Growers looking to refine their fertiliser strategy are encouraged to use test strips this season to help determine what nutrients are lacking and how much is required.

And, to help growers with this, GRDC has recently published a new factsheet which outlines how to set up fertiliser test strips and use the data generated to make fertiliser decisions.

Fertiliser test strips are sections of a paddock which are set up to compare the impact of different rates of nutrient on crop growth and yield.

Agronomy Solutions Director Sean Mason, who is leading the GRDC investment Using soil and plant testing data to better inform nutrient management and optimise fertiliser investments for grain growers in the southern region, says the use of pre-season soil testing results from within paddock zones together with test strips can fine-tune fertiliser recommendations and ensure growers are getting the most bang for their fertiliser buck.

“Application rates can be estimated using pre-season soil testing results from within paddock zones and then test strips can verify the effectiveness of those rates and whether in-season applications of fertiliser are warranted,” he says.

“Often the fertiliser rate used by the grower in the paddock is compared to a strip where fertiliser is applied at a higher rate or a strip with low to no levels of nutrient applied.”

Dr Mason says test strips can be used for any nutrient, however nitrogen test strips are the most common and can help growers to decide on top-up rates during the season.

“For nutrients only applied at sowing, such as phosphorus and zinc, test strips can gauge the effectiveness of the seeding application and whether any adjustments to fertiliser use need to occur for future crops,” he says.

Fertiliser strip trials established in different zones in the paddock can help growers and advisers understand what is limiting crop growth and yield. Photo: Establishing Test Strips video, GRDC

Comparing responses in fertiliser strips between different zones in the paddock can help growers and advisers understand what is limiting crop growth and yield.

“If the crop in the high rate of fertiliser strip looks better than grower rate, then increasing the application rate of that nutrient may boost crop performance, provided soil moisture is sufficient,” Dr Mason says.

“If plants in the high or low-rate strips are responding the same as those in the grower rate strip, decreasing rates may save money.

“It is important to remember that other factors such as soil constraints like acidity or compaction need to be considered, as they may be limiting growth and the response to fertiliser.”

Growers seeking more information about implementing and interpreting fertiliser test strips can refer to the Establishing Test Strips video found in the GRDC Best Practice Soil Testing Video Series.

The GRDC Using test strips to fine-tune fertiliser recommendations fact sheet can be found on the GRDC website.