changed cotton needs in a global marketplace (stronger focus on higher technology-based farm/business management practices; supporting acquisition, management and retention of appropriately skilled personnel; engaging younger more technologically savvy personnel across the cotton growing and agribusiness sectors; including expansion to all personnel sectors in the industry);
• Engagement with members of the People Program – and a group of additional Informed Persons – who could be instrumental/a catalyst for driving change in the industry;
• Extrapolation of these findings to a wider industry emerging issue – namely the fit of personnel management into wider, higher-level business management (rather than production) across all cotton industry sectors and which appears to be lacking in this changing marketplace;
• A series of example Informed Persons Case Studies – which can help demystify the issues and solutions; particularly at an on-ground level, relevant to growers at different stages of their business development (focused on personnel management);
• The data contains a number of approaches to personnel management gained from engagement with a range of Informed Persons – which could be used as the basis of industry conversations, strategic thinking and engagement around the project outcomes; in particular to support the proposed Cotton Industry Personnel Roundtable;
• Insights which can be benchmarked over time – using the Cotton Grower Survey and the Crop Consultants of Australia survey process to measure change over time and acquire additional data to ensure these matters are more fully understood (as needs evolve over time);
• The Catalyst for commencing an ‘Industry Conversation on Personnel and Business Management‘ – which draws together work in the People Program and Cotton Workforce Development Project activities; and hopefully ensures the conversation continues on.

(Information: Dr Jeff Coutts, ph: 0438 361 153; email: jeff@couttsjr.com.au and Gordon Stone; ph: 0408 063 229; email: gordon.stone@abdi.com.au)

Entrainment of native fish through irrigation systems is an environmental impact of irrigation activities. Entrained fish are almost always permanently lost to the river system and fish can also suffer significant mortalities as they pass through offtakes. In this study, entrainment rates of fish through different irrigation intake systems were evaluated. Various riverine pumps on the Comet, Nogoa and Mackenzie rivers and the irrigation diversion channels originating from Fairbairn Dam were compared. Irrigation outlets were sampled during natural and allocated flow events with specialised nets to capture all fish entrained over a 100-minute period. Entrainment rates were calculated as fish per unit time and as fish per megalitre (ML) extracted. Larval nets with flow meters were also set to calculate the number of fish larvae entrained per ML.

Nearby river and impoundment reference sites were sampled during the same flow events. Catch rates from the reference sites were used as a covariate in generalised linear models to harmonise comparisons between irrigation systems. Reference site catch rates, when compared with entrainment rates also helped identify species and size classes of fish that were more or less susceptible to entrainment.

The results from the diversion channels originating from Fairbairn Dam suggest that gravity fed diversions entrain significantly more fish per ML and per unit time than pumped diversions. The water extraction rate was far less important than whether the channel was gravity fed or pump fed.

Several factors were considered when comparing riverine pumps, including pump rate (ML/day), intake location and depth (intake configuration), and flow type pumped (allocated flow, natural within-bank flow or overbank flow).  For most species there was a general trend for increasing entrainment rates as pump rates increased, although the fish entrained per ML increased at a lesser rate than fish entrained per unit time as pump rate increased. Pump intake position and depth significantly impacted entrainment rates, with shallow bankside intakes generally entraining far fewer fish than bankside deep, mid-river channel or side-channel pump intakes. Some very large pumps with shallow bankside intakes entrained far fewer fish than some smaller pumps nearby with different intake configurations. There was some variation between species and size classes on which intake locations and depth had the greatest impact, but for most species and size classes, entrainment through bankside shallow intakes was consistently low.

Pumping from overbank flows (flows where the river covers the bench) entrained far fewer fish than pumping from both natural within-bank flows and allocated flows. However, it is highly unlikely that any irrigator pumps solely from overbank flows. There was no statistically significant difference between allocated flows and natural within bank flows in terms of total numbers of fish entrained. Allocated flows tended to entrain more small fish, whereas fish >100 mm length appeared to be more susceptible to entrainment on natural within-bank flows. The pelagic larvae of golden perch were only entrained on natural within bank flows. Pumping natural within bank flows probably has a marginally higher biological impact on fish than pumping from allocated flows. Further replication would help determine these differences more conclusively.

Based on individual pump licenses and operations it is possible to predict the likely severity of impact of a pump. This can be done by considering pumping rate, pump intake position and depth (intake configuration), flow type(s) pumped and annual licensed allocation (total volume licensed to pump of any flow type). By cross multiplying score metrics for these different categories, a score can be derived for different pumps in a river system. The scores can help prioritise pumps for mitigation actions such as screening. The highest scoring pumps will be those predicted to be in the greatest need of mitigation action. However, for mitigation actions, feasibility and cost, based on the site characteristics also need to be considered. Any group, agency or peak body wishing to invest in pump screening, in some cases may achieve better outcomes for fish per unit cost by screening several slightly lower ranked pumps, rather than expending a large amount of money on a single highly ranked pump that is logistically difficult and thus expensive to screen.

The following recommendations have been derived from this research project.

1. Gravity fed diversions should be considered a high priority for mitigation of impacts to fish. Further investigations into impacts of riverine gravity fed diversions are recommended.
2. Pumped diversions can be prioritised using a four-part scoring system that considers flow type being pumped, intake location and depth (intake configuration), pump rate and total volume pumped per annum. Consideration also needs to be given to feasibility of screening a site (including cost) as part of the prioritisation process.
3. Future pumped irrigation developments should consider factoring in screening at the design and construction phase when it will be cheaper to install screens, compared to retrofitting them later.
4. Further replication of sampling will provide more confidence in the metrics for flow type being pumped, intake location and depth, and pump rate.
5. Further research needs to be conducted into the cost benefits of screening to provide irrigators confidence that pump screening will not significantly impact on their financial position.

