Final Report for Project 1.01.34

The study of the dryland agricultural system shows, through pH/EC relationships, that EC is maintained at higher levels than the control where lime is applied, or where gypsum is applied alone after 2.5 years. Furthermore, the increases in EC due to lime generally result in a significant relationship between EC and aggregate stability. There is possibility of a synergistic ameliorative effect between lime and gypsum on soil sodicity levels, although this is not directly measured.For the irrigated agricultural system, it is observed that gypsum is the primary means of amelioration through Ca2+ exchange after 6 months, although these effects did not persist to 2.5 years. The EC effect of gypsum is not observed after 6 months or 2.5 years post-gypsum application and approximately 12.85 ML.ha-1 of infiltrating irrigation-water/rain. The results of this work show that the use of lime and gypsum in combination and alone is not necessarily viable for broadacre irrigated agriculture on two Lachlan Valley soils with pH >8.0.As it is apparent that the rate of gypsum dissolution is too high under the irrigated system studied, gypsum was combined with chicken manure/wheat straw compost (CMWSC) in order to investigate the potential of creating a slow release source of calcium (Ca2+). A leaching column experiment was conducted using a Brown Vertosol treated with C0G0 (CWMSC 0 t.ha-1, gypsum 5 t.ha-1), C0G5, C5G0, C5G5, C144G0, and C144G5. Columns were irrigated every two weeks for 14 weeks (6.5 ML.ha-1 of irrigation water in total). The application of gypsum alone was shown to be comparable to the C5G5 treated soil, although the C5G5 treated soil retained more Ca2+ and leached less Ca2+. Rapid decrease in soil electrolyte level was evident in all treated soils. The results of this study indicate that gypsum-enhanced CMWSC is more effective in ameliorating sodicity than the use of gypsum alone, due to a greater retention of exchangeable Ca2+.Despite mounting scientific evidence for the credibility of certain soil health management strategies such as those in this work, farmers remain hesitant to implement structured management plans and strategies. Hence, an investigation of the proportion of Lachlan and Macquarie Valley landholders who implement a structured soil health program was undertaken with focus on the impediments associated with the adoption of such programs. Non-parametric analysis of a mail-based survey supported with content analysis of landholder comments, suggests that the overall attitude towards soil health management is positive, although soil health management programs are often inconsistent, unstructured, or ad-hoc. Landholder knowledge of sodicity was found to be low, although landholders? do not believe that education is an impediment to program adoption. This research highlights that ongoing communication between landholders, agronomists, extension agencies and scientists is shown to be vital in the adoption of soil health management programs. While the initial investment in soil health management is perceived as an impediment, landholders indicate that production longevity and long-term financial gain are achievable.

This project has tackled the scientific challenge of predicting the key parameters of interest to the spinning mill manager from fibre quality measurements. The output of the project is a user friendly software package that can be used by spinners to predict the effects on their production of using higher (or lower) quality cotton. The software is potentially an important tool for marketing high quality Australian cotton fibre. For example, it could be used to illustrate quantitatively to a spinner the technical benefits of utilising a new variety of finer, longer cotton, e.g. Sicala 340BRF.

Final Report for Cotton Catchment Communities Project 1.01.09 and 1.01.49 . Titles Development of sustainable IWM strategies for use with low input cotton systems - the critical period for weed control strategy, and Project Title (1.01.49): Development of weed control thresholds and management of herbicide damage in cotton

