Nitrogen fertiliser requirements for representative soils of the - - PowerPoint PPT Presentation

13th October 2015

Nitrogen fertiliser requirements for representative soils of the Lower Burdekin cane growing district

Julian Connellan1, Phil Moody2

1Sugar Research Australia, Burdekin 2Queensland DSITI, Dutton Park

David Defranciscis

(Chairman) Steering committee

Background

• October 2009 the Great Barrier Reef Protection

Amendment Act was introduced requiring growers to follow a regulated method for determining N application rates.

• In response to industry concern DEHP funded a number
• f trials across the Burdekin.
• The trials began in 2011
• Aim is to assess the suitability of nitrogen application

rates in the Burdekin, giving consideration to profitability, sustainable production and the potential for impacts on the environment.

Current status

• To date established 23 replicated block trials in the

Delta and BRIA cane growing areas

• 10 established in 2011, 4 established in 2012, 1 in

2013, 4 established in 2014 and 4 established in 2015

• Active sites include:
• four plant
• four 1st ratoon
• one 2nd ratoon
• three 3rd ratoon
• possibly two 4th ratoon
• Sites range in size from 4 to 10 hectares

Three to four treatments

• Treatment 1 – low rate (P130 kg N/ha, R170 kg N/ha)
• Treatment 2 – rate determined by the Regulated Method/Six

Easy Steps (P170 kg N/ha, R210 kg N/ha)

• Treatment 3 – traditional grower rate (P210 kg N/ha, R250 kg N/ha)
• Treatment 4 – a high rate (P250 kg N/ha, R290 kg N/ha)
• Three to four replications at each site
• Six Easy Steps rate based on DYP of 180 t cane/ha and

discount for soil mineralisation potential

Trial design

3 1 2 2 3 5 7

Grower ID Treatments 170 kg N/ha 210 kg N/ha 250 kg N/ha 290 kg N/ha 2 16.3 16 15.9 6 18.8 19.2 19.1 19.4 7 20 19.4 19.2 19.2 8 13.7 14 14 14.4

Grower ID Treatments 170 kg N/ha 210 kg N/ha 250 kg N/ha 290 kg N/ha 2 107.5 105.8 106.2 6 107.7b 111.4ab 115.7a 117.2a 7 128.2 124.6 124.5 125.5 8 79.1b 81.6b 81.5b 85.6a

Mean cane yield (tc/ha) for each nitrogen rate treatment at six 2nd ratoon trial sites Mean sugar yields (ts/ha) for each nitrogen rate treatment at six 2nd ratoon trial sites

Sites with P<0.05 are highlighted Means followed by a common letter are not significantly different at the 5% level *Indicates elevated levels of nitrates in irrigation water (>2 mg/L of NO3-N)

2014 Harvest results

Grower ID Treatments 150 kg N/ha 190 kg N/ha 230 kg N/ha 15 196.6 201.4 198.5 Grower ID Treatments 150 kg N/ha 190 kg N/ha 230 kg N/ha 15 26.2 25.7 25.5

Mean cane yield (tc/ha) for each nitrogen rate treatment for a plant crop Mean sugar yields (ts/ha) for each nitrogen rate treatment for a plant crop

• Note. Moddus was applied to this trial site

Apparent nitrogen fertiliser use efficiency (aNUE) - kg of N applied to produce 1 tonne of sugarcane

kg of applied N to produce 1 tonne of sugarcane for 4 plant crops

Grower ID Applied N (kg/ha) Yield (tc/ha) kg of N applied to produce 1 tonne of sugarcane 2 170 141 1.2 6 170 111 1.5 8 170 131 1.3 15 150 197 0.8

Apparent nitrogen fertiliser use efficiency (aNUE) - kg of N applied to produce 1 tonne of sugarcane

kg of applied N to produce 1 tonne of sugarcane for 4 plant crops

Grower ID Applied N (kg/ha) Yield (tc/ha) kg of N applied to produce 1 tonne of sugarcane 2 170 141 1.2 6 170 111 1.5 8 170 131 1.3 15 150 197 0.8

Improving our understanding of where the applied N is going

• Can use a simplistic method of looking at kg of N applied

to produce 1 tonne of sugarcane as shown in the previous slide however this is only part of the story

• It does not explain:
• Where has the N has gone
• How much N the plant used
• How much N is left in the soil after the crop is

harvested

• To develop a better understanding of where the N is going

a partial nitrogen budget can be used

C

Above ground Biomass uptake

D

Below ground biomass uptake

B

Fertiliser Amendment inputs

A

Initial soil pools

E

Final soil pools

Leaching Runoff, sediment Mineralisation Denitrification C oxidation

Nutrient inputs, outputs and status components of a partial nitrogen budget

Partial Nitrogen Budget

Initial soil pools (A)

