https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:41068 2SO₄-H₂O₂ digested) was the dominant P fraction (37–51% of total P) in the aerobic soil under wheat, while it was decreased by 18–27% in flooded soil under rice cultivation. In contrast, the sparingly soluble Ca-bound P (HCl-Pi) increased from 25–31% under wheat cultivation to 41–50% under flooded rice (paddy) cultivation where reducing conditions are expected to prevail under submerged paddy soil conditions. The crop rotation not only altered the sparingly available P fraction but also influenced soil labile P, especially the organic P form. Compared with the rice soil, a 4-fold increase in the labile P fraction (NaHCO₃-Po) was observed in wheat soil. The moderately labile P fraction (NaOH-extractable) showed a similar trend to that of labile P pool, but the increased NaOH-Po in wheat soil was relatively small. The relatively rapid change in the residual P fraction was attributed to oxidation-reduction cycles of Fe oxides between flooded (rice) and aerobic (wheat) soil conditions. Conclusions: Wetting and drying cycles associated with a rice-wheat crop rotation promoted the transformation of the sparingly soluble soil P fraction between crops, which was attributed to changes in soil redox conditions, particularly Fe cycling. This indicated that the rice-wheat crop rotation can draw upon the sparingly soluble P fraction for crop production, thus relying less on fertilizer-applied P.]]> Wed 28 Feb 2024 14:57:36 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32948 Thu 16 Aug 2018 13:28:52 AEST ]]>