This project upgraded the harvesting equipment for CSIRO cotton breeding experiments, particularly for those sites located off the Australian Cotton Research Institute. The previous method of harvesting was heavily reliant on manual labour and bagging of samples from research plots. The new method is automated and computerised to speed up harvest.

Objectives: To purchase a new nitrogen analyser in order to provide faster, more accurate analysis of cotton samples for a wide range of projects

Over the period from 1990 to 1993, research was carried out investigating the regrowth of Australian cotton varieties after damage by haiI. The work was funded by the Cotton Research and Development Corporation and carried out in co-operation with the loss adjusters to the Australian cotton industry, Agricultural Loss Management Group. By comparing the regrowth characteristics of Australian cotton varieties, following simulated hail damage at various stages of plant development, the aim was to test the accuracy of the loss assessment procedures currently used in cotton hail loss adjustment and determine whether it was appropriate to apply these procedures to loss adjustment for the whole range of Australian bred varieties now grown.

A vision guidance system has been designed, built and commissioned which steers a tractor relative to the rows of a crop such as cotton. It was required to be insensitive to additional visual "noise" from weeds, while tolerating the fading out of one or more rows in a barren patch of the field. The system integrates data from several crop rows, testing for image quality. At the same time, the data processing requirements have been limited by the use of frame sequential strategies to reduce the image space which must be processed. The current prototype employs an embedded 386 PC notebook computer and shows great promise of cost effective commercial exploitation. Experimental results are reported and further sensing systems are explored to enhance performance in difficult environments.

OBJECTIVES 1993/4 Determine the common species of V AM fungi in the cotton areas of eastern Australia. Place the fungi in pot culture. From areas where 3 - 5 of the common fungi are found, collect further soil samples and determine the infectivity of the soils and individual fungal species. This gives information on the importance of the common species in individual sites and their usefulness as predictors of the population. 1994/5 Determine the sources of fungal infection (survival structures), their location in the soil profile and their density. This experiment would need to include representative soil samples from several climates. From individual fungi in pot culture, determine the survival structures, subject the fungi to factors like cultivation, fungicide application) fallow etc. Follow the fungi through to recovery. This work would continue into 9516. 1995/6 Experimentally, determine the fungal structures that survive long fallow or disturbance, the rates of recovery of fungal populations, and the effects on mycorrhizal infection and plant growth. We will also determine the location of propagules of VAM fungi in the soil profile

The objectives of this study were to: l) determine the role of soil instability and clay translocation in the formation of shiny-faced soil aggregates, 2) determine the roles of clay translocation and vehicular compaction in the formation of subsoil densification in cracking clays used for cotton production, and 3) examine the effect of aggregate surface fabric on the movement of water and solutes in these soils. The results of this study have extended the results of previous research on cracking clays to show that the past practices used in long-term irrigated cotton growing have resulted in substantial deep subsoil densification down to depths of 200 cm, and that such deep subsoil densification is likely to be widespread in these soils. This project has also identified that the cause of the deep subsoil densification in irrigated cracking clay soils used for cotton production is vehicular compaction (as a result of heavy axle loads) rather than clay translocation as has been previously suspected. The results indicate that the present trends and recommendations towards the use of lower axle loads and permanent bed systems in cotton production in Australia are very appropriate for these soils. The scanning electron microscopy study on the fabric of these soils has provided an understanding of the fundamental nature of this soil characteristic and provided a more rational basis for the measurement and subsequent interpretation of this soil characteristic. For example, the results of this project indicate that that dull ped fabrics cannot be taken to infer that structural instability in the form of clay mobilisation and translocation has not taken place in these soils. The fabric studies clearly show that there are clay coatings on the structural surfaces within these soils: the solute movement work indicates that at moisture contents below that where the large pore space is coated by conductive films of water, the presence of such clay coatings leads to preferential flow.

The effects of rotation crops and their management on soil properties, and irrigated cotton productivity and profitability were evaluated from 1993 to 1996 in some typical cracking clays (V ertisols) of the Namoi and Macquarie valleys of New South Wales. The project consisted of 3 field experiments: (a) an experiment on tillage systems and rotations (intensive tillage or minimum tillage sown with continuous cotton, and minimum tillage sown with a cotton-wheat sequence which were imposed in 1985, on which three rotations: cowpea-cotton, continuous cotton and fallow-cotton were superimposed in 1993) located at the Australian Cotton Research Institute near Narrabri; (b) a rotation crop management experiment (wheat+l40 kg ha-1 N-cotton, unfertilized wheat-cotton, and winter grain legume-cotton sequences where the legume grain was either harvested or incorporated) located near Wee Waa; and ( c) a rotation crop management experiment [high input (99 kg N and 17 kg P ha-1, irrigated) wheat-cotton, low input (16 kg N and 17 kg P ha-1, rainfed) wheat-cotton, rainfed field pea-cotton, summer fallow-cotton, low input wheat-dolichos-cotton, low input wheat-dolichos +24 kg P & 73 kg K ha-1-cotton, and continuous cotton sequences] located near Warren. (The low input wheat-dolichos/P+K fertilizer-cotton sequence was replaced by a faba bean-cotton sequence in 1995). Soil properties which were monitored to a depth of 0.6 min every site included organic matter fractions, plastic limit, strength, shrinkage indices derived from shrinkage curves, exchangeable Ca, Mg, Kand Na, pH, nitrate-N and electrical conductivity. Profile water content and water extraction to 1.2 m, nutrient uptake, crop vegetative growth, cotton lint yield and fibre quality were also quantified. Economic rerorns were evaluated by comparing gross margins for rotation crop-cotton sequences.

Objectives: A). To establish the uptake and partitioning patterns of potassium in cotton. B). To establish the most suitable predictor of deficiency amongst soil, leaf blade, leaf petiole and leaf petiole sap potassium; including the most appropriate potassium test. C). To establish appropriate methods of within season amelioration of potassium deficiency.

Aims: * Determine the economic impact of thrips on cotton and evaluate new means of control. * Evaluate the range and possible mechanisms of plant resistance to thrips and mites. * Investigate host preferences of thrips and manipulation of hosts to increase thrips predation. * Investigate further the impact of thrips on mites through predation, induced resistance and effects on plant quality. * Refine action thresholds for the control of two-spotted spider mites on cotton. * Evaluate the efficacy of new acaricides and investigate novel technologies for controlling mites. * Determine resistance levels in mites to acaricides and factors influencing development of resistance. * Evaluate the effect of early season insecticides on mites and their predators.

The goals of this research were: 1. measure the soil stresses and deformations due to "edge of bed" operations, and measure the changes to soil physical properties (infiltration, aeration, strength) that result. This was to be pursued in collaboration with the anticipated rotation experiments led by Cooper and the structure project led by Koppi; 2. correlate the field performance of operations with soil conditions, in order to detennine optimum conditions for operations; 3. transfer the conclusions via SOILPAK, the Australian Cotton Grower and Grower Conferences