The Variation of Nitrate in the Soil Profile for Continuous Spring Maize System under Different Soil Fertilities in the Northeast of China

In the continuous Spring Maize system in Northeast China,the nitrate accumulation and succession characteristics of different soils and fertility in three locations with five fertilization treatments, which included no fertilizer treatment (CK), farmer conventional treatment (FC), recommendation fertilization (RF), control-released fertilizer (CRF) and single fertilization (SF), was compared by 6 years’ long-term experiment. The results showed that nitrate accumulation was drastically significant in high pH soils; potential nitrate increasing trend of high fertility soil was lower; new type fertilizer, for example controlled release fertilizer (CRF), and recommendation fertilizer rate (RF) could obviously decrease nitrate accumulation in single fertilization and in split fertilization; the nitrate excessive accumulation in soils could be improved by not only controlling fertilization, fertilizer and fertilizer rate, but also considering of soil types and soil fertility; and at present, in Northeast China, nitrate accumulation was in rational and safety level, but still exist potential risk.