生物炭对冻融黑土中铵态氮和硝态氮淋失的影响

Effects of biochar on ammonium nitrogen and nitrate nitrogen leaching from black soil under freeze-thaw cycle

为了深入研究冻融条件下生物质炭对东北黑土中铵态氮和硝态氮淋失的影响效果,为解决冻融作用下黑土中无机氮素的淋失问题提供科学依据,采用室内模拟土柱淋溶实验方法研究了生物质炭对经过不同冻融循环次数处理土壤中铵态氮和硝态氮淋失的影响。研究结果表明：冻融会增加土壤氮素的淋失,且淋失量与冻融次数有关,施加生物质炭可以有效降低土壤因冻融作用引起的氮素淋失;玉米秸秆炭对无机氮素淋失降低率在76.15%～85.79%之间,树枝炭在55.26%～68.09%之间,可以看出玉米秸秆炭持氮效果较树枝炭更好;在冻融次数分别为3和1时,玉米秸秆炭和树枝炭持氮能力最强;两种生物质炭对铵态氮的固持能力均优于硝态氮。

Leaching is one of important nitrogen loss pathways. Biochar may reduce the leaching because of huge surface area. Here a laboratory column study was conducted to examine the effect of biochar applications on leaching of ammonium nitrogen and nitrate nitrogen in black soils from the Northeastern China under different freeze-thaw frequencies. Freezing-thawing increased nitrogen leaching, and the leaching amount was related to freeze-thaw frequency. Applying biochar effectively reduced the nitrogen leaching caused by freeze-thaw.Inorganic N leaching was reduced by 76.15% ～85.79% and 55.26% ～68.09%, respectively, by corn-stover and twigs biochars. Obviously,corn-stover biochar was more effective than twigs biochar did. At 3 and 1 of the freeze-thaw frequency, nitrogen fixation capacities of cornstover and twigs were respectively the highest. In addition, biochar effect on ammonium nitrogen was greater than on nitrate nitrogen. These findings shed light on measures of reducing inorganic nitrogen leaching in black soil under freeze-thaw cycle.