The effect of biochar on nitrogen availability and bacterial community in farmland

Purpose Nitrification and denitrification in soil are key components of the global nitrogen cycle.

This study was conducted to investigate the effect of biochar application on soil nitrogen and bacterial diversity.

Methods Pot experiments were conducted to investigate the effects of different biochar-based rates 0% (CK), 0.5% (BC1), 1.0% (BC2), 2.0% (BC3), and 4.0% (BC4) on soil nutrient and bacterial community diversity and composition.

Results The results indicate that the total nitrogen (TN) and ammonium nitrogen (AN) contents in the soil increased by 4.7–32.3% and 8.3–101.5%, respectively.

The microbial biomass nitrogen (MBN) content increased with increased amounts of biochar rate.

The application of biochar also significantly changed the soil bacterial community composition.

The copy number of 16S marker gene of related enzymes to the nitrification process in BC2 was reduced by 20.1%.

However, the gene expressions of nitric oxide reductase and nitrous oxide reductase in BC3 increased by 16.4% and 16.0%, respectively, compared to those in CK.

AN, nitrate nitrogen (NN), and NN/TN were the main factors affecting the structure of the soil bacterial community.

In addition, the expressions of nitrite reductase, hydroxylamine, and nitric oxide reductase (cytochrome c) were also significantly correlated.

Conclusion Therefore, the applied biochar improved soil nitrogen availability and which ultimately resulted in an environmental risk decrease by soil nitrogen release inhibition.