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

Citation

Jiang, X., Amelung, W., Cade-Menun, B.J., Bol, R., Willbold, S., Cao, Z., Klumpp, E. (2017). Soil organic phosphorus transformations during 2000 years of paddy-rice and non-paddy management in the Yangtze River Delta, China, 7(1), http://dx.doi.org/10.1038/s41598-017-10071-0

Plain language summary

Phosphorus is an essential element for agriculture, and soil phosphorus forms and concentrations will change over time with soil development. This study examined soils from a 2000-year chronosequence of a rice-wheat rotation in China, and compared them to an adjacent 700-year chronosequence without rice paddies. Soil phosphorus composition became stable after 194 years with rice paddies, and after 144 years without rice paddies, suggesting that phosphorus dynamics reached an equilibrium in these man-made soils after less than two centuries.

Abstract

The contents and properties of soil organic phosphorus (P ) largely drive ecosystem productivity with increasing development of natural soil. We hypothesized that soil P 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 composition using solution P-NMR after NaOH-EDTA extraction. Land reclamation promoted P 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 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 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 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. o o o o o o o 31

Publication date

2017-12-01

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