High Plains
When can I stop irrigating grain sorghum?
Irrigation cut-out will most likely occur prior to hard dough stage. The sorghum seed will proceed through grain development from watery ripe to milky ripe to mealy ripe (the seed when squeezed no longer squirts, but oozes a gel-like or mealy material) then begins to firm at soft dough on to hard dough. As a rule of thumb, if good soil moisture is still available to the plant (at least 2 inches) then terminate irrigation as sorghum moves past soft dough. It is not reliable to base irrigation termination on grain color as different hybrids do not change color in the same fashion. A final irrigation may be applied during hard dough only if soil moisture storage is completely depleted or drought conditions are severe enough to hinder stalk quality at harvest.
When examining the head for seed maturation be sure to check many heads and check the whole head. Some difference in maturity will be observed on each head as seeds at the tip could be up to 7 days older (and more mature) than seeds at the bottom of the head, and primary tillers may also be several days later than the main head.
As a general rule of thumb, if you have doubts about whether to irrigate one more time prior to hard dough then do so, especially when grain prices are high.
