Soil health and nutrient management

Permanent URI for this collectionhttp://elibrary2.sugarresearch.com.au/handle/11079/13842

Research outcomes: Soil health is improved with a resulting positive impact on the environment and yield growth. Improved reputation and relationship between industry and environmental groups.

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    A review of nitrogen use efficiency in sugarcane
    (2015) Bell, MJ; Biggs, J; McKellar, LB; Connellan, J; Di Bella, L; Dwyer, R; Empson, M; Garside, AJ; Harvey, T; Kraak, J; Lakshmanan, P; Lamb, DW; Meier, E; Moody, P; Muster, T; Palmer, J; Robinson, N; Robson, A; Salter, B; Schroeder, B; Silburn, M; Schmidt, S; Skocaj, DM; Stacey, S; Stanley, J; Thorburn, P; Verburg, K; Walker, C; Wang, W; Wood, A
    The Great Barrier Reef (GBR) is the world's largest coral reef ecosystem, providing both substantial economic benefit to Australia and significant international ecological value. The health of the GBR is under pressure from sediments, pesticides and nutrients (especially nitrogen) discharged from nearby catchments. Discharge of nitrogen is of particular concern as it stimulates outbreaks of the Crown of Thorns Starfish, a major predator of GBR corals. Recent research has shown that the amount of nitrogen fertiliser applied in excess of crop uptake is an important determinant of nitrogen discharge from catchments, so increasing the efficiency of nitrogen use in cropping systems is an important step in protecting the economic and ecological benefits provided by the GBR. Importantly, an increase in nitrogen use efficiency (NUE) also offers opportunities to improve productivity and profitability of agricultural industries, with such benefits a major incentive for industry adoption and practice change. The Australian sugarcane industry is a significant contributor to the anthropogenic loads of nitrogen entering the Great Barrier Reef lagoon, with recent estimates in the Reef Water Quality Protection Plan (2013) suggesting it contributes 18% and 56% of particulate and inorganic nitrogen loads, respectively. A focus on improving NUE in the Australian sugar industry to reduce these loads wherever possible is a logical outcome from these statistics. While the relative impact of dissolved inorganic nitrogen (DIN) and particulate nitrogen (PN) is still uncertain, recent NUE forums in the sugar industry in 2014 identified clear target reductions in DIN that would be needed in order to significantly improve water quality in line with Reef Plan (2013-18) targets. The forum also identified a clear need for a joint industry-government funded research program to improve NUE in sugarcane cropping systems. The review conducted for this report was commissioned and funded by the Australian Government Reef Programme to provide a foundation for this joint NUE research program. The review was tasked with providing an improved understanding of past and current research effort and available field trial information (both published and unpublished) relating to nitrogen management in the sugar industry. From this perspective the review was then tasked with identifying research gaps and opportunities for future research projects and field trials that would collectively contribute to improving NUE from both agronomic and production perspectives as well as delivering significant reductions in nitrogen lost to waterways and the Great Barrier Reef lagoon. It is widely recognized that in any crop, the demand for N is determined by the size of the crop and the fundamental efficiency with which that crop produces a unit of biomass or harvested product from a kg of acquired N (N use efficiency - NUE). Therefore a good understanding of yield potential at the spatial scale of the productivity unit (i.e., farm, several blocks of similar productivity, individual blocks or within-block) about which N fertilizer management decisions (rate, form, placement, timing) are made is required, along with an understanding of how that yield potential varies with seasonal conditions. Collectively, this could be called seasonal 'block' (or productivity zone) yield potential, and it will produce a crop N demand that may vary from year to year. The sugar industry is currently operating at the district level (generally comprising several thousand cropped hectares across variable soil types and landscapes), and basing N demand for all growers in the district on the best farm yield ever achieved over a 20 year time frame. It is apparent that overall NUE could be improved by basing N fertiliser inputs on the seasonal yield potential of the productivity unit.
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    Final report SRDC Project CG013 Growers working together to improve water quality in the Herbert Sugar Industry
    (2008) Wood, A; Wrigley, T; Phillips, K; Sheedy, P
