Effect of Potassium Application on Spatiotemporal Change of Available Potassium in Tobacco Field Soil under Drought Stress

A water-controlled experiment was conducted to study the effect of potassium application on spatiotemporal change of available potassium concentration in tobacco field soil under drought stress.The results showed that under drought stress,the concentration of available potassium decreased with the increase of soil depth,while it raised with the increase of potassium rate.With the prolonging of drought time,the concentration gradient of available potassium in rhizosphere(soil depth of 0-40 cm) increased obviously,and raised with the increase of potassium rate.The mathematic model for the gradient of available potassium concentration(K) in soil of 0-40 cm in depth against the length of drought stress time(t) was K=atb,which could be used to predict the change of concentration gradient of available potassium in tobacco field under drought stress.