In recent years the industry has increased their adoption of bankless channel or siphon-less irrigation systems. This is driven by a need to address labour resourcing, energy use, maangement efficiency and the reuse of tailwater.

In most bankless channel design, the field is split into bays and watered at a high flow rate. All furrows in a bay are irrigated at once without siphons or roto-bucks. While the most basic siphon-less systems principally remove the need for siphons and aim to minimise soil movement in the transition from siphon to siphon-less. There are different approaches being implemented, some with tail water reuse design and others that utilise existing tail drains and still pump tailwater.

The continuous reuse of tail water in adjacent bays can potentially reduce water loss from channels, reduce pumping costs and enhance efficiency of cultivation. Additionally, transitioning to a siphon-less or bankless channel design can enable higher flow rates through the field, this can minimise non uniformity and reduce deep drainabut irrigations may be more frequent. 

There has been limited research into the irrigation performance (application efficiency and distribution uniformity) of these designs, but the irrigators who are utilising some of these designs have found improved irrigation water use effiency.

EXECUTIVE SUMMARY

Improving water productivity is a high priority for Australian agriculture, especially given increasing competition for access to freshwater resources. The Australian cotton industry is a global leader in water use efficiency and is committed to continual improvements in water productivity and demonstrating responsible use of our shared natural resources.

NSW Department of Primary Industries (DPI) is working with the Australian cotton industry to assess and benchmark water productivity of cotton. The benchmarking helps the industry to improve the productive and sustainable use of water by using the results to track progress towards the industry’s target and to identify options for improvement.

This project has continued the long-term monitoring of water use in the cotton industry, delivering annual water productivity and water sustainability benchmarks for irrigated and rainfed cotton based on grower surveys.

Throughout the benchmarking period, water productivity of Australian irrigated cotton has increased from 0.60 bales/ML in 1997 to 1.22 bales/ML in 2021. Water productivity in 2021 ranged from 0.79 to 1.61 bales/ML with the top 20% of growers achieving 1.41 bales/ML or more. These results indicate potential for most growers to increase water productivity through improved water management and increased yield.

Data from the growers surveyed showed the annual rate of productivity improvement was 9% between 1997 and 2007, however it has slowed to an average of 0.6% since 2007.

The Australian industry’s average water productivity in 2021 was 30% higher than the maximum achieved in 1997.

Australian cotton water sustainability indicators have improved significantly. The water used to produce one bale of cotton in 2021 was 0.72 ML/bale, which is less than half the water used of 1.54 ML/bale in 1997.

On a global scale, Australia is a leader in cotton water productivity and sustainability. The average water productivity of Australian cotton for 2001 to 2021 is 1.08 bales/ML. This is 2.25 times the global average of 0.48 bales/ML, based on the latest available data published in 2011. The long-term average water consumption in Australia for 2001 to 2021 period was 0.93 ML/bale, which is less than half the global average of 2.07 ML/bale equivalents reported in 2011.

Improvements in water productivity of irrigated cotton in Australia are the result of increased yield, reduced water inputs and increased irrigation efficiency, during a period when rainfall was declining.

For rainfed cotton, a literature review of water productivity resulted in the adoption of a model to quantify water productivity and water sustainability. Crop water productivity is calculated as lint yield (kg) divided by total crop water use and is expressed as kg lint/mm. The inverse of crop water productivity is water sustainability indicator, which is expressed as mm/kg lint. The total crop water use is estimated as the sum of plant available water at sowing and total in-crop effective rain. The total plant available water at sowing can range from zero to 100% of plant available water capacity.

The average water productivity of rainfed cotton produced between 1995 and 2021 was 1.84 kg lint/mm (0.81 bales/ML). The range is between 0.4 – 5.3 mm/kg lint and the top 20% of growers achieved 2.51 kg/mm (1.06 bales/ML) or greater.

The water sustainability indicators for rainfed cotton suggest it used an average of 0.72 mm to produce each kg of cotton lint (1.63 ML/bale) for the same years. The top 20% of growers achieved 0.40 mm/kg (0.91 ML/bale).

The project activities and results have been widely communicated to growers, industry and other researchers. This has occurred through scientific publication, conferences, popular press, industry magazines, webinars, radio, YouTube and presentation both one on one and in groups.

The Technical Lead in the CottonInfo team has successfully supported key water research projects, facilitated collaboration with new research consortia, updated relevant myBMP modules, communicated project activities and results, and built capacity of growers and their advisers via training sessions, presentations and various multimedia platforms.

DAN2002 has fostered collaboration with a wide diversity of partners, including local, national and international collaborations to improve and extend capacity to assess and increase water productivity and sustainability of cotton and other crops.

The project has made the following key recommendations for the industry:

•  While the industry is approaching the average water productivity target of 1.32 bales/ML by 2023, the individual grower’s performance is highly variable, and the overall rate of improvement is slowing. New approaches are required to understand what factors are limiting water productivity improvement and what are the strategies used by the top 20% of growers do to achieve high water productivity.

•  Given that to date the average gross productivity water use index has been referred to by the industry as ‘the benchmark’, the industry should seek to adopt an aspirational benchmark of lifting water productivity to the level achieved by the top 20% of growers.