The results indicate that the land owner may see economic benefit (as per Gross Margin) from the uptake of variable rate technology in paddocks with varying soil types such as this trial paddock.

The objective of this GRDC / SPAA funded project is to increase the level of adoption of PA 'beyond guidance' by broadacre farmers. The project specifically aims to increase the level of adoption of variable rate (VR) by growers in the project to 30% by 2013.This goal will be achieved by demonstrating how to use PA tools to growers at a regional level and by increasing the skills of growers and industry in PA to a level where they can then use PA tools in their farming systems to achieve economic, environmental and social benefits. Fertiliser rates were selected after discussing with farmer that the lower yielding zones would never produce yields comparable to medium and high yielding zones, due to the low fertility and poor water and nutrient holding capacity of the soil. The farmer believed that that fertiliser was being wasted on the sand zones of his farm, and wanted to see if cutting fertiliser rates would be detrimental to yield in this zone.

NDVI satellite imagery was collected to establish dry matter production difference in 2011. The crop was sown as brown manure peas and therefore there were no yield results. Yield data will be collected in 2012 as part of the trial program.

In 2010, at Wass brothers’ property in Nyngan, a very wet season caused the normally poor performing areas to perform just as well as the good areas in this paddock regardless of additional nitrogen application. In other paddocks across the farm, there were significant yield differences across each paddock. However, in the previous years Wass’s have always wanted to apply N and have had mixed results possibly because of soil and water variability. Most seasons they have areas that burnout and areas which could use a higher application of N and give a better yield. In 2011, Hayden intended to try to understand what was driving these differences, and yield maps are a way of spatially determining different zones. Therefore, this trial was set up.

The objective of this GRDC / SPAA funded project is to increase the level of adoption of PA 'beyond guidance' by broadacre farmers. The project specifically aims to increase the level of adoption of variable rate (VR) by growers in the project to 30% by 2013.This goal will be achieved by demonstrating how to use PA tools to growers at a regional level and by increasing the skills of growers and industry in PA to a level where they can then use PA tools in their farming systems to achieve economic, environmental and social benefits.

Because there was no effect of fertiliser on the yield it meant any potential benefit from VR was greatly reduced. This can likely be put down to the high levels of soil N recorded at the start of 2011. The trial does suggest that this paddock was over fertilised as there was no significant loss of yield from a 40kg/ha reduction in urea in either trial.

There was no response shown to varying nitrogen rates across the 4 yield zones on this paddock. This could be due to the adequate levels of nitrogen present before seeding as show in the 0-10 and 10-60cm soil test results and also reinforced with the NDVI esults, this would stem from good fertiliser history and rotation from the Harkness’s.This could give confidence that rates could be reduced on the lower yielding areas without risk of impacting on yield and consequently increasing gross margins across the paddock by saving wasted inputs on poorer performing soil types and leaving rates higher on better performing areas to maximise returns when seasons are more favourable.

The trial has indicated that the application of the high rate UAN (140L/ha) over the entire paddock still proved to be a more profitable than applying the low rate over the entire paddock, however the overall gross margin benefits are not as visible due to the low yielding sand zone only occupying 9ha (13%) of the paddock. However these results confirm that the adoption of PA is an economically sound decision, indicating that the grower could make a saving of $48/ha if that extra nitrogen was not applied to the low yielding area via the use of variable rate fertiliser application. The trial results have solidly indicated that the overall gross margin would be profitably affected not having to spend the extra $62/ha on fertiliser. The gain of $53/ha in the high yield zone with high rate N (140L) is a substantial increase in profit over the low rate (60L) showing there is benefits to adding N in these zones.

Applying nitrogen on the sand soil zones has consistently delivered sound economic returns. The highest ROI achieved in the sand west zone ($123.20) and sand east zone ($37.85) was in the 115 and 130kg urea/ha treatments respectively. Applying nitrogen in the clay zone however failed to deliver an economic eturn and this has been realised in this paddock before. This trial highlighted that variable rate nitrogen is highly applicable to paddocks with high degrees of spatial variability in order to maximise yield and/or return on investment in individual paddock zones.

The NDVI map has a strong correlation to the final yield, which indicates that the variable rate nitrogen did not achieve the goal of levelling out crop yield. This may be due to the dry finish to the season. This result does however confirm the concept of using in-season satellite imagery (typically late July, early August) o manage final yield through a variable rate intervention.

The objective of this GRDC / SPAA funded project is to increase the level of adoption of PA 'beyond guidance' by broadacre farmers. The project specifically aims to increase the level of adoption of variable rate (VR) by growers in the project to 30% by 2013.This goal will be achieved by demonstrating how to use PA tools to growers at a regional level and by increasing the skills of growers and industry in PA to a level where they can then use PA tools in their farming systems to achieve economic, environmental and social benefits.

With good soil phosphorus reserves ‘P replacement’ is a safe and viable option that will help farmers manage their inputs and maintain soil fertility in high yielding areas of the paddock.

The objective of this GRDC / SPAA funded project is to increase the level of adoption of PA 'beyond guidance' by broadacre farmers. The project specifically aims to increase the level of adoption of variable rate (VR) by growers in the project to 30% by 2013.This goal will be achieved by demonstrating how to use PA tools to growers at a regional level and by increasing the skills of growers and industry in PA to a level where they can then use PA tools in their farming systems to achieve economic, environmental and social benefits.

