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.
Browse
3 results
Search Results
Now showing 1 - 3 of 3
Item Overcoming on-farm constraints to productivity and profitability in a wet tropical area(2003) Goodson, M; Thorburn, PThe CCS in the wet tropics has been declining steadily for over three decades, a period in which green cane harvesting-trash blanketing (GCTB) has become standard practice among growers throughout the wet tropics. In the Babinda Mill region, where this situation is most acute, it has been hypothesised that a part of the low CCS problem is due to the effect of GCTB in increasing soil moisture and soil fertility, which aggravates lodging and suckering in the crop and restricts the opportunity for drying crops out. During the 1990’s Babinda growers were assessing alternative management systems to overcome some of these perceived problems associated with trash blanketing. This project aimed to implement best-bet initiatives to overcome problems associated with trash blanketing, and so improve productivity and profitability in a wet tropics environment. The project was directed by stakeholders and conducted using a participative approach. There were four interrelated ‘strands’ of activity undertaken in this project: 1. Liaison and interaction with Babinda growers and the wider industry, achieved through establishment of a Grower Management Group, conducting all trials on farms (as opposed to research stations), distributing regular newsletters and holding regular bus tours and shed meetings to view demonstration sites and discuss trial results. 2. Demonstration of ‘best-bet’ trash management practices (for improved profitability). Trials were established on four farms comparing the impact of raking trash from the stool and/or incorporating it into the soil. 3. Exploration of improved nitrogen fertiliser placement (for improved profitability). Trials were established on two farms comparing different placement of N fertiliser (in the ground or on the trash blanket) and different N carriers (urea and Nitram). 4. Determination of soil and plant nitrogen status in response to different soils and/or management practices. Soil and crop N status were determined in all trials and a survey of amino-N in juice from sugarcane (a good indicator deficiency and over-supply of N to the crop) from all blocks on eight farms in the region. The trash management trial sites consistently failed to demonstrate any advantage of either raking trash from the stool, incorporating trash into the soil, or doing both. Thus the extra cost of purchasing and operating a trash rake is not justified. At one site, in a flood prone area where trash blanketing is impractical, trash burning consistently gave higher yields than trash raking and incorporation. This result suggests that raking and incorporation of trash is economically disadvantageous, in the short term, in these areas. However, damage to the stool during raking caused the lower yields in the raked incorporated treatments at this site and improved methods of raking trash may overcome this problem.Item Short and long term impacts of green cane trash blanketing on soil fertility(2005) Thorburn, P; Kingston, GIn the last three decades, there has been a widespread adoption of green cane harvesting-trash blanketing (GCTB) in the Australian sugarcane industry, generally motivated by the practical advantages (e.g. weed control, easier harvesting in wet times, etc.) associated with the GCTB farming system. While many studies have been conducted on the impact of trash blanketing on issues such as yield, soil erosion and soil physical properties, surprisingly little is known about the fate of nutrients in trash (whether burnt or retained), the decomposition of trash blankets, or impacts of GCTB on soil fertility and hence fertiliser management. This project aimed to provide information on these issues and so determine if canegrowers need to change their nutrient management strategies when they switch from burnt cane harvesting to a GCTB system. Principal findings from this project are: • Burning trash reduces trash dry matter by 70 % (pre-harvest burn) to 95 % (pre- and postharvest burn), and the loss of nutrients when trash is burnt is strongly related to the loss of dry matter. Thus GCTB can substantially increase organic matter and nutrient retention. • Rainfall will quickly leach some nutrients, especially potassium (K), from freshly harvested trash into the soil. • Trash decomposes slower than expected from its biochemical composition, with up to 10% of trash deposited on the soil after harvest still present one year later. However, the decomposition of trash can be accurately predicted across soils types and climates from sugarcane-specific residue decomposition models. • Trash blanketing, for up to 17 years, increases soil organic carbon (C) and nitrogen (N) concentrations in the top 50-100 mm of soil, but has negligible impact on concentrations of other nutrients in the soil. • The presence of trash blankets increases denitrification by 20 % on waterlogged, heavy soils in the period immediately following applications of N fertiliser. Denitrification in this situation could be accurately modelled, and this modelling provided the first test of the denitrification sub-model in The Agricultural Productions Systems Simulator (APSIM). • K from trash is plant-available, so fertiliser and trash K should have similar value as nutrients. However, there was not a significant yield response to K from trash in either pot or field experiments, possibly due to variability in the results. Thus it is not clear that recommendations of K management in trash-blanketed crops should differ from those for burnt crops. • Simulation studies of N dynamics in GCTB systems suggest that: o There may be a negative, short-term impact of trash blanketing on sugarcane yields for at least 5 years after initiating GCTB. This is due to the immobilisation of N by the decomposing trash. During this time it is important that N applications not be reduced below those used when trash was burnt. Following that time; o N fertiliser applications to ratoon crops in GCTB systems should be maintained at rates appropriate for burnt systems, despite N in trash being recycled in the GCTB 2 SUGAR RESEARCH & DEVELOPMENT CORPORATION FINALREPORT - PROJECT NO. CTA022 system. The additional N from trash is immobilised by decomposing trash blankets or lost to the environment. o In plant crops, N fertiliser applications in GCTB systems could be reduced to half that recommended for burnt systems. o Average environmental losses of N, from both denitrification and leaching, are likely to be greater from GCTB systems at all rates of N fertiliser (i.e. less than, equal to or greater than optimal rates) so particular caution should be taken to avoid overapplication of N in GCTB systems. During the project, information was disseminated through the industry in numerous presentations given at field days, shed meetings, Mill Supplier Committee meetings, CRCSugar meetings (at which BSES extension officers were present), ASSCT, etc. In addition, a series of workshops was run in collaboration with CRC-Sugar on the impact of trash blanketing on soil fertility and fertiliser management. The workshops were aimed at BSES, productivity board and fertiliser company advisers, and conducted using a participatory approach to information exchange, based on adult learning principles. 3Item Farming systems for green cane trash blankets in cool wet conditions : SRDC final report BS63S(1998) Ridge, DRThe three year project to evaluate different farming systems for green cane trash blanketing in cool wet conditions was directed at; evaluating the effect of different trash management practices on crop growth; evaluating improved drainage as a means of reducing any negative effect of trash blanketing. Trials were established at Childers and Rocky Point on relatively poorly drained soil types to compare full trash blanketing with trash raking off the cane row and bare cultivation; and, to determine any benefits from hilling-up or mole drainage in trash blanketed blocks. The trial sites were land planed at Rocky Point to improve surface drainage but this was not possible at Childers. The Rocky Point sites were dryland and the Childers sites received supplementary irrigation. The objectives of the report was to; determine the factors which affect ratooning under green cane trash blankets in cool wet conditions in south Queensland; to identify and demonstrate the cultural practices which minimise these factors; to extend the adoption of green cane harvesting in areas where this practice is considered appropriate.