氮肥配施纳米碳对植烟土壤氮素转化及N2O排放的影响

采用实验室静态培养方法,通过氮肥配施不同量纳米碳来探究纳米碳对植烟土壤氮素转化以及N_2O排放的影响。试验在等氮条件下共设置5个处理:CK,硝酸铵(N 200 mg/kg,下同);NC1,硝酸铵+纳米碳(2.5 g/kg);NC2,硝酸铵+纳米碳(5 g/kg);NC3,硝酸铵+纳米碳(10 g/kg);NC4,硝酸铵+纳米碳(15 g/kg)。结果表明:NC3和NC4处理较CK处理显著降低了土壤pH(P0.05);与CK处理相比,NC1、NC2、NC3和NC4处理在培养前期增加了土壤NH_4~+-N含量,相应降低了NO_3~–-N含量;在培养结束时,与CK处理相比,添加纳米碳处理显著降低了无机氮含量,而显著增加了CO_2累积排放量(P0.05);另外,添加纳米碳处理较CK处理增加了N_2O累积排放量,但仅NC4处理与CK处理间差异显著(P0.05),N_2O累积排放量与CO_2累积排放量呈显著正相关关系(R~2=0.50,P0.001)。可见,添加纳米碳能够降低土壤pH和无机氮含量,抑制土壤硝化作用,同时还可以提高微生物活性和增加N_2O排放量。

Effects of Nano-carbon on Nitrogen Transformation and N2O Emissions from Tobacco Planting Soils

A laboratory static culture was conducted in order to better understand the effects of different amounts of nano-carbon on nitrogen transformation and N₂O emission of tobacco-plating soil. The experiment included five treatments on equivalent N basis:CK, ammonium nitrate (N 200 mg/kg); NC1, ammonium nitrate + nano-carbon (2.5 g/kg); NC2, ammonium nitrate + nano-carbon (5 g/kg); NC3, ammonium nitrate + nano-carbon (10 g/kg); NC4, ammonium nitrate + nano-carbon (15 g/kg). The results showed that NC3 and NC4 treatments significantly decreased soil pH value compared with CK (P<0.05). Compared with CK, treatments amended with nano-carbon increased the concentrations of NH₄⁺-N in the early period of incubation and decreased the concentrations of NO₃^--N accordingly. At the end of the incubation, treatments amended with nano-carbon significantly decreased the concentrations of inorganic nitrogen compared to CK (P<0.05). Addition of nano-carbon treatment significantly increased the cumulative CO₂ emissions compared to CK (P<0.05). Compared with CK, NC4 treatment significantly increased the cumulative N₂O emissions (P<0.05). In addition, there was a significant positive correlation between cumulative N₂O emissions and cumulative CO₂ emissions (R²=0.60, P<0.001). The above results indicate that the addition of nano-carbon can decrease soil pH value and the concentrations of inorganic nitrogen, inhibit soil nitrification, improve microbial activity and increase N₂O emissions.