Results from the 2016 GRDC Farm Practice surveys has shown that soil sampling by growers is down 50 per cent compared to eight years ago.
This is a reduction from 40 per cent of cropped area in the southern region in 2008, to only 15 per cent of cropped area in the southern region in 2016.
What is concerning about this statistic is the known understanding that soil testing can assist in efficiencies for fertiliser use, with fertiliser accounting for about a third of production costs.
BCG fertiliser rate and timing trials at Curyo in 2017 showed that having an understanding of existing nutrient reserves will assist in more effective nutrient application.
“Phosphorus (P) deficiencies are difficult to correct after sowing and soil testing is an effective way to estimate soil P supply and ensure P is applied at an appropriate rate,” explained BCG project manager Louisa Ferrier.
Five different P rates were investigated in this barley trial with results showing that while visual differences occurred in incidents there was no efficiency in additional P application.
Ms Ferrier explained that “despite significant responses to P observed in NDVI up to mid-stem elongation, there was no additional benefit to applying more than 6kg P/ha, the equivalent of 27kg/ha of MAP at $650t ($17/ha for 6kg P/ha).”
And while there are financial implications of over supplying, results from the trial also showed that there are possible negative consequences apart from yield by undersupplying.
“There may be implications for a 7-10 day lagging maturity observed in the 0kg P/ha rate treatment. The impact of this on the cropping program probably depends on the issues at hand, if the crop is early, a delay may reduce frost risk, on the other hand if heat is a concern, low P status may increase risk heat stress.”
So, as we head into the 2018 cropping season growers are reminded that having a good understanding of nutrient reserves in paddocks can be very beneficial for production and profitability purposes.
For more fertiliser rate and timing trial results visit the BCG website; www.bcg.org.au. Alternatively, BCG is offering a soil sampling service, call the office on 03 5492 2787 to find out more and book in paddocks.
This article was published in the Stock and Land, 22 March.
