Project 2.1.8 - NESP Tropical Water Quality Hub

Using production unit yield potential and enhanced efficiency fertilisers to improve the efficiency of sugarcane N use Tony Webster, Mike Bell, Phil Moody, Danielle Skocaj, John Markley, Jayson Dowie, Bronwyn Masters, Chelsea Stroppiana 20 November 2017

Background • Video of GBR here • The GBR is great!

2 | Enhanced Efficiency Fertilisers | Tony Webster


Dissolved Inorganic Nitrogen

Nitrite 4 | Enhanced Efficiency Fertilisers | Tony Webster

Nitrate

Ammonium


Sugarcane Nitrogen Recommendations Six Easy Steps 1. 2. 3. 4. 5. 6.

Know and understand your soil Understand nutrient processes Regular soil testing Adopt soil-specific nutrient guidelines Check the adequacy of nutrient inputs Keep records and modify where necessary


Sugarcane Nitrogen Recommendations How they generally play out…. • Yield potential is used to determine nitrogen rate • 1.4 kg N per tonne for the first 100 t/ha of potential plus 1.0 kg N per tonne thereafter • Adoption of district wide yield potential

• Discount to nitrogen rate based on soil organic carbon (0-200 mm) • Look up table




Urea


What happens to urea in soil (1)

Urea


Water

Ammonium

What happens to urea in soil (2)

Nitrosomonas

Ammonium


Nitrobacter

Nitrite

Nitrate

Enhanced Efficiency Fertilisers Urea

Water

Ammonium

STOP Bacteria

Nitrate 13 | Enhanced Efficiency Fertilisers | Tony Webster

Nitrate

Hypothesis: The use of Block Yield Potential and / or Enhanced Efficiency Fertilisers will allow reduced nitrogen application rates to sugarcane, maintain yield and reduce nitrogen losses in comparison to District Yield Potential and Urea


Results Burdekin hand harvest (200 days) Treatment

Biomass (tonnes / ha)

Crop N uptake (kg / ha)

Zero N

77 c

88 b

200 N as urea (DYP)

115 b

141 a

150 N as urea (BYP)

95 bc

114 b

150 N as EEF (BYP)

135 a

141 a

170 N as urea

114 b

110 b


Results Burdekin machine harvest Treatment

Yield (tonnes / ha)

Crop N uptake (kg / ha)

Zero N

64 b

45 b

200 N as urea (DYP)

122 a

189 a

150 N as urea (BYP)

115 a

179 a

150 N as EEF (BYP)

123 a

217 a

170 N as urea

115 a

200 a


Results Silkwood hand harvest Treatment

Yield (tonnes / ha)

Zero N

31

100 N as urea (DYP)

55

16

52 N as urea (BYP)

45

13

52 N as EEF (BYP)

44

5

160 N as urea

56

160 N as EEF

80


N runoff (kg / ha)

15

Results Kamerunga hand harvest 100 90

Biomass (t/ha)

80 70 60 50

EEF

40

Urea

30

20 10

0 0

50

100

150

Nitrogen rate (kg N/ha)


200

250

Results Kamerunga soil mineral nitrogen Ammonium

Soil Nitrate (mg/kg) in 0-150 mm

10 9 8 7 6 5

EEF

4

Urea

3

2 1

0 0

5

10

15

20

25

Days after fertilising


30

35

Soil Ammonium (mg/kg) in 0-150 mm

Nitrate 50

45 40 35 30 25

EEF

20

Urea

15 10 5

0 0

5

10

15

20

Days after fertilising

25

30

35

Laboratory incubation study


Summary of results • Block Yield Potential can maintain productivity compared with District Yield Potential • EEF fertiliser treatments can yield higher than urea at higher rates of fertilisation • Maximum yield (plateau) may be reached at lower rates of application for EEF compared to urea • EEF retains fertiliser as ammonium for longer than urea (and urea has higher nitrate concentrations) • Losses of nitrogen are higher with urea than EEF for the same rate


Outcomes from the work to date The project and project team have contributed to the design and implementation of 60 trials across the sugarcane industry (Reef Trust IV) testing the efficacy of EEFs at Block Yield Potential in comparison to urea at District Yield Potential.


Thank you