Intercropped maize-soybean silage: Effects on forage yield, fermentation pattern and nutritional composition

Abstract

We investigated whether the intercropping of maize and soybean could improve the silage nutritional content without reducing the forage yield or worsening silage fermentation process and aerobic stability. Three crop arrangements were studied: maize monoculture, soybean monoculture and maize-soybean intercropping. The experimental design was completely randomized with 5 replicates per treatment. Maize-soybean intercropping decreased the dry matter (DM) and grain yield as well as the production of digestible dry matter per hectare. The crude protein content of maize-soybean intercropped silage was higher compared with maize in monoculture (by 40%), but, on average, both silages presented similar fermentation profile, in vitro digestibility (600 g/kg DM), dry matter loss (37.1 g/kg DM), gas loss (36 g/kg DM) and aerobic stability (60 hr). Soybean-crop silage presented an elevated content of volatile organic compounds, low lactic acid concentration (2 g/kg DM), high pH (5.26), and greater losses of dry matter (73 g/kg DM) and gas (98.5 g/kg DM) during fermentation. Aerobic stability was higher in soybean-crop silage (192 hr) due to the high content of volatile fatty acids (butyric acid > 87 g/kg DM) and low contents of residual sugar and lactic acid. In conclusion, maize and soybean intercropping increased crude protein content, but contrary to our hypothesis, the crop association did not result in greater silage digestibility or higher aerobic stability, nonetheless reduced both crop productivity. Additionally, ensiling direct-cut soybean crop with low DM content is not recommended due to the high risk of undesirable fermentation and nutrient losses.