The objective of this GRDC / SPAA funded project is to increase the level of adoption of PA 'beyond guidance' by broadacre farmers. The project specifically aims to increase the level of adoption of variable rate (VR) by growers in the project to 30% by 2013.This goal will be achieved by demonstrating how to use PA tools to growers at a regional level and by increasing the skills of growers and industry in PA to a level where they can then use PA tools in their farming systems to achieve economic, environmental and social benefits.

On upper Eyre Peninsula few people use EM38 mapping to support the use of VRT. Currently yield maps and paddock knowledge are the most commonly used methods for determining production zones within paddocks. The demonstrations show that increasing fertiliser rates did not have an effect on yields but yields did follow EM38 mapped soil zones.

Additional N did not have an economic advantage in this season. Paddock and demonstration site suffered from the dry 6 weeks period mid season. Stem rust devastated potential 3 ton crop reducing yield by 50%. This combination resulted in poor yields, low test weight and high screenings. Good soil showed improved protein over deeper sand regardless of extra N applied. Extra N marginally improved protein but not enough economically to apply more.

• Additional N did not have an economic advantage in this season.
• Paddock and demonstration site suffered from the dry 6 weeks period mid season.
• Stem rust devastated potential 3 ton crop reducing yield by 50%. This combination resulted in poor yields, low test weight and high screenings.
• Good soil showed improved protein over deeper sand regardless of extra N applied.
• Extra N marginally improved protein but not enough economically to apply more.

Birchip: The site was located in a paddock with moderate subsoil limitations (40 to 70cm layer had chloride reading of 1800ppm, and an EC of 0.6dS/m). The site had a previous legume history and was high in soil available N (prior to sowing the soil contained 230 kg available N/ha to 1m depth).

Kooloonong: The site was located on a Mallee land system, on a flat to sloping rise with a sandy loam soil to a depth of 40cm and at greater depth a sandy clay loam to at least 130cm. The soil has no subsoil limitations but because it is light and sandy, leaching of nutrients can be a problem. 2010 had a growing season rainfall of 329mm (decile 10).

The objective of this GRDC / SPAA funded project is to increase the level of adoption of PA 'beyond guidance' by broadacre farmers. The project specifically aims to increase the level of adoption of variable rate (VR) by growers in the project to 30% by 2013.This goal will be achieved by demonstrating how to use PA tools to growers at a regional level and by increasing the skills of growers and industry in PA to a level where they can then use PA tools in their farming systems to achieve economic, environmental and social benefits.

DBA Aurora and Mace showed similar ability to compete with weeds in 2014. Using higher seeding rates improved weed control. Increased crop seeding rate resulted in reduced crop screenings in 2014

This study has shown that substantial savings can be made with the use of this technology. It essntially allows the farmer to have a zero tolerance on summer weeds, without having to apply economical thresholds. The study also identified that the savings will not always result. If there is consistently, 60-70% ground cover, the economical returns may not be as great. This is due to the way the technology is designed. Often in relatively high densities, two sensors would come on to spray one weed, hence twice the amount of water. This is most likely the cause of more water being used in the areas with the High density. Overall, the Weed Seeker technology has the potential to reduce chemical costs and increase the efficiency of spray applications.

• Commercial viability has been difficult to demonstrate.
• Field trials demonstrated that the H Senor was able to accurately classify annual ryegrass in several broadleaf crops, including canola, faba bean, lentil and field pea.
• Other grass weeds such as brome grass and wild oats were also correctly identified as grasses in these crops.
• Broad leaf weeds were accurately classified in cereal crops, however this was more difficult due to the overlapping nature of the cereal crops at the time when the broadleaf weeds had emerged.
• Classification accuracy was lower for detection of grass weeds in cereal crops and broadleaf weeds in broadleaf crops, and these scenarios were not pursued for that reason.  

The objective of this GRDC / SPAA funded project is to increase the level of adoption of PA 'beyond guidance' by broadacre farmers. The project specifically aims to increase the level of adoption of variable rate (VR) by growers in the project to 30% by 2013.This goal will be achieved by demonstrating how to use PA tools to growers at a regional level and by increasing the skills of growers and industry in PA to a level where they can then use PA tools in their farming systems to achieve economic, environmental and social benefits.

• Commercial viability has been difficult to demonstrate.
• Field trials demonstrated that the H Senor was able to accurately classify annual ryegrass in several broadleaf crops, including canola, faba bean, lentil and field pea.
• Other grass weeds such as brome grass and wild oats were also correctly identified as grasses in these crops.
• Broad leaf weeds were accurately classified in cereal crops, however this was more difficult due to the overlapping nature of the cereal crops at the time when the broadleaf weeds had emerged.
• Classification accuracy was lower for detection of grass weeds in cereal crops and broadleaf weeds in broadleaf crops, and these scenarios were not pursued for that reason.  

• Commercial viability has been difficult to demonstrate.
• Field trials demonstrated that the H Senor was able to accurately classify annual ryegrass in several broadleaf crops, including canola, faba bean, lentil and field pea.
• Other grass weeds such as brome grass and wild oats were also correctly identified as grasses in these crops.
• Broad leaf weeds were accurately classified in cereal crops, however this was more difficult due to the overlapping nature of the cereal crops at the time when the broadleaf weeds had emerged.
• Classification accuracy was lower for detection of grass weeds in cereal crops and broadleaf weeds in broadleaf crops, and these scenarios were not pursued for that reason.