Objectives o Determine optimum nitrogen rates for cotton under a range of conditions. o Determine the best time to apply this nitrogen. o Measure the pattern of nitrogen uptake in relation to rate and timing and hence calculate fertiliser recovery. o Examine the relationship between soil nitrate test and subsequent nitrogen extraction by a cotton crop. Measure cotton crop requirements of the trace elements zinc, copper , iron and manganese . o Measure the effects of plant spacing, temperature and light on leaf growth in cotton. o Measure the penetration of light through cotton canopies . o Map the production and survival of cotton fruit. o Use the leaf growth, light interception and fruit map data to develop simulation models for cotton . Some success was achieved in all objectives . A summary of results from the major projects follows. More comprehensive results of all topics are attached. Difficulties encountered are outlined in the projects where they occurred.