Effect of Long-Term Reclamation on Soil Properties on a Coastal Plain, Southeast China

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Abstract

The coastal plain of Cixi City, in southeast China, has experienced more than a thousand years of land reclamation history. Since 1047, 11 dikes have been built, dividing our study region into 11 zones. The main aim of this study was to evaluate the effects of long-term reclamation on the variability of soil properties. Using an integrated transect and nested sampling approach, a total of 329 surface soil samples were collected. Soil pH, organic matter, electrical conductivity, and particle size distribution were measured. Data were evaluated using classical statistics and geostatistics methods. Results indicate that reclamation exerted quantifiable effects on various soil attributes. There were significant differences in soil properties among the zones. The ranges in semivariograms were approximately equal to or twice the average zone span, suggesting that there was usually a break in continuity of soil properties at the boundary of reclamation zones. As illustrated by the lower nugget effect or larger range distance in semivariograms, soil pH, electrical conductivity, and organic matter similarly showed more continuous patterns in space compared with particle size distribution. With the increase of time since reclamation, salt content, alkalinity, and particle size tended to decrease, while organic matter content tended to increase. Most properties varied greatly in the initial reclamation stages. A relatively steady state was reached within 10 years following the reclamation for pH, about 30 years for organic matter, and 60 years for electrical conductivity, respectively. Further, similar land uses and parent materials produced similar inherent soil properties. These findings can be applied to broader spatial scales in other coastal regions to assist in transitioning from a coastal tidal plain to productive agricultural land, through reclamation, and targeted land management practices.

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