Effect Of Applying Biomass Carbon On Nitrogen Leaching From Black Soil In Northeast Under Freeze-thaw Conditions

Applying biomass waste is a better approach with higher feasibility to controlnon-point source pollution measure. In this paper agricultural and industrial wastewere used as raw materials for preparing carbon materials and applied to black soilcombined with climatic characteristics of the Northeast to graduate the effect ofbiochar on black soil nitrogen leaching under freeze-thaw conditions inhibition.In thisstudy, leaching experiment simulation method was taken to study the effect ofbiomass carbon derived from different sources on nitrogen longitudinal migrationfrom black soil under different freezing and thawing conditions. Northeast was takenas experimental typical black soil to experimentize indoor simulated soil columnexperiments under freeze-thaw conditions. Depending on the raw material andnitrogen fixation of carbon sources at different freezing and thawing patterns，theoptimal biomass carbon which had inhibition of black soil nitrogen leaching lossesand the corresponding applying solutions were determined. The specific results are asfollows:When the frequency of freeze-thaw conditions was set by1,3and6cyclesrespectively applying corn stalks, twigs, leaves, mud biochar could effectively reducethe moisture and nitrogen leaching. Under the same temperature(500℃) conditions,biochar devived from different raw materials had different inhibitory effect onnitrogen leaching from black soil. With applying biomass carbon derived from cornstover into the soil column, the leaching solution of ammonium, nitrate concentrationwas the lowest, followed by the branches charcoal, again leaves carbon. TheInhibition of carbon sludge was relatively poor. This suggests that the applying ofcorn stover biomass could effectively suppress soil carbon nitrogen leaching lossesand reduce non-point source pollution. Compared with biomass charcoal devired fromother sources, corn stalk had the maximum cumulative mass loss and the lowest ashcontent. More volatile flammable gas indicated that straw charcoal had rough surfaceand irregular pores witch belonged to macroporous range. Corn stover charcoal hadnatural dispersion structure witch could be easy to form a loose porosity and this might be the reasons why corn stover biochar soil had advantange of adsorption ofnitrogen.When the freeze-thaw conditions was3cycles, the changes of preparationtemperature, particle size and the applying amount of biochar all have an impact onsoil nitrogen leaching. When pyrolysised at500℃, particle size of60mesh andapplied with an amount of2%of biochar, the effect of inhibitory of leaching losses ofnitrogen from black soil was the most cost-effective. Applying biochar in this methodunder this freeze-thaw conditions, the moisture content, pH, conductivity, redoxpotential and cation exchange volume has significantly increased the role; the sametime, the effect of ammonification and nitrification of black soil were enhanced byapplying biochar.Freeze-thaw patterns have a significant impact on the concentration of nitrogenleaching in Black. When thawing frequency is3, the amount of soil nitrogen leachingis the largest, and when compared with1frequency, the increasing amount of leachingof nitrate and ammonium nitrogen was significant (P<0.001). Change the type ofapplied fertilizer, NH4Cl,(NH4)2SO4and KNO3were chosen as the main fertilizerwere applied, the results showed that applying (NH4)2SO4can significantly increaseammonium nitrogen in the leaching solution of concentration and a significantincrease significantly of nitrate concentration in leaching solution by applying KNO3;when freezing and thawing time is changed, either freezing or thawing time increases,the concentration of ammonium nitrogen leaching solution were increased,the nitrateconcentration increases with increasing melting time; longer or shorter freezing timeboth increases the nitrate concentrations. Results of experiment of different freezingtemperatures show that, when freezing temperature is-25℃, the concentration ofammonium nitrogen leaching has the maximum value; when freezing temperature is-5℃, leachate concentration of ammonium has the minimum value; when freezingtemperature is-5℃or-25℃, nitrate leaching has a similar concentration and theconcentration was higher than that when the freezing temperature is-15℃.In this study, the effect of applying biochar on the amount of nitrogen leachingout of soil under freezing and thawing condition is researched in detail and different applying plan, external conditions were compared. This study provides reliableinformation for the inhibition of nitrogen leaching in the thawing season and has greatsignificance on the control of non-point source pollution of black soil.