Effects of Citric Acid and Tartaric Acid on Dynamic Microbial Community and Fermentation Quality of Corn and Soybean Mixed Silage

The combination of corn and soybean silage can offer high nutritional feeding value. The purpose of this study was to study the effects of citric acid (CA) and tartaric acid (TA) on the chemical quality, fermentation quality, and microbial community dynamics of corn and soybean mixed silage, and to analyze the bacterial and fungal communities after silage. 20 g/kg CA and TA are added into corn and soybean mixed for dynamic ensiling (3, 7, 14, 30, 60 days), respectively. The results showed that, compared with the control group, the pH of CA and TA can be rapidly decreased (4.1–3.3), the lactic acid (LA) content can be increased (5.48%−8.35%), and the ammonia nitrogen content can be reduced (1.22%TN–0.95%TN). In addition, the crude protein (CP) content can be effectively increased (12.37%−13.66%), acetic acid (AA) content (1.82%−1.14%) and butyric acid (BA) content (0.26%−0.06%) can be reduced to prevent undesirable odor. Additionally, the addition also contributed to the change of bacterial and fungal community. The above results suggested that 20 g/kg CA and TA could significantly improve the quality of corn and soybean mixed silage, and the effect of TA was better than that of CA.