COMPETITIVE ABILITY OF MIXED CROPPING SYSTEMS AGAINST WEEDS

Weeds have been identified as a threat to arable crop production because crop-weed competition may result in considerable yield losses. Weeds and crops often possess similar characteristics, making weed control challenging. Chemical weed control may lead to environmental and health issues, as well as troubles in crop production. Nowadays the tendency is towards more sustainable agricultural practices to control weeds including mixed cropping systems. In earlier studies, mixed cropping systems were observed to reduce weed biomass, whereas weed diversity was affected by environmental and temporal factors. The present study was conducted at the Knehtilä organic farm in Hyvinkää to evaluate the competitive ability of mixed cropping systems against weeds. Crop stands were 50:50:50% and 33:33:33% oat, pea, and camelina mixtures, along with 100% oat, 100% pea, and 100% camelina stands. Plant sampling was conducted 24 Days after seeding (DAS), 38 DAS, 52 DAS, 66 DAS, and 97 DAS. Crops and weeds were separated and the number of plants in each species was counted. Weeds at the species level were identified. Dry biomass of crops and weeds was recorded at each sampling time. Weed species richness, Shannon-Weiner diversity index, species evenness, and species dominance were calculated. The most common weed species was Chenopodium album L., while the least common species was Cerastium fontanum Baumg. Crop stands accumulated in weed biomass until 52 DAS, followed by a gradual decline over sampling times. Weed biomass was lower in 50% and 33% mixes than sole crop stands in early growth stages. Significant differences in the Shannon-Weiner diversity index, species richness, evenness, and species dominance were found in crop stands at 24 DAS and 66 DAS. There was a positive correlation between weed evenness and crop biomass. The study proved that mixed crop stands (50% and 33% mixes) have effective weed control ability, indicating low weed biomasses compared to sole cropping systems. Weed diversity indices fluctuated at 24 DAS and 66 DAS, indicating that sampling time influences weed diversity. The positive correlation between weed evenness and crop biomass indicates the impact on species dominance and intraspecific competition. The study suggests that mixed cropping systems are effective at controlling weeds and highlights the importance of understanding temporal dynamics and weed-crop interactions in cropping systems to enhance crop yield. Future research should focus on understanding the fundamental mechanisms behind weed-crop interactions across cropping systems.