The use of chronosequences in studies of paddy soil evolution: A review

摘要: article i nfo Chronosequencesand associated space-for-time substitutionsare animportant and fruitful means for investigat- ing the rates directions of soil ecosystem evolution across multiple time-scales ranging from decades to millions years. Thispaperreviews useof chronosequencesfor studying biogeochemistry paddy evo- lution improve our understanding fundamental processes, dynamic changes in properties associatedenvironmentalthresholdsatdifferentstagesofpaddysoilevolutionundertheintensiveanthropo- genic managements. Rice cultivation results accumulations various nutrients (e.g. organic carbon, ni- trogen, phosphorus) over a much longer time period than predicted by typical long-term (b50 years) field experiments, although it is not clear how long takes soils with different origins reach steady-state these important nutrients. Extensive investigations 2000-year chronosequence derived calcareous marine sediments coastal region Zhejiang Province (P.R. China) illustrate three phases pedogenic thresholds: an initial phase during first few dom- inated rapid desalinization, loss magnetic susceptibility, accumulation topsoil matter forma- tion compacted plow pan due extrinsic thresholds resulting anthropogenic activities; second phaselastsseveralcenturiescomprisingFeandclayenrichmentintheilluvialhorizon,andthelossofphosphorus