NEW DGT Phosphorus Test
GRDC trials have shown the DGT-PTM test to be more accurate and reliable for assessing
phosphorus availability to crops than any currently used method.
(DGT-P is a trademark of DGT-P Limited)
The GRDC is keen to see the DGT test become the standard phosphorus test Australia wide and it is already calibrated for wheat, barley, peas, chick peas and canola.
After a successful trial during 2012, APAL analysed more than 500 samples from around Australia and will now continue to offer the test as it becomes fully commercialised during 2013.
The DGT phosphorus test (from Diffusive Gradients in Thin films) has been developed by Dr Sean Mason of Adelaide University who has had a long association with APAL. The test mimics plant roots in the way they remove phosphorus from the soil solution and is not influenced by soil type.
The extracting solutions used in other phosphorus methods like Colwell and Olsen, can sometimes solubilise P that is not plant available and therefore over estimate the amount available to the crop. This can occur in a broad range of soil types including both calcareous (alkaline) and acidic. Even when adjusted with PBI, the current tests fail to predict crop response to phosphorus in a high percentage of situations.
The test involves placing a DGT device in direct contact with soil that has been brought to the point of saturation. The device contains a ferrihydrite gel that binds phosphorus diffusing towards it over a period of time and the gel is then analysed.
In extensive, replicated P response trials across southern Australia from 2006 to 2010, the DGT results have been correlated very closely to the phosphorus response curve in a way that no other testing method can match.
In the trials crop response to phosphorus was correctly predicted:
DGT in 91% of sites
Colwell with PBI interpretation in only 67% of sites
This shows that we may be making incorrect fertiliser decisions for 1 test in every 3 using Colwell/PB
APAL DGT P OPTIONS:
(1) APAL Premium Soil Test + DGT P
Premium Soil Test ($110) + DGT P ($20) = $130+GST/sample
APAL comprehensive soil analysis with DGT in addition
(2) Individual DGT + Colwell/Olsen tests$47+GST/sample
Send in any number of samples and we will test them for DGT plus either Colwell or Olsen P.
Download Submission Forms here:
Farmer / Producer
Premium Soil Test + DGT submission form
DGT + Colwell / Olsen submission form
CONSULTANT / AGENT
Premium Soil Test + DGT submission form
DGT + Colwell / Olsen submission form
For more comprehensive information, download the APAL Webinar with Dr Mason recorded on 28th March 2012 Click here