This project aimed to improve cotton irrigation WUE using dynamic deficits to (i) avoid plant stress and maximize yield and (ii) make the most effective use of in-crop rainfall. Our analysis of a large data set of soil water x plant stress (using leaf water potential (LWP) as a measure) x climate experienced by the crop confirmed that atmospheric vapour pressure or evapotranspiration (ETo) can alter the plant stress response at the same soil moisture content. That is, if ETo is high a plant will may experience higher stress at higher soil moisture levels, and conversely if ETo is low a plant might not be stressed despite lower soil moisture availability. This analysis includes six experiments from three previous projects and three further experiments from the current project.Two years of large scale field experiments have found that there is considerable utility in delaying irrigation timing and extending opportunities to capture rainfall when ETo was low. This allows for more flexibility in cotton systems that require a significant number of fields to be irrigated at a point in time, and potential irrigation water savings.In both years there was no detrimental effect on yield or water use efficiency. In 2009/10 there was no difference despite considerable delays (up to 6 days) in one irrigation, and in 2010/11 the forecasted low ETo period also allowed an opportunity to capture rainfall event resulting in water savings of 0.8 ML over the season in one treatment. Periods of low ETo are often associated with a depression or low pressure weather front which may bring an opportunity to capture rainfall. Yeates found that delaying irrigations without taking into account ETo during flowering could have significant impacts on yield with a yield loss of 2.7% for every day that an irrigation was delayed.Results from the past two experiments have indicated the need for a measure of plant stress used with soil water measurement to assist with a dynamic deficit irrigation approach. The results are showing that even when there are instances of high ETo, crops are not as stressed based on current understanding. We could continue to approach further analysis of the dynamic deficit approach without a measure of plant stress, changing the deficit accounting for crop stage, crop size, and boll load. This was similar to the approach used by HydroLOGIC to assist timing of irrigation.The outcomes of the experiments in this project showed that there was considerable utility in delaying irrigation timing and extending opportunities to capture rainfall when ETo was low. This allows for more flexibility in cotton systems that require a significant number of fields to be irrigated at a point in time, and potential irrigation water savings.The continuation of the research will involve determining a framework to provide a method to predict plant stress (based on a continuous measure) which couples current and future soil water with short term ETo forecast along with crop stage. This would allow the dynamic deficit approach to be used confidently and will accommodate local conditions. The approach used presently uses an average response of soil water, plant stress and ETo. There is also an opportunity to continually and directly measure plant stress directly using canopy temperature easily and being able to couple this with both soil water and forecast ETo would establish the value/risk of bringing forward and delaying irrigation.

Diseases of Cotton X

This project aimed to identify means to improve nutrient use-efficiency in Australian cotton production systems and to improve soil health/fertility. The NutriLOGIC DSS provides an updated resource for cotton growers to manage soil fertility and cotton nutrition. This program provides recommendations to optimise crop nutrition through interpreting soil and plant analyses.N use-efficiency has been benchmarked and indicates the cotton industry substantially over-uses N fertiliser. The industry can safely reduce N fertiliser inputs by about 25% without reducing yield.The cotton industry can become carbon positive by adopting minimum tillage practices, by incorporating all crop stubble, by including legume crops in the rotation and reducing fallow times. Producing cotton using sustainable soil and crop management and reducing our net CO2e emissions will greatly assist marketing Australian cotton.Soil health can be improved dramatically with legume cropping. Marked improvements can be seen in the soil physical environment, chemical fertility and biological activity in those cropping systems that include legumes. For example, the cotton-vetch-fallow-cotton rotation remains the highest-yielding system and requires very little N fertiliser and therefore produces low carbon emissions.

Final Report: Linking cotton-pathogen molecular interactions and black root rot management

Final report Quantifying deep drainage in an irrigated cotton landscape

The purpose of the economic evaluation reported in this paper was to determine the potential benefits of the Cotton CRC's scientific research to the Australian cotton industry. It was considered that the main effect of the Cotton CRC's research was to increase the scale and intensity of research and to expedite the delivery of new technologies to the cotton industry through the provision of additional research funding and by reinforcing the collaborative links that exist among Australian cotton research institutions. Estimates are made of the potential benefits to the Cotton CRCs five main scientific programs (diseases, insects, soils, water and weeds) and the entire Cotton CRC using well-recognised economic modelling methods that have been adopted in recent economic evaluations of other agricultural CRCs and of the large scale research programs supported by the Australian Government. The results of this evaluation indicate that the Cotton CRC could generate significant economic benefits to the Australian cotton industry where its research programs lead to increases in industry productivity by promoting faster rates and higher levels of new technology adoption. Evaluating the cotton CRC as a full entity generates maximum estimated potential economic benefits with a NPV of $1,067.2 million and a BCR of 7.8:I, yielding a marginal or incremental benefit (the difference between the NPV estimates for the with- and without- Cotton CRC scenarios) of $1,070. I million and an incremental BCR 6.8:I. Sensitivity-testing of key assumptions indicated that the results are the most sensitive to the assumptions regarding industry productivity growth, adoption ceiling and lag values. The overall result of the sensitivity analysis is that the positive benefit-cost outcomes of this evaluation of the Cotton CRC remain robust despite the large reductions in NPV and BCR values that can result from using parameter value assumptions that are significantly lower than those used in the base evaluation.