Summary

especially increases content of nitrates (Bezkorovainaya et al., 2001). By increase of
earthworm density, increases also concentration of phosphorus forms for plants
(Атлавините, 1975, 1990; Lee, 1985).
1.2. Earthworms and soil cultivation
Conventional soil cultivation methods, such as tillage, disking, harrowing have
negative impact on the earthworm population. Tillage changes water content,
temperature, and aeration of the soil. Greater soil organism density is in agriculture
systems, where tillage is not used, because the soil structure and water stability are
maintained (Kladivko-Eileen, 2001; Miura et al., 2008). To Aporrectodea caliginosa
reasonable cultivation usually is favourable (Edwards, Lofty, 1973).
Influence of pesticides on the earthworm populations is ambiguous.
Fungicides, chlorous and phosphoric organic compounds usually have negative
impact, but after herbicide applications, earthworm population increase is being
observed, because expands their nutrition base - remains of weeds decaying tissue.
Lumbricus terrestris are very sensitive if herbicides are being applied to the soil
surface, whereas Aporrectodea caliginosa are more sensitive if herbicides are being
cultivated into the soil (Lee, 1985; Атлавините, 1990; Werner, 1990; Riley et al.,
2008).
Fertilizer influence on earthworms may be different. It is known that applying
of organic fertilizer usually has a positive impact on the earthworm populations.
Regarding the non-organic fertilizer use in agriculture and forestry, their impact is
ambiguous, and research results often are contradictionary.
One of the factors, having impact on the earthworm density in agricultural
lands, is plant culture. The perrenial cultures are more favorable to earthworms than
the one-year cultures. Activities of earthworms also have positive impact on plant
growth and harvest (Атлавините, 1990).
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