Effects of intercropping Dolichos lablab with silage maize on the yield and quality of mixed forage in the Chengdu Plain, China

This study aimed to explore the best proportion of corn (Zea mays) and Dolichos lablab in the Chengdu Plain, and its impact on mixed forage production and quality. The corn cultivar ‘Demeiya No. 1’ was intercropped with different sowing rates of D. lablab ‘Rungai’, and the agronomic characteristics, fresh and hay yields, and forage nutrients of corn were determined at a suitable harvest time, and the increasing corn fresh yield was used to assess the economic benefit. With the increased seeding rate of D. lablab, plant height, stem thickness, stem-leaf ratio, and other indicators of corn were decreased, while mixed forage yield, crude protein, crude fat, in vitro digestibility, and dry-to-fresh ratio increased compared with the monoculture of corn. Among them, the fresh grass yield of mixed forage treated with 52 500 plant·ha⁻¹ corn intercropping 112 500 plant·ha⁻¹ D. lablab was the highest, at 63 711.86 kg·ha⁻¹, and the net increase was 20 081.69 CNY·ha⁻¹ compared with the monoculture of corn, but the content of neutral detergent fiber (NDF) and acid detergent fiber (ADF) was reduced. A comprehensive analysis of the fresh grass yield and nutrient components by the membership function revealed that the membership function value of 52 500 plant·ha⁻¹ corn intercropping 112 500 plant·ha⁻¹ D. lablab was the highest (0.83), and the comprehensive evaluation of the mixed forage under this treatment was the best. The synthesis showed that the intercropping of 52 500 plant·ha⁻¹ of corn with 112 500 plant·ha⁻¹ of D. lablab was the optimal planting mode for improving forage yield and quality in the Chengdu Plain.