植烟黄壤供氮特征研究

【目的】研究烤烟生长期间植烟黄壤的氮素矿化及供氮特征,为烟草氮素营养调控提供理论依据。【方法】选择两块有机质含量存在差异的黄壤试验田,每块试验田设休闲、植烟不施氮、植烟施氮90kg·hm-2、植烟施氮120kg·hm-24个处理,采用埋袋法进行田间原位培养。【结果】在烤烟生长期间,不施肥植烟土壤氮矿化存在两个高峰,一是在烤烟旺长期(烤烟移栽后42d左右),二是在烤烟打顶后(烤烟移栽后77d左右)。在烤烟生长期间,随着时间的推进矿化氮累积量增加,至烤烟移栽91d左右,矿化氮累积量趋于平缓。有机质含量为15.5和23.7g·kg-1的不施肥植烟土壤累积矿化量分别为80.4和88.5kg·hm-2,打顶后土壤矿化氮量占其矿化氮总量的58%、65%。土壤有机质含量对土壤氮素矿化动态影响不显著,肥料氮的施用导致土壤氮矿化动态波动幅度增大,在烤烟生长前期形成净固定,对烤烟生长后期土壤净矿化产生显著正激发效应。【结论】调控烟草生长后期土壤氮素矿化,能够减少烟草生长后期土壤氮素供应;减少烟草生长前期土壤无机氮固定,促进烟草生长前期无机氮释放,也能在一定程度上缓解烟草生长后期土壤氮素供应过量的问题。

The Characteristics of Nitrogen Supply in Yellow Soil Planted with Tobacco

Objective]In this paper,the characteristics of nitrogen mineralization and nitrogen supply of yellow soil planted with tobacco during the growing period of flue-cured tobacco were studied,thus providing a theoretical basis for nitrogen nutrition control of flue-cured tobacco. Method]The field plot experiment adopted the in situ incubation and two experimental fields of yellow soil with different organic matter content were selected.Each experimental plot contained four treatments,I.e.fallow,planting tobacco without N,planting tobacco and supplied 90 kg N·hm~2,planting tobacco,and supplied 120 kg N·hm~(-2).Result]The results showed as follows.In flue-cured tobacco growth period,two peaks of soil nitrogen mineralization were observed,one was at the flue-cured tobacco rapid growing stage(42 days after transplanting),and the second was at the stage of top pruning(77 days after transplanting).During the growth period of the flue-cured tobacco,with the advance of time,the cumulation of the mineralizable N increased,until about 91 days after transplanting of the flue-cured tobacco,the cumulative amount of mineralizable N tended to slow.The effect of soil organic matter content on the dynamics of soil nitrogen mineralization rate was not significant,the use of nitrogen fertilizers resulted in the large fluctuations of the dynamics of soil nitrogen mineralization fluctuations.The soil mineral nitrogen was net fixed at early growth stage of flue-cured tobacco and net mineralization had a significant effect at the late growth stage.Conclusion]Therefore,controlling soil nitrogen mineralization during the late growth period of tobacco can reduce soil nitrogen supply at late growth period of tobacco,at the sanle time,reduce the inorganic soil nitrogen fixation at the early growth stage of tobacco and promote the pre-release of inorganic nitrogen at the early growth stage of tobacco,and to a certain extent,can also alleviate the problems of excessive soil nitrogen supply at the late growth stage of tobacco.