Rolling with the Heat Punch

On May 31, as I was driving 40 miles to the west to take soil samples, the Otsego County Highway Department had closed a road for maintenance, forcing me to detour over gravel thoroughfare, much of it seasonal. I don’t mind using these secondary roads, if they save mileage (thus fuel) and hopefully time. A major drawback was dust, particularly when you’re following someone else; sometimes I slow down so an occasional gust of wind might clear the air ahead of me. Getting back on the highways, I drove by stands of corn, most of it less than five inches tall (note, most of these locations’ altitudes exceed 1,200 feet).

Once I got home and checked emails, I noted that the rather universal moisture shortage was spotlighted by an NBC article titled “U.S. Heat Sets Records, Spurring Cities to Take Action.” In that text was the following statement: “Earlier this month, Oregon’s workplace safety agency adopted some of the nation’s strongest rules to protect workers, particularly those in agriculture and other outdoor professions, from heat-related illnesses and death.” Dusty roads, heat stress in the news, short corn – all pointed to me making another plug for hot climate summer annuals: sorghums, sudangrasses, their hybrids and millets.

A hefty mental nudge in that direction came in the form of Tom Kilcer’s June newsletter, titled “Why BMR Sorghum?” In his memo to me, he always says “Feel free to pass it on.” I’ll do just that.

Quoting Tom: “Corn is in, or not. The weather has been in a wild swing cycle that we have seen before. No, burning an agronomist at the stake will not help. With any shifting weather patterns, not putting all your eggs in one basket (or one crop) could give you a much more stable forage supply. One of those alternative crops is the often-ignored Brown Mid Rib (BMR) forage sorghum or sorghum-sudan. It is planted when the soil is warmer than 60º F and the forecast is for warmer conditions. This occurs after most if not all haylage is harvested. Taking first cutting followed by sorghum is one way to increase the yield from a runout hayfield.”

He explains why he recommends sorghum over corn. His first reason is a savings of about $100/acre on seed costs. In terms of comparative yields, he explains that replicated trials near the Canadian border at Miner Research Facility in Chazy have consistently given yields (forage dry matter per acre) equal to or exceeding those of the corn variety trial planted next to it. Harvested properly and fed in a high forage NDF ration, milk production from BMR sorghum is equal to corn silage with only minor adjustments in the concentrate – slightly more cornmeal, significantly less soymeal. He cites other major pluses: Corn can follow sorghum with no rootworm issues, as sorghum kills the larvae and the adults look elsewhere to lay the eggs; drilled sorghum in narrow rows protects the soil from erosion and raindrop impact a month or more earlier than corn; and in moisture-short conditions sorghum, will yield 50% – 100% more than corn on the same water (at the University of Texas).

Quoting Kilcer again: “Deer hide in sorghum and come out to eat the neighbors’ corn. Finally, the rapidly growing issue – sorghum is not susceptible to corn tar spot. It has its own type of tar spot different from corn, but to date no sorghum agronomist has seen it in the U.S.”

Non-BMR sorghum is more appropriate for dairy heifers and dry cows. High starch in corn silage contributes more to body fat than size. The highly digestible BMR sorghum does the same. Managed correctly, non-BMR forage sorghum species usually run higher than corn silage in protein, thus reducing soymeal purchases. Non-BMR sorghums outyield their BMR cousins. Wisconsin research of forage sorghum species found that one-cut management of sorghum species, with a rowless corn head, will double yields, with little quality reduction and cut harvest cost nearly in half when compared to multi-cut management.

On the downside, Kilcer noted, “Our work found that most sorghum, even the Brachytic dwarf type, and especially sorghum-sudan stalks, will lodge as the grain fills past the early dough stage. Thus, the grower has the choice of harvesting at lower feed quality or dealing with lodging. This has been a major limit to farmer adoption. We tried photoperiod types that don’t head but they never got drier than 17% – 18% dry matter and never increased the digestible components to what we need for dairy. Even without a head it still lodged in our trial.”

Other work has shown that the majority of nutrients from the seeded type are sent from the leaf to the grain, the same as in corn. In sorghum matured past the early dough stage, the seeds are nearly all wasted. Sorghum seed becomes very hard, too small to effectively break with a processor. Wild birds and free-range poultry say thank you. These field losses led plant breeders to develop delayed harvest male-sterile BMR forage sorghum, specifically managed for “enhanced nutrient concentration.” This crop will not produce seeds.

New York research finds that of the BMR varieties, the male-sterile (without a fertile seed head) either sorghum or sorghum-sudan gave some of the highest yields and had the best standability with no maturing seed weight to bring the plant down. In paired comparisons, the male-steriles had higher neutral detergent fiber digestibility than their seeded counterparts. Most likely, photosynthetic energy continued to build in the plant cells after heading and was not translocated to seed storage because there is no fertile seed. Thus, the feed quality and milk-producing ability of the forage continue to increase, the more time we allow for the crop to grow after heading. So there you have it: An answer to the question of too little water and too much heat.

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