Water in open channels is subject to high evaporative losses. Some 701 gigalitres of

water is lost annually through evaporation from channels in Northern Victoria.

Research and field trials carried out by many workers over the last 50 years has

shown that applying small quantities of chemicals to form a monolayer, or surface

film, on the water surface is a cost effective method of suppressing evaporation on

bodies of water such as dams. The potential water saving from the use of such

monolayers on G-MW irrigation channels is approximately 11GL/year.

Through the CRC Irrigation Futures (CRCIF), G-MW is collaborating with the

University of Southern Queensland (USQ) to understand how this technology can be

applied to channels.

This project expands the scope of previous commercial trials, which have focused on

large water storages and farm dams, to consider evaporation suppression on

irrigation channels. There are researchable questions regarding the efficacy, cost

and application methodologies that relate specifically to evaporation suppression in

channels.

Goulburn-Murray Water is undertaking a research project (in partnership with the CRC

Irrigation Futures and the National Program for Sustainable Irrigation) into the

application of monolayers on irrigation channels in order to determine if this is a feasible

water savings measure.

This report presents a summary of all work undertaken as a part of this project.

Egg collecting has been critical to the success of the Helicoverpa resistance monitoring programs. Since 2007/08, the industry has engaged the services of the CCA in coordinating the regular collection of eggs by CCA members across a number of cotton growing regions. The partnership with CCA has assisted greatly in ensuring the monitoring programs have a reliable and quality supply of eggs from across more of the cotton industry.

The CCA developed a framework for engaging members from Emerald Queensland, to southern New South Wales, to make collections using a protocol provided by the NSW DPI and CSIRO monitoring programs. Researchers from the monitoring programs provide basic training for the participating members to ensure thorough knowledge and understanding of the tasks to be performed. CCA appointed a dedicated Project Manager to coordinate and administer the project as well as satisfy CRDC’s reporting requirements.

Australian cotton growers are exposed to and manage a variety of cotton diseases. This project had a number of objectives to address knowledge gaps and obtain data to improve the management of Fusarium wilt, Verticillium wilt and reniform nematode.

Many of the current strategies to manage Fusarium wilt have been developed as a result of the project work carried out at Mr Graham Clapham’s property ‘Cowan’. The “Cowan” trial site is recognised by the cotton industry as a high disease incidence site, providing unbiased information on disease management practices. Some specific outcomes include: (i) the identification of some agricultural practices, such as crop rotations, that may reduce the incidence of the disease. These practices reduce populations of Fov in the soil and increase yield potential, thereby contributing to the sustainability of cotton production.

A published PCR based diagnostic assay detects two of the three Australian strains of Fov. Testing in this project confirmed published results as well as confirming that the test detects the “Mungindi” strain. This test has enabled faster confirmation of Fusarium wilt to industry. Faster detection allows for faster implementation of strategies to manage this disease.

Nutrition trials where three cultivars differing in Fusarium resistance were grown highlighted the importance of planting the highest F. rank variety in Fusarium infested fields to maximise yield. Interestingly, fertilising with NPK had no effect on seed cotton yield or disease severity, except for one exception where the addition of P and K had a negative effect on yield for the lowest F. ranked cultivar compared to K alone. The lack of response is curious as the field plot was planted to crops for several seasons without fertiliser inputs so as to deplete the nutrition. This was done to enable the influence of nutrient inputs on disease to be assessed in a controlled experiment. Results indicate that for Sicot 74BRF and Sicot 75BRF there was no benefit to applying N, P or K on seed cotton yield or disease severity. Further work is needed to better understand fertilisation of soil, nutrient uptake and nutrient requirements for maximising yield.

Verticillium wilt caused by Verticillium dahliae, although present in Queensland has rarely been detected during annual disease surveys and historically has not caused significant yield reductions. However, in the 2014/15 season, the highly virulent strain VCG 1A of V. dahliae was detected for the first time, causing significant disease in susceptible varieties. Following molecular characterisation and VCG analysis of V. dahliae isolates it is known that three strains of the pathogen are present in Australian fields. The ‘defoliating’ strain VCG1A and ‘non-defoliating’ strains VCG 2A and 4B were identified using specific primers and VCG analysis.

