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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1996 - 199922000 - 20083

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Subject: search.filters.subject.APSIM

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    Improved environmental outcomes and profitability through innovative management of nitrogen SRDC research project CSE011 final report
    (2008) Thorburn, P; Webster, T; Biggs, J; Biggs. I; Park, S
    Nitrogen (N) fertiliser additions are an important contributor to productivity and profitability in intensive farming systems, including sugarcane production. However, applying N increases losses of N to the environment, and so all intensive agricultural industries face the challenge of maintaining productivity while minimising environmental impacts of N fertiliser use. This challenge has become particularly important for sugarcane production in Australia because community concern grows over the impact of N on the health of the Great Barrier Reef and sugarcane production has the largest use of N fertiliser in the region. It has been suggested that replacing the N lost from a crop through harvested cane and environmental losses will better align N fertiliser applications to the actual needs of sugarcane crops and the other potential sources of N available to the crop, and so improve the financial and environmental sustainability of the Australian sugarcane industry. In this project we tested and further developed an innovative N fertiliser management system, the N Replacement (NR) system.
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    Review of nitrogen fertiliser research in the Australian sugar industry
    (2004) Thorburn, P
    The management of nitrogen (N) fertiliser is important to the Australian sugar industry, as it is an important nutrient for sugarcane production. However, over application results in reduced profitability and sugar quality, and results in high concentrations of N in soils and water of sugarcane growing areas. An extensive review of current and past research on N fertiliser management in the Australian sugar industry was undertaken to identify possible improvements in N fertiliser management and establish priorities for future research into sustainable management of N fertiliser. The Australian sugar industry has a history of high N fertiliser usage, with applications increasing from the 1960s to the late 1990s. However, industry average sugarcane production has not kept pace with N fertiliser applications, resulting in a steady increase in N fertiliser applied per ton of sugarcane harvested. Historical and recently developed N management strategies rely on matching N applications to the predicted/expected yield of the forthcoming crop. Over-application of N fertiliser is a rational reaction by growers to uncertainty about the size of the coming crop and the long-term impact of N fertiliser on profitability – significant over-fertilisation reduces profits much less than significant under fertilisation. We suggest that past and current N fertiliser management strategies have not adequately accounted for these attitudes, and the resultant longer-term implications for soil and water quality and environmental impacts in sugarcane catchments. While long-term under application of N fertiliser undoubtedly reduces profitability, there is considerable evidence to show that greatly reducing N fertiliser applications for a single crop will not significantly reduce sugarcane production. Thus, the short-term risk of crop yields limited by N deficits is possibly much lower than generally appreciated. If this is so, a new philosophy of N fertiliser management can be developed that remove the uncertainties that drive growers to over-apply N, and so allow closer matching of N inputs to N outputs from a sugarcane system. Rather than aiming to fertilise the coming crop, it may only necessary to replace the N lost from the previous crop, the majority of which is in harvested cane and therefore be easily estimated. Over the past decade, there have been significant advances in our ability to simulate N (and carbon) dynamics in sugarcane production systems. We drew upon these advances to undertake a ‘desktop’ examination of this new ‘replacement’ N management strategy. Three N management scenarios were simulated: (1) the ‘replacement’ strategy, (2) the current recommended strategy and (3) the average amounts of N applied in the industry (i.e., 30 % greater than those recommended). The replacement strategy had similar productivity, greater profitability and lower environmental N losses, whether we simulated potential crop production or a more realistic level of production (resulting from the impact of pests, diseases, lodging, stool damage, etc.). Moreover, these advantages were greater in the simulations of realistic yields. The ‘replacement’ strategy is an evidence based, transparent and defensible N management strategy, all attributes that are important for the sugar industry to maintain self-regulation of N fertiliser management. We suggest that this strategy warrants further testing, through both simulation and field experiments.
