Phosphorus Availability in Rain Grown Cotton

Abstract

UNE 1501 – ‘ Phosphorus availability in raingrown cotton’, was conducted at ‘Colonsay’, via Brookstead, on the Darling Downs in Queensland, at a long term nutrition site, owned and maintained by Incitec Pivot for 30 years. The experiment was conducted in raingrown cotton cv SICOT 74 BRF.

At this experimental site, phosphorus had been applied to the same plots at the rates of 0, 10, and 20kg/ha P each year since the commencement of the experiment. For the 2015 experiment, the existing 50m plots were then split into three treatments to include the addition of deep applied P, applied at 20kg/ha to 20cm depth on 50cm spacing, and a tillage treatment to disperse any bands of enriched nutrient. Work by Bell et.al. 2015, and Dorahy 2004, has shown little response in cotton, in terms of yield or plant nutrient uptake, to the application of fertiliser P in the season that it is applied. This experiment provided the researchers with a unique set of circumstances where the soil had been enriched with P such that a gradient of background soil test values was achieved. In this particular experiment very good results with respects to both plant phosphorus uptake, and yield were achieved. Colwell P values in the 20kg/ha P treatments had been enriched to 64 mg/kg in the surface, whilst the 0 kg/ha P treatments were at around 8.6 mg/kg (Colwell), and had remained relatively unmoved for the duration of the Incitec Pivot experiment (30 years). The 20 kg/ha P treatments showed maximum plant P uptake of approximately 32 kg/ha, the yield being 7.92 ba/ha. The uptake in the 0 kg/ha P treatments was around 18 kg/ha in the plant tissue, with a yield of 5.62 ba/ha. It is not perfectly clear as to the mechanism driving these responses although it is postulated that the favourable early season growing conditions resulted in excellent surface root activity, or that soil enriched with P behaves differently than that with fertiliser P applied for that growing season, or a combination of both.

When looking at the response curve comparing yield and soil test Colwell P values, it appears as if the critical level, for cotton, using Colwell P ( 0-10cm) may be around 25 mg/kg, significantly higher than the accepted 6 mg/kg.

Very little response was observed when both deep applied P was added or when tillage was included to disperse bands of enhanced P. This may concur with other work by Wang et.al. 2007, and McLaren et.al. 2013, inferring that deeper in the profile the plant is likely to be drawing on native, and other residual reserves of P held in a range of P pools, and again that applied fertiliser P ( as the deep applied P ) is unlikely to provide a short term response in terms of either plant P uptake, or yield. Because of the favourable early season root activity in this particular experiment, it was difficult to distinguish differences in nutrient taken up from soil containing dispersed P, or soil containing P held in a band.

Plant tissue testing using the youngest mature leaf, still provides a valid basis for assessing in-crop P status in cotton. The reliability decreases after peak flowering, as plants partition plant P in to maturing fruiting bodies, and seed.

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Environmental Toxic Load for Australian Cotton, 2000-2018

Abstract

Sustainability targets are being developed by agricultural industries to help improve and report on environmental performance. In the Australian cotton industry, pesticides pose a potential risk to environmental health and the sustainable use of pesticides is therefore of interest to consumers, cotton growers and local communities. A key issue in setting targets is the identification of a measurable indicator that adequately represents the ecological risk of cotton pesticide use without relying on overly complex, time-consuming and costly input data. A number of different indicators have been proposed, but here we report on an indicator developed specifically for assessing insecticide use in the cotton industry (for the period 1995-2007), the Environmental Toxic Load (ETL). This report briefly outlines the ETL framework, before updating and expanding the assessment to include herbicides, defoliants, and where possible, fungicides, for more recent cotton-growing seasons (2000-2018). The aim of this update is to identify recent trends in the overall ETL for the Australian cotton industry and also to identify pesticides with higher hazard profiles that can be considered for targeted reduction to improve the industry’s ecological sustainability.

