SA - Burdekin WQIP Cane Implementation Plan Irrigation_FINAL 080319 (1) | Page 61

Percentage of growers from sample ( per cent )
25 %
20 %
15 %
10 %
5 %
0 %
0
up to 20 20 to 40 40 to 60 60 to 80
80 to
100
> 100
200 180 160 140 120 100 80 60 40 20 0
Nitrogen rate applied over Six Easy Steps starting N guideline ( kg / ha )
Average value of potenital nitrogen saving ($/ ha )
Plant (%) Plant N Saving ($/ ha )
Percentage of growers from sample ( per cent )
35 % 30 % 25 % 20 % 15 % 10 % 5 % 0 %
0
up to 20 20 to 40 40 to 60 60 to 80
80 to
100
> 100
Nitrogen rate applied over Six Easy Steps starting N guideline ( kg / ha )
300 250 200 150 100 50 0
Average value of potential nitrogen saving ($/ ha )
Ratoon (%) Ratoon N Saving ($/ ha )
Figure 6.1 . Estimates of nitrogen application above the nominal Six Easy Steps rate and potential cost saving for plant cane ( top ) and ratoon cane ( bottom ).
6.2 Priority areas for reducing nutrient and pesticide losses
Based on current knowledge of modelled and monitored DIN and PSII herbicide loads , pollutant loss pathways , and fertiliser usage and sales data , the following conclusions are drawn :
Fertiliser application rates recommended in the Six Easy Steps nutrient management program should not be exceeded in the Lower Burdekin sugarcane areas .
Improvements in water use efficiencies are equally important to reduce nitrogen losses from sugarcane in the region . This may be considered more important in the BRIA where there is comparably less deep drainage than in the Delta and greater capacity for surface runoff and therefore direct discharge to waterways . However , the catchment model also routes a proportion of deep drainage DIN to streams which may be a larger contribution than runoff except where irrigation tailwater is very large ( Dowling et al ., 1991 ).
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