长期连作对烤烟产量和土壤养分的影响

Effect of long continuous cropping on the yields of flue-cured tobacco and nutrients in soils

选择贵州省适宜烤烟连作的灰岩黄壤和不宜连作的第四纪黄壤,连续进行了6年的盆栽试验。结果表明,连作总体上降低烤烟产量,但降低幅度因土壤不同而异。在适宜连作的土壤上,短期连作(3季)烟叶产量无显著变化,连作至第4年烟叶产量开始下降;在不宜连作的土壤上,烟叶产量持续降低。连作过程中,烟叶氮、磷、钾含量在一定范围内波动,烟株养分吸收量持续降低;而土壤有效养分含量却不同程度地增加。其中,有效磷增幅最大,有效钾次之,有效氮最低。烤烟连作土壤有机质未发生显著变化,pH呈缓慢降低趋势,原因可能与单施生理酸性的复合肥有关。

A pot experiment with 6 years＇ continuous tobacco cropping was carried out to investigate the effect of continuous cropping on tobacco yields and soil nutrients.The tested soils are calcareous yellow soil originated from lime stone of Triassic（SL）and clay yellow soil originated from clay of Quaternary（SC）.The results show continuous cropping decreased the yields of tobacco leaves in general and varied with soils.Tobacco yields did not show difference in the first three years and decreased afterward on SL,but yields constantly reduced on SC.The concentrations of nutrients in the tobacco leaves,such as nitrogen,phosphorus and potassium,varied with the continuous cropping years.The nutrient absorption was decreased with the prolongation of continuous cropping,but available nutrients were increased with the order： phosphoruspotassiumnitrogen.Continuous cropping did not affect the content organic matter,but decreased pH slowly,It might be resulted from the solo application of physiological acidic complex fertilizers.To this effect,applying organic fertilizer was recommended to avoid the soil acidification.