Effect on forage yield and silage quality of silage maize and amaranth intercropping in subtropical districts

This study aimed to explore the optimal ratio of intercropping between silage maize and amaranth in the midlands of Yunnan and its effect on forage agronomic traits, yield, and silage quality. We designed three intercropping models for silage maize (Zea mays) and amaranth (Amaranthus hypochondriacus): T₁ (3 × 1), T₂ (3 × 2), and T₃ (4 × 2). The silage maize monoculture was CK₁, while the amaranth monoculture was CK₂. We determined agronomic traits, such as plant height, stem diameter, forage yield, and silage quality. The results showed that the different intercropping models significantly affected the plant height of maize silage and stem thickness of amaranth (P < 0.05). Compared with silage maize monoculture (CK₁) , the fresh grass yield under the T₂ and T₃ treatments increased by 6.84% and 11.33%, respectively, but the difference between the two treatments was not significant (P > 0.05). In all treatments, the total hay yield of the maize silage monoculture (CK₁) treatment was the highest at 24.57 t·ha⁻¹, which was significantly higher than that of the T₁ treatment (P < 0.05). Regarding the quality of mixed storage, the T₃ treatment had the highest dry matter content, significantly higher than that for other intercropping treatments (P < 0.01). For the mixed storage quality, the dry matter content of the T₃ treatment was the highest and was significantly higher than that for other intercropping treatments (P < 0.01). The crude protein content and acetic acid contents of the T₂ treatment were the highest, with values of 12.1% and 4.83%, respectively, significantly higher than that for other intercropping treatments and amaranth monoculture treatment (P < 0.05). Comprehensive analysis showed that the 3 × 2 intercropping of silage maize and amaranth in the midlands of Yunnan was an optimal intercropping model that could increase the yield of forage per unit area and improve the nutrient traits of the two crops.