Impact of crop rotation with chemical and organic fertilization on weed seed density, species diversity, and community structure after 13 years

Abstract We presumed that ecological engineering approaches such as pulse crop inclusion in crop rotation and integrated nutrient management (INM) would have higher weed seed density and diversity compared with continuous cereal-cereal rotation and chemical fertilization in long–run. Hence, we investigated the viable weed seed density and diversity in soil using the seedling emergence method in 0–7.5, 7.5–15, and 0–15 cm depth. Soil sampling was performed in 2016 after 13 years of field experimentation with same treatment combinations and layout on a sandy loam soil of Kanpur, India. The field experiment consisted of four crop rotations (since 2003): rice (Oryza sativa L.)–wheat (Triticum aestivum L.) (R–W), rice–wheat–mungbean [Vigna radiata (L.) R. Wilczek] (R–W–Mb), rice–wheat–rice–chickpea (Cicer arietinum L.) (two years rotation: R–W–R–C), rice–chickpea (R–C) and three nutrient management: control (without fertilization: CT), integrated nutrient management (INM), and recommended inorganic fertilization (RDF). Of the total 30 emerged weed species, 21 species were broad–leaved (70%), 8 grasses (26.7%), and 1 sedge (3.3%). Seed density of Leptochloa chinensis (L.) Nees was significantly higher in R–C(RDF) than R–W–Mb(RDF) and R–W(RDF). While, Lepidium didymum L., Dactyloctenium aegyptium (L.) Willd. and Anagallis arvensis L. were higher in R–W–Mb rotation over the R–W (P   0.05) > R–W–R–C (P  R–W (P   RDF > CT (P