Leaf traits of five riparian tree species common to cotton farms of the Northern Murray-Darling Basin were investigated to determine inter- and intraspecific variation. It was hypothesised that high intraspecific variation would be associated with broader distributions of tree species, and hence greater resilience to environmental change, while species with low intraspecific variation might be considered more vulnerable to hydrological and/or climate change.

Black root rot, caused by the pathogen Theilaviopsis basicola is an important disease in Australian cotton. Each season NSW DPI conducts surveys in commercial cotton crops to document the incidence and severity of cotton diseases. Currently there are 60 T. Basicola isolates in the long term culture collection as a result of isolating the pathogen from plants suffering symptoms. Black root rot does not generally kill plants but causes slow growing, stunted plants. The consequences of this is an uneven crop, maturity is harder to manage and pushes the crop back. This delay means the crop is slower to develop and increases the risk of a late maturing crop. This in turn has the potential to push the crop into cooler weather near the end of maturity, increasing the risk of Verticillium wilt disease.

The incidence and severity of black root rot has increased over the last decade, especially in the Namoi valley. The question is why? In order to answer this question we need to gain a better understanding of the pathogens morphology, growth rates and pathogenicity among isolates collected from different geographical regions within the production areas of NSW.

In recent years, the high level of activity required on-farm for cotton growers has resulted in a lack of time to network, both within the Dawson Valley and with growers and contacts outside the Valley. This networking provides a valuable opportunity for growers to not only socialise but also to learn from each other and view potentially new and innovative farming practices.

The Sticky Beak Tour was developed to address this omission and provide growers with the opportunity to view neighbouring cotton farms and potentially improve their own practices through information sharing. It is also an opportunity to re-invigorate their interest in the industry after some rather challenging seasons.

The cotton plant derived a large proportion of N nutrition from the soil organic pool (up to 70%) which is composed of N sourced from previous fertiliser application and the soil N pool that has built up over the millennia. The soil base is developing an equilibrium with the current land use. Over the last century for Australian agriculture has benefited from some soil chemical and physical properties inherited from the pre European condition. The size of the soil organic N pool is declining with the decline in soil organic carbon stocks, which means that in the future a greater rates on N fertiliser will need to be used to maintain agricultural yields. During the season 143 kg N ha-1 was lost, via atmospheric losses, run-off and deep drainage; and by far the largest losses were N2 from the soil surface. Nitrogen present in the run-off water equated ~8% of the applied fertiliser and this could be transformed into indirect N2O-N. The IPCC estimates of flux overestimate indirect emissions by a factor of at least 3.7. Applications of IPCC methodology to estimate indirect N2O emissions are unlikely to be accurate. A better understanding of the processes controlling N2O production, and attempts to reconcile top-down and bottom-up estimates are necessary if we are to develop better estimate and mitigate indirect N2O emissions.

Water is the most limiting input in irrigated cotton production. Compaction reduces access to the soil water resource and reduces soil health. Incorporating Controlled Traffic Farming (CTF) in 1.5 m row irrigated cotton improves water use efficiency (WUE). This investigation compared 1.0 m and 1.5 m row-spacing on cotton yield, fibre quality and WUE. The 1.5 m row-spacing cotton was hypothesised to have a similar gross margin and fibre characteristics but greater WUE and yield per plant through access to a larger soil water resource. This replicated study was conducted over two years (2013-14 and 2014-15) and had an RCB design with a field scale whole block experiment which contained nine replicates of 1.0 m and 1.5 m row treatments. The field scale whole block contained two large field blocks of 1.0 m and 1.5 m treatments. The 1.5 m cotton had a greater WUE by producing 0.09 more bales per ML. This reduced the irrigation requirement in the 1.5 m resulting in a higher gross margin than 1.0 m cotton ($2658/ha and $2466/ha, respectively). The 1m cotton out yielded the 1.5 m in both seasons by 1.8 bales/ha (16%) and 1.09 bales/ha (6%) respectively. Yield differences in the 1.0 m cotton were only achieved through an increase in inputs. Fibre quality was slightly better in 1.5 m cotton. The 1.5 m row-spacing, based on its capacity to improve WUE, is more suitable for water limited environments. Furthermore, CTF provides greater water use efficiency by minimising soil compaction.

