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|Title:||The form and fate of stubble phosphorus in cropping soils|
|Citation:||Proceedings of 16th Australian Agronomy Conference 2012, 2012 / Yunusa, I. (ed./s), pp.1-6|
|Publisher:||Regional Institute Online Publishing|
|Conference Name:||16th Agronomy Conference 2012: Capturing Opportunities and Overcoming Obstacles in Australian Agronomy (14 Oct 2012 - 18 Oct 2012 : Armidale, NSW)|
|Sarah Noack, Mike McLaughlin, Ronald Smernik, Therese McBeath, and Roger Armstrong|
|Abstract:||Phosphorus (P) within stubble can be released directly to soil as soluble P or assimilated by microorganisms and subsequently released back into the soil through mineralisation. The chemical composition of P in crop stubble may play an important role in the rate of stubble P release. Crop stubble sampled after grain maturity in 2010/11 and 2011/12 contained 1-5 kg P/ha. Nuclear magnetic resonance (NMR) spectroscopy was used to determine the different forms of P present in the stubble. On average 50% of the total stubble P was orthophosphate which is water soluble and readily available to plants and microorganisms. The remaining P forms were identified as phospholipids, ribonucleic acid (RNA) and pyrophosphate. The majority (65-90%) of P in the major stubble component (stems) was water-soluble, and most of this was detected as orthophosphate. However, this includes organic P forms that may have been hydrolysed during the water extraction. Results from a field leaching experiment show between 0 and 7.5% of stubble P was released from 52 mm (collected after 11 mm and 41.4 mm) of summer rainfall. That indicated crop stubbles in the field release some P into soil solution which could be readily accessed by plant roots. However, the slower release of stubble P in the field compared to the laboratory suggests that residues potentially play a more important role as a long term P supply to subsequent crops. Subsequent experimentation will measure the contribution of surface applied and incorporated stubble P to crop plant P nutrition using 33P isotopic techniques.|
|Keywords:||Crop residues; speciation; nutrient cycling|
|Rights:||Copyright status unknown|
|Appears in Collections:||Agriculture, Food and Wine publications|
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