In order to reveal the characteristics of nitrogen mineralization in reclaimed soil of coal mining subsidence area with different fertilization measures

this experiment used the method of intermittent leaching and aerobic culture to study the effects of five kinds of fertilization measures

such as no fertilizer application (CK)

single application of chemical fertilizer (CF)

single application of organic fertilizer (M)

chemical fertilizer combined with organic fertilizer (MCF)

and chemical fertilizer combined with biological organic fertilizer (MCFB) on the changes of mineral nitrogen and soluble organic nitrogen in reclamation soil for 4 years and 8 years

and the characteristics of nitrogen mineralization were also studied. The result showed that:As the years of reclamation increases

the accumulated NO3--N production in 8 years of reclamation is 2.63%~26.83% higher than that of 4 years

the cumulative production of NH4+-N increases 12.50%~32.14%

the accumulative production of soluble organic nitrogen (SON) reduced by 31.59%~62.50% under CF and M treatments

and the other treatments increased 3.44%~34.69%. Under the same reclamation years

the accumulative production of NO3--N

NH4+-N

and SON were the highest in MCFB. According to the mineralization parameters

the mineralization potential of the five fertilization measures was higher in 8 years than that in 4 years

and the increase range were MCFB(26.9%) > CK(15.9%) > CF(15.0%) > M(12.7%) > MCF(4.8%); Under CK and CF treatments

the potential mineralizable organic nitrogen (N0/N) decreased with the increase of reclamation years

with the decrease rates being 9.4% and 13.8%

while the other three fertilization measures (N0/N) showed an increasing trend

with the increase rate of MCF(13.2%)>MCFB(7.5%)>M(2.8%). Under MCF treatment

the mineralization rate (Nt/N) increased with the increase of reclamation years

and the increase rate was 13.2%

the mineralization rate of the other four fertilization measures was lower in 8 years than that in 4 years

and decreased by CF (12.1%) > CK (9.4%) > MCFB (7.5%) > M (2.7%). The values of N0

N0/N

and Nt/N in different treatments were the highest in 8 years of reclaimed soil with MCFB treatment. On the whole

after 8 consecutive years of reclamation

the biomineralization parameters of chemical fertilizer combined with biological organic fertilizer were improved to a greater extent than those of other fertilization measures. However

with the increase of reclamation years

the increase of N0

N0/N treated with chemical fertilizer and organic fertilizer was the largest

the reduction rate of Nt/N was the lowest in the treatment of chemical fertilizer combined with biological organic fertilizer

and the potential mineralizable organic nitrogen content decreased by (N0/N) in long term single application of chemical fertilizer.