%0 Journal Article
%T Sources and Pathways of Formation of Recalcitrant and Residual Phosphorus in an Agricultural Soil
%A Deb P. Jaisi
%A Mark Bowden
%A Sunendra R. Joshi
%A Wei Li
%J -
%D 2018
%R https://doi.org/10.3390/soilsystems2030045
%X Abstract Phosphorus (P) is an essential nutrient for sustaining life and agricultural production. Transformation of readily available P into forms that are unavailable to plants adds costs to P replenishment, which eventually translates into lower agronomic benefits and potential loss of soil P into runoff may degrade water quality. Therefore, understanding the sources and pathways of the formation of residual P pools in soils is useful information needed for the development of any technological or management efforts to minimize or inhibit the formation of such P pool and thus maximize availability to plants. In this research, we paired phosphate oxygen isotope ratios (¦Ä 18O P) with solid-state 31P NMR and quantitative XRD techniques along with general soil chemistry methods to identify the precipitation pathways of acid-extracted inorganic P (P i) pools in an agricultural soil. Based on the comparison of isotope values of 0.5 mol L £¿1 NaOH-P i, 1 mol L £¿1 HCl-P i, and 10 mol L £¿1 HNO 3-P i pools and correlations of associated elements (Ca, Fe, and Al) in these pools, the HNO 3-P i pool appears most likely to be transformed from the NaOH-P i pool. A narrow range of isotope values of acid-P i pools in shallow (tilling depth) and below (where physical mixing is absent) is intriguing but likely suggests leaching of particle-bound P in deeper soils. Overall, these findings provide an improved understanding of the sources, transport, and transformation of acid-P i pools in agricultural soils and further insights into the buildup of legacy P in soils. View Full-Tex
%K phosphate
%K oxygen isotopes
%K solid-state NMR
%K XRD
%K soil-P pools
%K transformation
%U https://www.mdpi.com/2571-8789/2/3/45