• Prior to planting all trial sites soil sampled

– Soil cores down to 1m in 20cm increments – Soil samples tested for mineral N (Nitrate N +Ammonium N)

• Kg/ha of mineral N in the top 60cm of the soil profile

calculated

– Generally mineral N levels vary widely from site to site (15 kg N/ha – 114 kg N/ha)

Fertiliser amendment inputs (B)

• Fertiliser applied using purpose build fertiliser box with

load cell technology – Recommend N application rate for plant crop according to regulated method (Six Easy Steps) is generally around 150-170 kg N/ha

Above ground biomass uptake (C)

• Conducted at harvest
• Stalks are sampled and broken down to components

such as millable stalk, leaf, cabbage and trash and analysed for N content

• Using yield data and the N content of the plant

components able to determine the amount of nitrogen captured by the crop

Crop N varies widely from site to site (80 – >200kg N/ha)

Below ground biomass uptake (D)

• Roots and stool
• Below ground biomass N is approximately

30% of the total above ground biomass N

• Little knowledge about the dynamics of N

accumulation in the below ground biomass

A crop with 100kg N/ha in the above ground biomass will have approximately 30kg N/ha in the below ground biomass

100 kg N/ha 30 kg N/ha

Final soil pools (E)

• Following harvest soil samples taken from all strips in

each trial site

• Soil samples taken in 20cm increments (0-20cm, 20-

40cm, 40-60cm, 60-80cm and 80-100cm) down to 1m and analysed for mineral N

• Mineral N following harvest was found to be low in all

treatments at all sites across the Burdekin.

• Often less than 30kg N/ha in the top 60cm of the soil

profile

C

Above ground Biomass uptake

D

Below ground biomass uptake

B

Fertiliser Amendment inputs

A

Initial soil pools

E

Final soil pools

Leaching Runoff, sediment Mineralisation Denitrification C oxidation

Nutrient inputs, outputs and status components of a partial nitrogen budget

Partial Nitrogen Budget

C

Above ground Biomass uptake

D

Below ground biomass uptake

B

Fertiliser Amendment inputs

A

Initial soil pools

E

Final soil pools

Leaching Runoff, sediment Mineralisation Denitrification C oxidation

Nutrient inputs, outputs and status components of a partial nitrogen budget

Partial Nitrogen Budget

N Budget

N inputs = N outputs

N Inputs kg of N/ha Fertiliser 170 Soil profile mineral N (0-60cm) 32 Irrigation Soil N mineralisation Unknown Subtotal (A) 202+ N Outputs kg of N/ha Crop Biomass (above-ground) 118 Crop Biomass (below-ground) 35* Mineral N remaining in soil post harvest (0-60cm) 23 Subtotal (B) 176

Sugar Mill Grower 6. Plant Crop (yield = 111 tc/ha)

26 kg N/ha is unaccounted for

Grower 6. Plant Crop (yield = 113 tc/ha) Sugar Mill

N Inputs kg of N/ha Fertiliser 210 Soil profile mineral N (0-60cm) 27 Irrigation Soil N mineralisation Unknown Subtotal (A) 237+ N Outputs kg of N/ha Crop Biomass (above-ground) 120 Crop Biomass (below-ground) 36* Mineral N remaining in soil post harvest (0-60cm) 30 Subtotal (B) 186

51 kg N/ha is unaccounted for

• Note. This budget does not take into account soil N mineralisation

* Below ground biomass N is estimated as 30% of above ground biomass N

N Budget

N inputs = N outputs

N Inputs kg of N/ha Fertiliser 150 Soil profile mineral N (0-60cm) 27 Irrigation Soil N mineralisation Unknown Subtotal (A) 177+ N Outputs kg of N/ha Crop Biomass (above-ground) 196 Crop Biomass (below-ground) 59* Mineral N remaining in soil post harvest (0-60cm) 34 Subtotal (B) 289

Sugar Mill Grower 15. Plant Crop (yield = 197 tc/ha)

112kg N/ha is being supplied through soil N mineralisation

Grower 15. Plant Crop (yield = 199 tc/ha) Sugar Mill

N Inputs kg of N/ha Fertiliser 230 Soil profile mineral N (0-60cm) 27 Irrigation Soil N mineralisation Unknown Subtotal (A) 257+ N Outputs kg of N/ha Crop Biomass (above-ground) 233 Crop Biomass (below-ground) 70* Mineral N remaining in soil post harvest (0-60cm) 24 Subtotal (B) 327

70 kg N/ha is being supplied through soil N mineralisation

• Note. This budget does not take into account soil N mineralisation

* Below ground biomass N is estimated as 30% of above ground biomass N

Closing comment

• N requirement calculated by the Regulated Method/Six Easy

Steps was more than enough for maximum cane and sugar yields for most crops harvested in 2014.

