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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Item Australian sugarcane industry soil health benchmarking in Central Queensland: Increasing profit and transforming soil health practices through cooperative industry research, extension and adoption(2021-12-13) Manatsa, GusActivity 1: Measure changes in soil health under a range of farming practices: potential soil health indicators, benchmarks & measurements recommended to enable grower/ industry demonstration of performance improvement through the implementation of IFS practices (i.e., cover cropping, organic amendments, row spacing, controlled traffic, minimal till). Over two years, ten paired sites were established across the three mill areas of the Central Region to determine the soil health, root health and business impact of transitioning to an Improved Farming System (IFS). Long-term IFS sites, of at least ten years, were matched with nearby sites using conventional farming practices. Physical, chemical, and biological soil parameters were measured, along with root development testing, to determine variation between the sites within each pair and therefore the long-term impact of implementing IFS practices. This work is building the evidence required to assist the industry to determine the best set of soil health indicators for the Central region. Combined results from the Central region indicate that microbial biomass, pH and soil compaction are positively impacted by improved farm management systems. Some measures that seemed to show very strong trends in the first year were more mixed in the second year, notably effective rooting depth. Soil texture emerged as a major influence on results, making it difficult to assess the effects of improved management practices in some cases. Root biomass averaged substantially higher in the IFS treatment, possibly reflecting a combined influence of other soil health factors. Activity 2: Innovative soil health/ IFS extension: regional synthesis of solution-based soil health messages to improve production, profit and sustainability through development, training in and implementation of the SRA Soil Health Toolkit (SHET). This project was an industry partnership of the Central cane growing region of Queensland. Collaboratively, the partners, led by Farmacist and SRA, ground-truthed potential soil health indicators and benchmarks for varying soil types and farming systems of the region. This work was needed so that growers could have increased confidence in soil, plant and root sampling data, to inform their decision making and build a greater understanding of how IFS practices deliver production, profit & sustainability outcomes, in addition to improved resilience to climatic variability and extreme weather. The development of the Soil Health Extension Toolkit (SHET) provided a way for local service providers to build their own knowledge in possible Central region soil health indicators, whilst working alongside “champion” growers keen to trial the tests included in the SHET and use the data to help inform the soil constraints most impacting their yield potential, and importantly, where to progress their investigations through further in-depth testing.Item Seeing is believing: managing soil variability, improve crop yield, and minimising off site impacts using digital soil mapping(2020-12-31) Triantafilis, Honorary Associate Professor JohnOver 70 % of sugarcane industry operates next to the Great Barrier Reef (GBR). Farmers are under pressure to improve practices to minimise off-farm pollution, while at the same time improve fertiliser (e.g. lime) and amelioration (e.g. gypsum) efficiency to minimise yield variation. While the biggest driver of variation is rainfall, differences in soil condition affect yield and farmers need to know its variation. For example, knowledge about soil cation exchange capacity (CEC – cmol(+)/kg) is important because it is a measure of how many exchangeable (exch.) cations (i.e. calcium [Ca], magnesium [Mg]) can be retained on soil surfaces and because it influences soil stability, nutrient availability, pH and reaction to fertilisers. If no action is taken to map soil and manage different soil condition, opportunities to sustainably improve application of fertilisers and ameliorants in a cost-effective way will be foregone as well as an opportunity to make a meaningful, economically viable contribution to reducing impacts of sugarcane growing on the GBR. The six-easy-steps (6ES) nutrient and ameliorant guidelines were developed to minimise in-field variation and reduce losses of inputs to the GBR. However, there was and is no practical way for farmers to apply the 6ES guidelines given there is no in-field data to enable its application. This project aimed to undertake case studies in four sugarcane growing areas to enable precision agriculture via the use of a digital soil map (DSM). A DSM requires collection of digital data, such as proximally sensed electromagnetic (EM) induction and gamma-ray spectrometry (ϒ-ray) and coupling this to soil data via mathematical models. The study areas, where a DSM approach was taken, include Mossman, Herbert, Burdekin and Proserpine. The results show that a DSM approach is valid with the potential to implement the 6ES nutrient and ameliorant guidelines to enable precise application of lime, gypsum and other fertilisers demonstrated via various case studies. They are provided here in brief and in summarised form in Section 5. All published papers or submitted manuscripts are provided in the same order and appear in the Appendices. In the Mossman area (see Section 5.1), a DSM approach was used to characterise soil condition in terms of topsoil (0-0.3 m) soil organic carbon (SOC, %) variation, with the DSM able to be used to apply the 6ES nutrient management guidelines (Schroeder et al., 2010) with varying N application rates for different levels of SOC to achieve