Sorghum for biomass can be harvested with similar techniques to maize. The optimal dry matter (DM) content for harvesting is between 28-34%. As the plant matures, the energy content decreases due to lignification. A simple rule of thumb is to harvest when the stalk cracks, indicating a DM content of about 25%.
Sorghum’s high sugar content makes it very easy to ensile. With a DM content of around 28%, leaching losses are minimal, even with its fibrous structure. This property is also useful in mixed cultivation, where sorghum can add moisture to maize silage that is too dry.
Larger sorghum grains can be shredded using a corn cracker in a maize chopper. The corn cracker should be placed as close as possible (about 1 mm).
Grain Varieties
Sorghum grains do not ripen uniformly. While the upper grains may already be dry, the lower grains may still be in the milk stage or not fully ripe. Shoots and lagging plants also affect the overall DM content of the harvest.
For optimal drying costs, the water content of the grains should be below 22%. Sorghum with less than 14% residual moisture is stable in storage.