Distribution of soil organic carbon and its relationship with soil physical and chemical properties on degraded alpine meadows

Soil organic carbon,soil active organic carbon,soil alkali-hydrolysable nitrogen,soil available phosphorus,soil available potassium,soil water content and soil bulk density were determined to study the distribution of soil organic carbon and soil physical and chemical properties on degraded alpine meadows in Dangxiong,Tibet.Results showed that the change orders of soil organic carbon content and its density both in the 0-10 cm and 10-20 cm soil layers were normal meadowslightly degraded meadowserious degraded meadow;soil organic carbon content and its density in the 0-10 cm soil layer were higher than those in the 10-20 cm soil layer.There were correlations between soil organic carbon and other soil nutrients.The regression analysis showed that there were significantly positive linear relationships between soil organic carbon and soil active organic carbon(y=0.074 3x-0.026 1,R2=0.913 9),soil alkali-hydrolysable nitrogen(y=2.676 8 x+14.425 0,R2=0.977 1),soil available P(y=0.245 9x+3.347 9,R2=0.931 4),soil available K(y=4.296 5x+71.667 0,R2=0.665 3) and soil water content(y=0.790 8x + 5.424 5,R2=0.715 6),respectively.A significant negative linear correlation existed between soil organic carbon and soil bulk density(y=-0.016 7x+1.553 1,R2=0.773 5).The loss of soil organic carbon resulted in reduction of soil nutrients and moisture and increasing soil bulk density.Path analysis indicated that the change of soil organic carbon had the most significant effect on the soil alkali-hydrolysable nitrogen.