Crop rotation is known as an eco-friendlier approach, as provides diversification in crop management systems, modifies intensive pressure on the agricultural ecosystem, utilizes various soil horizons, and prevents the establishment of specific pests and weeds. We set out here a study on the farms that have been managed over 50 years of specific continuous crop management programs. The experimental treatments were in a different management system: monoculture of maize, winter wheat, and soybean, 2-year crop rotation (winter wheat–maize) with and without chemical fertilizer, and 3-year crop rotation (winter wheat–soybean–maize) with and without chemical fertilizer and manure. We took soil samples six times from 2014 to 2017 prior to sowing and after harvesting each year. Weed seeds were extracted from soils and identified and counted by species. We, upon the data of a long term experiment of crop rotation, could conclude that crop rotations with more crops in the sequence are significantly effective in maintaining weed populations, a low-input crop production could reach a constant low population below an important damaging density, and therefore will be a more sustainable crop production while chemical fertilizers would change the soil’s chemical and structure and imbalance the plant population diversity and manures with high weed seed infestations have the potential to totally eradicate crop rotation effects, Therefore, clean manures or compost are highly recommended.

Knowledge and understanding of the size and composition of soil weed seed reserves can help in planning a successful and timely weed control strategy and assessing the dynamics of weed emergence. It is very important to have an insight into what percentage of the latent plant community will pass into the active community. The seedling emregence method gives the number and structure of seeds that have passed the dormancy phase. It was determined that in the monoculture of soybean 24.9% of seeds are ready to germinate out of the total estimated weed seed bank, while in the three-field crop rotation 23.61% of seed. The largest number of germinated seeds comes from the weed species Chenopodium albumand Chenopodium hybridum.

In order to cope with all the natural phenomena and survive on different types of soil and in different climatic conditions, plants have perfected their means of propagation. Weed seeds are characterized by high diversity in all segments, both physical and chemical. Knowledge of the morphological characteristics of seeds and fruits of weed plants (mass, size, shape, colour, luster, odor, appearance of surface structures) is of great importance in the planning of weed control measures. The subject of this study were the seeds of the species Chenopodium album, C. hybridum, Anagallis arvensis, Veronica hederifolia and Amaranthus retroflexus, which were isolated during the weed seed bank assessment in the soil. After the physical extraction from the soil samples, the seeds were separated from the admixture, determined and then photographed with a stereomicroscope. The dimensions (length, width, seed thickness and length of the navel) were measured and any changes in the seed coat produced as a result of physical damage were monitored. The aim of this research was to expand the database, which should contribute to a more efficient determination of weed seeds. It was found that the seeds of the species studied in this paper were often broken and damaged, although in most cases with similar morphological features, as indicated by the literature data. The seeds of the species C. album were an exception, with dimensions significantly different from the data available in the literature. This occurrence can be explained by the diversity of seed anatomy in the Chenopodiaceae family and also by the fact that during their stay in the soil, permanent changes in the seed surface structures are possible.