采用15N示踪技术和密闭培养法研究水稻和玉米秸秆15N在淹水土壤中的转化过程。结果表明 :土壤中秸秆15N的各转化过程相互制约 ,每个过程中15N含量都处于动态变化之中。秸秆种类和土壤类型对土壤矿质15N含量的影响随时间延长逐渐变小 ,培养 112d后土壤中矿质15N含量仅占加入秸秆15N的 0 96 %～ 1 6 8%。秸秆15N有 2 0 3%～ 4 2 5 %被微生物固持 ,0 2 3%～ 14 16 %被粘土矿物固定。粘土矿物类型影响土壤对秸秆15N的固定 ,变性土中固定态15NH+ 4含量明显高于红壤。秸秆15N的固定使其以气态形式损失的量减少 ,这在农业生产中将有助于保持土壤肥力。整个培养过程中秸秆15N的损失率为 2 9 70 %～ 46 30 %。 112d后秸秆15N实际矿化了 47 72 %～5 1 74% ,仍有 5 0 %左右的秸秆15N残留于土壤。 15N tracing technique and confined culture were used to study the transformation of 15N in maize and maize straw in flooded soil. The results showed that the 15N transformation of straw in soil was restricted by each other, and the content of 15N in each process was in dynamic change. The effect of straw types and soil types on the 15N content of soil minerals gradually became smaller with the extension of time. The content of mineral 15N in soil after culturing for 112 days accounted for only 0 96% -168% of that of 15N straw. Stalks 15N with 20.3% ~ 42.5% were retained by microorganisms, while 02-23% ~ 14-16% were fixed with clay minerals. Clay mineral types affect soil 15N fixation of straw, fixed soil 15NH + 4 content was significantly higher than red soil. Stabilization of straw 15N reduces its loss in gaseous form, which will help maintain soil fertility in agricultural production. The loss rate of straw 15N was 2970% -4630% during the whole cultivation process. After 112 days, the actual mineralization of straw 15N was 47 72% -51 74%, and about 50% of straw 15N remained in the soil.