A field experiment was conducted to study the effect of straw and biochar on ammonia volatilization and inorganic nitrogen content of the apple orchard soil using glycerolphosphate double layer sponge ventilation method. This experiment included four treatments

which were CK (N0)

N (applied urea 250 kg/hm2)

N+S (applied urea 250 kg/hm2+straw) and N+B (applied urea 250 kg/hm2+biochar). The results showed that there were significant differences in ammonia volatilization rate and losses amount among different treatments. Ammonia volatilization rate of the three treatments applied with urea (N

N+S and N+B) were significant higher than that of control (CK) treatment

and it increased quickly after fertilization

and the peak value of it appeared on the third day after applying nitrogen fertilizer

and then gradually declined. There were significant differences in the peak value of ammonia volatilization rate among different treatments

and the maximum peak value of it appeared in N treatment

which was 2.37 kg/(hm2·d)

followed by N+S treatment (1.65 kg/(hm2·d))

and then N+B treatment (1.32 kg/(hm2·d))

and the peak value of ammonia volatilization rate of N treatment was 1.44 and 1.80 times of N + S treatment and N + B treatment

respectively. The variation trends of soil ammonium nitrogen content in 0—10 cm soil layer were consisted with those of ammonia volatilization rate

and there was a significant positive correlation between these two parameters. The peak value of ammonium nitrogen content was different significantly among the four treatments

the maximum peak value of it was found in N treatment

followed by N+S treatment

and the value of N+B treatment was the lowest. After removing background value of the CK

the maximum ammonia volatilization loss occurred in N treatment

which reached to 15.29 kg/hm2 and accounted for 6.12% of the total amount of nitrogen applied

and the above two values of N+S treatment and N+B treatment were 9.32 kg/hm2 and 3.73%

and 6.01 kg/hm2 and 2.40%

respectively. Therefore

adding straw and biochar could significantly reduce the nitrogen loss through ammonia volatilization

and adding biochar could get the best effect.