Summary:

One of the most important problem of the Polish agriculture is soil acidification and the low content of basic nutrients as well as high mobility of heavy metals. The research was conducted on the basis of a long-term (38 years) field experiment, which was located on the area of the UTP Research Station in Wierzchucinek that was found in 1974 on Podzolis (WRB 2014). Natural fertilizing or liming were not applied in the research. The effect of the 38 years' application of high doses of nitrogen (N83, N167, N250) and potassium (K0, K53, K105, K158) as well as the fodder-industrial crop rotation was soil acidification. The fertilization applied in the experiment significantly determined the contents of the assimilable forms of copper and zinc in the examined soil. On average, independent of a dose of potassium applied, the highest values of the parameters observed were found after the highest doses of nitrogen (N250) were applied. Essential correlations between the contents of the examined microelements in soil samples and their basic chemical parameters were also determined. The contents of the assimilable zinc and copper were significantly lower than the national average, but they all were in the low and average soil fertility class.