THANK YOU

Soil moisture monitoring

Sites with P<0.05 are highlighted Means followed by a common letter are not significantly different at the 5% level * Indicates elevated levels of nitrates in irrigation water (>3 mg/L of NO3-N)

Mean yield (tc/ha) for each treatment at 10 trial sites Grower ID Treatments 130 kg N/ha 170 kg N/ha 210 kg N/ha 250 kg N/ha 1 * 125 a 118 a 128 a 133 a 2 135 b 141 ab 144 a 3 * 153 b 157 ab 163 a 163 a 4 * 143 a 145 a 139 a 144 a 6 106 a 111 a 113 a 113 a 7 * 150 a 152 a no data 151 a 8 126 b 131 ab 134 a 136 a 9 90 a 96 a 95 a 96 a 10 122 b 129 a 130 a 133 a 11 127 c 137 b 142 a Mean yield (tc/ha) 128 132 132 134

2012 Harvest data- Plant crops

Mean sugar yield (ts/ha) for each treatment at 10 trial sites Grower ID (Site) Treatments 130 kg N/ha 170 kg N/ha 210 kg N/ha 250 kg N/ha 1 19.2 18.5 19.5 20.2 2 20.6 21.3 21.6 3 20.7 20.8 21.0 20.6 4 21.2 21.7 20.6 21.2 6 14.4 14.8 14.5 14.8 7 23.5 23.5 no data 23.1 8 20.0 20.3 20.9 21.2 9 15.0 16.3 15.9 16.1 10 18.9 19.7 20.0 20.1 11 19.8 20.6 21.1 Mean ts/ha 19.3 19.8 19.5 19.7

No significant difference was found for sugar yield (ts/ha) at any site

2012 Harvest data- Plant crops

2013 Harvest data- First ratoons

1st ratoon crop yields (tc/ha) for each treatment at 9 trial sites Grower ID Treatments 170 kg N/ha 210 kg N/ha 250 kg N/ha 290 kg N/ha 2 107.4a 112.9a 113.8a 3* 150.6c 153.3bc 158.9ab 162.6a 4* 118.1a 117.5a 114.5a 124.6a 6 112.5b 122.1a 125.5a 123.9a 7* 124a 121.03# 122.5# 120.4a 8 78.9a 82a 83.6a 84.8a 9 58.6a 59.6a 60.3a 61.1a 10 117.1a 124.9a 127.5a 132.7a 11 105.8a 111.3a 113.7a Mean yield tc/ha 108.1 110.5 112.2 115.7

Sites with P<0.05 are highlighted Means followed by a common letter are not significantly different at the 5% level *Indicates elevated levels of nitrates in irrigation water (>2 mg/L of NO3-N) # Indicates that targeted N application rate was not achieved – N application rate is unknown.

1st ratoon sugar yields for each treatment at 9 trial sites Grower ID Treatments 170 kg N/ha 210 kg N/ha 250 kg N/ha 290 kg N/ha 2 16.9 17.3 17.6 3 21.5 21.8 22.1 21.9 4 18.4 18.1 17.6 18.9 6 16.8 18.1 17.8 17.8 7 19.9 19.3# 19.7# 19.1 8 12.8 13.3 13.6 13.6 9 9.5 9.7 9.7 9.8 10 18 18.7 19.1 19.7 11 16.3 16.7 16.8 Mean ts/ha 16.7 16.7 16.7 17.2

Sites with P<0.05 are highlighted Means followed by a common letter are not significantly different at the 5% level *Indicates elevated levels of nitrates in irrigation water (>2 mg/L of NO3-N)

2013 Harvest data- First ratoons

No significant difference was found for sugar yield (ts/ha) at any site

Sites with P<0.05 are highlighted Means followed by a common letter are not significantly different at the 5% level *Indicates elevated levels of nitrates in irrigation water (>2 mg/L of NO3-N) # Indicates that targeted N application rate was not achieved – N application rate is unknown.

Plant crop yields (tc/ha) for each treatment at 3 trial sites Grower ID Treatments 170 kg N/ha 210 kg N/ha 250 kg N/ha 5 94.2a 95.1a 96.4a 14* 108a 108.1a 105.9a Mean yield tc/ha 110.1 114.6 115 Plant crop sugar yields for each treatment at 3 trial sites Grower ID Treatments 170 kg N/ha 210 kg N/ha 250 kg N/ha 5 14.5a 14.7a 14.7a 14 16.2a 15.9a 15.6a Mean ts/ha 16.8 17.3 17.5

2013 Harvest data- Plant crops