Microbial transformation of nitrogen in soil after the biochar addition

Abstract

It is apparent from the several studies that soil amended with biochar (pyrolysed plant-derived material in absence of oxygen) can influence the abundance, diversity and activity of soil organisms. The objective of the present work is to characterize the impact of soil treatment with various amounts of mineral nitrogen fertilizers on specialized group of free-living N2-fixing bacteria (diazotrophic) bacteria as a potential indicator of the effect of biochar amendment on the soil nitrogen transformation in the planned experiments. The high sensitivity of diazotrophic bacteria from the genus Azotobacter to the increasing doses of nitrate fertilizers has been found out in our studies. In terms of model experiment it has been showed that the number of Azotobacter was reduced under the influence of nitrogen fertilizers. Moreover, the higher concentration of mineral nitrogen, the more distinct the decreasing trend in the percentage of nitrogen-fixing bacteria has been observed. It was found that soya bean cultivation has led to the increase of the amount of nitrate-nitrogen in the soil, which explains the significant reduction in the percentage of Azotobacter genus bacteria. Based on the high value of correlation coefficients between the inversely correlated studied values is to be recommended to use these as an indicator of the effect of above mentioned biochar amendment.