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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Does ratoon age impact on N-fertiliser requirements in the Wet Tropics? : ASSCT poster paper
(ASSCT, 2019) Skocaj, DM; Schroeder, BL; Park, G; Hurney, AP
Spatial distribution of potential soil constraints affecting nitrogen management in the Wet Tropics : ASSCT peer-reviewed paper
(ASSCT, 2019) Skocaj, DM; Schroeder, BL; Hurney, AP; Rigby, A; Telford, D
Position in the landscape and climatic conditions experienced during the growing season, especially following the application of nitrogen (N) fertiliser, has important implications for crop growth, N uptake and N losses. Understanding the spatial distribution of soils where crop growth and responsiveness to applied N may be constrained in wet or dry years will allow growers and advisors to refine N-management strategies. To identify soils where crop growth and responsiveness to applied N may be restricted, a system of grouping soils that better reflected agronomic performance under different climatic conditions was required. The categorisation system considered position in the landscape, N-mineralisation potential, soil water-holding capacity in both wet and dry years, propensity to waterlog in wet years and presence of a water table in wet years. In dry years, waterlogging and the presence of a water table do not impact crop growth to the same extent as moisture availability, and, hence, in dry years, it is more important to categorise soils based on water-holding capacity. The major sugarcane-growing soils in the Tully and South Johnstone mill areas were categorised using this system. This resulted in five soil groups to describe the impact on crop growth and N responsiveness in wet and dry years. Given the application of N fertiliser to ratoon crops predominately occurs around spring, wet years were defined as receiving high spring-summer rainfall, whereas dry years were defined as receiving low spring-summer rainfall. Classifying wet and dry years according to spring-summer rainfall also allows growers and advisors to refer to seasonal climate forecasting indices for guidance on the likelihood of experiencing a wet or dry year. In wet years, the impact on crop growth, responsiveness to applied N and potential for lower N uptake is greatest for soil group five. These soils tend to occur in the lowest positions in the landscape, experience severe waterlogging and a persistent water table. They are also subject to frequent water inundation following extreme rainfall events. The spatial identification of soil constraints will complement the development of whole-of-farm nutrient-management plans in the Wet Tropics region. Knowledge of soil constraints influencing sugarcane growth and responsiveness to N will allow growers and advisors to better identify areas where nutrient-management strategies may require further fine-tuning. This information may also be of value in improving other management decisions including varietal selection and harvest scheduling
Assessing clonal and nitrogen interaction on ccs in sugarcane in the wet tropis ; SRDC project BSS180 final report
(2003) Hurney, AP; Berding, N; Grace, D
There has been a negative trend in CCS in the Tully-Mossman region since the mid-1960s that has been linked to increased extraneous matter and suckers in the cane supply. The situation had become particularly bad during 1990-1996, with most mill districts within the region experiencing problems with low CCS. An increase in the frequency of lodging and incidence of suckers was possibly contributing to this problem and there was a perception that this was related to inappropriate use of nitrogen fertiliser for the locally grown cultivars. There were also concerns that current cultivars were not suited to the local environmental conditions. Growers choosing to grow inappropriate cultivars for particular locations were thought to be exacerbating the problem.Decisions on what cultivar to grow and how much fertiliser to apply are management options that could be modified if they were contributing to the low CCS problem. These issues were addressed in this project by studying the effects of four rates of nitrogen (0, 70, 140, 210 kg N/ha) on lodging, suckering, CCS and cane yield of the three cultivars Q117, Q120 and Q138. These experiments were conducted on three different soil types at three locations within the Tully mill district. The objectives of this project were to provide a better understanding of the role of nitrogen and cultivars in the low CCS issue to facilitate the development of improved management options.In the plant crops, which were planted after a fallow, nitrogen had no influence on cane yield, CCS, lodging or suckering under the environmental conditions in which these crops were grown. However, it did increase both cane yield and lodging in first- and second-ratoon crops. Responses were limited by adverse interactions with the wet conditions and nitrogen losses due to leaching and/or volatilisation. Nitrogen had no direct influence on CCS in the ratoon crops, but it did have an indirect negative effect, because it increased the incidence of lodging. Rates of N application could be reduced in both plant and ratoon crops, which would reduce production costs. It would also be beneficial environmentally.There was no evidence of nitrogen accumulation in the soil from high nitrogen fertiliser application even following a low-yielding crop. This is of concern from an environmental viewpoint if inappropriate nitrogen rates are applied, as any excess nitrogen will be lost from the soil due to leaching or denitrification. The data suggested that the critical leaf nitrogen concentration might vary between cultivars. This provides an opportunity to reduce nitrogen rates for cultivars with lower nitrogen requirements.Current cultivars do have high potential CCS, but this cannot be realised, partially because of their susceptibility to lodging and suckering. All three cultivars tested, Q117, Q120 and Q138, are susceptible to lodging in well-grown crops. It appears that the susceptibility of Q120 and Q138 is high in crops yielding more than 70-80 t/ha under the wet conditions of the wet tropics.The potential reduction in CCS from total lodging was estimated at about 10% across all cultivars in these trials. The actual loss in CCS is governed by the actual proportion of lodging in the crop and was estimated at 0.4 units in crops that had 25% lodging. This is a hidden cost of which growers are generally not aware. There are no management options that can be implemented to minimise this loss. Severe