黄土区几种土壤培养过程中可溶性有机氮的变化及其与土壤矿化氮的关系

研究了黄土高原12种土壤(农地和林地)35 d好气培养过程中可溶性有机氮(SON)含量及其占可溶性全氮(TSN)的比例,以及SON与土壤矿化氮间的关系。结果表明,随着培养过程的进行,不同类型土壤SON的含量均呈明显增加;土壤SON占TSN的比例在培养的前3 d内明显下降,随后这一比例基本保持在24%左右。根据总可溶性氮确定的供试土壤氮素矿化势No平均为45.8 mg/kg,较由矿化的无机氮确定的土壤氮素矿化势No(平均36.5 mg/kg)高约1/4左右;培养过程中土壤SON含量与利用无机氮拟合得到的土壤氮素矿化势No间的相关性未达显著水平。研究表明,评价土壤氮素矿化特性时仅仅测定矿化的无机氮数量,可能会低估土壤氮素矿化潜力和氮素损失的数量和效应。

Dynamics of Soluble Organic Nitrogen and Its Relation to Mineralization of Soil Organic Nitrogen During Incubation of Several Soils in Loess Region

Laboratory analysis was conducted to investigate nitrogen mineralization of soils in the Loess Plateau of China.The aims of our study were to determine the content of SON(soluble organic nitrogen),and the percent of TSN(total soluble nitrogen) to SON,and the relate SON to mineralized nitrogen.Results showed that the content of SON of all soils increased significantly during incubation.The percent of TSN to SON was the highest at start stage.From day-0 to day-3,the percent declined to the lowest level.After that the percent increased gradually.In the end of incubation,SON accounted for 24% of TSN.Soil mean mineralization potential(N0) based on total soluble nitrogen(45.8 mg/kg) was a quarter higher than mean mineralization potential(36.5 mg/kg),which was based on mineralized inorganic nitrogen.The positive relationship was found between the content of SON and mineralization potential that based on mineralized inorganic nitrogen,but not reach significant level.Our results suggested that in order to evaluate nitrogen mineralization,the content of SON was only measured during incubation may underestimate mineralization potential and the amount of nitrogen losses.