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    Evaluating the potential for improved sugar yields by assessing the climatic and soil constraints to production in southern cane-growing districts
    (1999) Muchow, RC; Hughes, RM; Horan, HL
    This project conducted strategic research to better understand the processes of yield accumulation in low temperature NSW environments and to identify limits to yield. The fundamental knowledge gained in this project can be used to assess yield limitations and the scope for yield improvement. In addition, the findings are a pre-requisite to the design of management and genetic improvement strategies to boost production in southern sugarcane growing environments. An additional spin-off of this project is a better functional basis of the processes of yield accumulation encapsulated in the APSIM Sugarcane systems model to allow extrapolation of the findings more broadly across the sugar industry. An analysis framework was used to express sucrose yield in terms of biomass accumulation and the proportion on biomass present as sucrose. Crop biomass was analysed in terms of radiation capture and utilisation. Partitioning was examined in terms of the proportion of crop biomass present as stalk and the stalk sucrose concentration on a dry matter basis. Crops growing under "potential yield" conditions were analysed and compared to those growing under "commercial yield conditions".
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    Adopting systems approaches to water and nutrient management for future cane production in the Burdekin SRDC Research Project CSE020 final report
    (2008) Thorburn, P
    There is concern about environmental impacts of cropping in catchments of Australia’s Great Barrier Reef, especially losses of nitrogen (N) and herbicides from cropping systems. Sugarcane production in the Burdekin region in the dry tropics stands out from other crops/regions because, (1) it is fully irrigated, which may enhance the losses of any chemicals from farms, and (2) it has the highest N fertiliser application rates of any sugarcane producing region in Australia. There are few measurements of N and/or herbicide losses from sugarcane production, especially fully irrigated production. More complete information is needed to evaluate, develop and underpin the adoption of management practices to reduce environmental impacts of sugarcane production. Four streams of work were undertaken to provide this information: Monitoring water quality leaving sugarcane farms. Demonstrating water quality and productivity benefits of farm management practices. Harnessing the information from these two components to describe and classify management practice systems typical of past, current and future ‘best practice’, and estimate the water quality, productivity and economic benefits of these systems. Communicating results of these activities widely within and beyond the region. Water, N and herbicide losses were measured at three sites in different parts of the Burdekin region, covering a range of soil types and irrigation managements. The experimental data were then used to parameterise the APSIM-Sugarcane cropping systems model, and then used to infill missing data and develop complete water and N balances for each of the three crops measured at the sites. N losses in runoff were relatively small, being less than 10 kg N ha-1 crop-1. Herbicide losses were similar to those measured previously. More N was lost via deep drainage than runoff at all sites, even those with slowly permeable soils. The results were consistent with the known ground water nitrate contamination issues in the region.
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    Final report to the Sugar Research and Development Corporation CTA007 A modelling framework to integrate research on nitrogen management of sugarcane
    (1996) Keating, BA
    This project used a measurement and modelling approach to explore the processes controlling nitrogen supply and losses in the crop and soil elements of sugarcane production systems. Measurements took place both in the field and laboratory. These measurements, together with data coUected from other sugarcane research projects in Australia and overseas, lead to the development of the APSIM-Sugarcane simulation model. This model captures the main elements of our understanding of sugarcane growth, yield, N uptake and utilisation and water use. APSIM is a modular modelling system, and the Sugarcane module is compatible with other APSIM modules of soil processes and crop management. Within the life of this project, APSIM-Sugarcane was used to investigate N management strategies in sugarcane production systems. A major outcome of these modelling studies was the recognition of the potential for substantial N losses via leaching in situations where N fertiliser inputs exceeded crop demands. This project drew together different threads in nitrogen research on sugarcane for the first time. Prior to this, the focus was on either empirical "rates and dates" experiments, which while underpinning current N fertiliser recommendations, were not advancing our understanding of N in the crop-soil system, and on studies of particular N processes(eg volatilisation or mineralisation), which were not integrated with one another or with the broader system performance.