Completed projects and reports

Now showing 1 - 4 of 4

Sodic soils and rising groundwater management in the Burdekin
(2013) Milla, R
Sodic soils are a production limiting issue for large areas of the Burdekin region. Saline soils, saline groundwater and rising groundwater tables also have a high possibility to further limit yield potential. Rising groundwater levels are a very serious threat and there is some urgency in being able to efficiently deal with the issue. Many growers and advisors in the region are not well educated about the interaction between all of these factors, as well as the most appropriate management strategies. This project developed structured workshops to build awareness and understanding by growers and advisors in the underlying science of sodic and saline soils and groundwater interaction. It presented and discussed management options for a range of scenarios. The workshop help to identify the best amelioration strategies (gypsum, lime, mill mud) for growers and with gypsum prices increasing significantly (from $100 to $180/T spread over the last few years) the most cost effective solution needs to be adopted to promote more sustainable farming systems. The project assisted the private consultant Roger Shaw to travel to the Burdekin region and share his knowledge on the issues described. These workshops were facilitated by Rob Milla (Burdekin Productivity Services) and attended by 22 technical advisors and 39 growers. The workshops were an excellent opportunity for growers and advisors to increase their knowledge and be able to discuss practical management options with a very experienced consultant. Collective agreement with advisors and growers was that an industry wide (and industry led) approach is required to address the very serious and potentially production limiting issue of rising groundwater and conjunctive use of this high conductivity water with low conductivity channel water.
A stocktake of the levels and sources of nitrate in groundwaters associated with sugarcane areas
(2000) Thorburn, PJ; Weier, KL; Biggs, JS
Water containing high concentrations of nitrate is unfit for human consumption and, if discharging to freshwater or marine habitats, can contribute to algal blooms and eutrophication. Previous studies have found elevated nitrate concentrations in groundwaters underlying sugar-growing areas, particularly the Bundaberg and Burdekin areas, and that in Bundaberg the problem was escalating. Nitrate pollution of groundwaters of the sugar industry is of particular concern because of the proximity of the industry to environmentally sensitive areas and the large number of people (in cities and rural areas) relying on groundwaters for drinking water. However, apart from recent studies in Bundaberg, data on nitrate in groundwater has generally come from inconsistent studies. These studies examining either a limited number of groundwater bores, or large databases of groundwater chemistry where sampling and analytical methods have been variable and, in some cases, inappropriate. So a reliable, consistent, industry-wide definition of the problem does not exist. This project determined the extent of nitrate contamination in groundwater underneath sugargrowing regions of eastern Australia, and examined the likely source of the nitrate. In bores where nitrate concentrations were elevated, and therefore likely to be a result of human activities, concentrations were monitored to provide an assessment of trends in nitrate concentrations. This information was used to promote “best management practices” through relevant extension, industry and regulatory groups, to restrict leaching of nitrate to groundwater.
Nitrate retention at depth under sugarcane in Far North Queensland Wet Tropics
(2002) Rasiah, V; Armour, JD; Menzies, NW; Heiner, DH; Don, MJ
Nitrogen mass-balance studies for sugarcane grown on Ferrosols (Krasnozem) in the Far North Queensland (FNQ) wet tropics have shown 30 to 50 kg N/ha/yr of the applied fertiliser+N leached below the root-zone (<0.75 m) as nitrate-N compared to <10 kg/ha/yr transported in surface runoff. Because, large quantities of N (guesstimate of ≈ 3,000 tonnes per annum for the catchment) was leaching below the root-zone, major emphasis has been placed on its fate, particularly in relation to off-site land and water resources and ecosystem health issues and more specifically that related to the Great Barrier Reef (GBR). The leached nitrate could be adsorbed at anion exchange sites, denitrify, enter streams/rivers through lateral-flow and/or aquifers by deep drainage. Because the ferrosols in general possess the capacity to absorb and retain nitrate-N at anion exchange (AE) sites, there exists the potential reduced risk of contamination of off-site water bodies, including GBR. The issues address in the project include (i) the assessment of sub-surface nitrate loading in Ferrosols of north Queensland wet tropical coast (ii) measurement of those physical and chemical properties, which influence nitrate mobility and retention (iii) provide from inferred processes, estimates of future nitrate movement to ground and surface waters (iv) propose management strategy(s) with regional industry group(s) to address the nitrate problem (v) improve industry and community understanding of water and nutrient dynamics and the potential environmental impacts. Soil cores to 12.5 m depth were taken from 28 sites distributed across the catchment, representing 9 Ferrosol soil types under sugarcane cultivation for at least 50 yr and from rainforest. Depth incremented (0.5-1m) sub-samples from the cores were analysed for nitrate- N, cation- (CEC) and anion- (AEC) exchange capacities, pH, exchangeable cations (Ca, Mg, K., Na), soil organic C (SOC), electrical conductivity (EC), sulphate (SO4 2-) and chloride (CI-), Nitrate-N concentration under sugarcane ranged from 0 to 72.5 mg/kg compared with 0 to 0.31 mg/kg under rainforest. The average N-load, in 12 m depth, across the 19 Pin Gin soil type was 1550 kg/ha compared with 185 kg/ha unde4r 8 non-Pin Gin and 11 kg/ha in rainforest and most of the retention in the catchment and the source of this nitrate was that leached below the rootzone. Compared to the current average N-load, the average maximum potential nitrate retention capacity (MPNRC) of 10.8 t/ha for the Pin Gin and 4.7 t/ha for the non-Pin Gin indicates these soils still possess large capacity to adsorb and retain nitrate in profiles.
Development of criteria for draining shallow watertables in the Isis irrigation area
(1993) Kingston, G
This project was proposed to the Sugar Research Council because qualitative data suggested a significant problem with waterlogging and salinity in hydromorphic sedimentary soils in the Bundaberg to Maryborough region. Also there were no quantitative data to indicate elevation of watertables in areas of hazard, nor were there any criteria to determine an approach to management of shallow watertables in the region.

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