| Tidal flat wetland is one of the most important ecological type in the coastal region,where the quantity and category of resources are rich,and it has important ecological value.In the case of the current problems between people and land are becoming increasingly prominent contradiction,the tidal flat reclamation has become one of the most important measures to expand homeland space and increase the reserve land resources for some coastal countries and regions.Jiangsu Province has the coastline of 954 km,and it is rich in resources and has a large tidal silt growth potential,and the reclamation of tidal flat in Jiangsu Province has a long history.Tidal flat reclamation has promoted the social and economic development of Jiangsu Province,and alleviated the contradiction between people maintain homeostasis and other aspects of the province’s arable land has brought great effect.But large-scale transformation reclamation activities on this fragile ecological zone bring a more profound impact.With Jiangsu Province coastal development as a national strategy,the extent of beach reclamation will be further intensified,and increasingly complex environmental problems will occur in the tidal flat reclamation,especially affecting the soil environment during the process of use the reclamation.According to the beach reclamation plan,the agricultural development is the most important advantage land use type of the new reclaimed land.The soil quality is an important factor that affecting agricultural output,and soil nutrient status is an important measure of soil quality.Thus,soil environmental study on soil nutrients in the reclamation process changes in this typical beach reclamation area of Jiangsu Province will improve the efficiency of land use reclamation and provides an important basis for the foundation.In this paper,two regional scales of Rudong tidal flat reclamation zone was chosen as the study area,and the whole reclamation area and divided units reclamation zone with different years.Then this paper discussed the overall soil nutrient content distribution of the whole tidal flat reclamation zone.Secondly,taking the reclaim years as characteristic scale,soil nutrient content of surface and profile distribution of each divided zone was analyzed;Based on the "quantity" study of soil nutrients,further research was about the correlation between difFerent soil properties and its changes,including the relationship between soil pH,particle size and organic matter and the main nutrients content,to reveal the spatial distribution of soil nutrients and rendering time-varying conditions in tidal flat reclamation process,the main results are as follows:Firstly,taking the Rudong tidal flat reclamation area as a whole for the study,the descriptive statistical analysis of soil pH and nutrient content reveals the distribution of soil nutrients,main findings show that the soil is alkaline to weakly alkaline.The soil nutrient content is low in general.Except for potassium and available phosphorus,other nutrients are below the average content of Rudong County.Secondly,each tidal flat reclamation zone is characterized by reclamation years,select the reclamation zone of 10 years,20 years,40 years,50 years,60 years of reclamation area for the study,with theory of space for time to explore ways of thinking in the tidal flat area the main nutrients content changes in the surface soil during the reclamation process,studies have shown that with increasing age of reclamation,decreased soil pH,alkaline soil gradually becomes weak alkaline;soil organic matter,total nitrogen,total phosphorus,total potassium and presents the overall increasing trend nitrogen,and available phosphorus showed obvious fluctuation,the overall content is increased,while soil available K is decreased.These V results show that during the process of reclamation utilization of tidal flats,through a series of farming and improvement measures,the soil fertility has a certain improvementThirdly,at different times in the inning reclamation in five samples were selected to study the typical profile distribution of soil nutrients,the results showed that soil organic matter,total nitrogen,available nitrogen content of the surface will be higher than in the middle layer or the bottom,showing obvious the surface agglomeration,while other nutrients don’t performance obvious surface aggregation.Total potassium and available potassium large differences between the layers,and the volatility is higher than the soil pH and other nutrients,especially in the most dramatic fluctuations in available potassium;total phosphorus and available phosphorus content has the smaller difference in the layers.Fourthly,on the basis of soil nutrients study further exploration about relationship between attributes and the main differences between the different age reclamation,the study showed that:with a long time reclamation,relationship between soil pH and nutrient is closer to the results of general tillage soil,but in a shorter life reclamation,the cultivated soil between mature and there are obvious differences.At different stages of reclamation,soil gravel,silt and clay composition of each has a certain impact on soil nutrients,and this effect has also some differences between different nutrients.In general,at the beginning of the reclamation,mainly sand effect is obvious on the nutrient distribution,and along with the increasing length of reclamation,particle size smaller silt and clay,respectively larger influence on the distribution of soil nutrient content.Dependencies organic matter and nitrogen(total nitrogen and available nitrogen)is greater than the relationship between organic matter and phosphorus,potassium.It shows that at the beginning of the reclamation,soil nutrient content was less from the decomposition of organic material mineralization,to a certain extent it was from the inorganic composition of soil minerals,but after a fixed number years of some agricultural measures,the soil properties change,the proportion of the soil nutrient content come from organic matter mineralization increases.ⅥLastly,canonical correlation analysis method was applied to determine the relationship between soil pH,particle size,organic matter and total and available N、P、K content.This method can distinguish between the different variables.The results show that there is negative correlation between soil pH and total nitrogen,alkali solution nitrogen,total phosphorus content while there is positive correlation between soil organic matter and total nitrogen,alkali solution nitrogen,total phosphorus.The particle size index is higher related with soil total potassium than other N、P、K nutrients. |
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