An increase in the area under soybean and other legume crops in Europe is one of the assumptions of the European Soya Declaration. A study was undertaken to evaluate the influence of cropping system and tillage system on yield, some quality characteristics of soybean seeds and economic evaluation. Therefore, this paper is of interdisciplinary nature. On average over a four-year study period, the soybean seed yield was significantly higher in monoculture compared to the yield obtained in crop rotation. A decreasing trend in yield of monocultured soybean was only observed in the 4th year of the experiment. Seeds grown in monoculture were characterized by a significantly higher percentage protein content and a lower fat content compared to obtained in crop rotation. Plough tillage affected more beneficially soybean yield. Under no-tillage conditions, soybean seeds were shown to have a higher percentage protein content and a lower fat content. The average income per ha of soybean grown under plough tillage system was higher by EUR 64.6 than that under no-tillage. In comparing production profitability depending on the cropping system, it can be noted that it was more beneficial to grow soybean in monoculture. In monoculture, both plough tillage and no-tillage generated a higher income per ha than in the case of soybean grown in crop rotation.

Environmental factors, including weather and soil conditions, can affect the competitive effects of weeds on crops. This work aimed at a comparison of the competitive abilities of winter wheat toward bentgrass (Apera spica-venti (L.) P. Beauv) with single herbicide resistance, multiple herbicide resistance, or a susceptible biotype in different environmental conditions of Poland. A replacement series competition model was applied in field conditions in 2017–2018 and 2018–2019 across the country. A competitive ratio (CR) was calculated for the relative biomass of plants and grain number. A canonical variate analysis (CVA) was performed for biological parameters and a day-difference in emergence between winter wheat and bentgrass with the hydrothermal coefficient and soil texture in all of the sites in each season separately. Winter wheat emergence was correlated with the amount of precipitation after seeding, and was fastest for five days in humid conditions, and slowest up to 22 days, when the precipitation in October was low. The CVA proved that winter wheat’s competitive effects toward the susceptible or herbicide-resistant biotypes of bentgrass are site-specific. During the dry season, the bentgrass biotype with multiple herbicide resistance was more competitive toward winter wheat than the susceptible one. The wheat CR < 1 with regard to biomass and both biomass and the grain number was in 64% and 50% of all the combinations with the resistant biotype. In conclusion, weather affects the competitive effects of winter wheat toward herbicide-susceptible or resistant bentgrass.

This study evaluated weed infestation and health of the soybean crop grown in crop rotation (CR) and monoculture (CM) under conventional tillage (CT) and no-tillage (NT) conditions. The research proved that growing soybean in monoculture and under no-tillage conditions increases weed infestation and infection of soybean with fungal diseases. In these treatments, increased numbers of most of the dominant species were also found. A significantly higher percentage of monocotyledonous species and a much lower percentage of dicotyledonous ones in total weed dry weight were shown in the CR treatment relative to CM and in the NT system compared to CT. The biodiversity of the weed community was similar in monoculture and crop rotation, and slightly greater in the NT system in comparison with CT conditions. In both tillage systems, Amaranthus retroflexus was the weed species that most infested the soybean crop. In soybean grown after itself, Amaranthus retroflexus was the weed that occurred in the greatest numbers, while, in crop rotation, this was Echinochloa crus-galli. In all years of the study, soybean was infected with Septoria glycines to the highest degree, which was followed by Cercospora sojina, whereas infection with Ascochyta sp. was the lowest. Weather conditions in individual years of the study were proven to affect weed infestation and infection of soybean with fungal diseases. The study results prove that cropping systems and tillage systems significantly affect weed infestation and health of the soybean crop.

The effects of previous crops (soybean (Glycine max (L.) Merr.) and winter oilseed rape (Brassica napus L. ssp. oleifera Metzg)), as well as of conventional tillage (CT) and no-tillage (NT), on yield and some quality parameters of winter wheat (Triticum aestivum L.) grain were evaluated based on a four-year field experiment. Wheat was grown in a four-field crop rotation: Soybean—winter wheat—winter oilseed rape—winter wheat. The study revealed that growing winter wheat after soybean, compared to its cultivation in the field after winter oilseed rape, significantly increased grain and straw yield, as well as all yield and crop components evaluated. After the previous soybean crop, higher grain protein content, Zeleny sedimentation value, and grain uniformity were also found. After winter oilseed rape, only a greater value of the gluten index was obtained. Statistical analysis did not show the tillage system (TS) to influence the grain yield of winter wheat. Under the CT system, relative to NT, straw yield, number of ears per 1 m2, and plant height of winter wheat were found to be significantly higher. The NT system, on the other hand, beneficially affected the thousand grain weight. Wheat grain harvested under the CT system was characterized by a higher grain test weight, better grain uniformity, and lower gluten index than under NT.

Direct drilling is one of the methods to reduce tillage costs. Low labor intensity of this system also makes it possible to grow crops in locations where it is a problem to maintain optimal sowing time. However, the use of no-tillage can cause increased weed infestation of crop plants and as a consequence a decline in crop yields. The present study investigated the effect of two tillage systems, plough tillage and direct drilling, on the species composition, density and air-dry weight of weeds in crops of two soybean cultivars (‘Aldana’ and ‘Augusta’). A three-year field experiment was set up on loess-derived gray-brown podzolic soil. The study showed that the use of direct drilling for soybean cropping resulted in a significant increase in the density and dry weight of weeds relative to plough tillage. The study also found richer floristic composition of weeds and an increase in the numbers of dominant species under no-tillage conditions. <em>Elymus repens</em>, <em>Echinochloa crus-galli</em> and <em>Chenopodium album</em> were dominant weed species in all experimental treatments. <em>Chenopodium album</em> and <em>Galinsoga parviflora</em> were characterized by the highest constancy (constancy classes V and IV) in crops of both soybean cultivars, whereas <em>Echinochloa crus-galli</em> showed the highest constancy value in the ‘Aldana’ crop. Under direct drilling, most weed species were found to exhibit higher constancy compared to plough tillage.