Pathogenicity studies determined that VCG’s 1A and 2B are highly pathogenic and VCG4B is mildly pathogenic, on cotton. Current management strategies such as crop rotation with non-hosts are not successfully managing the highly virulent strains and further research into management strategies are required.

Seed plating studies showed that V. dahliae was not detected in any of the seed, hand-picked from plants showing wilt symptoms from the CSIRO breeding program. This data suggests that Verticillium is not seed-borne in Australian cotton. Testing is on-going.

In 2012 reniform nematode was detected for the first time in the Dawson/Callide region of Central Queensland. This nematode was determined to be widespread in this region causing up to 40% yield reduction. In this project, monitoring of fields was a non-destructive way of providing an indication of possible nematode problems and provided useful information towards developing economic threshold levels of reniform nematode in Australian cotton. Management strategies were also investigated such as crop rotation and seed treatments.

Data from three seasons suggest that a population of 1000 reniform /200mL of soil post-harvest results in a 10% yield reduction. Deep coring to 100 cm has shown that reniform are present at depth, thereby providing a reservoir of nematodes that may reinfest the planting zone when cotton is sown. Corn and sorghum are non-hosts of reniform and significantly reduce soil populations compared to cotton and are therefore good rotation options for growers to manage this pest. However even after two rotations out of cotton, populations returned to high levels when cotton is grown. Seed treatments tested in this project had no significant effect on soil population of reniform. Multiple strategies will be required to manage this pest.

The research results obtained during this project have been widely disseminated throughout the industry.

This project seeks to design, develop and test an integrated measuring tool that can be installed and recovered from the bed of streams and rivers. The tool will comprise temperature and water level loggers and newly developed probes to monitor fluid electrical conductivity, the concentration of chloride in the water and oxygen levels (as a measure of water quality).This project will develop field equipment and a proven scientific methodology that will quantify surface water loss to groundwater below surface water bodies and therefore contribute to the mapping of the many and complex connections and interactions between groundwater and the surface water - dams, lakes, rivers, wetlands. The project will allow development of a prototype that should be capable of commercialisation.

As a result of this project, there will be much improved knowledge and understanding of a process that can, in turn, inform policy development and water allocation decisions. The new knowledge will allow development of consultancy services based upon deployment and interpretation of the sondes.

In addition field data acquired by the sondes could provide much needed independent confirmation of various other modelling studies.

Based on the data that has emerged from this project, the initial objectives were condensed to the following key issues of interest to the industry:

1. The scope and coverage of the cotton agribusiness sector

2. The expected professional staffing needs of the cotton agribusiness sector over the next 5-10

years

3. Factors affecting succession and professional development in the cotton agribusiness sector

4. The extent to which a program – focussing on young professionals and/or cotton industry

succession and professional development – is relevant to the future of the industry

5. The extent to which current service providers could or would support addressing identified

cotton industry succession and professional development issues.

The aim of the this collaborative project is to improve the long term viability of irrigated

enterprises in Western Australia by increasing their capacity to effectively assess

requirements, manage and secure water resources under the pressure of proposed statutory

and predicted climate change.

This project funded by the NPSI and delivered by Curtin University with its collaborative

partner the Department of Agriculture and Food Western Australia (DAFWA) aimed to assist

growers, irrigators and state/local government bodies in understanding proposed changes to

water law in W. A.

Along with this the project also provided the targeted audience with background information

of the drivers behind the proposed statutory reforms required by the National Water

Initiative, with particular focus on climate change and the importance of sustainability of

ecological systems reliant on water, i.e. environmental flows and groundwater dependant

ecosystems.

To achieve these aims a series of eight presentations were taken to the target audience across

key agricultural regions of Western Australia being: Carnarvon, Swan Valley, Harvey,

Albany, Scott River, Margaret River, Manjimup and Myalup. Using the database of contacts

held by DAFWA invites were sent to growers etc. to participate by attending the presentation

in their region.

The presentations each consisted of four separate topics being: “Preparing Irrigated

Agriculture for Statutory and Climate Change”; “Climate Change: Observed and Projected

Changes in Western Australia”; “Environmental Flows and Groundwater Dependant

Ecosystems” and “Using Water Wisely”.

