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There are marginal differences between the modelled PSII herbicide load in the BRIA and the Delta regions . However , it is likely that more residuals are applied in the BRIA as standard practices use less cultivation and therefore weed pressure can be greater . While it is recommended that both the BRIA and Delta region have equal importance to reduce pesticide loads entering the GBR , greater attention may be placed on the BRIA in terms of application rates .
The legacy of irrigation area management has resulted in a situation of rising watertable levels and emerging surface soil salinity that may increase over time , but now is at a critical stage requiring a concerted effort to attain a sustainable watertable regime . The Lower Burdekin Groundwater Strategy Project is designed to address these issues ( DNRM , 2017 ). It is suggested that any further inaction in controlling groundwater levels will result in sugarcane lands being taken out of production ( Shaw , 2014 ).
Given that the predominant pollutant loss pathway in the BRIA is by surface runoff ( and therefore faster response times between pollutant reductions and responses in the receiving environment could be expected ), there are less farms in the BRIA , the average farm is larger and practice changes are typically more cost effective , the Burdekin WQIP 2016 suggested that improving sugarcane management actions in the BRIA may be a higher priority than in the Delta . However , due to variations in current practice adoption , specific site characteristics , proximity to sensitive freshwater waterways , a lack of understanding of the contributions of deep drainage to overall loads and the rates of ultimate input to streams , and a range of complex social factors in the region , it not feasible to prioritise action in one area over another . Further discussion with industry experts confirms this view , recommending a whole of district approach to water quality in the region .
Spatial management prioritisation to a smaller scale is difficult at this point due to limitations in our understanding of the hydrological complexities of the system but is possible can be progressed immediately . For example , more detailed information on key factors such as accurate block-scale yield mapping ( to determine nitrogen requirement ) and data on current fertiliser and PSII herbicide use and water use efficiency would inform smaller scale targeting of effort . In addition to this , more frequent and intensive nutrient and PSII herbicide monitoring at a range of scales including individual paddocks and farms , supported by data along major drainage channels and coastal creeks , will inform finer scale spatial priorities across the Lower Burdekin and provide greater confidence in management priorities for investors , managers and the local farming community .
Knowledge of current practice adoption , farm size and cost effectiveness of practice improvements should be used as a guide for targeting management until other knowledge is progressed . For example , it is possible to target a smaller number of growers by focusing on larger farms ; farms > 1,000ha are recommended for targeting based on current data .
6.3 Factors affecting adoption 6.3.1 Barriers and enablers
There are several factors that may affect a sugarcane farmer ’ s management adoption decision . These may be social , economic or related to skills and capacity . For example , in a recent study by Thompson et al . ( 2014 ) ( based on the results of 61 farmer surveys in Ayr ( 30 ), Ingham and Tully ) potential constraints to adoption of variable nutrient rates within blocks included high capital investment and the requirement for new skills , and a perceived negative impact on farm profitability . Perceptions of the impact on farm profitability and compatibility with existing farming practices were critical factors impacting on the adoption decision . Socio economic factors and farm characteristics were generally found to be insignificant in determining an adoption decision . However , a proportionally higher number of younger farmers ( aged 45 or less ) were found to have adopted best management practices . It is also acknowledged that growers will be unlikely to adopt new practices that import high risks to farm production and profitability ( see Smith et al ., 2012 ; Smith et al ., 2014 ; Poggio et al ., 2014 ). Adverse weather conditions , incursions of disease , as well as increases in fixed costs have applied pressure on grower margins which is likely to influence management decisions ( Smith et al ., 2014 ).
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