Regional evaluation of high density planting : SRDC final report BSS241 (revised)
This project was successful in comparing two systems: conventional 1.52-m single rows and the High Density Planting system (HDP), which consists of four rows on a 2.1-m wide bed using controlled-traffic and minimum-tillage principles.Site-replicated strip trials were used to compare the performance of the two systems under field conditions in all the major sugarcane districts of Queensland and New South Wales. A significant yield response was measured in 8 of the 21 plant-cane trials and 9 of the 15 first-ratoon trials, a further trial gave an apparent yield increase in both plant and first ratoon crops however this trial could not be statistically analysed. Where a response was measured between the two planting configurations, the HDP treatment produced an average of 39% and 20% more cane compared to the 1.52-m rows in the plant and first-ratoon crops, respectively. No difference in yield or CCS was measured between the two systems in any of the second-ratoon crops. Frequent stalk counts taken throughout crop growth and sample harvests were effective methods of monitoring the dynamics of biomass accumulation and stalk development in the trials.Poor germination in both planting configurations was a significant problem particularly in trials planted in the wet tropics in the 1999 season and it is likely that plant stands in many conventionally-planted crops are sub-optimal for cane and sugar yield. Of the seven trials planted, only one had acceptable germination. Adverse weather conditions that year also caused widespread germination failures in commercial plantings throughout this district. The stalk-count data and associated cane-yield data collected from the trials highlight the importance of good establishment. It is likely that several approaches can be taken to improving plant stands in commercial crops, including improved quality of planting material and planting systems, matching row and bed profiles to machinery and improved soil health. Unfortunately, many of the factors controlling germination are difficult to control or as yet unknown. A more scientific approach to assessing if a cane set will germinate is required.The trials in this project did not provide enough information about the performance of the HDP system over the entire crop cycle. The second-ratoon harvests showed no difference in yield between the 1.5-m rows and the HDP configurations. In the second ratoon, many of the HDP treatments appeared very gappy compared to the single rows. There is no doubt that the lack of appropriate vehicle guidance on the harvester caused some harvester navigation problems which resulted substantial stool damage. However, it is uncertain that this was the only reason for a lack of response in the second ratoon. Mechanical harvesting appears to cause substantial stool damage throughout the entire industry; methods of reducing this damage warrants further investigation.A major part of this project was the design and construction of equipment to allow management of the trials. Over the project, significant modifications were made to the harvester to improve the feeding characteristics and overall machine performance. When correctly adjusted, the bed-forming and planting equipment worked well in most soil types. The installation of a guidance system (DGPS or similar) on the harvester would have overcome the navigation problems. Considering the vast range of harvesting conditions experienced, the equipment performed extremely well.