Health & Environmental Research Online (HERO)


Print Feedback Export to File
3366585 
Journal Article 
Release and migration of colloidal phosphorus from a typical agricultural field under long-term phosphorus fertilization in southeastern China 
Liang, X; Jin, Yi; Zhao, Yue; Wang, Z; Yin, R; Tian, G 
2016 
Yes 
Journal of Soils and Sediments
ISSN: 1439-0108
EISSN: 1614-7480 
16 
3 
842-853 
WOS:000370958100011 
Colloid-facilitated migration of phosphorus (P) is a widely accepted phenomenon in surface and subsurface environment. Release and migration of colloidal P (P-coll) in agricultural fields are closely related to P fertilization regimes. In this study, a site-specific experiment with rice/oilseed rape rotation was conducted to determine the export potential of P-coll from the field and literatures reporting the impact of P fertilization regimes on release and migration of P-coll in other agricultural fields were compared.



In this 2-year field experiment, four P fertilization regimes (no fertilizer control, inorganic P fertilizer of low and high rates, and swine manure treatment) with three replicates were conducted. Floodwater and runoff samples were collected in flooding season and the 100-cm-depth soil samples were collected after both crops' harvest seasons. Colloidal particles were separated by microfiltration and ultracentrifugation processes and determined gravimetrically. The P-coll value was calculated as the difference between the concentration of total P in non-ultracentrifuged and ultracentrifuged samples. The same method was applied for the colloidal mineral elements (Fe and Al) and organic carbon.



Total P concentration in paddy floodwater significantly increased after fertilization but decreased quickly in the following days, maintaining at 6.0 mg m(-2). In soil extracts, concentration of P-coll was low but stable, which ranged from 6 to 22 % of total P after oilseed rape season and from 7 to 18 % after rice season. In runoff samples, there were positive correlations between P-coll, colloidal Fe (Fe-coll), colloidal Al (Al-coll), and colloidal TOC (TOCcoll); the majority of P forms was molybdate reactive P. In both crops' seasons, the amount of colloids increased with soil depth. Content of soil P-coll was low and occupied 0.1-2 % of total P. The literature review showed that P-coll in soil solution, runoff, and leachate ranged from 1.4 to 94 % of total P.



These results suggested that although the concentrations of P-coll were not high, they widely distributed in paddy floodwater, runoff, and soil profile. Fertilization regimes and planting systems had a significant influence on the contents of P-coll. Moreover, the P-coll binding with Fe/Al minerals and organic carbon might be an alternative route of P loss in paddy field. 
Colloidal phosphorus; Paddy field; Phosphorus fertilization; Runoff; Soil profile