| The area of coastal tidal mudflat in Jiangsu province is about 653 thousand hectare, and the net increase is about 1100 hectare every year. As a result of ocean tide and sea water type ground water, the main characteristics of the soil are as follows:high contents of salt, low contents of nutrient and the main composition is chloride. Under the pressure of continuously increasing of population, continuously decreasing cultivated land and deficiency of freshwater, how to improve and use large area of saline soil efficiently and reasonably is an imperative problem. The paper was discussed the effects of different amelioration measures on coastal saline soil in David's Deer Reserve in Dafeng Jiangsu province and aims to provide theoretical support and application gist of reasonable use and development of coastal saline soil in Jiangsu province.To study the effects of different engineering and biological measures on coastal saline soil, four different trail demonstrative plots were collected in Dafeng County David's Deer Reserve. The plots are coastal wilderness (plot A),temporary ameliorated plot by digging channel combined with planting salt-tolerance plants(plot B),perennial ameliorated plot by digging deep channel combined with planting salt-tolerance plants(plot C) and a plot keeping on further improvements on the basal mode of plot C(plot D). Soil samples of 0～20cm and 20～40cm layers of soil were collected to determine the contents of total water soluble salts,pH values, the contents of organic matter, the contents of efficient nutrient and the contents of water soluble salt ions(Na+,K+,Ca2+,Mg2+,Cl-,SO42-,HCO3-). The major conclusions are as follows:1. Improvement measures such as ditching, making ridge, planting salt-tolerant plants and land cover has a great promotion to improvement and curing of coastal saline soil. The contents of total water soluble salt and water soluble salt ions decreased, the contents of organic matter and efficient nutrient had trend of increase, and soil properties was improved after improving. 2. Different amelioration measures on coastal saline soil have different effects. The effects of comprehensive amelioration measures are superior to single measure. The effects of carrying on land cover on the basis of digging deep groove combined with planting salt-tolerant plants are the best. The average salt contents of upper and lower layer in plot D respectively decreased to 2.9g/kg and 2.2g/kg. It belonged to slight alkaline land according to classification standard of coastal saline soil in China. Soil pH decreased to 8.16～8.35, shown as weak alkaline soil. The contents of organic matter and efficient nutrient increased greatly compared to plot A. The contents of water soluble salt ions has sharply decreased. The proportion of Na+ and Cl- which do more serious harm to plants has decreased by 93.0% and 88.6%. Soil physical and chemical properties have been improved, It was suitable to plant many kinds of crops.3. The effects of different depth of drains (25cm and 40cm) on coastal saline soil are different. With the depth of drains increased, the leaching intensity of salt increased. The rate of desalination accelerated. The total salt contents significantly decreased. The contents of Na+ and Cl" which do more serious harm to plants has significantly decreased (50.1% and 5.8%). But because of ditching for a short time, the differences of change of soil pH are not obvious. And the contents organic matter and efficient nutrient has slightly reduction due to its leaching with water. In all, the measure of digging desalting drainage ditch has some limitations, but it can still improve properties of coastal saline soil certain extent, and promote improving and aging of saline soil preliminarily. |
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