Study On Soil Water Characteristic Curve Of Herbaceous Peat And Its Influencing Factors

Soil water characteristic curve(SWCC)is an important parameter to study soil hydraulic properties,which is a significant basis for reflecting the soil water-holding capacity and lagging ability.The study of SWCC in peat and its influencing factors can help us to better understand the influencing mechanism of moisture on carbon cycle in peatland.In this study,we studied the SWCC variation in both natural and mining peatland,analyzed the influencing factors of SWCC and established the function relationship between water potential and CO2 release rate.Results are as follows:1.The relationship between soil water content and soil water potential could be successfully described by the power function which was proposed by Gardner etal.,and the correlation coefficient was between 0.90 and 0.99.With the increase of water content,the SWCC at different sampling points showed a trend of fast descending-slow descendingbasically stable.The parameters of the wetting curve of Jinchuan peat were between 0.2583 and 0.328,and that were between 0.4291 and 0.5205 in the drying curve.The parameters of the wetting curve of Liaoyuan peat were between 0.4134 and 0.4823,and that were between 0.7175 and 0.8983 in the drying curve.The soli water characteristic curve of peat shows that peat can absorb water rapidly and maintain a large amount of water.The water-holding and water-absorption capacity of Liaoyuan peat is better than that of Jinchuan peat.2.Hysteresis in Jinchuan peat and Liaoyuan peat was observed during the wetting curve and drying curve.The hysteresis parameters of Jinchuan peat were between 0.0326 and 0.0427,and that of Liaoyuan peat were between 0.0657 and 0.0848.The hysteresis degree of Liaoyuan peat was more obvious than that of Jinchuan peat.In Liaoyuan peat,the hysteresis degree was the highest at the surface,lower at the intermediate,and the lowest at the underlying peat.3.Bulk density,capillary porosity,total porosity and fiber content are the key factors of the SWCC of peat,which were significantly correlated with the parameters of drying curve,wetting curve and hysteresis parameter.There was no significant correlation between cellulose,hemicellulose,lignin and SWCC,and also to the hysteresis parameter.4.The relationship between CO2 release rate of peat and SWCC could be described by the power function formula,and the correlation coefficient was between 0.87 and 0.99.With the increase of water potential,the CO2 release rate at different sampling points showed a trend of fast descending-slow descending-basically stable.