Soil Quality Evolution in Coastal Reclamation Zones:A Case Study of Rudong County of Jiangsu Province
Wang Qiqi;Pu Lijie;Zhu Ming;Li Jianguo;Zhang Meng;School of Geographic and Oceanographic Sciences, Nanjing University;The Key Laboratory of the Coastal Zone Exploitation and Protection, Ministry of Land and Resources;
Reclaiming coastal wetlands for cultivate lands transformed the wetland soil to agricultural soil, soil properties changed a lot. To explore the effects of soil ecological environment due to the reclamation activities in coastal zone and determine the key modified factors, it can provide guidance for soil improvement. In this article, soil samples collected from reclamation area under different years and tidal flats in Rudong Country of Jiangsu Province were analyzed. ANOVA was used to test the difference among soil indicators in different reclamation area(LSD test). The method of soil quality index(SQI) is used to evaluate the soil quality. The model of limiting factors diagnosis is used to analyze the key improvement factors of soil quality. The result shows that since 60 years from reclamation, the trajectory of soil quality change in study area is"improve sharply-relative stability-improve sustainability". SQI increased sharply from 0.19 to 0.37 at the first 10 years after reclamation, average annual rate of growth is 11.84%,the difference is significant; SQI increased from 0.37 to 0.42 between 10 years to 30 years after reclamation and average annual rate of growth is 0.54%; SQI increased from0.42 to 0.45 between 30 years to 40 years after reclamation and average annual rate of growth is 0.71%, there has no obvious difference. Therefore soil quality is in a relatively stable state after reclamation at 30 years.While SQI increased sustainability from 0.45 to 0.56 between 40 years to 60 years after reclamation and average annual rate of growth is 1.22%, the difference is significant. The limiting factors diagnosis showed that the lower TOC, TN and clay content are the major limiting factors of soil quality and have significant negative correlation with p H and salt, therefore decreased salinization is the basic reason for improving soil quality after reclamation. The improvement of fertility as well as soil texture are the key to further improve soil quality.