GameChanger

Case study TRIAL: Variable rate nitrogen application

Based on zone yield potential

LANDHOLDER: John and Phil Deguara

LOCATION: North Eton, 25 km SW of Mackay

Catchment: Sandy Creek

Rainfall: 1620 mm

Property size: 282 ha

Landuse: Sugarcane

GameChanger...Innovation in SugarCaneThe fast-tracking adoption of ‘game changing’ sugarcane nutrient and pesticide management practices (GameChanger) project is funded by the Australian Government Reef Programme. GameChanger management practices focus on the use of precision agriculture technologies and advanced planning to provide opportunities for cane farming to be more economically and environmentally sustainable.

John and Phil are Game Changer farmers of North Eton, 25km SW of Mackay.

THE GAMECHANGER PROGRAM IS MANAGED BY REEF CATCHMENTS (MACKAY WHITSUNDAY ISAAC) LIMITED NRM GROUP IN THE MACKAY-WHITSUNDAY REGION.

GOAL Phil and John have aimed to develop a project which allows them to identify different management zones within blocks of sugarcane. Their goal was to apply variable rate applications of nitrogen based upon the identified yield potential of each management zone within the paddock. They wanted to test if lower yielding zones could receive lower nitrogen rates and still maintain cane production.

OVERVIEWA major impediment to this type of precision agriculture approach has been identifying reliable sources of spatial variability in sugarcane paddocks. Phil and John are testing whether analysis of archived satellite yield data over an extended period alongside detailed soil boundary maps as derived from EC mapping, will allow for the identification of defined management zones at an intra-paddock scale.

CURRENT ACTIONFarmacist, a local agronomic service provider, supported Phil and John in selecting a suitable trial block after a cross section of locations on the farm were analysed utilising coarse soil survey digital data, EC soil mapping surveys and satellite yield information. The trial design incorporates nutrient rates as determined by zone yield potential analysis, compared against traditional nutrient rates using Six Easy Steps protocols.

The variation in yield on this site is largely driven by topography and lack of water from irrigation (Figure 1). The low yielding zone does not receive adequate water from the centre pivot irrigator and is also on a ridge that dries out at a faster rate than elsewhere in the block.

The trial design incorporates low, average and higher rates of N application. A basal rate of liquid fertiliser at 3.8m3/ha was applied across the site and N adjusted with a top-up of Urea S at varying rates (Table 1).

Innovation in SugarCane | GameChanger P2

www.reefcatchments.com

OUTCOMES TO DATE As can be seen in Figures 2 and 3, cane yield in the higher yielding zone where higher N rates were applied (170 kg/ha) had a high of 119 t/ha and averaged 110 t/ha. The yields in the higher yield zone where lower rates of N were applied (155 kg/ha) also had a high of 119 t/ha but averaged slightly lower at 105 t/ha. This is not a significant difference and would indicate that response to higher N rates is limited.

In the low yielding zone where low rates of N were applied (130 kg/ha) the highest yield was 105 t/ha and averaged 96 t/ha. By contrast, yields in the low yielding zone where high N rates were applied (155 kg/ha), the highest yield was 91 t/ha and averaged 88 t/ha. This would indicate no yield response to increasing N rates for the low yielding zone.

The results from this project indicate that there are no yield responses to increasing nitrogen rates for the low yielding zone.

Increasing nitrogen inputs on those zones does not lead to an increase in production, but will unnecessarily increase production costs and the potential for nutrient losses off farm.

The nitrogen use efficiencies calculated for this site also indicated that the highest efficiencies existed in locations where lower N rates were applied in the lowest yielding zone, and the lowest efficiency exists where high N rates were applied in the lowest yielding zones.

N rates Dunder Product

Rate (m3) Urea S (kg/ha)

Total N (kg/ha)

Total P (kg/ha)

Total K (kg/ha)

Total S (kg/ha)

Low LOS 2.9 132 0 75 13 17

Avg LOS 3.5 160 0 90 15 20

High LOS 3.7 170 0 95 16 22

table 1 Fertiliser application rates for Deguara’s variable rate N trial

THIS PROJECT IS COORDINATED ON-GROUND BY REEF CATCHMENTS, MADE POSSIBLE THROUGH FUNDING FROM THE AUSTRALIAN GOVERNMENT REEF PROGRAMME.

figure 1 yield variation, soil sample and site location

Innovation in SugarCane | GameChanger P3

www.reefcatchments.com

figure 1 Cane yields and Nitrogen Use Efficiency

figure 2 Sugar Yields

- 3 of 5 -

OUTCOMES TO DATE

As can be seen in Figures 2 and 3, cane yield in the higher yielding zone where higher N rates

were applied (170 kg/ha) had a high of 119 t/ha and averaged 110 t/ha. The yields in the higher

yield zone where lower rates of N were applied (155 kg/ha) also had a high of 119 t/ha but

averaged slightly lower at 105 t/ha. This is not a significant difference and would indicate that

response to higher N rates is limited.

In the low yielding zone where low rates of N were applied (130 kg/ha) the highest yield was 105

t/ha and averaged 96 t/ha. By contrast, yields in the low yielding zone where high N rates were

applied (155 kg/ha), the highest yield was 91 t/ha and averaged 88 t/ha. This would indicate no

yield response to increasing N rates for the low yielding zone.

Break out The nitrogen use efficiencies calculated for this site also indicated that the highest

efficiencies existed in locations where lower N rates were applied in the lowest yielding zone, and

the lowest efficiency exists where high N rates were applied in the lowest yielding zones.

Figure 2. Cane yields and Nitrogen Use Efficiency

- 4 of 5 -

Figure 3. Sugar Yields The results from this project indicate that there are no yield responses to increasing nitrogen rates for the low yielding zone. Break out By identifying the lower yielding zones within blocks, growers are able to reduce nitrogen inputs for these zones and maintain yield expectations. Increasing nitrogen inputs on those zones does not lead to an increase in production, but will unnecessarily increase production costs and the potential for nutrient losses off farm.

1. Image (preferably jpeg file) 2. Image Description

a.

b.