Project investigates deep P potential

With declining fertility combined with the rising cost of P-based fertilisers a major concern for growers across the country, growers will be intrigued to learn about the research, which has found yield gains of more than 10 per cent from deep banding.

The long-term research has found that deep banding, defined as placing the fertiliser at a depth of between 10 and 30cm below the surface in concentrated bands, boosted yields in some instances in trials in southern and central Queensland by more than 10pc compared to traditional surface applications alone.

The next step is to research the most economically beneficial deep phosphorus-banding methods, and how long the residual benefits of deep banding last.

David Lester, principal research scientist, crop improvement research, development and extension at DAF said the work was important both economically and environmentally.

"Phosphorus is a finite resource, so making sure it is placed in the soil optimally for plant recovery is important," Dr Lester said.

He said generating more biomass had important environmental benefits.

"Better crops can mean better ground cover with more carbon that decreases runoff, allowing farmers to save money and improve the health of our waterways," he said.

GRDC grower relations manager Rebecca Raymond said the joint project is part of a long-term, multi-million dollar investment by GRDC looking into fertiliser efficiency and how to get the best returns across a range of diverse soil types.

"GRDC has invested more than $6 million to date into this research to improve our understanding of phosphorous fertiliser use efficiency and assess how grain growers can maximise their use of this input in different soil types, for different crops, at different rates and levels to determine the genuine return on investment at a farm-level," Ms Raymond said.

"We are also investing in additional research to investigate where phosphorus fertiliser goes and what agronomic practices effect its uptake."

Nine new research sites from Condamine in the east, Roma in the north, and Mungindi in the south have been established, and large plots will allow growers to measure yield responses at harvest, mirroring commercial scale farming operations.

Smaller plots will be used to experiment with different fertiliser intensities and spacing between banding, and how various environments might interact with these regimes.

A separate complementary project with plots at Capella, Jimbour West, Goondiwindi, Condamine, and west of Roma, will analyse the long-term residual benefits of deep phosphorus-banding.

This work will build on more than 11 years of research by DAF, GRDC and the University of Queensland, and apply those learnings at a broadacre scale.

The background for the project goes back over a decade, with the first deep banded phosphorus plots established at these sites between 2013 and 2016.

Researchers will re-assess these sites to determine the residual benefits of banding six to ten years after application.

A key aim of the project is to find the most efficient depth that provides most nutrition to the plant while at the same time reduces the risk of nutrient leeching via run-off.