The influence of long-term application of mineral fertilizers on the content of exchange cations in the soil

Abstract

The purpose of the work was to detect the effect of the long-term application of certain mineral fertilizers (N, P, K) and pair combinations (NP, NK, PK) on the content of exchange cations (Са2+, Mg2+, Na+, K+) in the chernozem typical heavy loamy. The research was conducted in the field stationary experiment, which was laid in 1990 in the research farm of NSC "Institute for Soil Science and Agrochemistry Research named after O. N. Sokolovsky" in the Kharkiv region. Eight variants with the following average fertilizer rates (kg/ha active substance) were selected for research during 26 years of the experiment: 1 without fertilizers (control); 2 N100; 3 P96; 4 K83; 5 N100P96; 6 N100K83; 7 P96K83; 8 N100P96K83. Soil samples for analytical studies were taken from a layer of 0-30 cm in August 2016. The content of exchange cations was determined by the Schollenberg method, the pH of soil solution - in aqueous suspension by potentiometric method. The largest losses of exchange cations from the soil (as compared to control) were detected in areas with nitrogen fertilizers (N) and their combinations with phosphoric (NP) and potassium (NK). The content of cations in soils, fertilized with phosphate-potassium fertilizers, changed slightly. The degree of saturation of the colloidal complex with exchange cations is 85-87%. In order to investigate the possibility of increasing the amount of exchange cations at the expense of calcium, it was determined that the colloidal soil complex can also absorb Са2+ 3.48-3.67 mmol/100 g of soil.