| As a kind of important reserve land resources,tidal flat area is of great development potential,especially under the background of the shortage of arable land resources and low quality of arable land in China.The mainly land-use type of tidal flat was reclamation in Jiangsu coastal area.As tide flat was reclaimed towards the sea constantly,the height of reclamation becomes lower and lower.Due to fast speed and large scale of tidal flat reclamation,reasonable utilization of these reclamation land becomes a difficult problem.Agriculture was always the main land type after tidal flat was reclaimed,but high soil salinity and low fertility will limit the exploitation of agricultural land efficiency.It is of great importance both in theoretical and practical meaning that to carry out studies on characteristics and evolution of reclamation soil.In this study,the reclamation area in the eastern area of Dafeng city was chosen as the study area.Changes in the particle size characteristics,pH,TN,TP,K and soil organic matter source with different reclamation age were analyzed in this paper.Some problems during the land-use of reclamation area were put forward.And some countermeasures on agricultural development and utilization of new reclamation areas were proposed.The main conclusions were listed as follows.1.Soil particle-size showed obvious changes in the core after reclamation.The content of sand decreased while the content of silt increased along the reclamation time.Silty loam soil was the mainly texture of the reclamation area,with silt content over 70%and clay content less than 20%,general mechanical composition of soil profile change tends to be stable in the process of soil development.2.pH of soils ranged from 7.92 to 9.51,which is alkaline to strong alkaline.It decreased with the reclamation time,and the differentiation degree also increased among different soil profiles.pH decreased from 9.51 in the beginning of reclamation to 7.92 after 43 years of reclamation.Salts content ranged from 0.15 to 15.88 g kg-1,with mean content 3.09 g kg-1,which is the typical saline soil in coastal areas.The average salinity of soil profile was obviously different in each sampling area,with FH5(9.92 g/kg)>F1(4.56 g/kg)>FH1(0.82 g/kg)>DL1(0.39 g/kg).3.The content of soil organic matter ranged from 1.83 to 13.40 g kg-1,it was significantly higher in the reclaimed area than that in tidal flats,and it increased along the reclamation time.After years of farming,affected by ploughing,ditching and fertilization,soil salinity content decreased clearly,physical characteristics improved markedly and soil microorganism quantity also increased,which could promote the conversion and accumulation of organic matter.The mean value of total nitrogen was 0.40 g kg-1,ranges from 0.08 to 0.89 g kg-1.The distribution trend of total nitrogen content has similar characteristics with soil organic matter content.Total phosphorus ranged from 0.55 to 0.94 g kg-1,with mean value of 0.64 g kg-1.Total potassium content ranged from 20.5 to 26.1 g kg-1,which belonging to third nutritional level,and the mean value was 22.1 g kg-1.4.On the basis of analysing soil characteristics of tidal flats reclamation area,problems during the land-use of reclamation area were put forward,and some countermeasures on agricultural development and utilization of new reclamation areas were proposed,which includes space planning technology,land consolidation technology,improvement of saline-alkali technology and farmland ecological management and maintenance technology. |
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