Development of a precision mill mud applicator for a new farming system : SRDC Grower Group Innovation Project final report

Abstract

This aim was to construct an innovative mill mud spreader capable of accurately applying mill mud in a narrow band between 2m dual rows. The group postulated that applying mill mud in a band would increase the area that a load of mill mud would treat thereby making mill mud amendment cheaper per hectare in comparison to a broadcast application. Another way to explain this is that a load of mill mud applied on a band at 50 tonnes/ha would treat three times the area of a load of mill mud broadcast at 150 tonnes/ha. This was tested theoretically with a desk-top economic analysis and practically with a large scale replicated trial. An economic analysis tool was constructed in Microsoft Excel by Trish Cameron from FutureCane (QDPI & F). The tool showed that if 50 tonnes/ha is applied in a band rather than 150 tonnes/ha broadcast there is a saving of $6.63/tonne of mill mud spread (provided the yield of the two practises is the same). The subsequent replicated trial showed that this was the case in the plant crop, with no significant difference in cane or sugar yield between the two practices. The yield will be recorded in next few seasons to ascertain if there is a difference in subsequent ratoons. The project suggests that current practices of applying mill mud are wasteful, time consuming and expensive. Additionally the truck used to spread the mill mud rarely fits in with a controlled traffic system. By applying mud in a band with machinery that fits in with a controlled traffic system significant savings can be made. It could also be argued that applying mill mud between dual rows on a 2 metre bed system has potential to reduce the amount of off-farm nutrient loss although this was not tested in this project.