Combination of cover crops and bacterial consortia reduce weediness in organic spelt wheat in Central Europe

Cultivation technologies based on the use of microbiological preparations or the introduction of cover crops in organic farming are alternatives to chemical plant protection products. To confirm this hypothesis, field studies were conducted in central Poland in 2019–2022 to determine the effect of bacterial consortia and green fertilizers from cover crops on the dry mass, abundance and species composition of dominant weed species occurring in spelt wheat grown in organic farming. Two factors were researched: I. Bacterial consortia: control treatment (no bacteria), bacterial consortium I (Azotobacter chroococcum + Azospirillum lipoferum Br17), bacterial consortium II (Bacillus megaterium var. phosphaticum + Arthrobacter agilis), bacterial consortium III (Azotobacter chroococcum + Azospirillum lipoferum Br17 + Bacillus megaterium var. phosphaticum + Arthrobacter agilis), II. Cover crops: control treatment (no cover crops), red clover, red clover + Italian ryegrass, and Italian ryegrass. Spelt wheat was harvested in late July. Just before harvesting, weeds were sampled to determine their dry matter, number, and species composition. The research clearly demonstrated that the application of bacterial consortia with cover crops significantly reduced the dry matter and number of weeds, including the dominant species. The greatest reduction in weed number was recorded in treatments after the application of bacterial consortium III in combination with plowing cover crops of red clover and a mixture of red clover and Italian ryegrass.