Browsing by Author "Berthelsen, S"

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Final report on SRDC project CLW002 (previously CSS02 & CSS2S): The role of root growth and activity in determining sugarcane productivity
(1999) Magarey, RC; Nable, R; Reghenzani, J; Smith, J; Berthelsen, S; Grace, D; Robertson, M
When the current project was initiated, poor root growth and activity were widely believed to be a major constraint to sugarcane productivity. However, there was no technology available to assess whether or not root growth and activity were constraining cane productivity. The project was established to examine the relationship between root growth and activity and sugarcane productivity. The strategic information to be generated was expected to provide the basis for estimating the potential value of overcoming poor root growth and/or activity by managing various soil constratints such as soil pathogens, poor soil structure, or low soil fertility. Initially, the objectives of CLW002 were to: quantify the relationship between root system characteristics and crop productivity; assess the methods for measuring root activity as indicators of root system constraints on crop productivity - with particular emphasis on methods that would allow remote assessment of root activity.
Final report SRDC Project CLW009 Improving yield and ccs in sugarcane through the application of silicon based amendments
(2003) Berthelsen, S; Noble, AD; Kingston, G; Hurney, A; Rudd, A; Garside, A
Under high leaching environments common to the wet tropics, soils undergo significant weathering, which, when combined with accelerated chemical and physical degradation due to soil perturbation and crop removal, results in increased soil acidification and dissolution of the alumino-silicate clay minerals (de-silication). The consequences are both a loss of plant available Si through leaching and a decline in cation exchange capacity and hence an inability to retain essential plant nutrients. The current project has highlighted that large areas of cane-growing soils in North Queensland have sub-optimal levels of plant-available Si. Based on the current soil test, some 85% of soils that were evaluated in the six mill areas on the wet tropical coast have sub-optimal to marginal levels of available Si. Hence the implications of silicon deficiency for substantial areas under sugarcane production, and therefore the benefit of prophylactic applications of silicate materials may have a significant impact of productivity. One of the primary objectives of this study was to quantify responses in cane yield and ccs to Si application. To address this objective, three field trials were established in Bundaberg, Innisfail and Mossman, using a range of application rates of calcium silicate slag. At Innisfail, over the 2 years of the trial, a rate of 9t/ha Ca-silicate gave a 32% increase in total cane yield (189 t/ha) when compared to the control treatment (128 t/ha). At Mossman, a rate of 12 t/ha gave a 35% total yield increase (161 t/ha) compared to the control (105 t/ha) over the same period. At Bundaberg, over a crop cycle of 3 years, the 12 t/ha rate of Ca-silicate resulted in a 23 % increase (278 t/ha) compared to the control (213 t/ha). The results clearly indicate that Si should be treated as an integral part of any fertilizer strategy associated with cane production on these soils.
The role of root growth and activity in determining sugarcane productivity : SRDC final report CLW002 (previously CSS02 & CSS2S)
(1999) Magarey, R; Nable, R; Reghenzani, J; Smith, J; Berthelsen, S; Grace, D; Robertson, M
Research conducted in this project aimed to better understand the relationship between root and shoot growth, in areas such as how the size of the root system affects shoot growth, do particular root parameters have a controlling influence on shoot growth, how do soil characteristics affect root penetration rates, and how the root system develops through the life of a sugarcane crop. This was achieved through the application of a wide range of experimental techniques in both the glasshouse and field situation. The study of root systems in sugarcane is difficult - due to the size of the crop and the length of the cropping period. As a result there have been few previous studies on sugarcane root systems in Australia, and indeed around the world. A number of techniques were either developed, or adapted, in this project research. A soilless aeroponic culture technique was installed and refined at Tully Sugar Experiment Station. This allowed sugarcane roots to be examined on a daily basis and root measurements made, or root pruning to occur. This overcame the difficulty of dealing with the bulky, opaque soil medium. A tall pot system was adapted for sugarcane where sugarcane could be grown for an extended period in controlled conditions. This enabled plant water relations to be studied in association with modification to root growing conditions. Root image analysis techniques were further refined for sugarcane, allowing measurement of both whole glasshouse-grown root systems, or the quantification of root lengths in material from soil cores obtained in the field. A technique for growing sugarcane with a split root system was also adapted enabling the direct and indirect effects of water stress and root pruning in a soil culture to be examined, and the likely presence of root signals as a mechanism for control of shoot growth. Studies using these techniques facilitated an examination of the relationship between roots and shoots under various experimental conditions - ranging from controlled conditions with no soil in the glasshouse, through other soil-based glasshouse trials, to the field situation. This gave depth to project results and a broader understanding of root-shoot relationships using a range of experimental observations.