不同施肥模式对烤烟生长和根际氮素营养的影响

为探索烤烟的科学施肥模式,采用根箱培养法研究了不同施肥模式对烤烟生长和根际氮素营养的影响。结果表明,有机无机肥配施模式下烟苗的生物量和氮素吸收量比对照分别提高了120.45%和141.35%;铵态氮和碱解氮在土壤中的移动速率低于烟苗根系的吸收速率,施肥显著提高根际土壤中的铵态氮和碱解氮含量,有效增加了土壤氮素的供应强度;硝态氮在土壤中容易向根系表面迁移,施用化肥可提高根际土壤硝态氮含量,施用有机肥则相反;近根区(距根系3mm以内)土壤脲酶活性高于远根区(距根系10mm以外),施用有机肥提高了根际土壤脲酶活性,土壤有机质含量与脲酶活性呈正相关;近根区土壤pH显著低于远根区,单施化肥显著降低了根际土壤pH,有机无机肥配施对根际土壤pH无显著影响,单施化肥容易造成土壤酸化,有机无机肥配施可避免单施化肥产生的负面影响。

Effects of Different Fertilization Models on Growth of Flue-cured Tobacco and Rhizospheric Nitrogen Nutrition

For the purpose of exploring a scientific fertilization model of flue-cured tobacco,flue-cured tobacco seedlings were cultured in root boxes to investigate the effects of different fertilization models on seedling growth and rhizospheric nitrogen nutrition.The result showed that compared with CK the biomass and nitrogen absorptive amount were increased by 120.45% and 141.35% respectively when fertilized with organic and inorganic fertilizers.Absorption rates of NH+4-N and NaOH-hydrolized N by the seedlings were faster than its movement speed in soil.Fertilization raised the contents of NH+4-N and NaOH-hydrolized N in the rhizosphere of tobacco significantly,and increased nitrogen supply intensity.NO-3-N in soil moved to the surface of root system easily.Chemical fertilizer remarkably increased the NO-3-N in rhizospheric soil in contrast to the organic one which behaved otherwise.Furthermore,the activity of urease was higher in the soil near the roots than that far from the roots.Organic fertilizer also increased obviously the activity of urease in the rhizospheric soil.There was a significant correlation between organic matter in soil and urease activity.Soil pH was lower near the roots than that far from roots and chemical fertilizer decreased soil pH.In contrast,there was no significant influence of the mixture of organic and inorganic fertilizers on soil pH,indicating the acidification caused by chemical fertilizer and less effect of chemical fertilizer in combination with organic manure.