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Ongoing project

Improved tree and fruit nutrition for the Australian apple industry (AP14023)

Key research provider: Tasmanian Institute of Agriculture

What’s it all about?

Research into optimising nitrogen-use efficiency has the potential to boost productivity in apple growing. This project is developing a multi-season nitrogen budget underpinned by fertigation research, to in turn produce a user-friendly decision-support tool to assist growers across the country in optimising irrigation and fertigation application.

The project’s activities continue to include nitrogen-use trials, soil analysis and more – all working towards a common goal of validating an international research model for predicting tree water and nitrogen use, known as SPASMO. This will then be used as the basis for the project’s grower-friendly decision-support tool, referred to as ‘SINATA’ – the Strategic Irrigation and Nitrogen Assessment Tool for Apples.

It is expected that SINATA will ultimately allow growers to look up their soil type, local climate and tree information to determine average irrigation and nitrogen requirements, assess the efficiency of their current management practices, and explore potential savings associated with changes in irrigation and nitrogen application (such as switching from calendar-based irrigation schedules to targeted schedules based on soil moisture status).

To learn more about SINATA or to provide ideas for the tool’s usability, contact Marcus Hardie from the Tasmanian Institute of Agriculture at marcus.hardie@utas.edu.au

The research team has now completed all the background data calculations that are required for the Strategic Irrigation and Nitrogen Assessment Tool for Apples (SINATA). Next steps will involve the development of a user-friendly tool for growers.

Grower engagement was a focus for the research team in the second half of 2019, with presentations made on apple nutrition physiology at Hort Connections, the Fruit Growers Tasmania conference and the APAL Industry Update Forum. At the APAL event, the apple soils website was also launched (www.applesoils.com) which provides growers with important information about the soil in their area.

In 2020, the project team is planning to participate in the mid-year Future Orchards workshops to deliver the SINATA training manual to all apple growing regions across the country. Keep an eye out in industry communication channels for further details.

The project team has made headway in learning about tree nitrogen uptake, water use, and soil characteristics from trial results, and they are using the new data to boost the accuracy of the international research model for predicting tree water and nitrogen use, known as SPASMO. The model was developed in New Zealand and needs Australian data to make it useful here.

The nitrogen apple fertigation field trial is now complete, with trees excavated at commercial harvest in March 2019. The results showed that pre-harvest applied nitrogen was highly effective, resulting in efficient use by the trees, and that post-harvest application is not required to maintain a sufficient nitrogen balance in the trees.

As reported last milestone, the team carried out a survey of soil characteristics, soil quality and water retention at eight apple growing sites in Victoria, nine sites in South Australia, nine sites in NSW, and five sites in Tasmania. The work is now complete. Site reports were prepared for each orchard tested, revealing substantial variation across regions in factors including water holding capacity, levels of organic carbon and cation exchange capacity (which reflects the soil’s ability to retain and supply nutrients). For each of the sites, the team suggested ways to improve the soil, which often included recommendations to add compost, mulch or lime, improve drainage or grow living mulch.

Additionally, the team validated the research model on young apple trees and presented the data at a conference in Italy.   

The new data on nitrogen, tree water use and soil characteristics will be added into the dataset to strengthen the accuracy of the SPASMO model. This will make the grower decision support tool, SINATA (which is based on the research model) more useful.

Now that the soil characterisation, nitrogen use and tree water use datasets are complete, next steps for SINATA are to add climate data from all Australian growing regions, and import phenology (development) and yield data from Orchard Net.

SINATA will then be ready for roll out once a user manual is developed. Keep an eye out for an announcement in industry news.

ACT NOW

The team has been continuing various avenues of research, which means they’re developing a significantly better understanding of nitrogen and irrigation management and use as they work towards underpinning predictive tools.

  • Soil samples have been taken from each major apple growing region and analysis is underway. This soil data will underpin the SPASMO model for predicting tree water and nitrogen use and make it useful across growing regions.

  • Soil mineralisation analysis using soil from a field site in Plenty in Victoria has begun, which will add more information to the nitrogenbudget for apple orcharding that the team is developing.

  • The first season’s fertigation trial usingnitrogen fertiliser (enriched with isotope nitrogen-15 for tracing) has finished and results will add accuracy to the nitrogen-use models under development.

  • At winter dormancy in July 2018, 16 apple trees previously treated with fertiliser were excavated for analysis. This will allow the team to see how nitrogen moves from soil into a tree’s storage organs.

  • Two avenues of research have begun to find out how much contribution plant litter makes to nitrogen soil levels when it decays, and how that varies with factors including particular soil microbial communities.

In mid-2017, the project established a new fertigation trial on a commercial orchard at Plenty in Tasmania’s Derwent Valley to contribute to this work. In the trial, the researchers are using a nitrogen fertiliser enriched with isotope nitrogen-15, which is allowing them to trace the fate of the applied nitrogen through the trees, under different application timings. Through the trial, the team is undertaking productivity and fruit quality assessments, while also looking at nitrogen use and efficiency, and comparing the efficiency of uptake between pre- and post-harvest nitrogen application. The first season of assessments has now been completed, and data is being analysed.

The researchers have also been working to characterise soils in each of the major apple-growing regions of Australia. At the time of writing, sampling had recently taken place in South Australia, with the data being used to underpin the SPASMO model.

Most recently, the project has been establishing new trials in a commercial apple orchard to track the fate of nitrogen within the tree-soil system, under different nitrogen application timings. In pot-based, preliminary work in this area, the researchers found nitrogen-use efficiency is strongly influenced by application timing. This new work is described in this short article from the industry’s levy-funded communications program.

The project is also continuing one of the longest-running irrigation/fertiliser trials in an Australian apple orchard, if not globally. Among observations recently reported, there is a cumulative effect of multi-season nitrogen application being seen, with fruit colour more pronounced in the 2016/17 season than all other years in the five-year trial.

These are just some of the number of activities under this project working towards the common goal of validating SPASMO and developing SINATA. 

The first season of trials for this project, taking place in Lucaston, Tasmania, are now complete – representing the fourth year of study in this area, including the work of previous project Precision fertigation for improved apple orchard productivity (AP12006).

The researchers have reported that current season nitrogen lifted fruit nitrogen content significantly, which decreased firmness. They did not observe colour difference associated with nitrogen treatments, which highlighted the role of climate variability on fruit colour development. Data from this season will be compiled with previous fruit quality and yield data to parameterise the ‘plant’ component of the model for tree-crop monitoring tool SPASMO. A methodology has also been developed for detailed soil characterisation, which will be used to parametrise the ‘soil’ component of SPASMO.

Related levy funds
Details

This project is a strategic levy investment in the Hort Innovation Apple and Pear Fund