Fate of Azolla spp. and urea nitrogen applied to wetland rice (Oryza sativa L.)
Fate of Azolla spp. and urea nitrogen applied to wetland rice (Oryza sativa L.)
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满江红的命运。
DOI：
10.1007/bf00257752
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发表时间：
1989
影响因子：
6.5
通讯作者：
D. Eskew
中科院分区：
文献类型：
--
作者：
I. Watanabe;W. Ventura;G. Mascarina;D. Eskew
国际水稻研究所（IRRI）以15n为试验材料，研究了氮素与氮素和尿素分别施用于湿地水稻的命运。在附近较大的地块上，也用未标记的氮源测定了产量响应和氮吸收。用标记硫酸铵反复标记小叶偶氮。在移栽后0天和42天交替施用标记氮和未标记氮，以确定施用时间对氮唑兰有效性的影响。氮唑兰的掺入量在同位素区比尿素氮（30 kg N ha - 1）的掺入量多23%，在产量响应区则少7%。在产量响应区，尿素处理的水稻产量和总氮吸收量均高于氮唑兰处理，但氮唑兰的生理效应（产量响应/氮吸收量增加）高于脲。研究了水稻第一季和第二季后的标记氮平衡。第一季后，尿素处理的氮素损失（30% ~ 32%）高于olla处理（0% ~ 11%）。移栽后42 d侧施氮的损失小于基施氮。第一次收获后，15n没有进一步损失。第一季水稻基施氮氮回收率为39%，侧施氮氮回收率为63%。基施尿素15n回收率为27%，侧施尿素15n回收率为48%。第二季氮素从氮肥和尿素中回收的残留量相似。氮唑兰的室内培养和土壤中标记交换态氮的变化表明，至少65%的氮唑兰（氮含量4.7%）在10天内矿化。
Using15N, the fate of N applied to wetland rice either asAzollaor urea was studied in a field at the International Rice Research Institute (IRRI). In bigger plots nearby, yield response and N uptake were also determined with unlabelled N sources.Azollamicrophylla was labelled by repeated application of labelled ammonium sulfate. Labelled and unlabelled N were used alternately in applications ofAzollaor urea 0 and 42 days after transplanting, in order to determine the effect of the time of application on the availability ofAzollaN. The quantities ofAzollaN incorporated were 23% more than those of urea N (30 kg N ha−1) in the isotope plots or 7% less in the yield response plots. Grain yield and total N uptake by the rice plants in the yield-response plots were higher in the urea-treated plots than in theAzolla-treated plots, but the physiological effect ofAzollaN (grain yield response/increase in N uptake) was higher than that of rea. The labelled N balance was studied after the first and second crops of rice. Losses of labelled N after the first crop were higher from urea (30%–32%) than fromAzolla(0%–11 %). Losses in N applied as a side dressing 42 days after transplanting were less than those of N applied basally. No further losses of15N occurred after the first crop. The recovery ofAzolla15N in the first crop of rice was 39% from the basal application and 63% from the side dressing. The recovery of urea15N was 27% from the basal application and 48% from the side dressing. Recoveries of residual N from bothAzollaand urea during the second rice crop were similar. Laboratory incubation of theAzollaused and the changes in labelled exchangeable N in the soil showed that at least 65% ofAzollaN (4.7% N content) was mineralized within 10 days.