Weed flora in spring maize and atrazine residues in its green fodder and silage under three maize-based rotations.

Maize (Zea mays L.) is sown for fodder and silage in the spring season (February-June) by commercial dairy farmers in northwestern India and its sowing time varies under different crop rotations. A 2-year field study was conducted during 2020-21 and 2021-22 to study the weed flora and quantification of atrazine residue in green fodder and silage of spring maize sown in different maize-based rotations. Spring maize was grown as fodder for silage making in three crop rotations {maize – oat (Avena sativa L.) or toria (Brassica rapa ssp. oleifera) or rapeseed (Brassica napus L.) – spring maize}. Winter season weeds namely Chenopodium album L., Coronopus didymus (L.) Sm. and Rumex dentatus L. and spring season weeds namely Oenothera laciniata Hill and Gnaphalium purpureum L. were not reported in spring maize grown in maize-rapeseed-spring maize rotation. During 2022, growth of Digitaria sanguinalis (L.) Scop. and Cyperus rotundus L. was favoured in maize-rapeseed-spring maize rotation than in other two crop rotations. After 60 days of application, atrazine residue level of 0.01 mg kg−1 was found in green fodder of spring maize grown in maize-oat-spring maize and maize-toria-spring maize rotations, while it was below limit of quantification (LOQ < 0.01 mg kg−1) in green fodder of spring maize grown in maize-rapeseed-spring maize. Atrazine residue in spring maize fodder at harvest and in silage is below LOQ in three crop rotations. Thus, atrazine can be safely used in spring maize grown for silage making. [ABSTRACT FROM AUTHOR]