From stubble to crop – transfer of phosphorus investigated

Date: 23 Jul 2012

Sarah Noack

Studies funded by the Grains Research and Development Corporation (GRDC) are investigating whether crop stubbles offer useful amounts of phosphorus (P) to plants during the growing season.

The research is being conducted by the University of Adelaide which plans to develop a better understanding of how P is released from stubble and then taken up by subsequent crops.

Research student Sarah Noack says a key fertiliser management consideration for growers is just how much P will stubbles supply and when will this P be available to plants during the growing season.

“Many previous studies suggest that the timing and quantities of P release vary and are not well explained by the total amount of P in the residues,” Ms Noack said.

“Stubble type, size, placement and moisture all can significantly influence the timing and amount of P released from stubbles to the soil.

“Our research aims to better identify P forms in crop stubble, understand how these forms influence P release and breakdown from stubble and thereby provide a better estimation of the contribution stubble P makes to subsequent crop P uptake.”

crop stubbleSpeaking at a GRDC grains research Update, Ms Noack said phosphorus within the stubble can be released directly to the soil as soluble P (where it can be used immediately by the crop or chemically fixed onto the soil) or be absorbed by micro-organisms which can be later released back into the soil.

She said the chemical composition of crop stubble plays an important role in the rate of nutrient release and that the presence of different chemical P forms in the stubble is likely to influence the proportion of P that undergoes direct release or microbial uptake and decomposition.

Current studies are looking at just how much stubble P is released directly or incorporated into the microbial P pool and subsequently released under paddock conditions.

An experiment has also been established in a paddock at Karoonda in South Australia to measure P release during summer rainfall events, and a current glasshouse experiment aims to determine how stubble placement (surface and incorporated) and size influence the release of stubble P and uptake by a crop.


ENDS

Caption: University of Adelaide research student Sarah Noack is involved in a study which plans to develop a better understanding of how P is released from stubble and then taken up by subsequent crops. Image courtesy University of Adelaide

Caption: Studies funded by the GRDC are investigating whether crop stubbles offer useful amounts of phosphorus to plants during the growing season. Image courtesy Sarah Noack

GRDC Project Code: DAV00095

Media releases and other media products can be found at www.grdc.com.au/media


For further information: Sarah Noack, University of Adelaide
Phone 0420 218 420

Contact: Sharon Watt
Porter Novelli
0409 675100

GRDC Project Code DAV00095

Region South, North, West