Effects of grazing on nitrogen contents in rhizosphere and non-rhizosphere soil of Stipa breviflora

The present study focused on the difference between rhizosphere and non-rhizosphere soil nitrogen in the Stipa breviflora desert steppe in Inner Mongolia. The results showed that soil nitrogen contents in rhizosphere were always higher than those in non-rhizosphere in S. breviflora under every treatment. With the increase of soil depth, the contents of total nitrogen, ammonium nitrogen and nitrate nitrogen in both rhizosphere and non-rhizosphere soil decreased. For 0-10 and 20-30 cm soil depth under different grazing rates, total nitrogen contents in rhizosphere soil and non-rhizosphere soil had similar change. The ammonium nitrogen and nitrate nitrogen contents increased in rhizosphere soil of same depth with light grazing rate which suggested that optimal grazing was positive for nitrogen accumulation. In vertical direction under different grazing rate, the total nitrogen contents in soil 0-10 cm was higher than those in 20-30 cm soil.