Weeds do great damages to agriculture, facilitate the spread of diseases and pests, worsen produce quality, make the work of machines and soil-cultivating devices more difficult, increase energy consumption to produce agricultural output.

Over 1500 kinds of weeds are found in our country, including 300 kinds of those which are the most widely-spread, massive and harmful.

Farm practices, which envisage scientifically-grounded alternation of agricultural crops in crop rotations in compliance with the diversification law, high quality tillage, rational use of fertilizers, timely performance of field work, play a very important role in the efficient control over weeds.

The purpose of the research is to study the regularities of weed infestation in crop rotation fields depending on different tillage systems in short crop rotation.

The research was carried out in the fields of Odesa state agricultural experimental research station of NAAS in 2017. The main method of the research was a field one which was supplemented with analytical studying, measurements, calculations and observations according to the conventional methodology and methodological recommendations in arable farming and crop production.

 

 

The analysis of the generalized data about the weed infestation of winter wheat fields which were received in the field of crop rotation with different tillage systems showed the tendency towards the increase of weed number.

As the systematized statistics confirmed, the total number of weeds under various tillage systems did not differ much, except for the tillage under pattern MShShMSh. The best results were observed under moldboard system of tillage (MShShMSh).

When analyzing weed infestation of the 2^nd crop of winter wheat, another effect of forecrops and tillage systems was recorded, as compared with the 1^st crop. Thus, almost the same weed infestation was recorded on black fallow under two tillage patterns – MShShMSh (49.8 pcs./m²) and WMShShWMShММБМ (50.2 pcs./m²). The worst indicator was received under tillage pattern ShShShMSh (54.5 pcs./m²).

Average indicators of weed infestation after forecrops show the increase of weed number on the 2^nd and 4^th crop after black fallow, if compared with the 1^st crop (winter wheat), and in the 3^rd crop, where oats were sown, some decrease of weed number was found: black fallow has the best results in regulating weed number in winter wheat fields (43.4 and 51.8 pcs./m²); after-effect of black fallow remains in the second year, but weed infestation increases, which amounts to 19.8 % as compared with the previous year; in oats fields after black fallow weed infestation decreases by 4.9 pcs./m² and by 13.3 pcs./m², respectively, as compared with the 1^st and 2^nd crop; on the 4^th crop (winter wheat) after black fallow weed number increases to the level of the 2^nd crop (50.1 and 51.8 pcs./m², respectively).

Key words: crop rotation, tillage, weeds, winter wheat.