Determination of grass and silage yield and feed quality in the maize-sorghum intercropping system and life cycle assessment

This study, conducted in Bilecik province during 2023 and 2024, aimed to compare the yield, forage quality, and environmental impacts of sole and intercropping systems involving silage maize (SM) and sorghum-sudangrass (SSM), as well as their combinations with sunflower (AY) and soybean (SF). The evaluated treatments were: sole crops of SM, SSM, SF, AY and 75% SM + 25% SSM, 50% SM + 50% SSM, 25% SM + 75% SSM, 50% SM + 50% SF, 50% SSM + 50% SF, 50% SM + 50% SF (UG-), 50% SSM + 50% SF (UG-), 50% SM + 50% AY, and 50% SSM + 50% AY intercropping systems. In hay evaluation, the dry matter yields, crude protein (CP) yields in dry matter, ADF, NDF, condensed tannin, and RFV ranged from 1212.0 to 2813.3 kg da⁻¹, 89.59 to 254.2 kg da⁻¹, 37.56–43.30%, 48.04–73.47%, 0.507–0.748%, and 70.37–106.76, respectively. Silage yields and silage crude protein yields of the treatments varied between 3246.4–7535.7 kg da⁻¹, 414.8–708.9 kg da⁻¹, respectively. The nutrient composition (ADF, NDF, RFV, condensed tannin) and fermentation quality (pH, Flieg score, organic acid content) of the resulting silages were determined to be sufficient for animal nutrition. LCA revealed that, among the eleven categories evaluated, the 25% SM + 75% SSM in six categories (ATPF, EP, GWP, HT, ODP, METP), the 50% SM + 50% SSM in two categories (AP, POCP), the sole SSM in two categories (ATPE, TETP) and the sole AY in one category (FETP) resulted in the lowest environmental burdens. Conversely, the sole SF accounted for the highest environmental burdens in 10 of the 11 categories. The findings suggest that SM + SSM intercropping systems can be recommended as alternatives to SM by their yield values and forage quality. Such systems may contribute to feed supply security under conditions of increasing temperatures and decreasing and irregular precipitation caused by climate change. Moreover, based on the LCA results, the 25% SM + 75% SSM intercropping system is prioritized due to its lowest environmental impact across six categories, while the 50% SM + 50% SSM system can be considered as an alternative, given its relatively low environmental impact in two categories.