Ecosystem services are the benefits that humans get from the environment. Many ecosystem services are relevant to cotton production (e.g. natural pest control, bioremediation of residues, water filtration, spray drift mitigation, prevention of weed invasions and erosion control) as outlined by Reid et al. (2003). Ecosystem services generated on cotton farms also benefit the wider community and as such, attract incentive payments for growers that can supply them (e.g. environmental stewardship payments from the Australian Government) or are tradable assets (e.g. carbon sequestration). Ecosystem services generated by native vegetation on cotton farms therefore have the potential to contribute to farm profits. Currently, many growers are unaware of the potential value of their on-farm native vegetation and those that are aware, may lack the knowledge or skills to determine the condition of their vegetation or manage it for different outcomes.

This project will quantify some of the key services generated by native vegetation on cotton farms, calculate the value of different vegetation communities for ecosystem service provision and determine the impact of management on service provision. Sites will be established in vegetation types common on cotton farms across inland eastern Australia (from Emerald in the north to the Murrumbidgee in the south) to target three services: carbon storage, erosion mitigation and biodiversity conservation. Data collected on the three services will form the basis of spreadsheet calculators that growers can interrogate to discover the value of their vegetation for service provision after accounting for vegetation condition and management. The calculators will be linked to MyBMP and on-ground support from Catchment Management Authorities will be sought to ensure the greatest exposure of the project and promote uptake of the research. This project will develop the tools to encourage an innovative approach to environmental stewardship in the cotton industry.

Over the past 25 years soil carbon sequestration has been assessed in many experiments. In most, sequestration has been negative even when conservation farming practices such as crop rotation, stubble retention and minimum tillage were implemented. Recently Kirkby et al. (2013) suggested that a fixed ratio of nutrients (“stoichiometric ratio”) must be present for atmospheric carbon to be sequestered. Intensive agriculture may alter the pools of carbon (C), nitrogen (N), Phosphorus (P) and Sulphur (S) by addition of fertilizers, soil erosion, nutrient export and management of plant residues. This project will determine the long term C:N:P:S ratios of soil in some cotton farming systems.

Archived soil samples from the rotation/tillage experiments conducted by the Cotton CRC in the Namoi and Macquarie Valleys, Darling Downs and Emerald between 1993 and 2014 will be used to determine C:N:P:S ratios at selected time points with LECO analyses. The influence of these ratios on soil carbon sequestration rates will be assessed. Further, the relationship between theses stoichiometric ratios and cotton productivity will be assessed from yield data during the selected years of investigation.

The project will be carried out at ACRI and ANU. This project will build capacity and develop linkages among NSW DPI, CRDC and the ANU

The Spring edition of CRDC's magazine, Spotlight, puts soil and nutrition under the microscope in the lead up to planting. We look at novel measures using satellite telemetry to measure nitrogen status in crops, and how long-term CRDC research is tracking changes in salinity in the south. We also look at research undertaken of floodplain soils, and the role they have in deep drainage.

Also in this issue, we take a look at the new era in cotton as Bollgard 3 becomes commercially available. Integral to the success of this new technology is the Resistance Management Plan (RMP): we highlight the process involved in putting the RMP together, and the role that good refuges play in keeping resistance at bay. We also outline CRDC's new five-year project into dryland farming systems, which is focused on assisting growers to take advanced of the introduction of Bollgard 3.

The 2015-16 Cotton Growing Practices survey was conducted by Roth Rural on behalf of CRDC. It gathers valuable information about cotton farming practices to give a greater understanding of the industry’s current practices and performance in relation to a number of key areas for the 2015-16 cotton crop, and so that trends can be monitored over time. This survey particularly focused on seasonal management, managing limited water, replant and damaged cotton and mining exploration wells. Information was also gathered about research priorities and grower perceptions of research and CRDC.

In this project the performance of 40 centre pivot and lateral move overhead irrigation systems will be continuously monitored throughout the 2014-15 cropping year to ascertain the performance of the systems and collect data to establish the water use productivity and energy use of these systems within the Queensland Murray Darling Basin. The Gross Production Water Use Index and Irrigation Water Use Index for a range of crops (cotton, winter cereals, summer grains, annual forages) will be determined, along with the establishment of energy benchmarks. Participating irrigators will be provided with recommendations on how to improve system performance where necessary.

The results for the 2014-15 year will complete a five year longitudinal study which provides benchmarks on the performance of these systems across a range of season types and crops. This information can be used by irrigators to assess the cost:benefit of investing in overhead irrigation systems.