Grain and Forage Sorghum Production with No‐Tillage on Dryland

Abstract

AbstractGrain sorghum [Sorghum bicolor (L.) Moench] is adapted to the Southern and Central Great Plains, but water stress at critical reproductive stages can sharply reduce grain yields of the crop on dryland. In contrast, forage sorghums (S. bicolor sudanense or saccharatum) have no such critical stages and, hence, do not require such timely rainfall to attain good yields. This study compared growth, production, water use, and water‐use efficiency of grain and forage sorghums under no‐tillage conditions on dryland from 1984 to 1986. All cultivars attained similar heights at 30 d after planting, but forage sorghums were taller at later times. Average total dry matter (TDM) production by grain and forage sorghums (8.14 vs. 8.61 Mg ha−1) was not significantly different. Total (grain plus stover) crude protein production was higher for grain than for all forage sorghums except ‘Sugar Dan’. Total digestible energy (DE) and metabolizable energy (ME) production also were higher for grain sorghum. Grain sorghum stover, however, has low nutrient value and usually is not harvested. When only grain of grain sorghum is considered, nutrient production (crude protein, DE, and ME) was lower than that for forage sorghums. Water‐use efficiency for TDM and nutrient production was lower for grain than for forage sorghums because grain sorghum had a longer growing season, which resulted in higher growing season precipitation and total water use than that for forage sorghums. In conclusion, forage sorghums are viable alternative crops to grain sorghum on dryland in the Southern Great Plains where forages can be used by the cattle (BOS spp.) industry.