Study of the Mechanism of Migration and Transformation of Biochar-N and Its Utilization by Plants in Farmland Ecosystems

摘要

Nitrogen (N) is the most important nutrient for the growth of crops. In order to improve plant utilization of biochar-N and select the best preparation conditions of high-quality biochar with rich N, we studied the dynamics of N in the soil-plant-soil microorganisms-atmosphere ecosystem after returning biochar to the soil. We used N-15-labeled wheat straw to produce biochar under pyrolysis to determine the mass and distribution rates of N-15, as well as the microbiological information on the ammonia process after the return of biochar to the field. Several important conclusions were drawn: (1) The mass distribution of biochar-N in the soil, plants, soil microorganisms, and atmosphere were 77.71-99.06%, 0.38-6.91%, 0.23-6.93%, and 0.27-8.46%, respectively. (2) The N mass in the plants cultivated with biochar produced at 400 degrees C (BC400) was the highest, accounting for approximately 1.66 times the amount in the original wheat straw and 2.57 times that in the biochar produced at 200 degrees C (BC200). Moreover, the return of biochar to the field reduced the volatilisation of N. (3) There is a certain relationship between the content of N-15 in the soil microorganisms and the content of N-15 absorbed by the plants, that is, when the microorganisms-N are high, more N can be utilized by the plants, and vice versa. The two values showed a consistent positive correlation with each other. (4) In the ammonia oxidation reaction, Thaumarchaeota was the most important group (66.7-75.8%).