Much of the corn in the Northeast has been affected by drought, suffering lower starch build-up levels due to less water during the growing season. But most areas have received (and are still receiving) enough rainfall.
In the latter areas, growers are seeing corn’s whole plant dry matter continuing to increase. In moisture-deficient areas, cobs won’t have much more space to fill out. That scenario likely spawns lower yields, lower starch/energy values and lower bushel weights. Corn is a lot more sensitive to very limited moisture levels compared to the crop category of hot climate summer annuals (HCSAs).
As you read this, all but the longest season corn varieties (and/or really late-planted stands) are quite well dented and would fare quite well, should an early frost hit. Corn is a member of a special grouping of plants called C-4s. But let’s target our discussion on other members of this group – namely, ripening sorghums.
Sorghums can be classified as HCSAs, along with sudangrass, sorghum/sudangrass hybrids and millets. They are all in the C-4 grouping (along with corn and sugarcane). C-4 means that their “body” tissues consist of four-carbon modules. This trait means that member plants are much more efficient at conserving moisture than is the case with non-C-4 species.
Not surprisingly, more farms are now growing sorghum or sorghum relatives. Its proper harvest timing differs from that of corn silage. Sorghums can be a wetter, high-sugar, low-starch forage. In a properly balanced ration, sorghum can support the same milk at potentially less cost than corn. Chopping sorghum with a short length of cut, and worse, processing, will produce forage the consistency of applesauce – not beneficial to good fermentation, high milk components or preserving nutrients (lost leachate is 100% digestible). The good news is that there are steps to take to maximize results and minimize potential problems.
Replicated research supported by the New York Farm Viability Institute examined various harvest stages of brown mid-rib (BMR) sorghum. The results were analyzed by Dr. Larry Chase using the Cornell Net Carbohydrate & Protein Systems model. This animal science professor and his team discovered that for seeded-type sorghum, the milk potential increased from the boot stage, as the fertilized seed heads started filling. The milk potential decreased as they compared parts of the seed head, going from the tip of the seed head, just starting soft dough, to soft dough halfway down the head. This is because at the soft dough stage there are significant decreases in fiber digestibility of the whole plant, where most energy is stored.
This, in turn, according to Chase, is compounded by the loss of energy in hard, undigestible seeds. Thus, waiting for matured grain can decrease milk production.
For sorghum species, the chopper cut length setting is critical. At Chazy, NY’s Miner Institute, research on effective fiber and feed quality found that as forage quality decreases, the shorter the length of cut, the greater the milk production from poorer forages. They found that the reverse is true for highly digestible forages such as flag leaf triticale and BMR sorghum species. The smaller they’re chopped, the faster they’re flushed out of the rumen before the cow “enjoys” the full extent of digestion. Larger particles stay confined in the rumen mat until rumen bacteria extract the majority of the nutrient components.
The other problem with chopping these silages fine is it increases the number of plant cells cut open and, especially if processed, will release hundreds of gallons of leachate. Leachate, besides making a smelly mess, removes the most digestible part of the plant. (As stated earlier, it’s 100% digestible.) Additional cuts, with shorter chop length, open more plant cells for the liquid to run out. Chase’s team harvested sorghum species at 0.5-, 0.75- and 1.14-inch length of cut, with no processing. As long as they did not process, they observed excessive liquid (leachate) from the half-inch cut but not from the other two cut settings.
I believe that thus far, 2024 has been a good year for growing sorghum, sudangrasses and their hybrids, because there were so many days in our region with temperatures in the 90s; corn does not benefit from temperatures over 85º. Sorghum is shown to keep performing with heat pushing 105º – not surprising, since the crop originated in sub-Saharan Africa.
Additionally, in terms of soil structure health, HCSAs outperform corn because of their fibrous root systems, which corn lacks. (As I’ve pointed out in earlier columns, fibrous root systems are instrumental in building up soil organic matter.)
Another plus for sorghum species is that their root systems secrete prussic acid (hydrogen cyanide, or HCN), which carries over into the next year in the rotation. That’s a good time to plant corn, because HCN kills corn rootworm.
The C-4 trait is not always beneficial to crop people. For example, there are least two weeds which enjoy that trait. The most well-known one these days is Palmer’s amaranth (Amaranthus palmerii), which can tolerate heat extremes. Sadly, A. palmerii, a broadleaf, has also become resistant to almost every herbicide in Big Ag’s chemical arsenal. Fortunately for us, A. palmerii hasn’t been able to colonize much Northeast farmland.
Another annoying weed, this one in the grass category, has the scientific name Sorghum halepense (a cousin to all the other sorghum species).
According Charles Walters, in his “Weeds: Control Without Poisons” (Acres USA Press), S. halepense “is an annual or perennial with both seed and rhizome reproduction. Its fibrous root system allows it to exercise a vicious reproduction cycle, with few if any geographical limitations.”
But plant breeders, mostly at University of Minnesota, through selectively breeding S. halepense strains have developed a crop which they call kernza, which is a fibrous root perennial grain. Its human nutrition and environmental pluses make it a winner. Not bad, considering it descended from a weed whose common name is Johnson grass!
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