Soil organic phosphorus transformations during 2000 years of paddy-rice and non-paddy management in the Yangtze River Delta, China.

ABSTRACT: The contents and properties of soil organic phosphorus (P_o) largely drive ecosystem productivity with increasing development of natural soil. We hypothesized that soil P_o would initially increase with paddy management and then would persist under steady-state conditions. We analyzed soils from a 2000-year chronosequence of a rice-wheat rotation and an adjacent non-paddy 700-year chronosequence in Bay of Hangzhou (China) for their P_o composition using solution ³¹P-NMR after NaOH-EDTA extraction. Land reclamation promoted P_o accumulation in both paddy and non-paddy topsoils (depths???18?cm) until steady-state equilibria were reached within 200 years of land use. Greater P_o concentrations were found, however, in the non-paddy subsoils than in those under paddy management. Apparently, the formation of a dense paddy plough pan hindered long-term P_o accumulation in the paddy subsoil. The surface soils showed higher proportions of orthophosphate diesters under paddy than under non-paddy management, likely reflecting suppressed decomposition of crop residues despite elevated microbial P compounds stocks under anaerobic paddy-rice management. Intriguingly, the composition of P_o was remarkably stable after 194-years of paddy management and 144-years of non-paddy management, suggesting novel steady-state equilibria of P dynamics had been reached in these man-made ecosystems after less than two centuries.

SUBMITTER: Jiang X 

PROVIDER: S-EPMC5589726 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature