Book Description

Corn (Zea mays) is the dominant silage crop for irrigated dairy regions. Sorghum's (Sorghum bicolor) drought tolerance shows potential to be grown for silage under conditions of water shortages. A two year experiment was conducted in Five Points, CA to determine the yield and nutritive quality of forage corn (CORN), conventional sorghum (CONV) and brown midrib sorghum (BMR) at 100%, 80% and 60% of full irrigation (ETc) under a center-pivot irrigation system. Yields were measured and forage quality was determined using % Neutral Detergent Fiber (NDF), % NDF digested in 30 hours (NDFD30), % Crude Protein (CP), and % starch as quality parameters. Results in 2014 had a high degree of variability leading to no significances in yields. In 2015, CORN yield's reduced 57% more than BMR per unit of water, whilst CONV and BMR maintained yields from the 100 to 80% levels. The decline in NDFD30 with additional water was significantly larger in CONV than in CORN and in BMR. BMR had NDFD30 values up to 10% higher than those of CORN. CORN % starch decreased significantly with a 20% decrease in water application. Sorghum had a negligible amount of starch at all levels. CP decreased uniformly across all three types of forages with increased irrigation. We can conclude, therefore, that during water shortages, sorghum can provide high-yielding (>15 Mg/ha), digestible (>60% NDFD30) silage for use in dairy rations. However, sorghum must be supplemented with grain to compensate for the low starch.