Sorghum: Another perennial grass crop for grain and forage

The August 2021 CSA News magazine article on Kernza (https://doi.org/10.1002/csan.20522) prompted me to provide some information on another perennial grass crop, sorghum, which is the fifth most important grain crop in the world. In nearly 40 years of talking about crop growth and development, I always point out that corn is an annual and sorghum is a perennial. This fact is very important in physiology, development, and management of the two crops. Although sorghum is normally grown as an annual, this is only because it is killed either by (1) freezing temperatures, e.g., Kansas; (2) prolonged dry seasons, e.g., India or sub-Saharan Africa where it is grown as a food crop and the stover fed to animals or otherwise used; or (3) desiccants in some tropical areas to preserve stored soil moisture.

Where I grew up in north-central Kansas, we grew tall, grain-producing forage sorghum, basically two-dwarf grain sorghum. The whole plants were harvested and threshed. The grain was fed to hogs and chickens, and the threshed stover got the cattle through the winter. I would consider this now replaced by grain-producing forage sorghums grown for silage and/or grain sorghum grazed after grain harvest. In the latter case, the remaining stalks provide protection against wind erosion and trap snow.

In the 1960s in Hawaii, Don Plucknett produced, I think, five grain sorghum crops from a single planting (ratoon cropping). The practice failed because of bird problems. Google “ratoon cropping of sorghum,” and you will get more than 62,000 results.

Grain sorghum is grown on more than 5 million acres in the U.S. There is no good estimate of the number of acres of forage (silage or hay) sorghum grown in the U.S.

Incidentally, the Land Institute at Salina, KS, which produced Kernza, tried for many years to cross grain sorghum (Sorghum bicolor) with Johnsongrass (Sorghum halepense), a perennial weed that can overwinter, to produce a freeze-tolerant grain crop.

Respectfully,

Richard Vanderlip, ASA and CSSA member and Professor Emeritus, Kansas State University