Dynamics of the mobile forms of phosphorus and potassium in the soils of prolonged trials

Abstract

During prolonged field experiments performed with various types of loamy soils, the application of phosphorus and potassium fertilizers increases the content of mobile forms of phosphorus and potassium mainly at the first rotations of field crop rotations only. Later, under positive balance, the content of mobile forms of these elements in soil does not increase and even tends to decrease due to the more intensive transformation. In the case of the negative balance of phosphorus and potassium, plants are supplied with nutrition by immobilization of fixed forms of these elements. In the sandy loam soils, these processes are less pronounced due to the lower absorption capacity of the soils to phosphorus and potassium.