EN
Three field experiments on comparison of the effects of organic and mineral fertilizations on the changes of reaction and acidity of soil were conducted. Slurry fertilizing influenced the change of soil reaction to a small extent but manure caused the soil reaction increase. Mineral fertilizers decreased the soil reaction in each experiment. Fertilizing, except for fertililizing with manure, influenced the increase of acid hydrolysis. More extensive growth of hydrogen cations was observed in those experiments where the only mineral fertilizing was used than where the organic and mineral ones were applied together. The changes in a cation content in comparison to the control experiment were not significant. Their decreasing tendency was noticed. The contents of active manganese and exchangable aluminium were higher in experiments with mineral fertilizers than in those with organic ones.