Completed projects and reports

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Sugar Research Australia, Sugar Research Development Corporation and BSES reports from completed research projects and papers.

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Does ratoon age impact on N-fertiliser requirements in the Wet Tropics? : ASSCT poster paper
(ASSCT, 2019) Skocaj, DM; Schroeder, BL; Park, G; Hurney, AP
Spatial distribution of potential soil constraints affecting nitrogen management in the Wet Tropics : ASSCT peer-reviewed paper
(ASSCT, 2019) Skocaj, DM; Schroeder, BL; Hurney, AP; Rigby, A; Telford, D
Position in the landscape and climatic conditions experienced during the growing season, especially following the application of nitrogen (N) fertiliser, has important implications for crop growth, N uptake and N losses. Understanding the spatial distribution of soils where crop growth and responsiveness to applied N may be constrained in wet or dry years will allow growers and advisors to refine N-management strategies. To identify soils where crop growth and responsiveness to applied N may be restricted, a system of grouping soils that better reflected agronomic performance under different climatic conditions was required. The categorisation system considered position in the landscape, N-mineralisation potential, soil water-holding capacity in both wet and dry years, propensity to waterlog in wet years and presence of a water table in wet years. In dry years, waterlogging and the presence of a water table do not impact crop growth to the same extent as moisture availability, and, hence, in dry years, it is more important to categorise soils based on water-holding capacity. The major sugarcane-growing soils in the Tully and South Johnstone mill areas were categorised using this system. This resulted in five soil groups to describe the impact on crop growth and N responsiveness in wet and dry years. Given the application of N fertiliser to ratoon crops predominately occurs around spring, wet years were defined as receiving high spring-summer rainfall, whereas dry years were defined as receiving low spring-summer rainfall. Classifying wet and dry years according to spring-summer rainfall also allows growers and advisors to refer to seasonal climate forecasting indices for guidance on the likelihood of experiencing a wet or dry year. In wet years, the impact on crop growth, responsiveness to applied N and potential for lower N uptake is greatest for soil group five. These soils tend to occur in the lowest positions in the landscape, experience severe waterlogging and a persistent water table. They are also subject to frequent water inundation following extreme rainfall events. The spatial identification of soil constraints will complement the development of whole-of-farm nutrient-management plans in the Wet Tropics region. Knowledge of soil constraints influencing sugarcane growth and responsiveness to N will allow growers and advisors to better identify areas where nutrient-management strategies may require further fine-tuning. This information may also be of value in improving other management decisions including varietal selection and harvest scheduling
Improving the yields of ratoon crops of sugarcane : SRDC Final report BS7S
(SRDC, 1992) Chapman, LS; Ferraris, R; Ludlow, MM; Hurney, AP
The economics of sugarcane growing improve with the number of ratoon crops which can be grown from a single planting. In Australia, declining yields with increase in the number of ratoons limit a cycle to three to five ratoons, according to district. However, studies by BSES indicate that the most economic strategies involved growing up to six ratoons. If this decline in yield could be reduced, then more ratoons could be obtained from a single planting with the associated economic benefits.
