光叶紫花苕生物固氮能力及其还田氮素对玉米的当季有效性

Biological Nitrogen Fixation of Vetch and the Availability of Vetch Incorporation N to Maize as Successive Crop

为探明豆科绿肥光叶紫花苕的生物固氮能力以及还田绿肥氮素对后茬玉米的当季有效性,采用15N自然丰度法和15N同位素标记稀释法,测定了大田不同施氮处理下(N0、N75、N150、N225)光叶紫花苕的生物固氮效率和生物固氮量;采用盆栽试验方法,测定了光叶紫花苕不同翻压还田量下春玉米的产量、氮肥利用率以及还田绿肥15N的当季回收率。结果表明,施氮量(N0、N75、N150、N225)对光叶紫花苕生物量(5233.71~6659.86 kg/hm^2)、氮素产量(218.61~278.58 kg/hm^2)及生物固氮量(156.81~189.66 kg/hm^2)均无显著影响,但对生物固氮效率(56.35%~85.63%)有显著影响。同等施氮量(N75或N150)下,15N自然丰度法和15N同位素稀释法测定的生物固氮效率并无显著差异。光叶紫花苕翻压还田量显著影响玉米地上部15N吸收量(0.51~0.94 mg/株)和氮肥农学利用率(40.13~51.28 g/g),但对还田绿肥15N的当季回收率并无显著影响。本试验条件下,豆科绿肥光叶紫花苕大田种植时可以不追施氮肥,以全量翻压还田为宜。本研究结果为豆科绿肥种植的合理施氮和翻压还田利用提供了理论依据。

In order to determine the capacity of biological nitrogen fixation of vetch and the recovery rate of N after vetch returning back to field in maize growth season,one field trial and two pot experiments were conducted in Sichuan Province in China.Two methods,15N isotope dilution(ID)and 15N natural abundance(NA),were employed to determine the efficiency of biological nitrogen fixation(BNF)and the amounts of BNF by vetch cultivated with different N fertilizer application rates(N0,N75,N150,N225)under field conditions.In pot experiments,the biomass production,N fertilizer use efficiency of maize,and 15N recovery rate after soil incorporation with different amounts of vetch were determined.N fertilizer application rates(0,75,150,225 kg/ha)did not significantly influence biomass(5233.71-6659.86 kg/ha),nitrogen yield(218.61-278.58 kg/ha)and amounts of BNF(156.81-189.66 kg/ha)of vetch.However,N fertilizer application rates did significantly change the efficiency of BNF(56.35%-85.63%).There was no significant difference in BNF efficiency estimated with ID or NA methods,when same N fertilizer rate(75 or 150 kg/ha)was applied.The 15N amount accumulated by maize shoots(0.51-0.94 mg/pot)and the agronomic use efficiency of N fertilizer(40.13-51.28 g/g)of maize were significantly influenced by the rates of vetch incorporation.However,the rates of vetch incorporation did not significantly change the vetch-derived 15N recovery rate by the spring maize as successive crop.Therefore,the mineral N fertilizer should not be applied to vetch cultivation on soils with a middle level of fertility and the entire aboveground biomass of vetch should be incorporated into the soil for the following spring maize.The study provided a guideline for the N fertilization for the vetch cultivation and its utilization as green manure plant.