Abstract form

and Na is decreasing up to 6-8% and 1-1.8%, the indices of pH environment and total
alkalinity decreased to the side of soil neutralization (pH 7.8-8.4), the content of
calcium carbonate increased (6.2-7.9%).
Vegetative residuals favoured intensive development of the main physiological groups
of microorganisms (see Table). Their stimulating effect is especially seen in the soil
under lucerne (4820 ths/g), sainfoin (4694ths/g), rye+vetch+rape (4517ths/g). But in the
soil under wild vegetation and pure rye sowing, the stimulating effect of vegetative
residuals is lower.
The ratio of the main physiological groups of microorganisms in the irrigated meadow grey soil
(layer-0-25cm, ths/g of soil) in spring
Plant
Total number of
microorganisms
Percent of the total number of microorganisms
Wild vegetation
Lucerne
Sainfoin
Rye
Rye+vetch+rape
1489
4820
4694
2849
4517
Bacteria Actinomycetes Microscopic
fungi
58
76
75
68
75
42
24
25
32
25
0.09
0.19
0.18
0.11
0.18
Spore
forming
bacteria as
percent of
total number
of bacteria
15.0
9.8
9.4
13.9
9.7
In the composition of microflora, the number of nonspore-forming bacteria increases,
but that of spore-forming bacteria decreases. In the virgin soil, the content of
actinomycetes is higher (up to 50% out of the total number of microorganisms), but the
number of spore ammonifiers is lower (up to 10-19% out of the total number of
bacteria).
The qualitative composition of microorganisms in the soil under lucerne and
rye+vetch+rape is rich compared to the soil under rye and wild vegetation. Here among
the ammonificating bacteria the representatives of Bacillus prevail. Bac. mesenteicus
multiplied intensively (38-45%). The number of bacilli was at its highest point in
rhizosphere close to the flowering period.
The number of microscopic fungi in the virgin soil is low and they are only from
Aspergillus genus. In the soil under lucern and rye+vetch+rape there are an increasing
number of microscopic fungi and enrichment of their qualitative composition
(Aspergillus, Penicillium, Trichoderma, and Alternaria). The appearance of the
representatives of Penicillium, Trichoderma, and Alternaria along with Aspergillus
indicates the formation of favorable environmental conditions in the soil under lucerne,
rye+vetch+rape. The vegetative residuals of these plants have a stimulating effect on the
intensive development of the main physiological groups of microorganisms.
In the soils under all the variants, we could observe seasonal fluctuation of the number
of the particular physiological groups of microorganisms as well as their total number
(maximum exceeds minimum 2-2.5 times as much).
While observing the soil profile under all the crops downwards, it was found that the
absolute and relative number of microorganisms decreased drastically. It was also
found experimentally that correlation coefficient among the number of microflora, and
the total reserve of vegetative residuals of lucerne and rye+vetch+rape is 0.127-13,
together with living roots – 0.380-0.401, together with dead roots- 0.680-0.715.
The sowing of lucerne and rye+vetch+rape and the application of organic and mineral
(N 90 P 120 K 60 kg/ha) fertilizers, improving physical and chemical properties of meadow
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