Keywords: peat soils, organic matter, evolution, transformation, fractions, potassium, properties

// Мелиорация. – 2015. – №1(73).– С. 111-121

The article describes how drainage and long­term (50 yeas) agricultural use of peat soils causes transformation in composition, structure and reserve of potassium fractions. In peat­bog soils reserve of gross forms of potassium in 0­40 cm layer is 560 kg/ha, exchangeable peat forms – 100 kg/ha. In agro peat soils of different stages of evolution gross peat form increases in 2.5­4.9 times, moving fractions and others increase in 5­10 times or more. In organic mineral soils with organic matter less than 20 % all fractions decrease. The lowest reserves of peat fraction are in mineral post­peat soil (exchangeable, moving, and available forms are 0.5­0.52 t/ha and water­soluble form is 0.14 t/ha.