The use of conventional tillage techniques for a long period of time was considered the main way to create favourable water-physical soil properties for most crops. However, erosion processes, increase of unproductive moisture losses in soil, reduction of humus content cause new alternative ways to save soil fertility to be sought of.

The aim of research was to establish the impact of no-till and conventional tillage on soil structure.

The research has established that use of plowing as the main cultivation technique during 10 years had a negative impact on the soil structure. At the time of sowing the best structuring results were shown by the variant without tillage, and this trend continued in all the soil layers under study. In this study, the top 0-10 cm layer contained the least number of units. The same trend was observed in case of traditional tillage, but with a difference of 8 % downward. The next layer under study was characterized by increased content of units ranging from 10 to 0.25 mm by 4.4 % for the "zero" cultivation and 3.4 % for plowing.
In the layer 20-30 cm in no-till variant this index did not change significantly. In case of traditional cultivation there was a significant increase in the number of units ranging from 10 to 0.25 mm that exceeded LSD almost twice. Besides, in this case, the least difference (2.1 %) between the studied variants was observed.

In post-harvesting period in case of "zero" tillage improvement of the soil structural condition was observed. The average amount of agronomical valuable aggregates in three layers increased respectively by 3.8 and 4.5 % compared to the figures in the period of harvesting and at the beginning of the growing season. It should be mentioned that the significant positive changes took place in the top 10-cm layer (+ 5 %), and in lower layers the index fluctuated within 3 %. In control variant in the layers
0-10 and 10-20 cm the largest variation of data was observed, compared to those obtained in period of spring barley harvesting.
In addition, in the aforementioned layers improved the soil structure by 9.2 % and 9.4 % respectively. The average difference value between the results that were obtained at the time of harvesting and autumn amounted to 8.8 % (2.3 times more than in case of "zero" tillage).

Increase of pulverized and lumped structure fraction content has negative impact on the agrophysical soil properties, deteriorating its water-air regime, seed germination, root development, etc. During the period of the present study the share of these fractions in soil structure varied over time and differed in variants. In no-till variant the pulverized structure content at the time of sowing was 2.6 %, which differed little from the conventional tillage (2.9 %). During spring barley vegetation period the trend towards increase of the number of dispersed structure in direct sowing to 4.9 % was observed, while in case of traditional tillage this figure increased more than twice (6.6 %). In the autumn period there was a further increase of dispersed structures by 16.3 % in no-till variant compared to the index that was obtained during the full maturity period. In case of plowing the index was 33 % higher and amounted to 7.6 %.

The maximal index of the lumped structure content was observed at the beginning of the growing season in both direct sowing and plowing – 19.2 and 20.7 % respectively. In the harvesting period this index decreased in both cases – 3.0 and 2.3 % respectively. In the autumn period in case of direct sowing the lumped structure share was 11.6 %, which was 39.6 % less the initial value. In conventional cultivation the lumped structure content in autumn also significantly decreased and amounted to 12.1 %, which was 41.5 % less the value at the sowing time.

In both traditional tillage and no-till the average yield of spring barley during the two-year period was 4.37 and 4.73 t/ha, respectively.

Key words: soil structure, soil, plowing, no-till, barley.