中文摘要：

采用室内恒温培养试验研究了在太湖地区乌栅土和黄泥土上添加15N标记秸秆后，秸秆15N在矿质氮、微生物氮和不同粒径土壤组分中的分配情况，并应用氮同位素库稀释法测定了秸秆在两种土壤上的氮总矿化速率。结果表明：两种土壤添加秸秆后，土壤矿质氮量在7～28 d之间迅速下降，微生物氮在前7 d逐渐升高，随后维持稳定。随着秸秆的分解，秸秆15N进入矿质氮库和微生物氮库，矿质15N在第7 天时最高，占添加秸秆15N的9.24%～12.3%，微生物15N在第14 天时最高，占添加秸秆15N的21.3%～40.5%，随后矿质15N和微生物15N量均下降。在培养的第7～28天之间，矿质15N 和微生物15N出现下降，可能存在秸秆氮的损失。培养56 d时，10.5%～13.3%的秸秆15N进入土壤53 μm～2 mm组分，24.5% ～ 26.5%进入2～53 μm组分，30%进入〈 2 μm组分，有5.7%～14.9%的秸秆氮损失掉，仍有15.4%～29.1％的秸秆未分解，秸秆在乌栅土上分解的更多，但损失也更多。添加秸秆后0.5 d时，秸秆在乌栅土和黄泥土上的氮总矿化速率分别为1.61 mg kg-1 d-1和1.48 mg kg-1 d-1；56 d时，秸秆在乌栅土和黄泥土上的氮总矿化速率分别为0.26 mg kg-1 d-1和0.36 mg kg-1 d-1。

英文摘要：

An incubation experiment was conducted to study the distribution of 15N in mineral nitrogen, microbial biomass nitrogen and soil different size fractions after 15N labeled rice straw was added into the wushan and huangni soil. Gross nitrogen mineralization rates of rice straw in the two soils were also measured using 15N isotopic pool dilution technique. Results showed that soil mineral nitrogen decreased between 7 days and 28 days after straw was added into soils. Microbial biomass nitrogen increased before 7 days and changed less after 7 days. Mineral 15N was the highest at 7 days and accounted for 9.24%～12.3% of added straw 15N. Microbial biomass 15N was the highest at 14 days and accounted for 21.3%～40.5% of added straw 15N. Mineral 15N and microbial biomass 15N decreased between 7 days and 28 days after straw addition, which suggested that straw nitrogen was possibly lost at this time. At 56 days after straw addition, 10.5%～13.3% of added straw 15N existed in soil 53 ？m～2 mm fraction, 24.5%～26.5% was in soil 2～53 ？m fraction, and 30% was in 〈 2 ？m fraction. 5.7%～14.9% of added straw 15N was lost at 56 days. Straw decomposed more rapidly in the wushan soil than that in the huangni soil, and more straw 15N was lost in the wushan soil. Gross nitrogen mineralization rates of rice straw in the wushan and huangni soils were 1.61 and 1.48 mg kg-1 d-1 at 0.5 days and were 0.26 and 0.36 mg kg-1 d-1 at 56 d after straw addition, respectively.