The influence of the season and rotation on interactions between soil pH and phosphorus availability to crops will be the focus of a series of new trials in the central wheatbelt over the next four years.
A significant, but preliminary, finding of research carried out as part of this project at the research station Wongan Hills in 2012 found a history of lime application significantly increased soil pH, phosphorus uptake by crops and grain yields.
Through the GRDC-funded ‘More Profit from Crop Nutrition Initiative’ program, Department of Agriculture and Food, Western Australia (DAFWA), researchers found a strong grain yield response to past lime applications and phosphorus uptake in year one of the trials.
DAFWA research officer Dr Craig Scanlan says although it is early days, the results indicate soil pH should be considered in fertiliser regimes and recommendations.
- Lime history and crop rotation affect soil phosphorus availability
- Lime applications can lift soil pH, phosphorus uptake and grain yields
- Soil pH should be considered in fertiliser regimes
He says the 2012 trials showed phosphorus uptake and grain yields were significantly higher in plots where lime had been previously applied.
The highest-yielding plots of 2.2 tonnes per hectare were achieved where lime was applied in 2009 at 3.5t/ha and then sown with lupins, followed by wheat in 2010, 2011 and 2012.
The plots sown continuously with wheat between 2009 and 2012 that had lime applied at 3.5t/ha in 2009 produced an average crop yield of 2t/ha.
The plots with no lime history and a lupin, wheat rotation yielded an average 1.68t/ha and the no lime, continuous wheat plots had an average yield of 1.69t/ha.
DAFWA researcher Dr Craig Scanlan.
Dr Scanlan says response to the application of an extra 10 and 20kg/ha of phosphorus in the trial was only seen in the plots that had been limed. He says grain yield was best explained by crop biomass at flowering, indicating that the response to phosphorus availability had occurred early in the season.
These preliminary findings point to lime history having a greater impact than rotation history on soil phosphorus availability and wheat yields.
Yield potential in the trials was higher where lime was applied, regardless of the rotation. It also appears fertiliser phosphorus may be used more effectively where lime has been applied in the past, although more research is needed in this area.
Importantly, researchers found that wheat plant biomass increased and ryegrass biomass dropped in plots where lime had been previously applied and phosphorus rates of five, 10 and 20kg/ha were used.
Dr Scanlan presented the preliminary findings from this project to the 2013 Agribusiness Crop Updates in February. He says further trials are planned to 2015 to continue investigating seasonal and rotation influences on soil pH and phosphorus interaction.
Dr Craig Scanlan, DAFWA
08 9690 2174
See 2013 Agribusiness Crop Updates Paper at www.grdc.com.au/UpdatePapers
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