Each of these presentations was followed by a survey completed by the attendees designed to

provide a greater understanding of grower’s and irrigator’s opinions on a range of issues

surrounding water use and governance.

A range of resource materials were developed for attendees and in some cases were sent to

those unable to attend, these included: a CD Rom of the presentations; background

documents produced by both state and federal government agencies and useful factsheets,

produced by DAFWA, to aid growers etc. in better managing sustainable water use.

In summary, the project, which began in August 2011 and completed at the beginning of

March 2012, achieved all of the aims outlined in the project application.

Increasing competition on supply of fresh water for irrigation by agricultural, domestic, sports and industrial users demands water use efficient irrigation methods and compliance with environmental regulations. Drip irrigation (DI) and subsurface drip irrigation (SDI) are advocated for improvements in water use efficiency (WUE) and are increasingly being adopted by horticultural industries in Australia and overseas. Greater flexibility for automation and versatility of application of drip irrigation technology encourage wider-scale adoption by these industries. However, the higher initial investment for installation and lack of significant yield gains due to drip irrigation compared to conventional irrigation methods are somehow deterrents for broad-scale adoption.

Ways to optimise the use of DI and SDI will have multiplier effects on water savings for irrigation in agricultural and other industries and minimize environmental impacts associated with traditional irrigation methods. One of the significant areas where greater optimization of DI and SDI is realized is through the use of aerated water for irrigation (oxygation). Sustained wetting fronts around emitters associated with DI/SSDI impose hypoxia in the rhizosphere. This impedes root respiration leading to sub-optimal plant performance. As irrigation water exits an emitter, it purges soil pores of soil air (containing up to 20% by volume of oxygen) with water that contains less than 10 ppm oxygen, a quantity we have shown is used up quickly by roots and soil microbes. Rising soil temperatures, salinity, and soil compaction will exacerbate this effect, as may disease such as Phytophthora of pineapple. Plant roots and soil microbes require oxygen for respiration.

In soils with inadequate aeration the lack of oxygen results in reduced plant growth and diminished productivity for many reasons, including: reduced root growth and root size; reduced root ability to absorb minerals and water; reduced photosynthesis and plant growth due to stomatal closure; loss of soil N due to the in-activity of microbes; adverse changes in soil chemistry; increased susceptibility to disease, and an alteration of the balance and supply of plant growth regulators.

Aeration of the irrigation stream, a process termed ‘oxygation’, overcomes this constraint. Oxygation is a new innovation in irrigation technologies. Aerated DI and SDI by different methods, such as venturi for air injection, allows for the simultaneous application of water, air and other agro-chemicals directly to the crop root zone. Therefore, it can potentially improve crop yield and water use efficiency. Conventional irrigation methods such as flood irrigation have large inefficiencies due to run-off, drainage and evaporative loss. SDI can significantly improve the WUE over that of flood irrigation, and oxygation can significantly improve WUE of SDI.

Oxygation involves mixing air with water using a venturi and delivering via a surface or subsurface drip irrigation system. An oxygation system can be installed as part of a new SDI system or may be retrospectively fitted to any existing SDI system. A venturi air injector is installed within the pipeline and draws air directly into the water stream. A single venturi can be installed immediately after the pump outlet and the air distributed through the main line to sub mains and lateral drip lines, or a single injector may be fitted to the beginning of each drip line. The amount of air ingress depends on the pressure differential across the venturi and the motive flow through the venturi.

Mazzei or Netafim Air Injectors improve soil aeration by entraining air (in the form of micro-bubbles) into irrigation water. The added air improves growing conditions, increasing root respiration and microbial activity. These improved soil conditions have resulted in significant increase in yields. All NPSI funded project activities in this report utilized Mazzei air injectors.

System requirements include drip/subsurface drip irrigation, water flow must be 3.8 LPM - 30.3 LPM per drip line (for MI 384, 584 and 1583 injectors) and the terrain must be level to moderately sloped. We are also evaluating alternative approaches for super saturating irrigation water with air using twin vortex, oxysolver and Seair diffusing systems and plan researching benefits on furrow and sprinkler irrigation. We also present our research progress on diversifying the use of oxygation in landscape (lawn) and sports industries (sport grounds) to improve the WUE of these industries and to minimize the offsite movement of pesticides and nutrient from such hidden landscapes.

