Comparisons weed density and diversity in two low and high input systems in soybean (Glycine max)

Identification long term effects of agricultural practices on the weed community help to weed sustainable management. Dynamic weed population is influenced by environment, soil properties and agronomical systems. This experiment was carried out in order to investigate levels of input consumption (values of herbicide, cultivation intensity and fertilizer) on weed abundance, density and composition in soybean fields. So,714 samples were taken in 2013 from 34 soybean fields in two low- and high-input systems located in an area extending from Qarakheyl in the middle of Mazandaran province to Sarjecor in the eastern Golestan province. In both input levels, 33 species belonging to 18 families were identified that were mainly broadleaf and annual species. Number of species had not any significant difference in both systems. In high input system number dominant species were low (two species) and in low input were more. Species richness and weed density were influenced by input levels, so that weed density and diversity were more in low input systems than in high input systems. Frequency of all of functional groups (vegetative cycle, life form and photosynthetic pathway) in low input system were significantly more. This study demonstrates that weeds in low systems are able to remain alive due to complete their life cycle, and due to limitation in herbicide usage, the role of tillage and fertilization must be bold.