Deep phosphorus research

Department of Agriculture and Fisheries principal research scientist Dr David Lester. Picture: DEPARTMENT OF AGRICULTURE AND FISHERIES.

Understanding how to maximise the efficiency of phosphorus fertiliser use is becoming more important than ever as the fertility of Queensland grain-cropping soils diminishes

Long-term research has found that deep banding — applying phosphorus between 10 and 30 centimetres below the soil surface in concentrated bands — boosted yield for some central and southern Queensland grain growers by more than 10 per cent compared to surface application alone.

Now, the Queensland Department of Agriculture and Fisheries (DAF) and the Grains Research and Development Corporation (GRDC) are taking the research a step further.

DAF is conducting research projects that investigate the most economically beneficial deep phosphorus-banding methods and how long the residual benefits of deep banding last.

The work is part of long-term, multi-million dollar GRDC investment on behalf of Australian grain growers to understand phosphorous fertiliser use efficiency, its behaviour in different soil types, its residual benefits and, importantly, the economic returns on-farm.

Nine new research sites from Condamine in the east, Roma in the north and Mungindi in the south have been established, with large plots allowing 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.

Deep-banded phosphorus plots were established at these sites between 2013 and 2016.

Researchers will re-assess these sites to determine the residual benefits of banding six to 10 years after application.

This data can then be fed back into cost-benefit analyses based on the amount of fertiliser applied and the timeframe until reapplication is required.

This research aims to maximise the efficiency of phosphorus fertiliser use and thus return on investment for grain growers by locating it at the most ideal depth in the soil for crop uptake, which also significantly reduces the risk of runoff.

Dr David Lester, principal research scientist, Crop Improvement RD&E, Department of Agriculture and Fisheries said this important research could help Queensland grain farmers increase their crop yields, as well as soil and water productivity.

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

“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.”

GRDC grower relations manager Rebecca Raymond said GRDC had invested more than $6 million to date into this research to improve understanding of phosphorous fertiliser use efficiency.

“(We) 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,” she said.

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

“It is important these key research learnings are validated and tested at a farm level in different environments, so we can understand the cost benefits for growers.”