The Effect Of Weathered Coal On The Soil Salinity And Orgainic Carbon Fraction In Saline-Sodic Soil

Alkali-saline soils are valuable land resources,and it is necessary to improve and utilize saline soil.Saline-sodic soil is a major type of saline soils.Itis urgent to improve and use saline-sodic soil for crop production.This experiment investigated the mechanism and effect of saline-sodic soil improvement in Datong basin,Shanxi Province by using an approach of combining biological and chemical methods.This study consisted of growth chamber study,micro plot,and field plot experiments.At first,we screened various maize cultivars in the growth chamber environment and identified salt tolerant cultivars for further experiments.Then we investigated effects of weathered coal as soil amendment on physical and chemical properties of soda-saline soil and optimum rate of the weathered coal for saline soil improvement in the field experiments.At the same time,the micro plot experiment was used to explore the mechanism of weathered coal and the change of organic carbon components by applying weathered coal on improvement of saline-sodic soil.1、The results from the salt tolerance screening experiment in the growth chamber showed that Luyu 39 had the greatest biomass production and the least increase in antioxidant enzyme activity among the six cultivars tested,and was classified as a relatively salt tolerant cultivar.2、The results from the field plot experiments showed that the application of weathered coal reduced soil pH,the alkalinity,Na+,CO32-and HCO3-content,increased crop yield.The greatest positive effects of weathered coal on saline soil improvement was observed at the rate of of 22500 kg/hm2.The weathered coal applied at 22500 kg/hm2 reduced the soil pH by 8.6%,the alkalinity by 47%,Na+ and HCO3-by 82% and 32%,respectively,and increased grain yield by 40% when compared to the control.3、In the micro plot experiment,we analysed the change of soil salinity in the soil layer of 0-60 cm and further explored the mechanism of improvement of soda-saline soil.The results showed that the weathered coalapplication at 22500 kg/hm2 decreased Na+,CO32-,and HCO3-in the soil layer of 0 to 10 cm by 2.3%,61%,32%,66%,and 15%,respectively,when compared to the control.As soil layer got deeper,the phenomenon of migration of salt down ward was observed.The soil p H and alkalinity were increased by 11% and 550%,respectively in the lower soil layer relative to upper soil layer.In addition,Na+,CO32-and HCO3-content were increased by260%,810%,and 40%,respectively,in the lower soil layer relative to upper soil layer.4、The weathered coal treatment caused the changes in soil organic carbon components and increased the soil fertility.When applied at 22500 kg/ hm2,the weathered coal increased the total organic carbon in 10-20 cm soil layer by 104%.The weathered coal application at 22500 kg/hm2 also increased the soil water-soluble organic carbon by 69% in the 0-10 cm soil layer,93% in 10-20 cm soil layer and 23% in the 20-40 cm soil layer increase.In addition,the weathered coal treatment increased soil organic carbon of fine particle by 114% in 0-10 cm soil layer;and 77% in the 10-20 cm soil layer.The weathered coal application increased labile organic carbon by146% in 0-10 cm soil layer,41% in the 10-20 cm soil layer and 41% in the20-40 cm soil layer.5、The weathered coal can improve the soil physical properties,reduce the soil bulk density,change the soil three-phase ratio.When compared to the control,the weathered coal treatment,bulk density decreased by 3% in 0-10 cm soil layer,2% in 10-20 cm soil layer.The weathered coal treatment increased the ratio of gas and the liquid to the total soil volume.The weathered coal application increased soil gas ratio by 0.6%,liquid ratio by8% in 0-10 cm soil layersoil gas ratio by 7%,liquid ratio by 12% in 10-20 cm soil layer when compared to the control.