|Double crop grain sorghum at mid-bloom 60 days after planting - 8/23/15|
Usually my double crop grain sorghum has been a pretty low-input crop with low yield goals. Most of the time, I've fertilized with about 30 lb. of N, hoping for something around 30-40 bu. per acre, although at $3.50/bu right now, I'm not making much money with those low yields anymore. If everything goes perfect there's the possibility for much higher yields, and if everything goes wrong I tend to look at it like I grew a cover crop instead of a cash crop. In the past, I've either baled it, grazed it over the winter, or I've just disced it under and planted wheat.
Since I've looked at a double crop grain sorghum crop as a low-input crop, previously I've tended to plant a low seed rate that was in the 2.5 lb/acre range (~35,000 seeds/acre). The theory is that sorghum will compensate for lower plant populations by tillering to fill any gaps in the row and because of that tendency yields have the possibility to be as high as a higher planting rate. But whenever I've lowered seeding rates, even though it tillers the way it's supposed to, the heads on the tillers don't emerge and mature at the same time as the main heads and sometimes it's hard to get the moisture levels low enough for harvest until much later in the fall (because of a bunch of green heads on all those tillers).
With all that in mind, about the only new thing I tried with this plot is that I decided to plant about 68,000 seeds/acre (or ~5 lb/acre) in my double crop test plot this summer in an attempt to reduce or eliminate the amount of tillering. Sorghum seed is relatively cheap, so doubling the amount of seed only ends up costing about $8 more per acre which is a heck of a bargain if I can harvest a couple of weeks earlier. At this point, it looks like the theory is working because there isn't much tillering that I can see.
We've had decent growing conditions this summer (adequate moisture and reasonably warm temperatures) which means that when we hit about 60 days since planting the field was at mid-bloom which was right on schedule, so if everything stays on track it should be close to being ready to harvest in about 40 more days (sometime in early to mid October).
This summer it's become more obvious to me that good growing conditions in the summer are one of the main keys to successfully growing double cropped grain sorghum. I only have about 100 days between about July and the first freeze in the fall (mid-October to early November) for the crop to grow, mature, and dry for harvest. If it gets too dry, too hot, or a freeze comes earlier in the fall, the yields suffer and it's tough to make it worth growing double crop sorghum. In the past, with my double crop sorghum, I've had two mediocre grain harvests, one complete failure due to drought, and two crops that I baled for hay (and it wasn't much hay). With that track record, I'm starting to wonder why I'm even thinking about planting any more.
I always knew it was sort of a gamble to try growing double crop grain sorghum, but after looking closer at what it takes to successfully grow a crop this summer (almost everything has to be perfect), and also factoring in the lower price being paid for grain sorghum lately, it seems more and more like I'm gambling with some pretty long odds.
At this point I'm not sure where or if double cropped grain sorghum fits into the farm. I might be better off treating it as primarily as a cover crop with the off chance of a grain harvest if everything goes perfect. That would mean dropping my planting rate into the 1.5 lb. per acre range to encourage more tillering, fertilizing even less or not at all, and being prepared to graze it, mow it, or bale it in time to follow it with something like wheat. Of course, I might be better off to just use the planter to plant about 5 lb. of sorghum-sudangrass as a cover crop, and forget about planting grain sorghum on the hope that I might somehow get a grain harvest.
As soon as I get this test plot harvested this fall, I'll know a little bit more about whether I'll double crop grain sorghum in the future. It's entirely possible that I might be singing an entirely different tune in a couple months and telling the world that double cropped grain sorghum is the best crop to grow around here. Stay tuned.