Defining best management practice for nutrient , pesticide and irrigation management in the Lower Burdekin ( Section 4 )
� The priority issues for improved water quality and sugarcane management in the Lower Burdekin are the management of fertiliser and pesticide application rates and timing , low irrigation efficiencies and rising water tables . Section 4.1 describes the current understanding of management options for these issues in the Lower Burdekin sugarcane area .
� A holistic approach to managing these is required , and therefore this document , intended to focus on irrigation management , also refers to the management of nutrient and pesticide losses from sugarcane areas . Groundwater management is also acknowledged as an integral component of the Lower Burdekin Groundwater Strategy Project led by DNRME .
� The Reef 2050 WQIP Paddock to Reef Integrated Monitoring , Modelling and Reporting program ( Paddock to Reef program ) establishes a Water Quality Risk Framework to identify the management practices with greatest potential influence on off-farm water quality and articulate a reasonable best practice level which can be expected to result in a moderate-low water quality risk . The framework has recently been updated to reflect the latest knowledge .
� The primary principles for improving water quality from sugarcane areas are outlined in Section 4.2 :
- For reducing nutrient losses : Optimising fertiliser use ( e . g . lower surpluses and lower rates , splitting applications and sub-surface application ), reducing erosion to reduce particulate nutrient losses , factoring in other sources of nutrients to crops ( e . g . mill mud ) and minimising runoff .
- For reducing pesticide losses : Rate of application ( e . g . reducing overall usage and use of precision application such as banded sprayers ), integrated weed management , maximising the time between application and likely runoff events , minimising runoff and sediment loss and choosing products with rapid degradation rates ( e . g . some ‘ knockdown ’ herbicides ).
- For increasing irrigation efficiency and reducing runoff : Matching irrigation applications as closely as possible to crop water requirements ( e . g . automation of furrow irrigation systems , accounting for slope and furrow length , correct irrigation scheduling ), choice of irrigation system selected to suit the local characteristics and minimise runoff ( e . g . furrow , drip or overhead low pressure systems ), practices to improve water penetration ( e . g . green cane trash blanketing , delaying irrigation after fertiliser and pesticide applications and capturing tailwater to minimise runoff ( e . g . recycle pits and particularly in the BRIA ).
Modelling pollutant loads from irrigated sugarcane ( Section 5 )
� Paddock scale modelling of pollutant loads through the Paddock to Reef program provides information on water quality in runoff or deep drainage for sugarcane in the Lower Burdekin . It links the management practice adoption data with the catchment model by providing estimates of sediment and nutrient loads and pesticide concentrations for management practice scenarios . A suite of defined farming systems which represent plausible management practice combinations and scenarios are simulated for a large number of combinations of soils and climates .
� The modelling framework including assumptions and input data is currently being updated to reflect the latest knowledge ( described in Section 5.1 ). This update is critical for continuing to improve confidence in the model outputs .
Current adoption of management practice options for improving water quality outcomes from Lower Burdekin sugarcane ( Section 6 )
� Management practice adoption data is available and interpreted through the Paddock to Reef program which draws on several sources in the region ( see Section 6.1 ). The Paddock to Reef program has recently undertaken a major exercise to update the benchmarks for reporting current adoption . The benchmarking data is informed by information from 2015-16 , 2016-17 and some 2017-18 data , and will be reported in 2019 as the reporting benchmark for the 2016-17 year .
� Current information indicates that a large proportion of the sugarcane area in the Lower Burdekin is currently managed using High or Moderate risk management practices .
xi