    The sugarcane area of the Herbert River district is located adjacent to the Great Barrier Reef (GBR). The quality of water entering the GBR lagoon from the Herbert district is one of the most important environmental issues facing the Herbert sugar industry. However, little data on water quality are available from catchments consisting entirely of sugarcane. This project was conducted to establish a number of water quality monitoring sites in relatively small catchments where the land use is solely sugarcane and where individual growers or groups of growers could measure the quality of water in farm drains using simple tools and relate it to their farming practices. Eleven growers volunteered to participate in the programme. They were keen to participate because they felt that sugarcane growers’ reputation of being good custodians of the land had been tarnished by various external studies of water quality and they were eager to demonstrate that their activities were not polluting drainage water. A series of suitable sites for taking and testing water samples were established and V notch weirs were inserted in the drains for the purpose of measuring rates of water flow. A series of simple tools were developed for measuring sediment and nutrients drainage water leaving the farms. An experienced water engineer who had worked in the district for many years agreed to coordinate the project and proceeded to train the growers involved. He also set up and equipped a water analysis laboratory so that the measurements taken by the growers could be validated. Occasional samples were also sent to a NATA accredited laboratory for further validation of the nutrient determinations but also for measurements of pesticide residues. The growers involved in the project have recorded water quality measurements for three years and have also maintained records of on-farm practices that may impact on water quality such as tillage, fertilising, land levelling and herbicide applications and other activities that may impact on water quality. The growers were provided with information on desirable water quality levels. If their measurements exceeded these levels, growers reacted quickly to seek possible explanations for the elevated readings. The project was evaluated at the commencement, mid-term and just before its conclusion. The growers involved developed a list of the critical factors that needed to be achieved in order for the project to be successful. The mid-term evaluation was conducted with members of the Project Consultative Group and the final evaluation was again conducted with the growers involved in the project. Feedback was generally positive but there were a few areas where things could have been improved. The project outcomes consisted largely of improved knowledge, particularly amongst the growers, of what simple techniques are available for measuring nutrients, pH, dissolved oxygen and turbidity of farm drainage water. Growers learnt what constituted high, medium and low levels for the different water quality parameters and developed a better understanding of the relationship between rainfall and discharge characteristics of drains on their farms. They improved their understanding 4 of the relationship between on-farm management practices and water quality and of the accuracy and reliability of the different tools used to measure water quality. An important outcome has been the continued engagement and support of growers involved with the project, and the engagement and support of regulatory and other government support agencies through the project consultative group. This is important for the next phase of the project which aims to expand from 11 growers to around 100 growers conducting water quality monitoring. The existence of a committed nucleus of growers will be essential for helping to inspire others to participate. Likely economic benefits of the project will be increased farm profitability arising from improved farm practices associated with better management of farm inputs such as fertilisers and herbicides. Reduced input costs arising from reductions in soil tillage and more targeted applications of nutrients and herbicides will also contribute. Environmental benefits will arise from improved water quality on farm and in the downstream ecosystem, and improved soil health arising from changes in farming practices. Social benefits will include the empowerment of growers, who are now armed with better information about their farm practices and the likely impacts on water quality; greater confidence amongst growers when interacting with government and environmental groups; and improved attitudes and engagement by growers in sustainable land management.
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    Final report - SRDC project BSS268 - Accelerating the adoption of best-practice nutrient management in the Australian sugar industry
    (2010) Schroeder, BL; Moody, P; Wood, A
    This project BSS268 developed further the SIX EASY STEPS program, including additional compentents to its integrated package. It aimed to accelerate the adoption of sustainable nutrient management by: 1: Improving knowledge of the constraints to the adoption of best-practice nutrient management using grower surveys. -- 2: Developing a Soil constraints and management package (SCAMP) for improving on-farm management decision making. -- 3: Facilitating the use of nutrient management plans at block and farm scales and the implementation of soil/site specific fertiliser applications using a participative approach -- 4: Assessing the risk of on- and off-site impacts of land management paractices using vulnerability maps at catchment scales -- 5: Demonstrating the benefits of best nutrient management practices with on-farm strip trials. -- 6: Reviewing the N-use efficiency factors associated with relevant trials. 6: Reviewing the N-use efficiency factors associated with relevant trials. -- 7: Developing a computer based decision support system for the SIX EASY STEPS nutrient management package.