The effect of long-term crop rotation on the amount of weed seeds in the soil

Abstract

The spread of characteristic weeds is one of the main factors limiting crop productivity and soil productivity in crop rotations. The similar chemical composition of weeds and agricultural crops leads to interspecies competition in agrocenoses – for nutrients, moisture, heat and light. The investigations were carried out at Vytautas Magnus University Experimental Station in 2018. The aim of the experiment was to determine the influence of long term crop rotations influence on weed seeds in the soil. The three courses, the Norfolk, the field with row crops, the fodder, the intensive, for green manure crop rotations, the rye monoculture and the 50 year bare fallow. In these crop rotations, the studies of amount of weed seeds are carried out on the crops of wheat Triticum aestivum L. (summer form), rye Secale cereale L. (summer form) and barley Hordeum vulgare L (summer form). Seeds of frost-blite (Chenopodium album L.), pale persicaria (Polygonum lapathifolia L.), cockspur (Echinochloa crus-galli L.) and lady's thumb (Persicaria maculosa L.) dominated in different crop rotations, monocultures and continuous bare fallow. Different crop rotations and continuous bare fallow had not significantly differed of amount of weed seeds. Short-lived weeds dominated in wheat, barley and rye crops. Distribution trends of short-lived weed in different crop rotations, monocultures and continuous bare fallow was established similar like general distribution of weeds. The amount of perennial weed seeds in the soil was established in continuous bare fallow and barley crops where pre-crops were potatoes, sugar and fodder beets.