烤烟连作对重庆土壤养分状况的影响

Effect of Continuous Cropping on Soil Nutrient Status in Chongqing Tobacco Field

通过田间取样和室内分析相结合的方法,调查研究了重庆市石柱、奉节和南川3个县烤烟连作土壤的养分状况。结果表明:烟田连作后土壤pH值下降,相邻茬次之间平均下降0.05,土壤酸化;有机质含量逐年下降,相邻茬次之间平均衰减0.56%g/kg;全氮、全磷、全钾含量随连作年限延长表现出不同程度的升高趋势,表现为P(6%～31%)>K(6%～21%)>N(2%～12%);速效磷、速效钾含量随连作年限延长逐年降低,且降低程度P(6%～24%)>K(2%～10%),速效氮含量略有上升;速效养分N/P、N/K和K/P比值明显增加,土壤养分比例失调。

By means of field sampling and laboratory analysis,we investigated the soil nutrient status of Chongqing after continuous cropping.Preliminary results showed that the pH value decreased,average decrement of neighboring stubbles uas 0.05 unit the soil acidification and soilorganic matter content would decrease year after year,average decrement of neighboring stubbles uas 0.05 due to the tobacco field continuous cropping.The total nitrogen,total phosphorus and total potassium content of soil increased differently with the extension of cropping year(P(6%～31%)>K(6%～21%)>N(2%～12%)).Available phosphorus and potassium content lowered year after year.The level of reducing of P(6%～24%) is larger than that of K(2%～10%),and available nitrogen content had a slight increase.The ratios of N/P,N/K,K/P increased significantly,which resulted in the imbalance of soil nutrient.