Hands-on training in soil management was given to one hundred & seventy members of the Australian cotton industry at a series of 11 courses between October 1997 and September 1999. The main aim of the courses was to demonstrate how to use 'SOILpak for Cotton Growers, Third Edition. They were held in the Narrabri, Warren, Moree, Emerald, Dalby, Wee Waa, Goondiwindi, Gunnedah, Theodore, Walgett and Bourke districts.

The introduction of legumes into the cotton cropping system improves the N nutrition of the cotton following the legume crop. N fertilizer rates for cotton can be reduced by up to 50% when preceded by well-grown legume crops that can efficiently fix atmospheric N. The most effective N fixing legumes identified within this project include soybeans, lablab, faba beans, field peas and forage legumes, particularly vetches. While most growers aim for some financial return from their rotation crops, substantial benefits can be gained from green-manuring most legume crops, even those which have little value as seed crops (lablab and vetch). Where legume crops have preceded cotton the maximum yield attained has been consistently 4-5% higher than the maximum yield attained where non-legume rotation crops were used. This is probably a result of improved soil structure (tilth) enabling better root development, which is reflected in improved crop nutrition and soil water relations. Yield improvement and saving in N fertilizer application are typified in Figure I.

In Australia, cotton is generally grown using furrow irrigation on cracking grey clays with slow drainage, and is therefore usually subjected to some degree of waterlogging. This problem is made worse by imperfect land preparation or by rainfall after irrigation. Yield reduction of 10 to 40% have been reported (Hodgson & Chan, 1982), resulting in millions of dollars annual loss to fanners (Dennis et al 2000). Therefore, ameliorating this problem would be highly beneficial to the industry

Water use has become an important issue locally and globally. There is increasing competition between agricultural, industrial, domestic and environmental sectors. Concurrent with this increase in competition, there has been increasing public debate about water and environmental issues. This imposes additional pressure on irrigators, including cotton growers, to be accountable for the way water is used. Even without these external pressures, water use efficiency (WUE) is a key issue for producers. If water is a limiting resource, optimising production per unit of available water is clearly an important component of maximising returns. Further, efficiencies in water use may indicate losses from the system which can cause additional difficulties on the property: excessive rim-off leading to erosion, seepage leading to localised ground water rise and possibly salinisation. To assess the current water use efficiency within the cotton industry we calculated water use efficiency at the crop and the farm level using producers' historical water management data. A whole farm water use efficiency was calculated and then two components of this: the efficiency with which water was supplied to the crop (irrigation efficiency) and the efficiency with which the crop converted the water it actually used into lint(crop water use efficiency). Our results indicate significant opportunities for improving water use. Using this simple technique, producers can assess their own water use efficiency and compare their performance to others in their area or to industry benchmarks.

Damage caused by chewing and sucking pests does not necessarily lead to a yield loss in cotton. There is ample evidence indicating that cotton can fully recover from levels of vegetative and fruit damage above the current industry threshold. The ability to compensate for tissue loss in cotton is attributed to an improved canopy development stimulated by pre-squaring tip damage, and to fruit substitution for damage and increased fruit production during the reproductive stage. However, cotton's ability to compensate for fruit loss declines dramatically as boll development accelerates (3-4 weeks after first square), therefore, a more cautious pest management is necessary for about 2 months (until cut out)to avoid yield loss. A look-up table of the estimated fruit damage caused by Helicoverpa larvae at different fruiting stages is provided to allow assessment of a crop's ability to tolerate fruitloss. To ensure full compensation, it is important to maintain a healthy crop canopy (ie. , keeping mite damage under control) but not one with excessive leaf area (which leads to yield loss), particularly during the boll forming stage. Excessive growth response to pest damage may be minimised by selecting okra leafcultivars and by managing nitrogen and irrigation properly. A well managed crop may even respond to damage such as early season tipping out with yield gain over an undamaged crop. Clearly, the potential for reduced pesticide use in early and mid-season clearly exists and so do the attendant benefits of that. Harnessing the compensatory capacity of cotton is a key component of Integrated Pest Management and sustainable cotton cropping. This research continues the effort to ascertain ways of fully utilising the compensation potential of cotton for future incorporation into decision support systems for pest management.

Bioassays were conducted to investigate the effect of milk powder additives on the performance of a heliothis nucleopolyhedrovirus (Gemstar) and Bacillus thuringiensis (Dipel SC) on mungbeans and cotton. Larval mortality increased when the calf feeding supplement, Denkavit , was added at I kg/ha to both Gemstar and Dipel SC. Other powder additives and a liquid formulation, Amino Feed, were mostly equivalent to Denkavit. While Envirofeast and Pred Feed would not be considered for use solely as an additive to Gemstar or Dipel SC, the data indicate that improved performance from Gemstar could be expected if added to these food sprays. The mode of action of these additives has not been determined

The obvious symptoms of waterlogging response in cotton are leaf chlorosis (yellowing) and dropping squares & bolls. In addition, Huck (1970) showed that tap root growth stopped within 30 min of reducing the oxygen in the soils, and that the growing point of the root was completely dead within 3 hrs. In other plant species, these responses have been associated with the effect of ethylene, produced in response to lack of oxygen (Pratt, 1953; Jackson, 1984; 1985; Jackson & Drew, 1984; Raskin & Konde, 1984; Stead, 1985; Voesenek & Blom, 1989; Osborne, 1991;Reid & Wu, 1991; Brady & Speirs, 1991; Voesenek et al, 1992; Drew, 1997). Ethylene is known to accelerate premature senescence, defoliation and boll dehiscence in cotton (Hall et al, 1957; Kirzek, 1986), but the involvement of ethylene in cotton's response to waterlogging has not been demonstrated. AVG (aminoethoxyvinylglycine)is an inhibitor of ethylene production. It can be used to indicate the involvement of ethylene production in physiological processes. Improvements in commercial production of AVG provide an exciting opportunity to explore the importance of ethylene production in plant responses to waterlogging in the field. To achieve meaningful results, dose-response tests are necessary to establish the concentration of AVG that is high enough to inhibit ethylene formation while low enough to minimise nonspecific and possibly toxic effects to the plants from AVG itself(Jackson, 1991).

Australia-wide insecticide resistance surveying of cotton aphid populations identified pirimicarb, organophosphate, endosulfan and pyrethroid resistance. Resistance levels were often high to extreme and have been linked to field control failures for the first time. Resistant cotton aphids have the potential to seriously impact the Australian cotton industry and their resistance management should now be an industry priority

Machinery contributes around 54% of the cotton farm input costs. Research conducted by the National Centre for Engineering in Agriculture (NCEA ) into on farm energy efficiency has found that for cotton production: * There is significant variation in energy use between cotton enterprises and this is largely due to irrigation. * Energy usage was 3.7 to 15.2 GJ/ha at a cost of $80 to $310/ha. *275 to 1,404 kg CO2 equivalent/ha of greenhouse gas emissions are generated.

The ovicidal and larvicidal activity of Tracer Naturalyte Insect Control and conventional ovicidal standards was investigated on Helicoverpa spp. under Australian conditions. Two trials were carried out; the first used laboratory reared Helicoverpa armigera eggs, and the second used Helicoverpa spp. eggs naturally laid on field cotton. The results showed that Tracer killed 10-30% of eggs and 20-80% of hatching neonates. The ovicidal activity of Tracer was slightly less than conventional ovicidal standards (Larvin, Ovasyn and Lannate'), however, the combined ovicidal and larvicidal action was generally equivalent to , or greater than the standards. These data show that Tracer should be applied at the brown egg stage to utilise both the ovicidal and Larvicidal action of this product.