Effects of biochar reapplication on ammonia volatilization and nitrogen use efficiency during wheat season in a rice-wheat annual rotation system

ObjectivesA field experiment was conducted to investigate the effect of aged and fresh biochar amendment on ammonia volatilization, nitrogen use efficiencies and wheat yield during wheat season in a rice-wheat rotation system.

MethodsSix treatments were carried out in this experiment, including two control treatments N0B0 (no nitrogen + no biochar), N1B0 (N 250 kg/hm² nitrogen); two aged biochar amendment treatments N1B1 (N 250 kg/hm² nitrogen + 20 t/hm² biochar), N1B2 (N 250 kg /hm² nitrogen + 40 t/hm² biochar); two aged with fresh biochar amendment treatments N1B1 + B (N1B1 add 10 t/hm² biochar), N1B2 + B1 (N1B2 add 20 t/hm² biochar).

ResultsResults showed that the N1B1 and N1B1 + B treatments significantly decreased the cumulative NH₃ volatilization by 36.6% and 6.4%, increased the nitrogen use efficiency by 30.1% and 14.1% and increased the wheat yield by 55.6%, 26.9% compare with N1B0. In contrast, compared with N1B0 treatment, N1B2, N1B2 + B1 treatments significantly increased the cumulative NH₃ volatilization by 20.3% and 40.5%, the nitrogen use efficiency increase by 35.9% and 14.3% and the wheat yield significantly increased by 72.5%, 18.9%, respectively. Moreover, compared with the aged biochar amendment, biochar topdressing significantly increased the NH₃ volatilization, and decreased the nitrogen use efficiency and wheat yield.

ConclusionsBiochar amendment could significantly increase the nitrogen use efficiency and wheat yield during wheat season in paddy field. Aged biochar at the rate of 20 t/hm² can decrease the ammonia volatilization loss while increase the nitrogen use efficiency and wheat yield.