Abstract: In order to provide scientific guidance for reasonable nitrogen fertilizer application,the soil nitrate accumulation of croplands under Chinese medicinal plants and food crops in Anguo city,Heibei province was investigated by field sampling and chemical analysis.The results showed that ranges of nitrate contents in 0-20,20-40 and 40-60cm layers of herbal fields were 37.96-436.86,26.27-435.64 and 12.91-383.23mg·kg-1,while ranges of nitrate contents in 0-20,20-40 and 40-60cm layers of grain fields were 3.71-184.65,8.14-198.11 and 6.04-145.81mg·kg-1,respectively.The results indicated that(1)nitrate content in 0-20cm soil layer of herbal fields were higher than that of 20-40cm（P＜0.01）and 40-60cm soil layers（P＜0.05）,while soil nitrate contents between 20-40 and 40-60cm soil layers showed no significant difference;(2) Soil nitrate content in 20-40cm soil layer of grain fields were slightly higher than that of,but no difference was found between 0-20 and 40-60cm soil layers;(3)Soil nitrate content decreased with the soil depth for two kinds of croplands,and soil nitrate content in herbal fields was significantly higher than that of grain fields at the same soil layer (P<0.01).There were 35% that their nitrate contents topsoil had exceeded critical value of safety.Also,about 10% herbal fields had been seriously polluted by nitrate.The data showed that soil nitrate of grain fields were in safe range basically.To conclude,nitrate accumulation of herbal fields was more severe than grain fields,which posed potential problems for sustainable production.

Key words: Anguo city, Nitrate, Herbal field, Grain field, Soil depth