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Maximising the efficiency of Bt refuge crop

Abstract

The use of transgenic (Bt) cotton (Ingard® and more recently Bollgard II®) has greatly reduced the use of insecticides in Australian cotton production and the status of key lepidopteran pests such as Helicoverpa spp. But the potential for these moths to develop resistance to Bt remains a major challenge for the industry. A resistance management plan has been adopted, part of which is the mandatory requirement for Bt cotton growers to provide refuge crops (no Bt exposure) as sources of susceptible moths. Such moths are expected to mate with potentially resistant moths arising from the Bt crops and help reduce the chance of resistance developing more broadly. During the Ingard® era, the relative moth productions of various refuge crop options were identified. However, only limited research has been devoted to identifying the degree of cross-mating of moths between refuges and Bt cotton crops.

This project’s research determined the incidence of cross-mating of Helicoverpa in key refuge crop ‐ Bollgard II® cotton combinations. It concluded that mating of H. armigera moths from different plant host origins occurs at random – as assumed under the Resistance Management Strategy adopted by the Australian Cotton Industry. However, our knowledge for H. punctigera in this regard remains very limited – and H. punctigera has emerged through recent surveys of Bt resistance alleles to be surprisingly important too. In addition, we began to identify the degree of coverage achieved spatially (landscape-scale) by refuge-derived, susceptible moths, by surveying intensively all refuge crops within a single cotton production region (St George) throughout a growing season. This work will be continued in a new project (2009‐12). Further, we identified means by which the performance of refuges (production of Helicoverpa) can be enhanced, in particular through the use of moth attractants such as those in , and through novel refuge crop options (e.g. pigeon pea and mixed crops for dryland systems, split-planting of unsprayed conventional cotton for irrigated systems). The ultimate aim of the research is to optimise the efficiency of refuges, and enable maximum, effective production for least input by farmers.

We also maintained our ongoing monitoring programs for Helicoverpa moths (pheromone trap grids in the L. Namoi and St George regions) to provide local guidance to growers of population trends, as well as identifying long-term patterns in the abundance of these key pests at seasonal and regional scales. The abundance of Helicoverpa spp was in general low during the tenure of this project. Rearing of field-collected eggs, larvae and pupae of Helicoverpa also suggested that the incidence of natural enemies (e.g. pupal parasitoids) is currently quite high. This raises concerns for the effective production of susceptible moths from refuges. Whilst the abundance of Helicoverpa within refuges was relatively low during 2006-09, it was not outside the range documented in previous years. The performances of refuges will be closely monitored in the new project.

During the project, we re-analysed old data sets to determine e.g. the degree of evidence that exists that supports the notion that rainfall patterns in inland areas of Australia drive the production and migration of H. punctigera from there to the eastern cropping regions, such as the L. Namoi. We found little evidence of correlations between inland rainfall patterns and the numbers of H. Punctigera subsequently trapped near Narrabri since the early 1990’s. Rather, we found some evidence of early season abundance of H. punctigera being related to numbers at the end of the previous cropping season – suggesting greater local over-wintering than previously thought to occur. Clearly, we still have much to learn concerning the ecology of these key pests.

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International Congress of Entomology 2016, Orlando

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This travel sponsorship enable two researchers to attend and present research outcomes from Australia relevant to other parts of the world at the International Congress of Entomology in Orlando and to inform ourselves of the latest research in IPM and pest issues relevant for our research in the cotton industry as well as other industries. Attending various symposia and discussions with researchers from other countries also gave us new ideas that could be incorporated into experiments. These discussions also provide opportunities to connect and collaborate with other researchers working on similar problems.

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2015-16 Grower RDE Advisory Panel Capacity Building

Abstract

The Cotton Australia Grower RD&E Advisory Panels function in providing practical advice on research, development and extension (RD&E) needs and priorities within the industry. This advice forms important guidance to CRDC for strategic R&D planning, annual operation planning, development of Expressions of Interest and resultant CRDC decisions as to project investments.

Cotton Australia facilitates 4 advisory panels that are aligned with the CRDC strategic plan priorities. The panels consist of up to 40 grower, consultant or ginning Member Representatives from every cotton growing region in Australia.

