To determine the rate of nitrogen reduction possible on a plant cane crop following a soybean fallow affected by severe flooding
Soybean are commonly planted during a fallow season to assist in fixing nitrogen in the soil for the following cane crop. The yield of the soybean crop is a reliable indicator of how much nitrogen the soybean plant will have fixed. However, there is limited information available in regard to the amount of fixed Nitrogen lost during a severe rainfall and flooding event. In situations of uncertainty, full rates of Nitrogen are usually applied.
Following cyclone Debbie, many paddocks that had grown a successful soybean crop were inundated with flood water. Nitrate strip tests of these fields indicate minimal available Nitrogen is present in the top 30cm of the soil, however we do not have enough knowledge of this type of situation to determine the amount of Nitrogen fertiliser that should be applied for the following cane crop.