Assessing clonal and nitrogen interaction on ccs in sugarcane in the wet tropis ; SRDC project BSS180 final report
(2003) Hurney, AP; Berding, N; Grace, D
There has been a negative trend in CCS in the Tully-Mossman region since the mid-1960s that has been linked to increased extraneous matter and suckers in the cane supply. The situation had become particularly bad during 1990-1996, with most mill districts within the region experiencing problems with low CCS. An increase in the frequency of lodging and incidence of suckers was possibly contributing to this problem and there was a perception that this was related to inappropriate use of nitrogen fertiliser for the locally grown cultivars. There were also concerns that current cultivars were not suited to the local environmental conditions. Growers choosing to grow inappropriate cultivars for particular locations were thought to be exacerbating the problem.Decisions on what cultivar to grow and how much fertiliser to apply are management options that could be modified if they were contributing to the low CCS problem. These issues were addressed in this project by studying the effects of four rates of nitrogen (0, 70, 140, 210 kg N/ha) on lodging, suckering, CCS and cane yield of the three cultivars Q117, Q120 and Q138. These experiments were conducted on three different soil types at three locations within the Tully mill district. The objectives of this project were to provide a better understanding of the role of nitrogen and cultivars in the low CCS issue to facilitate the development of improved management options.In the plant crops, which were planted after a fallow, nitrogen had no influence on cane yield, CCS, lodging or suckering under the environmental conditions in which these crops were grown. However, it did increase both cane yield and lodging in first- and second-ratoon crops. Responses were limited by adverse interactions with the wet conditions and nitrogen losses due to leaching and/or volatilisation. Nitrogen had no direct influence on CCS in the ratoon crops, but it did have an indirect negative effect, because it increased the incidence of lodging. Rates of N application could be reduced in both plant and ratoon crops, which would reduce production costs. It would also be beneficial environmentally.There was no evidence of nitrogen accumulation in the soil from high nitrogen fertiliser application even following a low-yielding crop. This is of concern from an environmental viewpoint if inappropriate nitrogen rates are applied, as any excess nitrogen will be lost from the soil due to leaching or denitrification. The data suggested that the critical leaf nitrogen concentration might vary between cultivars. This provides an opportunity to reduce nitrogen rates for cultivars with lower nitrogen requirements.Current cultivars do have high potential CCS, but this cannot be realised, partially because of their susceptibility to lodging and suckering. All three cultivars tested, Q117, Q120 and Q138, are susceptible to lodging in well-grown crops. It appears that the susceptibility of Q120 and Q138 is high in crops yielding more than 70-80 t/ha under the wet conditions of the wet tropics.The potential reduction in CCS from total lodging was estimated at about 10% across all cultivars in these trials. The actual loss in CCS is governed by the actual proportion of lodging in the crop and was estimated at 0.4 units in crops that had 25% lodging. This is a hidden cost of which growers are generally not aware. There are no management options that can be implemented to minimise this loss. Severe and multiple lodging events had a negative impact on CCS and cane yield in Q120 and Q138, reducing profitability. In these circumstances, the negative effects of lodging can be reduced if the time between harvesting and occurrence of lodging is reduced. Increased returns to the grower of $200 $300/ha are possible using this strategy.Lodging was less extensive in Q117 and lower-vigour cultivars, such as Q117, may offer a more appropriate ideotype for the wet tropics, because of their lower susceptibility to lodging. Economic impact was estimated at a loss of $7.5 million to growers within the region from a moderate lodging event affecting 25% of the crop. Adoption of agronomic practices to improve physical support of the crop is only partially successful in reducing the intensity of lodging. This can only be achieved by the implementation of a research program to select cultivars with a low incidence of lodging, while maintaining or improving productivity.The cultivars Q117, Q120 and Q138 are representative of those being grown in the wet tropics and demonstrated a high propensity to sucker. Lodging is not a pre-requisite for sucker initiation, as the emergence of suckers was generally first noted under a closed canopy. Suckers have a negative effect on CCS, because they dilute the cane juice through their high moisture and low sucrose composition. In these experiments, 10% by weight of suckers in the cane supply reduced CCS by a little over 1 unit. The increased cane yield from suckers is inflating productivity estimates but not improving profitability; the level of suckering experienced in these experiments would reduce regional grower-income by approximately $6 million. It is possible to select against suckering propensity and this has already been introduced into the crop improvement program. However, research into the relationship between suckers and longevity of ratoons is required because of the potential impact on productivity.An appropriate extension program needs to be developed to disseminate the findings of this research to growers. The results from this project have been extended to the industry. There have also been extension programs for BMP of cultivars. However, there is still a large gap between extension and adoption, which is why additional extension programs are recommended. Adoption of findings on nitrogen will reduce production costs, as well as have a positive environmental impact. Management strategies are available to partially alleviate the negative impacts of lodging and suckering. However, further research is required to fully overcome the effects of these phenomena.
