Influence of Vegetation Restoration Process on Mineral Nitrogen Accumulation in Soil Profile in Hilly and Gully Region of Loess Plateau--Sample with Zhifanggou watershed experimental area

• 黄土高原丘陵沟壑区植被恢复过程对土壤剖面矿质氮累积影响--以纸坊沟流域试验区为例