Іnfluence of long-term use of primary tillage systems on weed infestation of agrocenosis

Topicality. The study of the long-term use of different primary tillage systems will allow us to identify, and consequently predict, possible impacts on production from their use. Purpose. To study the impact of long-term use of different systems of primary tillage on weed infestation of fields. Methods. The research was conducted in a ten-field crop rotation of the stationary experiment in 1989–2000, five-field in 2001–2008, four-field in 2009–2016, and four-field in 2017–2022 at the Khmelnytskyi State Agricultural Experi- mental Station of the Institute of Feed Research and Agriculture of Podillia. In the first (1989–2000) and second (2001–2008) periods, seven systems of primary tillage were studied, including1) moldboard tillage for all crops; 2) chisel tillage for all crops; 3) combined system 1 – surface disking under winter crops after annual crops, moldboard tillage for sugar beet, chisel tillage for all other crops; 4) combined system 2 – surface disking for winter crops after annual crops, chisel tillage for sugar beet, moldboard tillage for all other crops; 5) subsurface tillage for all crops; 6) variable-depth ploughing for all crops; 7) surface tillage – surface disking for all crops. Five systems were studied in the third (2009–2016) and fourth (2017–2022) periods: 1) moldboard tillage for all crops; 2) chisel tillage for all crops; 3) subsurface tillage for all crops; 4) disk tillage for all crops; 5) minimum tillage – shallow disk tillage for all crops, and since 2020 – differentiated tillage, which includes moldboard and moldboardless tillage in crop rotation. The crop cultivation technology is generally accepted for the zone, with the exception of the studied variants of the primary tillage systems. Results. The results of studies of the impact of long-term use of different systems of primary tillage on the quantitative and species composition of the weed component of agrocenosis are presented. It was found that the most favourable phytosanitary condition for all crops was observed under the moldboard system, which resulted in the lowest weed infestation, the chisel system being the closest to it. In all moldboardless systems, the number of weeds was 38–110 % higher than in the moldboard system, their vegetative air-dry weight increased by 15–47 %, and the number of species increased by 6–31 %. Conclusions. As a result of long-term use of different systems of primary tillage, it was found that the best phytosanitary condition for all agrocenosis was in the moldboard system, which was characterised by the lowest number and weight of weeds, the closest to it was the chisel system. In general, the number of weeds in moldboardless systems was 38–110 % higher than in moldboard systems, their vegetative air-dry weight increased by 15–47 %, and the number of species increased by 12–29 %. During 33 years, the field agrocenosis was purified from weeds due to all systems of primary tillage with a decrease in the number of weeds by 53–71 %, their vegetative air-dry mass by 52–70 %, and the number of species by 33–58 %, with the simultaneous formation of a small group of resistant species that are present in agrocenosis permanently in all systems. Key words: moldboard tillage, chisel tillage, subsurface tillage, disking, weeds