不同质地黑土净氮转化速率和温室气体排放规律研究

为探讨黑龙江省半干旱地区不同质地黑土的净氮转化速率和温室气体排放规律,以壤砂土和粉壤土为研究对象开展室内培养试验,对土壤净硝化速率和净矿化速率、N2O和CO2排放速率与累积排放量进行研究。结果表明:7d培养期间壤砂土的平均净矿化速率和CO2平均排放速率分别为0.49mgN kg-1 d-1和0.30mgCO2-C kg-1 h-1,显著低于粉壤土的平均净矿化速率(1.37 mgN kg-1 d-1)和CO2平均排放速率(0.47mgCO2-C kg-1 h-1)。壤砂土的平均净硝化速率和N2O平均排放速率分别为1.65mgN kg-1 d-1和212.6ngN2O-N kg-1 h-1,显著低于粉壤土的5.02mgN kg-1 d-1和521.3ngN2O-N kg-1 h-1。壤砂土和粉壤土的N2O排放比率分别为0.081%~0.301%和0.210%~0.254%。研究表明,土壤质地显著影响土壤净氮转化速率和温室气体排放,壤砂土较低的pH、有机碳和水溶性有机碳含量是导致其净硝化速率、净矿化速率以及N2O、CO2排放速率显著低于粉壤土的主要原因。

Regularity of net nitrogen transformation rates and greenhouse gas emissions in black soil of different textures

To better understand the net nitrogen transformation rates and greenhouse gas emissions in black soils, a short-term(7 day)laboratory incubation experiment was conducted on two soils of different textures(loamy sand and silt loam)from the semi-arid region in Heilongjiang Province, China. The rates of net nitrification and net mineralization, N₂O and CO₂ emission rates, and cumulative emissions were determined. Our results showed that the average net mineralization rate and CO₂ emission rate of loamy sand soil during the 7-day incubation period was 0.49 mg N·kg^-1·d^-1 and 0.30 mg CO₂-C·kg^-1·h^-1, respectively, which was significantly lower than the rates for the silt loam soil(1.37 mg N·kg^-1·d^-1 and 0.47 mg CO₂-C·kg^-1·h^-1, respectively). The average net nirification rate and N₂O emission rate of loamy sand soil was 1.65 mg N·kg^-1·d^-1 and 212.6 ng N₂O-N·kg^-1·h^-1, respectively, which was significantly lower than the rates for the silt loam soil (5.02 mg N·kg^-1·d^-1 and 521.3 ng N₂O-N·kg^-1·h^-1, respectively). The N₂O emission ratio from loamy sand soil and silt loam soil ranged from 0.081% to 0.301% and 0.210% to 0.254%, respectively. Soil texture significantly affected net nitrogen transformation rates and greenhouse gas emissions. The lower soil pH and the lower organic carbon and water-soluble organic carbon concentrations in the loamy sand soil were the main reasons for the significantly lower net nitrification rate, net mineralization rate, and emission rates of N₂O and CO₂, as compared with the silt loam soil.