Environmental stimuli for sugarcane suckering in the wet tropics : SRDC final report BSS221
(2003) Berding, N; Hurney, AP; Bonnett, GD; Joseph, F
The northern section of the industry has been in crisis for most of the years in the decade up to 2002 because of declining CCS. This decline has been due to increased extraneous matter levels due largely to increased sucker culm content of the crop. These have developed because of marked wet episodes during the harvest period in the majority of years in this period. This resulted in open canopy situations, because of sprawling and lodging, increased light penetration, and initiation and development of sucker culm populations.A hypothesis was proposed that excessive mature-crop moisture, combined with continued excessive nitrogen use, particularly early in the decade were initiating variables for the problem. Observations suggested that light, via an open canopy situation, also was a driver.The project tackled the problem with a preliminary series of experiments that allowed optimisation of management and data collection techniques for use in a main experiment proposed. The main experiment sought to establish the importance of levels of three environmental variables, light, nitrogen and moisture, on sucker initiation, and their interaction with each other and with two cultivars of known suckering propensity under commercial conditions.The preliminary experiments allowed us to make the following recommendations for the design and methods for the main experiment:1. The late nitrogen application of 70 kg N will be in late April early May if the weather is suitable and as soon as possible thereafter if the weather is too wet to allow the application at the desired time.2. That spectroradiometry measurements will be made in the core plots at a height of 10 cm and 1 m to determine the effect of plant spacing on the spectral composition received. Photosynthetically active radiation measurements will also be made.3. A similar soil sampling and nitrate measurement regime will be made in the main experiment as that in the preliminary experiment with the exception that more frequent smaller diameter cores will be taken to speed up sampling.4. Sucker counting and other trial management will continue as originally proposed.5. Applications of late N will be made in separate experiments on different cultivars and if possible to soils with low basal nitrate levels.
Soil compaction studies - Mossman
(1975) Hurney, AP
Study was initiated to investigate the effects of the different bin transport systems on soil compaction. Compaction under dry soil conditions does not appear to be a serious problem and can ve overcome by cultivation. Compactive effects are more marked under wet soil conditions and there are indications of residual effects following cultivation.
Factors affecting the sugar content of sugar cane in the wet tropics of Queensland: statistical analysis of ccs data at Babinda and Tully
(BSES, 1972) Sturgess, OW; Hogarth, DM; Hurney, AP; Leverington, KC
In the wet tropics, the sugar content of crops is usually below the state's average and is a critical factor in farm economy, particularly during years of low sugar prices. This aspect of sugar production has been the subject of detailed investigation.
Influence of harvester basecutters on ratooning of sugarcane : SRDC Final report BSS123
(2005) Hurney, AP; Croft, BJ; Grace, D; Richards, DR
Current single row mechanical sugarcane harvesters use twin rotary basecutters with multiple blades to produce an impact cut in the stalk at or near ground level. However, the cane stubble is often damaged during harvesting, which is considered to be caused by the basecutter. Many instances of poor ratooning have been attributed to either basecutter damage increasing the risk of infection by stalk diseases, or due to a reduction in the number of viable buds. While this matter was discussed regularly, there were no data that quantified the level of damage occurring in the field or the relationship between stubble damage and ratooning. In addition, if stubble damage was affecting ratooning, harvesting and cultural practices contributing to stubble damage need to be identified. This was addressed in this project by conducting surveys in harvested fields in the Tully, Burdekin and Mackay districts to assess the level of damage that occurred during harvest.
evelopment of a strategy for selection of high-CCS cultivars for high-fertility environments in northern Queensland : SRDC Final report BSS179
(2004) Berding, N; Hurney, AP; Swain, RS
The need to develop a strategy for cultivar development for high-fertility soils present in northern Queensland was driven by industry concerns regarding a declining CCS pattern in years prior to commencement of this project. The strategy embodied in this project was to grow three populations of clones of commercial yield and CCS potential under these conditions, as typified by Innisfail and Tully series soils, and determine whether above-ground traits could act as predictors of crop erectness at harvest.
Farm assessment of productivity limits in the wet tropics : SRDC Final report BSS159
(2000) Hurney, AP; Bown, PA
There is an ongoing concern in the wet tropics over productivity levels, particularly with regard to low CCS. Previously, productivity trends within the region have been assessed utilising mill area statistics (Smith, 1991; Hurney, 1995; Leslie and Wilson, 1996). These studies indicate there has been a negative trend for CCS over the last 30 years in the wet tropics. Consequently, sugar yields have remained relatively static during the same period despite an increase in cane yield and, therefore, economic viability has been adversely affected.While mill area statistics can be of value in assessing broad issues, they suffer from the disadvantage that problem definition may be limited because causal factors can be confounded. This project has assessed productivity trends at the farm and district level rather than mill level. It was considered that assessment of production functions at this level rather than the mill level may provide a clearer understanding of factors influencing productivity, particularly CCS trends. The concept was to focus on high performance farms to determine if there were exceptions to general productivity trends. If exceptions could be identified, detailed evaluation of this group might assist in a better definition of the problem, diagnosis of causes and may even identify some solutions to factors influencing productivity.

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