A number of controlled environments studies in pots and the glasshouse showed positive response to oxygation in medium and heavy textured soils. With this recent innovation of aerating the irrigation stream (oxygation), returns, yields and water use efficiencies (WUE) of SDI crops all increase (see Advances in Agronomy 88: 313-377 (2005)). This preliminary research clearly highlighted the opportunities of harnessing the potential benefits of oxygation for yield, quality and crop water use efficiency in Australian horticultural industries across diverse crops, soil types and irrigation water qualities. On large-scale field trials with SDI and surface drip, yield increases in cotton of 19% and in cucurbits of 12-60% were achieved, with significant improvements in product quality as measured by increase in ºBrix percentage of the fruit (sweetness). We have undertaken trials on heavy clays and lighter soils and for surface trickle under mulch, and trickle above the ground, showing positive and beneficial effects of aerated water irrigation. In this report we summarize the outcomes of oxygation research carried out by CQUniversity Australia in collaboration with Australian primary industries in a range of annual and perennial crops, and suggest the approach for large-scale adoption by irrigation industries in Australia.

Tendifferent crop industries (cotton, pineapple, lucernes, capsicum, strawberry, fig, table grapes, melons, vegetables and apricot), plus crops consultants and irrigation businesses in QLD were involved in testing the benefits of oxygation in field scale research. Data collected over 2- 4 seasons on yield and water use efficiency suggested that yield benefits of 4 – 19% were achievable with oxygation. Oxygation involves installation of an air injector (pressure differential venturi) in-line for mixing air with irrigation water. The installation cost of air injector can be AU$ 600-1000 per hectare depending on size of air injectors and requirements of accessories and fittings. Air injectors can be installed into new irrigation installations or retrofitted into existing drip irrigation systems.

The response to oxygation varies with crop and soil types, quality of irrigation water and type of drip irrigation. Horticulture industries in Australia span the range of these variables, therefore there is need for collaborative research, industry engagement and involvement of multidisciplinary research teams in the field of oxygation research to harness the full potential benefits of this technology to the industry.The project has resulted in significant benefits to cotton, with an average lint yield increase of 14%. Large cotton areas in Australia are furrow irrigated, hence, adoption of oxygation within the realms of existing cotton irrigation practices is currently limited. Future research is therefore suggested on use of aerated water with furrow irrigation, the primary method for irrigation of cotton. Increase in yield (6% in industry yield and 26% in total yield) and suppression of Phytophthora has been recorded on pineapple. In other crops (capsicum, strawberry, grapes) yield increases by 4-10% have been recorded. In apricot and fig the crop is still in the juvenile stage, and will be ready for harvest in 2012/2013 season only. Data will be collected from these crops beyond the funded project duration.

Oxygation as a tool delivers air into the crop root zone. Oxygen limitations can be significant in compacted, saline, and water logged soil, and with high BOD effluent irrigation water. Therefore, potential applications of oxygation can go beyond the improvement of water use efficiency and increased yields with ordinary drip and subsurface drip irrigated crops, into amelioration of other conditions that impede the diffusion of oxygen in the rhizosphere.Air within the irrigation water is a two phase flow fluid, hence, it imposes challenges for uniformity of air distribution along the irrigation line. This situation may be severe particularly when the drip irrigation is run over long row distances. Development of monitoring tools for measurement of air fraction and ways to minimize the heterogeneity of air bubbles distribution are currently underway. A number (7) of refereed journal articles have been published, postgraduate and undergraduate students have been involved (8), active collaboration with irrigation business, crop and irrigation consultants has been developed, and more field testing by independent crop consultants is underway, suggesting a gradual dissemination of the technology beyond the project timelines and resources. The following pictures highlight industries under collaboration for oxygation research in Queensland, Australia, showing diversity in terms of crops and focus in terms of soil aeration.