The Transgenic and Insect Management Strategies Committee (TIMS) functions as a cotton industry stewardship group, with broad representation from growers, research organisations, crop consultants and members of the pulse and grains industries. The agricultural chemical, biotechnology and seed companies that provide crop protection tools to Australian cotton growers approach the TIMS committee for advice on issues associated with developing or amending resistance management plans for new or existing technologies. Cotton Australia is represented by 6 grower representatives, the TIMS Committee Chair, the Chairs of the three technical panels and the Executive Officer.

The Cotton Industry Biosecurity Group (IBG) serves to ensure that the cotton industry’s responsibilities under the Emergency Plant Pest Response Deed (EPPRD) are met. It is anticipated that the IBG will constitute 1 staff and up to 3 grower representatives of Cotton Australia as well as representatives from CRDC, Crop Consultants Australia, CSIRO, NSW DPI, QDAF and Plant Health Australia.

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N2O Emissions And Soil Mineral N Effect From Cotton Residues During Fallow Phase

Abstract

The incorporation of crop residues post-harvest can provide an important source of nitrogen (N) for the subsequent crop but can simultaneously lead to elevated nitrous oxide (N2O) emissions. The magnitude of N supply and corresponding N2O emissions strongly depends on the quality of the added crop residues, and soil and climatic conditions. However, little data is available for subtropical cotton systems. The primary aims of this study were to (i) quantify carbon dioxide (CO2) and N2O emissions, and corresponding emission factors (EFs) following cotton residue incorporation, and (ii) determine the contribution cotton residues have to soil N content for the subsequent crop. Using a semi-automated sampling system, CO2 and N2O emissions were monitored during a cotton fallow period following cotton residue incorporation under varying rainfall conditions compared to residue removal. The high C/N of the incorporated residues, low temperatures and the limited C substrate resulted in low N2O emissions. EFs were found to be 0.016 and 0.064% for average and high rainfall conditions, respectively which is significantly lower than the IPCC EF of 1%. The majority of decomposed residues were recovered in the soil of up to 68% with the remaining undecomposed and a very minimal amount was lost. There was a net mineralisation or loss/immobilisation observed across sites indicating soil conditions and management practices significantly influence N dynamics. The study suggests that the current IPCC methodology should be re-evaluated and that EFs need to be lowered to reflect the low N2O emissions from high C/N cotton residue N inputs. It also shows that effect of crop residues on soil N dynamics needs to be considered in N fertiliser management strategies in order to maximize the benefits from crop residue incorporation.

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Gunnedah High School Field trip and Cotton Camp

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"When schools, families & community groups work together to support learning, children tend to do better in school, stay in school longer & like school more" (Henderson & Mapp, 2002)

" The key to improving student achievement is not parental involvement in schooling but parental engagement in learning" (Harris & Goodall, 2007)

The annual educational excursion to discover the Australian cotton story was once again a huge success for the year 12 Students of Gunnedah High School and Calrossy high School, Tamworth.

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SVCGA Weigh trailer for Southern NSW trials

Abstract

A number of research trials have been planned for the 2016/17 season which require an effective and accurate measurement of yield soon after harvest. Over the past few seasons trial coordinators have either relied on hand picking sections of treatments to estimate yields (which is time consuming), or designed trials so six modules could be weighed out over the weighbridge at at the gin.

CSD have a bale weighing trailer which is available for a limited time after their trial work is complete, and the wet weather following the 2015/16 harvest made it challenging to gain access to the trailer for local trial work in a small window of opportunity. The CGA trailer will have the same specifications as the CSD weigh trailer.

With the growth of the cotton industry in the Southern Valleys and with consideration of the climatic differences from the northern cotton growing region to the south, there is a requirement and need for research to be carried out within the local area, so the bale weighing trailer will prove to be a convenient and accessible resource to accurately weigh cotton round modules from research trials.

This project enables effective and timely research results for the Southern NSW cotton community

each season. It will also encourage on farm trials with more rigour due to replication of treatments

and effective measurement.

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