半腐解秸秆覆盖下旱作水稻对^(15)N的吸收和分配

Distribution of ^(15) N Applied at Different Stages in Different Parts of Rice Cultivated on Upland Soil Mulched with Half-Decomposed Rice Straw

在模拟田间条件下的水泥池 (微区 )内 ,用半腐解秸秆覆盖旱作水稻 ,两个水平的1 5N标记尿素分别作基肥、分蘖肥和穗肥施用 ,研究了不同时期施用的 1 5N在水稻各部位的分配、1 5N的利用率和土壤 -植株系统的氮素平衡。结果表明植株氮素含量中来自肥料氮的百分比 (Ndff% )、水稻对 1 5N的吸收和利用率以及 1 5N的土壤残留率因标记肥料的施用时期和用量的不同而有很大差异。分蘖肥的1 5N在水稻各部位中的 Ndff%最高 ,而作为基肥施入的1 5N在水稻体内的 Ndff%最低。植株对氮肥利用率的最低和最高值分别为 5 .5 8%和 5 1.5 3% ,氮肥的土壤残留率最低和最高值分别为 13.81%和 2 9.87%。

Urea 15 N fertilizers were applied at different stages of rice growth to the soil mulched with half decomposed rice straw in which rice plants were grown on upland condition to study the distribution of 15 N in different parts of rice plant. Results indicated that plant Ndff% (percentage of nitrogen content from nitrogen in fertilizer), 15 N uptake, 15 N use efficiency and 15 N remained in soil were significantly affected by timing of 15 N application treatments and 15 N rates. Maximum Ndff% was obtained with the 15 N topdressing at tillering stage, and the minimum was found in the treatment of 15 N applied as basal fertilizer. The minimum and maximum of total 15 N use efficiency by the plant were 5.58% and 51.53%, and those remained in soil were 13.81% and 29.87% .