Research on soil nutrient of three returning farmland to forest vegetation in hilly region of Loess Plateau

Authors analysed shady slope soil nutrients in three returning farmland to forest vegetation(Hippophae rhamnoides,Hippophae rhamnoides+Pinus tabulacformis,Hippophae rhamnoides+Robina pseudoacacia) which were in different growth status in hilly region of Loess Plateau,the results showed:(1) The soil nutrients were very low in study area;(2) The spatial variation of total nitrogen,available nitrogen,available potassium,available phosphorus was obvious in study area;(3) The order of the soil nutrients in the study area from big to small was Hippophae rhamnoides(good)Hippophae rhamnoides+Robina pseudoacacia(good)Hippophae rhamnoides(bad) Hippophae rhamnoides +Robina pseudoacacia(bad) Hippophae rhamnoides +Pinus tabulacformis(good) Hippophae rhamnoides +Pinus tabulacformis(bad).The soil nutrient of Hippophae rhamnoides+Pinus tabulacformis(death) was better than good and bad one.