WEED COMPONENT IN AGROCENOSIS WHICH IS FORMING IN NO-TILL SYSTEM

Abstract

When using no-till technique, weed seeds, which remain on the soil surface, are influenced by environmental conditions. They are eaten by animals and birds and partially die. In
2008, in the conditions of forest steppe zone of Western Siberia in the experimental production farm “Elitnoe” in Novosibirsk Region on the leached chernozem, long-term stationary
experience in a comparative study of the conventional method based on deep nonmoldboard
loosening and no-till technique in two three-field crop rotations was laid: 1) wheat – wheat – oat; 2) wheat – wheat – cabbage family (brown mustard, oilseed radish). Usage level of fertilizers and protective agents was the same in both t techniques. At the beginning of the experiment, determination of potential soil infestation before seeding showed that, on average, the
0-10 cm layer contained 31800 weed diaspores per 1 m2. Among 17 identified weed species,
the dominant were Amaranthus retroflexus – 64, Chenopodium album – 13, and Poaceae –
8%. After the third crop rotation, the amount of weed seeds in the soil decreased by 5.7 times
with the conventional method and by 8.1 times with no-till technique. However, the amount
of Poaceae weeds increased to 68% and 48%, respectively. The composition of broadleaf
weed species was not extensive. Common species were Fallopia convolvulus, Solanum
nigrum, Chenopodium album, Persicaria lapathifolia, Galeopsis tetrahit and Melilotus officinalis. Convolvulus arvensis, Viola arvensis, Linaria vulgaris, Amaranthus retroflexus were
added to this list with no-till technique. Raphanus raphanistrum, Galium aparine, Chenopodium aristatum L. were added with conventional method. When optimizing chemical weeding
of crops, the proportion of weeds in the total aboveground mass of the phytocenosis in the
combined wax-ripe and milk-ripe stage of grain did not exceed the harm threshold (10%) and
was 2.8% with conventional method and 3.0% with no-till technique. Weeds are not an obstacle to the development of no-till technique in the forest-steppe of Western Siberia on chernozem soil.