IMPACT OF FERTILIZERS ON SOIL PROPERTIES IN THE CASE OF SOLANUM TUBEROSUM L. DURING CONVERSION TO ORGANIC FARMING

In organic farming the use of mineral fertilizers is highly restricted; hence biofertilizers are often used. The aim of the research was to investigate the effects of different fertilizers on soil microbial communities and enzymatic activity after conventional production. A field with potato cultivation under conversion to an organic system was established. The nitrogen organic fertilizer Bioilsa and two microbial biofertilizers - UGmax and EM - were used. The highest values of dehydrogenase activity (DHA) were observed in the soil where UGmax was used alone. Application of biofertilizers also caused an increase of DHA in variants with Bioilsa fertilizer. The differences in activity of phosphatase in relation to application of different biofertilizers were observed, but it was higher than in variants with Bioilsa. Application of Bioilsa had a positive effect on activity of acid and alkaline phosphatases, but probiotic EM reduced this positive effect. The total number of bacteria and actinobacteria was the highest in EM variants, not fertilized with Bioilsa. In the case of the fungal population no correlation with fertilization was noted. We conclude that biofertilizers can activate the microbial and enzymatic activity of the soil after intensive agriculture production and can neutralize the negative impact on these parameters of nitrogen fertilizer.