Monitoring cane at the mill to improve nitrogen management on the farm, a pilot study : final report CSC21A

Abstract

The project examined variation in amino-N in cane supply at the Macknade Mill during the 1996 crushing season. This variation was related to factors such as crop class, variety, time of harvest, ccs, and farm supplying the cane. Extensive variation in amino-N concentrations was found in cane supplied to Macknade Mill over this season. There was a large crop class effect detected, with plant crops on average registering 50% higher amino-N concentrations in their juice than later ratoons. There was no significant variety effect detected. A major factor determining amino-N level was the farm from which the cane was sourced. Some farms always supplied cane with high levels of amino-N in the cane, indicating excess N supply. Others consistently supplied cane with low to adequate levels of amino-N. Overall approximately 45% of the cane supply to Macknade Mill during the 1996 crushing season was estimated to have been grown under conditions of excess N supply. Excessive N fertilisation rates is thought to be the most probable explanation, but this suggestion is being explored in follow up research.

The project also explored some options for rapid and cost effective analysis of amino-N concentrations in cane juice, that might be suited to installation into the juice stream of mills. Near-infrared Spectrometry (NIR) was shown to have considerable promise and this technique is being further evaluated in follow-up research.