Brown Manure Species, Weeds and Maize in a Co-Culture in the Field: Who Stands More Competitive?

A field experiment was carried out during rainy season (kharif) 2017 at New Delhi to evaluate the competition among the brown manuring species, Sesbania bispinosa and Crotalaria juncea, weeds and maize in a coculture/mixed stand. Results showed that maize was the most competitive with significantly higher growth rates at 25 and 35 d after sowing (DAS). The order of competitiveness was: maize > Sesbania > Crotalaria > weeds. After knocking down Sesbania and Crotalaria, maize continued to be superior competitor than weeds. In terms of weed suppression (∼weed control index 91.9%), mixed stand of Sesbania bispinosa (12.5 kg seed ha⁻¹) + Crotalaria juncea (12.5 kg seed ha⁻¹) after knocking down at 35 DAS using 2, 4-D was most superior and similar to weed-free control. But, when Sesbania + Crotalaria was knocked down at 25 DAS, it resulted in greater maize plant height (189.2 cm), crop biomass (692.1 g m⁻²), total N uptake (123.4 kg ha⁻¹) and cob yield (6.94 t ha⁻¹) than at 35 DAS. Therefore, co-culture of brown manure involving a pre-emergence herbicide was more competitive against weeds and the dead residue proved to be stimulative to maize crop for boosting growth and yield.