Effect Of Elevation And Slope Direction On The Vertical Distribution Characteristics Of Grassland Soil Nitrogen In Yili

To study the vertical variability of soil nitrogen,this study is based on the typical grassland soil of altitude from 1400 m to 2800 m in zhaosu and chabuchaer county,Xinjiang.Bremner's acid solution was used to analyze the vertical variability of total nitrogen,inorganic nitrogen,soil organic nitrogen,organic nitrogen components in different slope and elevation at different soil deapth.The results showed that:(1)The total nitrogen(0.33?3.24 g/kg),soil organic nitrogen(256.90?2569.10 mg/kg)and each components of soil organic nitrogen of south slope were increased with the increase of altitude from1400 m to 2000 m,and then they decreased with the increase of altitude from 2200 m to 2800 m.The nitrate nitrogen(1.43?76.33 mg/kg)and ammonium nitrogen(22.84?110.17 mg/kg)decreased with the increase of altitude from1400 m to 2800 m.The total nitrogen(0.08?1.13 g/kg),ammonium nitrogen(27.96?132.73 mg/kg),soil organic nitrogen(77.72?977.35 mg/kg)and the components of soil organic nitrogen increased with the increase of altitude from 1400 m to 1800 m,and than decreased from 2000 m to 2800 m.The nitrate nitrogen(0.73?13.8 mg/kg)increased with the increase of altitude from1400 m to 2800 m.(2)In the altitude area of 1400?2800 m,the proportion of soil organic nitrogen in the soil total nitrogen of 0?20 cm,20?40 cm,40?60 cm respectively were 73.76?86.91%,74.64?88.62%,and 74.34?92.82%.In the north slope the proportion of soil organic nitrogen in the soil total nitrogen of 0?20 cm,20?40 cm,40?60 cm respectively were 76.10?90.38%,74.39?93.59%,81.39?95.13%.Along with the increase of soil thickness the ratio of organic nitrogen to total nitrogen increased.(3)In the south slope,at the soil depth of 0?20 cm,20?40 cm,elevation showed positive correlation with soil water content,a negative correlation with ammonium nitrogen,and no correlation with nitrogen fractions.At the soil depth of 40?60 cm,elevation showed no correlation with soil physical and chemical properties.In the north slope,at the soil depth of 0?20 cm,20?40 cm,40?60 cm,the elevation significantly correlated with total nitrogen,soil organic nitrogen,amino acid nitrogen,ammonia nitrogen,but physical and chemical properties were not correlated with elevation.(4)In addition to the soil ammonium nitrogen of north slope was higher than the south slope,and the other nitrogen fractions of south slope were higher than the north slope.