Effect Of Biochar And PRD Irrigation On Nitrogen Residue And GHG Emission From Vegetable Soil In Suburban Of Beijing

In the managements of vegetables production, there are so many problem such as overdose fertilizers and frequent irrigation, those have increase soil, surface water and groundwater nitrate pollution levels and greenhouse gases(CO2, N2O) emissions, reduced a series of major environmental problems. In this paper, we are taking biochar and PRD drip irrigation as an improvement practices, and the field and lab experiments were carried out. The field trial that conducted to investigated the soil inorganic nitrogen leaching in four different treatments:conventional fertilizer and drip irrigation(CK);conventional fertilizer and PRD drip irrigation(PRD);conventional fertilizer mixed biochar and drip irrigation(B), conventional fertilizer mixed biochar and PRD drip irrigation(B+PRD).The main purpose of lab experiment was to investigate two greenhouse gas(CO2,N2O)emissions with biochar addition under different fertilizers,and the results could provide theoretical suggests on reducing inorganic nitrogen leaching and greenhouse gas emission that happened in the vegetable soil ecosystem. The main results are summarized as follow:(1) Different degrees of the inorganic nitrogen leaching occurred in soil profiles under different treatments during the different periods. In 63 d, there was a significant increase in the content of inorganic nitrogen in the deep layers(40-100cm) in M treatment when compared with 0d,but it is not occurred in M+B, It means M+B treatment may al eviate the leaching process of soil inorganic nitrogen. The same phenomenon also happened in the 126d?189d and 234 d.(2) Comparing two drip irrigation methods o n soil inorganic nitrogen distribution changes under M and M+B fertilization mode, we found that in the 189 d and 234 d,due to the increase in the amount of rainfall and irrigation, a large number of soil inorganic nitrogen leaching have occurred. Compared with conventional drip irrigation, PRD treatment could increases inorganic nitrogen content in the profile soil, that means, when compared to conventional drip irrigation, PRD drip irrigation can reduce the migration velocity of inorganic nitrogen that moving toward deep layers of the profile, and reducing inorganic nitrogen leaching losses.(3) By comparing the accumulation of inorganic nitrogen in 0-100 cm soil with addition of biochar under different irrigation, we found that when inorganic nitrogen leaching occurs, the accumulation of inorganic nitrogen was highest in B+PRD treatment, indicating that biochar binding PRD drip irrigation is more effective in al eviated inorganic nitrogen leaching in the profile as compared with the conventional treatment.(4) The effect of biochar application on soil CO2, N2 O release varies with time, In the early time of incubation(0-25d) biochar application had a significant improvement on the release of CO2 and N2 O, but this promotion was waning with time(27-60d).(5) Under different fertilization, the influence of adding biochar on the release of CO2, N2 O is different. CK and M mode, add biochar had no significant effect on accumulation of CO2, N2O; F and M + F mode, the cumulative release of CO2 and N2 O were significantly increased under biochar application.(6) Correlation analysis showed that the inputs of biochar could change the content of DOC, DON and inorganic nitrogen and thus affect the release of CO2 and N2 O respectively.