Global warming is surmised to result in major increases in climatic variability (i.e. severe deficiencies and excesses of water for plant production, higher frequency of sub- and supra- optimal growing season temperatures) and changes in pest incidence. In order to maintain yields and profitability, and thus ensure sustainability of the cotton industry, cotton farming systems need to demonstrate resilience in the face of the above mentioned environmental stresses. Resilience can be improved by using suitable tillage and stubble management systems, and crop rotations to improve soil quality and water conservation. Such improvements can be best demonstrated by monitoring in long-term experiments. Indicators of resilience include improvements in soil carbon and nutrients, water storage, soil physical and chemical quality, yield maintenance/profitability improvements over time, and changes in key soil faunal indicator species.

To maintain the productivity of the Australian Cotton Industry, cropping systems that are resilient to these climatic events and the associated soil processes must be identified. This is best done through long-term experiments that capture seasonal variability. The aim of this project was to continue three on-going long-term experiments on selected cropping systems that include practices such as crop rotations, stubble retention, tillage systems and fallow length. Measurements made on an annual basis will include soil carbon and nutrients, physical and chemical quality, crop yields and profitability. Collaborative projects with CSIRO, UNE and other research groups will research soil microbial dynamics of resilient cropping systems, carbon storage in the subsoil, disease incidence, nutrient decline and maintenance, and drainage.

During the previous research the short-term benefits of sowing corn on cotton yield, disease control and subsoil increases in soil carbon were observed. The longer-term impacts of sowing corn in cotton-based farming systems were further investigated in this project. In addition, benefits have been demonstrated in a long term experiment at ACRI with respect to soil faunal indicator species, N, energy use and water conservation in a retained stubble cotton-wheat-vetch system. This long-term investigation is being continued.