Cotton industry participants Peter Cottle and Harvey Gaynor recently graduated from Course 5 of the Australian Rural Leadership Progra

The stated objectives/proposed outcomes in the grant application were: * Testing of biocontrol agents in diverse geographical regions. * Sharing of methodology to study endophytic biocontrol agents. * Potential for faster development of biocontrol agents for use on commercial cotton farms.

The principal tasks of the conference were to: * review progress in the context of agriculture and related land-use towards the principles containect in the United Nations Conference on Environment and Development, Rio de Janeiro - specifically, the Declaration on Environment and Development Agenda 21: "Program of Action for Sustainable Development"; * identify new practices and the necessary enabling environments that will lead to less degradation and ultimately to sustainability; * identify the main issues to be addressed, taking into consideration the continually evolving nature of agriculture and related land-use.

Deep drainage of cotton based rotation systems were estima!ed on two soils in the Macquarie Valley: on a heavy cracking clay at "Auscotf', Warren and on a hard setting reel soil on the Twynam property "Elengerah", near Trangie. Analysis of soil chloride profil~s at the beginning and end of the 18 month rotations showed that none of the systems were maintaining chloride levels at a steady state (ie. The mass of the solute applied to the soil profile was not equal to the mass of the solute leaving the profile). Water entry into the soil profiles decreased markedly after the first irrigation in the hard setting red soil. Estimations of deep percolation were made on all rotations. In both soils, the treatments not including a winter crop had a substantiaily higher calculated deep percolation. The calculated deep percolation was much higher on the cracking grey clay than the hard setting red soil.

The N nutrition of cotton crops was investigated with respect to the effectiveness with which rotation crops improve the supply of N to cotton and reduce the amount of N fertilizer required. The CRC farming systems experiments were examined to demonstrate these principles by monitoring the N status of each system. This has helped to identify the more N efficient cropping systems and allow for more effective N nutrition of cotton. Summer and winter growing rotation crops (including grain, green-manure and forage legumes) were compared in field experiments at ACRI and the benefit of these legume systems and savings in N fertilizer for cotton was assessed. Both back-to-back and rotational cotton systems were investigated. The biofumigatory effect of Brassica species will also be determined through lint yield and VAM assessment. The value of other rotation crops was evaluated in terms of improved N nutrition, soil structure, weed and insect management, VAM and cotton pathogen survival. Improvements to soil and crop nitrate tests for predicting N fertilizer requirement and crop N status will enhance grower confidence and adoption of this technology by allowing on-farm determination of soil nitrate levels. These results will be incorporated into the Nutripak /Nutrilogic program

Our network currently consists of 18 Campbell Scientific automatic stations spread across the Darling Downs (see enclosed map). The cost of network was approximately $130,000 and we believe it to be the largest privately operated network in the country.

Sucking pests of cotton (aphids and mirids) that are expected to become more significant as the use of synthetic chemical sprays is replaced by the deployment of transgenic cotton. The objective of this project was to characterise genes encoding proteins toxic for sucking pests of cotton. Eight acts prepared over 100 strains of bacteria from three different genera were tested by bioassay for their toxicity to three major sucking pests: the green mirid, cotton aphid and silverleaf whitefly. Extracts of several bacterial strains were found to be toxic for the sucking pests; no strain was most toxic for all three pests. One protein with toxicity for cotton aphid was purified

The second edition of the BMP Manual now includes new sections on the storage and handling of pesticides, dryland specific issues and farm hygiene. All other sections were comprehensively revised and updated, and the format of the document was also extensively revised to improve its useability. A detailed guide to use was developed to help the transition from the first edition to the second edition, and colour coding has been used to highlight both the different sections and the relevant best practices.

Gin trash and mixtures of gin trash were composted using a minimum of equipment and labour inputs. Questions of cotton pathogens and synthetic chemical residues were addressed by lab testing pre- and post- composting. Guidelines were developed for overcoming practical problems. Wetting the trash initially was a problem until water was applied at low rates often, timed to operate during the early hours of the morning to minimize drift and evaporation. The trash was handled so that all of it spent enough time in the hot zone within the windrow for the heat to remove pathogens and chemical residues. Work was done to develop better methods of determining the time to end composting so that immature compost does not compete with young plants for nitrogen. Guidelines are included on how to use the compost for best agronomic results.

Polymeria longifolia grows concurrently with the cotton crop making management very difficult. Active shoot growth of P. longifolia can occur at any time of the year in uncultivated areas and is probably linked to soil water status. Polymeria longifolt'a competes strongly with cotton, and is particularly detectable at soil moisture levels found immediately prior to irrigation. Although competition for major nutrients was suspected, no evidence was found in this study. Anatomical studies suggested there was some evidence that P. longifolia interfered with cotton through the production of allelochemicals but this requires further investigation. Densities of over 100 stems per square metre that are commonly found in weed patches reduced the yield of cotton lint and seed below 50%