Abstracts. Studies were carried out in an experimental orchard in the years 2008–2009. Apple-trees of ‘Topaz’ cultivar were planted in five “soil localities”: 1 – directly in grubbed up rows of an apple-tree orchard, 2 – in herbicide fallow belts of grubbed up apple-tree orchard, 3 – in turf belts of grabbed up apple-tree orchard, 4 – in a locality after a four-year break in apple-tree cultivation, without any preparatory treatments and 5 – in a soil after previous agricultural use – virgin soil. During the studies realization, an evaluation of the soil biochemical properties was carried out. This evaluation was done on the basis of activity of enzymes: dehydrogenases, proteases, acid phosphatase and urease, IAA content, total content of organic carbon and of organic carbon soluble in water. Our studies have shown a significant influence of the soil locality and of the term of soil sampling for the identification of the biochemical properties of soil expressed by the enzymatic activity. The activity of three studied enzymes was significantly lower in the locality 1 in comparison with the soil in a locality 5. Also in case of indole-3-acetic acid (IAA), its highest value was found in the soil of combination 1 while the highest value of the IAA acid was found in combination 3. The previous method of soil utilization also exerted a significant influence on the content of organic matter in the soil. The content of total organic carbon and organic carbon soluble in water were significantly lower in the soil from the orchard planted directly after previous agricultural use. Enzymatic activity and content of organic carbon were the highest in the autumn period, while the lowest value was shown in summer.

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