Utilization of labelled mineral and organic phosphorus sources by grasses common to semi-arid mulga shrublands [south-west Queensland]
1993
Armstrong, R.D. (Queensland Dept. of Primary Industries, Emerald (Australia)) | Helyar, K.R. (New South Wales Agriculture, Wagga Wagga (Australia). Wagga Agriculture Research Inst.)
The uptake of 3 sparingly soluble sources of mineral P (amorphous FePO4, crystalline FePO4 (strengite), and amorphous AlPO4) was compared with that of a soluble P source, KH2PO4, over 34 days. All P sources were uniformly labelled with 32P. For the 4 grasses studied (Cenchrus ciliaris, Aristida armata, Digitaria ammophila and Thridolepis mitchelliana), the addition of strengite produced the lowest yields and plant P content, followed by FePO4, and then AlPO4 and KH2PO4. Recovery of the labelled P by the grasses was in the order: strengite less than FePO4 less than AlPO4 less than KH2PO4. C. ciliaris recovered more of the added strengite, but less FePO4 and AlPO4, than the other grasses. Where soil treatments were the same, there was no evidence that these species differed in their ability to utilize sparingly soluble sources of mineral P. The reutilization of P from 32P labelled plant residues by 2 grasses was examined in a second experiment. The net release of P from the residues was significantly increased in the presence of plants but was not affected by the species present. D. ammorphila and A. armata obtained similar proportions of their P content from the added residues (6.6 percent).
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