and multiple lodging events had a negative impact on CCS and cane yield in Q120 and Q138, reducing profitability. In these circumstances, the negative effects of lodging can be reduced if the time between harvesting and occurrence of lodging is reduced. Increased returns to the grower of $200 $300/ha are possible using this strategy.Lodging was less extensive in Q117 and lower-vigour cultivars, such as Q117, may offer a more appropriate ideotype for the wet tropics, because of their lower susceptibility to lodging. Economic impact was estimated at a loss of $7.5 million to growers within the region from a moderate lodging event affecting 25% of the crop. Adoption of agronomic practices to improve physical support of the crop is only partially successful in reducing the intensity of lodging. This can only be achieved by the implementation of a research program to select cultivars with a low incidence of lodging, while maintaining or improving productivity.The cultivars Q117, Q120 and Q138 are representative of those being grown in the wet tropics and demonstrated a high propensity to sucker. Lodging is not a pre-requisite for sucker initiation, as the emergence of suckers was generally first noted under a closed canopy. Suckers have a negative effect on CCS, because they dilute the cane juice through their high moisture and low sucrose composition. In these experiments, 10% by weight of suckers in the cane supply reduced CCS by a little over 1 unit. The increased cane yield from suckers is inflating productivity estimates but not improving profitability; the level of suckering experienced in these experiments would reduce regional grower-income by approximately $6 million. It is possible to select against suckering propensity and this has already been introduced into the crop improvement program. However, research into the relationship between suckers and longevity of ratoons is required because of the potential impact on productivity.An appropriate extension program needs to be developed to disseminate the findings of this research to growers. The results from this project have been extended to the industry. There have also been extension programs for BMP of cultivars. However, there is still a large gap between extension and adoption, which is why additional extension programs are recommended. Adoption of findings on nitrogen will reduce production costs, as well as have a positive environmental impact. Management strategies are available to partially alleviate the negative impacts of lodging and suckering. However, further research is required to fully overcome the effects of these phenomena.
Soil compaction studies - Mossman
(1975) Hurney, AP
Study was initiated to investigate the effects of the different bin transport systems on soil compaction. Compaction under dry soil conditions does not appear to be a serious problem and can ve overcome by cultivation. Compactive effects are more marked under wet soil conditions and there are indications of residual effects following cultivation.
Soil constraints to productivity improvement
(1991) Croft, BJ; Magarey, RC; Hurney, AP; Reghenzani, JR
Evidence from investigations into fumigation, fungicide application, fallowing and growth of sugarcane on recently cultivated soils strongly suggests that yields in established cane growing areas are being restricted by soil-borne biological factors. The yield restriction may be in the order of 20-40%. The soil-borne pathogens Pachymetra, Pythium and also nematodes probably account for a proportion of this yield loss, but other unknown deleterious microorganisms may be involved. In most cases nutrient deficiencies do not appear to be limiting growth. Zinc deficiency which has recently been identified in northern districts may be affecting growth on some soil types. Excesses of some nutrients, such as phosphorus may be interacting with other nutrients and/or soil-borne pathogens. A multi-disciplinary study of soil-borne limits to yield in sugarcane is needed to identify the major factors involved and to develop satisfactory treatments to ameliorate the problem.
Soil constraints to productivity improvement
(1990) Croft, BJ; Magarey, RC; Hurney, AP; Reghenzani, JR
Yields of most crops are known to decrease if that crop is grown continuously without fallowing or rotation with other crop species. Sugarcane has been grown continuously on many fields in Queensland for 50-100 years. As early as 1934 soil-borne factors which restricted root and shoot growth were identified in fields which had grown sugarcane for a number of years. During the 1970s nematodes were found to be causing serious losses in Bundaberg on certain soil types and a serious root disease complex known as poor root syndrome was identified in northern Queensland. During the 1980s intensive research into poor root syndrome identified the important new disease Pachymetra root rot and a number of minor fungal pathogens. Poor root syndrome has been identified in all regions of Queensland and general poor root health has been noted in all soils which have grown sugarcane for a number of years. Yield increases of 50-100% were obtained in areas severely affected by poor root syndrome in northern Queensland by soil fumigation with methyl bromide and metham sodium, and by soil solarisation. Recent experiments have recorded yield responses of 20-40% to methyl bromide fumigation in all major sugarcane regions. These experiments suggested that yield losses due to soil-borne factors may be greatly restricting yields throughout the sugar industry. Research to identify the causes of the yield losses has commenced and progress to date is summarised in this paper.
Phytotoxic substances associated with the decomposition of sugarcane trash residues. (Final report SRDC Project BS31S)
(1992) Hurney, AP; Ridge, DR
Ratooning through trash blankets is generally effective with minor exceptions for certain varieties and in cold or waterlogged soils. Information was required to determine whether these effects are normal reactions of slow ratooning varieties to the cold conditions or poor aeration, or whether there are toxic effects attributable to trash residues, ie allelopathy. The project was a preliminary investigation to assess potential allelopathic effects from trash residues on the growth of sugarcane. It was concentrated mainly on north Queensland soils and varieties due to the high percentage of trash retention in that area. A smaller test program was carried out at Bundaberg to take into account a wider suite of varieties and soils.

Soil health and nutrient management

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