Evaluation of available microelement contents in tobacco soils of Chongqing

Available contents of Fe,Mn,Cu,Zn,B and Mo in 334 soil samples taken from tobacco field in 14 counties in Chongqing were measured and distribution patterns were discussed.The results show that more than 20% of the tobacco fields are deficient in available Zn and Mo,while more than 75% have extremely low(nearly unavailable)amount of B.Available Fe and Mn is high,while the soils are quite rich in available Cu.A significantly negative correlation is observed between available Fe,Mn,Cu and Zn and soil pH,while there is a significantly positive correlation between Mo content and soil pH.When pH is below 7.0,available B content increases with increasing pH,but when pH exceeds 7.0,its content decreases.Available Fe and Cu contents have significant positive relationship with organic matter content of the tobacco soils,while available Mn,B and Mo have no significant relationship with tobacco soil organic matter content.