a district yield potential of 120 t/ha after a bare fallow (Wang et al., 2021). In various areas (see Section 5.2), the DSM approach could be used to predict topsoil (0-0.3 m) clay content across any of six study sites in the Mossman, Herbert, Burdekin, and Proserpine districts. The site-specific approach to making DSM of topsoil clay was optimal, however site-independent (universal calibration) and a spiking approach give almost as good prediction agreement and accuracy (Arshad et al., 2021). In the Herbert (see Section 5.3), a DSM approach was used to characterise soil condition in terms of topsoil (0–0.3 m) and subsoil (0.6–0.9 m) CEC (cmol(+)/kg) variation, with the topsoil DSM able to be used to apply the 6ES nutrient management guidelines (Sugar Research Australia, 2013) with varying lime application rates for different levels of CEC (Li et al., 2018). In the Herbert (see Section 5.4), a DSM approach was used to identify zones by clustering digital data (i.e. EM and -ray data). The DSM was more accurate in predicting topsoil (0-0.3 m) and subsoil (0.6–0.9 m) chemical (e.g. CEC, exch. Ca and Mg and ESP) properties. The 6ES guidelines of Schroeder et al. (2009) were applicable to ameliorate topsoil ESP; the latter shown to influence yield percentage (Dennerley et al., 2018). In the Herbert (see Section 5.5), a wavelet transform of the digital data (i.e. EM and -ray data) was used to enable prediction of topsoil (0-0.3 m) ESP. The DSM, using all the wavelet transformed digital data (i.e. elevation, EM and -ray data) gave the most accurate predictions. The 6ES guidelines of Schroeder et al. (2006) to manage ESP through variable rates of gypsum was also demonstrated (Li et al., 2021a). Sugar Research Australia Final Report 2017/014 4 In the Herbert (see Section 5.6), a DSM approach was again used to identify zones by clustering digital data (i.e. EM and -ray data). The DSM was more accurate in predicting topsoil (0-0.3 m) and subsoil (0.6–0.9 m) chemical (e.g. CEC, exch. Ca and Mg) properties than a traditional texture map or field delineations. The 6ES guidelines of Schroeder et al. (2009) were applicable for these properties (Arshad et al., 2019). In the Burdekin (see Section 5.7), a DSM approach was used to predict topsoil (0-0.3 m) exch. Ca and Mg. The DSM was more accurate than a traditional map (Li et al., 2019a) and useful for applying lime and magnesium, respectively, using 6ES guidelines (Schroeder et al., 2009). In terms of calibration, 30 samples were enough to predict exch. Ca with 40 for exch. Mg (Li et al., 2019b). In Proserpine (see Section 5.8), a DSM was developed to predict topsoil (0-0.3 m) ESP. A map generated using ordinary kriging of 120 soil samples was satisfactory, but, a minimum of 100 samples was required. When digital data was used to value add to soil data, Cubist-RK outperformed OK with only 60 samples required. The 6ES guidelines of Schroeder et al. (2009) were applicable to ameliorate topsoil ESP (Li et al., 2021b). In Proserpine (see Section 5.9), a DSM was developed to predict topsoil (0-0.3 m) and subsoil (0.9-1.2 m) CEC. Topsoil prediction required 80 calibration samples whereas for subsoil only 30 were needed. Using both digital gave best results although -ray used alone slightly better than EM. Small transect spacing (i.e. 5 m) was recommended for topsoil, but larger spacing OK for subsoil (i.e. 5 – 60 m). The 6ES guidelines of Proserpine (Calcino et al., 2010) were applicable to ameliorate topsoil CEC (Zhao et al., 2020). Given the results presented in this Final Report and the published research, it can be concluded that the DSM approach can be applied to map various topsoil and subsoil physical (e.g. clay, silt and sand) and chemical (i.e. CEC, Exch. Ca, Exch. Mg and ESP) properties at the field and multi-field scale in different sugarcane growing districts. The final DSM can be used to apply the 6ES nutrient and ameliorant guidelines in the four sugarcane growing areas investigated and including Mossman, Herbert, Burdekin, and Proserpine. In terms of operational aspects, the following key conclusions can be made; i) Various soil physical (e.g. clay, silt and sand) and chemical (i.e. CEC, Exch. Ca, Exch. Mg and ESP) properties can be mapped using a DSM approach, but regardless of modelling technique, the number of soil samples required to make a calibration was approximately the same (i.e. 1 sample per hectare) regardless of the soil property (i.e. topsoil Exch. Ca and Mg and ESP) or study area. ii) Mathematical methods such as LMM are useful when digital data are correlated with soil data, with hybrid methods of machine learning (i.e. Cubist) and regression kriging (Cubist-RK) useful when correlations were statistically significant but not as strong and if residuals were spatially auto-correlated. Alternatively, wavelet analysis can also be useful to predict soil properties (i.e. topsoil ESP) where there was no direct relationship with digital data but a relationship with scale specific variation in digital data (i.e. ϒ-ray, EM and DEM). Moreover, fuzzy k-means or k-means clustering can be used to make management zones from -ray and EM data when the digital data is not directly correlated to the soil data of interest and produce superior predictions than traditional soil texture maps and or using field delineations to predict soil properties. iii) Digital data of elevation, ϒ-ray and EM were best used in combination rather than alone, regardless of which modelling technique was considered (e.g. LMM, Cubist-RK and wavelet analysis). In terms of the density of digital data transect spacing, the smaller the spacing the better (i.e. transect every 7.5 m) with a maximum transect spacing of 30 m allowing large areas to be measured in a day (~ 400 ha).Item Effect of the soil-binding adjuvant Grounded® on herbicide efficacy and runoff losses in bare soil in ratoons : ASSCT peer-reviewed paper(ASSCT, 2021) Fillols, E; Davis, ATo reduce