Attendance and presention of my paper on long-term cotton experiments and changes in soil organic carbon in Australian cotton soils at the European Geosciences Union (EGU) Assembly, Vienna, Austria. I presented results on changes in SOC in the long-term experiments being conducted at ACRI in fields C1, D1 and F6. Soil Organic Carbon(SOC) decreased with depth, with the exception of rotations that had standing or incorporated stubble, however there was no one rotation that stood out from the others. Differences between the experiments at ACRI reflected the fact that two had subsoil constraint while the third did not. Also, the starting level in SOC differed between the three experiments and this is reflected in the rate of change in SOC levels in the 0-30 cm depth over time. Including tillage resulted in a decline in SOC, while rotations increased SOC over time.

Final Report Executive Summary

The sustainability of crop production is a key issue for agricultural systems. Maintaining soil

biodiversity is important for promoting soil health and sustainable crop production. The root zone

is rich with microorganisms and nutrients. Soil type and agricultural management practices have

great influence on soil biodiversity. Mixed vegetation contributes to an increase in soil

biodiversity, while intense mono-cropping supports the growth of only a subset of soil microbes and

suggested to be causing a decrease in biodiversity. Furthermore, increased use of fertilisers and

pesticides might compromise both the activity and survival of certain microbes in the soil. The

first aim of this study was to test cotton-growing soils in Australia that are under different

management strategies for the abundance of microbes involved in nitrogen fixation and

denitrification. It has been achieved using the quantitative PCR technique – extracting DNA from

soils and measuring the presence of nitrogen fixation genes (nifH) and denitrification genes (nirK,

nirS and nosZ). Soils that were relatively poor or rich in nitrogen cycling genes were identified.

It has been noted that soils richer in nitrogen cyclers had also a more intense and diverse carbon

utilization patters, indicating larger microbial community with higher biodiversity. Soil N content

did not vary much under the different management strategies, but higher soil organic carbon was

associated with increased functional capacity. Possible factors influencing the nitrogen cycler

community in the tested soils that should be further investigated are the use of organic

amendments, soil enhancers and rotation with other crops as well as the intensity of nitrogen

fertilisation.

Every soil has potential to promote plant growth, with the most important players being the soil

microbial communities. Plant growth promoting microbes contribute to biofertilization, biocontrol,

and phytostimulation. Cotton seedling-disease complexes reduce crop establishment and lead to yield

loss by causing stunted growth and, in severe cases, plant mortality. The period from seed

germination to the establishment of cotton seedling is a critical stage in plant development. The

seedling at this stage, lasting up until the development of two to four leaves, is particularly

susceptible to soil-borne diseases. Improved plant nutrition and use of plant growth promoting

microbes as inoculants could sustainably increase the success of crop establishment and reduce the

impact of soil-borne diseases in cotton growing systems. The second aim of this project was to

isolate indigenous plant growth promoting microbes from Australian cotton-growing soils with the

aim of developing successful isolates into inoculants for local soils. Methods for direct and rapid

isolation of pathogen-suppressive bacteria and fungi were developed in this project and used in an

related project for further isolation of a collection of microbes, suppressing black root rot

caused by Thielaviopsis basicola and pathogens of other seedling diseases such as Rhizoctonia and

Verticillium wilts. The collection is ready for testing under field conditions. Selecting for

indigenous beneficial microbes increase the chances of survival of the re- introduced microbes in

the soil. Other plant-growth-promoting microbes of interest were those that influence water

retention and soil aggregation, secrete plant growth hormones, mediate stress response, solubilise

phosphate or suppress pathogen growth. Methods for the isolation of such beneficial microbes were

optimised for cotton-growing soils and then fine- tuned and used in a related project for producing

a collection of beneficial bacteria is ready for testing under field conditions.

In recent years soil scientists have made enormous progress toward understanding soil organisms and

their roles in ecosystems. Nonetheless, much remains to be discovered to allow the development of

practices that will promote the sustainable use of soils. Understanding what causes changes in the

belowground biodiversity and how diversity is linked to soil function, as well as how it influences

crops, would contribute to sustainable

agriculture and restoration of ecosystems.

Each year, Crop Consultants Australia - with support from CRDC - conduct a qualitative survey of cotton consultants regarding their practices and attitudes, as well as those of their cotton grower clients. The resulting report provides valuable information to the Australian cotton industry regarding on-farm practices , helping to benchmark the industry's performance in a range of key areas over time. This report, published in November 2017, looks at the 2016-17 cotton growing season.