The effects of long-term fertilization on nitrogen mineralization and nitrification in black soil wereinvestigated by a 28 d incubation experiment. The main results were as follows: soil nitrogen mineralized andnitrified significantly among different treatments in the duration of incubation

showing that long-termfertilization had a pronounced effect on mineralizable nitrogen content. Mineralizable nitrogen contentincreased with increasing application of chemical fertilizer

however

application of organic manure togetherwith NPK fertilizer further enhanced nitrogen mineralization

which indicated that organic amendmentsignificantly increased soil nitrogen bioavailability. The nitrification rate had strong relationship with Napplication

whereas a weak correlation was found between nitrification rate and application of PK fertilizer.Chemical fertilizers amended with organic manure significantly increased nitrification rate

conclusively

changes of nitrification rates were driven by soil pH and the mineralizable nitrogen content of black soil.