the impact of pesticides, in particular pre-emergent herbicides, on fresh and estuarine water bodies of the Great Barrier Reef catchment, while maintaining productivity, the sugar industry is exploring innovative options to reduce the movement of herbicides off site. Previous research work has shown the oil-based adjuvant Grounded® added at 3 L/ha to the herbicide tank reduced runoff losses by 17 to 40% across all tested herbicides at 48 h and 3 weeks after product application, when applied on bare soil in a tilled plant cane in far northern Queensland. Herbicide efficacy was maintained above 90% for 200 days after product application with or without the addition of the adjuvant. Conversely, Grounded® did not reduce runoff loss when added to herbicides applied in trash blanketed ratoon. This paper presents additional research work carried out to assess the impact of Grounded® on pre-emergent herbicide efficacy and on runoff losses when applied to ratoon cane on bare soil. This scenario is typical of the Burdekin and New South Wales regions. Two trials were conducted in untilled ratoons after burning the trash blanket in far northern Queensland. Grounded® was added to six registered pre-emergent herbicides: imazapic (94.5 g/ha), hexazinone (472.5 g/ha), isoxaflutole (150 g/ha), amicarbazone (700 g/ha), atrazine (1350 g/ha) and pendimethalin (1001 g/ha). Herbicide efficacy trials were implemented as randomised complete blocks with three replicates and adjacent untreated controls. Losses of the tested pre-emergent herbicides in runoff were monitored using replicated rainfall simulations, delivering 80 mm of simulated rain, 48 h or 3 weeks after herbicide application. Both runoff trials generated similar herbicide concentrations in runoff. As expected, higher concentrations for all herbicides were found in runoff 48 h after spraying compared to 3 weeks after spraying. The adjuvant Grounded® added to the spray tank did not decrease herbicide loss via runoff in both trials. Topsoil samples taken before and after rainfall, generally showed higher percentage herbicide in topsoil after rainfall when Grounded® was added to the tank mix compared to no added adjuvant. However, this slight binding improvement to the soil did not result in lower herbicide loss in runoff. These runoff and soil results mirrored previous research results when Grounded® was applied on trash blanketed ratoons. In both efficacy trials, weed control varied at each site between herbicide treatments depending on the environmental conditions and the weed species. However, the addition of Grounded® to each herbicide treatment did not affect the efficacy of any herbicide treatment in both trials. These results show that the oil-based adjuvant Grounded® is unlikely to improve the quality of runoff water leaving sugarcane paddocks when applied to untilled ratoon cane on bare soil.Item Smart blending of enhanced efficiency fertilisers to maximise sugarcane profitability : final technical report RRDP1718(Cotton Research and Development Corporation;, 2020) Reeves, S; Wang, WJointly funded by the Department of Agriculture, Water and the Environment, Sugar Research Australia, Queensland Government, and industry and research partners, this project aimed to: (1) characterise PCU N release dynamics in relation to crop N uptake and identify the most desirable PCU formulation for enhanced synchronisation between N supply and crop N uptake; (2) assess the potential benefits of blending PCU with conventional urea as a means to improve N use efficiency and profitability; (3) investigate if use of NI+U or PCU blend could decrease nitrate leaching; and (4) develop a decision support tool to assist with product selection and use.Item Improved nitrogen use efficiency through accounting for deep soil and mineralisable N supply and deployment of EEF to better match crop N demand : final report RRDP1717(Sugar Research Australia Limited, 2020) Rust, J; Van Zwieten, L; Rose, T; Rose, M; Morris, S; Beattie, RItem Protecting our chemicals for the future through the accelerated adoption of best management practices : final report 2016/002(Sugar Research Australia Limited, 2020) Billing, BThe project ran in the Wet Tropics for three years from September 2017. The project set out to improve water quality in Great Barrier Reef catchments through increasing the uptake of management practices to reduce losses of herbicides and pesticides to the environment with sugarcane growers in the Tully, Innisfail/Babinda and Mulgrave milling areas. The project utilised tools such as rainfall simulation, grower group work and field demonstrations to connect sugarcane grower collaborators and sugar industry extension staff with science and solutions to water quality and weed and pest issues facing the farmers. The project used behaviour change principles to inform project design, messaging and interactions with industry and the grower community aner program run in the Wet Tropics by behavioural science experts Behaviour Innovation. The project focussed on the promotion of selected principle-based key messages, giving grower collaborators the opportunity to identify their own means of applying these on-farm: Less on = Less off d also drew on the learnings of the Cane Chang Timing really matters Apply imidacloprid products according to label Do I have canegrubs, or is it something else? Protecting our Chemicals for the Future has resulted in practice change among participating growers and collaborators, the provision of resources and messaging for industry extension staff and resellers, and shifted culture among many involved to be accepting of an ability to influence water quality for the better. Key messages have been shared beyond the immediate project collaborators through regular updates in SRA’s Cane Connection magazine, presentations at shed meetings and industry events and provision of information and resources to extension staff outside of the Wet Tropics.