In the late 1980s, growing concern over the impact of irrigated agriculture on the surface and ground waters of NSW, lead the Department of Land and Water Conservation (DLWC), to conduct a water quality monitoring program in the Macintyre, Gwydir, Namoi and Macquarie valleys of NSW. This program commenced in 1991/92 and has been jointly funded by the DLWC and the water users of these valleys, whose on going concern, contributions and support are gratefully acknowledged.

There has been a heavy reliance on agri-chemicals in the Australian cotton industry over the past 20 years to increase production and profitability. The off-farm movement of these chemicals has created a number of environmental issues of concern for the industry (Edge, 1996). There is an urgent need for the development and adoption of management practices which reduce our reliance on chemicals and are agronomically and environmentally sound. Recent industry funded research has identified key transport mechanisms and highlighted the importance of storms and sediment in moving pesticides off-site. High risk periods include early season (when ground cover is low) and soon after chemical application (when field burdens of pesticides are high). Research in the grain industry has identified the capacity of stubble cover to reduce erosion and that winter cereals provide the most effective cover. Plot scale (<1ha) research in cotton found that a significant reduction in pesticide movement was achieved from surface treatments such as wheat stubble (Simpson et al, 1996 and Silbum et al, 1996). Our CRDC project commenced in June 1997 to develop management strategies to minimise offsite movement of pollutants at the paddock or farm scale. In particular, our goal was to apply the research findings with wheat stubble at the paddock scale and to assess the practicality and feasibility of this management practice.

The cotton industry is one of the largest user of pesticides among the Australian agricultural sector. It has been estimated that endosulfan and pyrethroids account for 70% of all insecticides. In addition to insecticides, herbicides are also used extensively to control the weed menace in cotton. However, reliance on herbicides to control weeds in cotton production system has the potential to cause concern about their presence in the environment and contamination of waterways. Recent monitoring conducted by the New South Wales Department of Land and Water Conservation (Cooper and Muschal 1998) show that residues of some herbicides are also being transported into rivers in cotton growing areas. The herbicides atrazine, diuron, prometryn and fluometuron have been detected consistently daring last three years of monitoring program in Northern New South Wales. The challenge for the industry is to cope with the public demand for clean and safer agricultural practices, reducing the environmental damage that is mainly on the excessive use of pesticides, while maintaining profitability. This article, as part of a new CRC research project we provide information that can help growers select herbicides that will have a minimum impact on water quality and sustainable cotton production. Some elements support for best management practices needed to sustain favourable environment to grow cotton is also presented.

Funding toward the purchase of an atomic absorption spectrometers (with flame and graphite furnace facilities). The instruments were purchased from Vanan Australia

last year for a price $109,755.80 and CRDC's contribution has been highly valuable in getting our chemical analytical facilities up to date. The new instruments have been used for the

analyses for a number of common elements including potassium, calcium, magnesium, sodium and several other elements for the research projects involving cotton industry.

The objective of NFF's trade strategy is to achieve a more profitable international trading environment for Australia's farmers. To realise this goal Australia has to expand its international lobbying effort for agricultural trade reform by harnessing the resources of NFF and Australian agribusiness and working with the Australian Government and like-minded industry groups in overseas countries.

The long term production of cotton it the same field often leads to low yields, even with 1:large amounts of nitrogen (N) and phosphorus (P) fertiliser. In the Macquarie Valley of NSW this is often due to soil compaction and poor soil structure (McKenzie et al, 1991). Initially, the problem was corrected by deep ripping the soil, but experiments have shown that drying the soil with crops such as wheat and safflower' can produce similar benefits (Hodgson and Chan, 1984). Rotation crops such as wheat are also used to reduce the incidence of diseases such as Verticillium wilt. In 1992, a survey of cotton growers in the Macquarie, Namoi and Gwydir Valleys was conducted to find out now widely rotations are used, which rotation crops are used, and what problems glowers had encountered with rotations. The survey found that rotation clops were widely used, but the choice of rotation crop was mainly based on convenience eg. it did not need irrigation, it could be sown late, or it was easy to sell. Many growers were interested in using legumes and other crops, but lacked the information to make sound decisions. Can legumes extract as much moisture as cereals, what soil structure benefits do they give, which crop provides the best disease break, are typical of the questions growers had about rotation crops

What are 'survivors'? Are they resistant to Bollgard II?, Control of Helicoverpa larvae in Bollgard II, Helicoverpa thresholds , Insecticide selection for Bollgard II crops.

Helicoverpa spp. remain the key pests of cotton in Australia. The cotton bollworm, H. armigera is becoming resistant to many insecticides. With this increasing resistance as well as environmental concerns with insecticide use, we need to look into viable alternative tools that can be useful in the integrated approach to manage this pest. Semiochemicals or insect behaviour-modifying chemicals fit well in an integrated pest management system due to their specificity and low toxicity. Sex pheromones, have been successfully used in pest monitoring systems and mating disruption techniques for a number of orchard pests. In Egypt, attract-and-kill methods using sex pheromones have successfully contributed to the management of another cotton pest, the pink bollworm, Pectinophora gossypiella (Mafra-Neto & Habib 1996).

Fusarium oxysporum f.sp vasinfectum, (FOV) the causal organism of Fusarium wilt, is a significant threat to the Australian cotton industry. It is therefore essential that various strategies for the development of solutions to this problem are explored. It is hoped that an improved understanding of the genetic factors responsible for the pathogenicity of Fov will uncover novel approaches for disease control. We are implementing a transformation protocol for Fov and developing a project aimed at identifying pathogenicity genes using gene disruption and tagging techniques. We are also generating Fov transformants expressing marker genes to facilitate studies of the interactions of the host and the pathogen.

Precision agriculture (PA) research for cotton in Australia began in 1997 and has followed a clear path aimed at discovering key information for the Industry. The potential benefit of PA management techniques within a particular field over the current "field average" management techniques is directly linked to the amount of spatial variability present, therefore a key question was "how much variability is typical in Australian cotton fields". The second question follows from the first and is "if I have variability in my cotton field, how may I manage it so as to achieve economic and environmental benefits for myself and my community"Γ The answers to these questions have been the goal of two research projects conducted by the University of Sydney with cooperation and funding from the Cotton Research and Development Corporation and the Australian Cotton CRC. The results are detailed in two parts of this paper. The first section "Measuring variability " discusses methods of measuring yield variability and presents results of research into the accuracy of on picker yield monitors. The second section discusses "managing variability" and looks at a method of determining how to better manage nitrogen within a variable field.