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The Study Of Salinized Land Improvements In The Hexi Corridor Of Gansu Province

Posted on:2008-01-03Degree:MasterType:Thesis
Country:ChinaCandidate:W G WangFull Text:PDF
GTID:2143360242968505Subject:Forestry
Abstract/Summary:PDF Full Text Request
With more studies on the issue of salinized soil being conducted, it has been realized gradually by people that complete control of salinized soil is not practical; and it is necessary to find solutions to balance water and salts in the soil. A study on salinized land improvements, consisting of drain for salts, salt leaching by fresh water, and soil covering, was conducted. Results showed that draining was an effective way to improve salinized land when the water table was exceeding the critical level in the Xiaoquanzi of Linze county in the Hexi Corridor. A drain for leaching salts, 890m long, 2.5m deep, with an interval of 200m, a 2/1000 bottom slope, and a 50o side slope, could not only ensure its steady operation but discharge 92,250m3 of water containing 250.5t of salts, as a result, improving markedly the salinized land. Mechanical method was a necessity for salinized land use, aiming to reduce the salinity of soil below the limit for plants growth.Leaching salts by fresh water was another effective way to improve salinized land. The theory is that solid salts are dissolved in gravity water and discharged off with movements of the gravity water. Salts leaching should be carried out with a small quota and more frequencies of watering. In this study area, the total quota for leaching was 7,000m3/hm2. it was necessary to plough and sun the soil before leaching. Sunning the soil could increase the solubility of salts, which was useful for desalting. In this study area, sulfate is dominant, its solubility is highly affected by temperatures; so the season for leaching should be summer of high temperatures.Straw covering could reduce significantly evaporation from the soil and salts accumulation on the surface; in addition it could increase organic matter in the soil but reduce ground temperatures. Sand covering could also significantly reduce evaporation from the surface and salts accumulation on the surface, however it could result in sandy desertification of sandy salinized land. Straw and sand coverings are to be used in the light of conditions. In a summer season of high temperatures, plastic film, straw and sand coverings could greatly reduce evaporation from the surface and salts accumulation on the surface. Plastic mulching should be conducted in the whole plots; the quota for straw to cover the soil surface was about 2,934.8kg/hm2; and thickness for sand covering was 4cm.
Keywords/Search Tags:the Hexi Corridor, draining, salts leaching by freshwater, covering soil surface, technology for improvements, study
PDF Full Text Request
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