Friday, August 28, 2015

Double Crop Grain Sorghum Update

Double crop grain sorghum at mid-bloom 60 days after planting - 8/23/15
On the same day that I planted my test plot of double crop soybeans, I also planted about six  acres of double crop grain sorghum. Unlike soybeans, I have a little experience growing grain sorghum both as a full season crop planted earlier in the year and as a double crop after wheat. Even though I've grown grain sorghum as a double crop before, it's usually been hit or miss at times when it comes to having a successful harvest which means I'm still trying to figure some things out about double cropping grain sorghum. It also doesn't make anything easier that it's almost like sorghum planted in April is close to being an entirely different crop than sorghum planted in June.

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. 


  1. Learned a new word today, tillering. Never heard that until now. I don't have any grain sorghum experience but what you are describing makes sense. It will be interesting to see if your thoughts on planting rates come to fruition here this fall.

    1. Depending on the hybrid and the planting rate, sorghum will grow a main stalk then it will start to grow secondary stalks from the base of the plant (similar to suckers on a corn plant). Depending on the fertility, the weather, etc. more tillers will continue to come up until harvest. Winter wheat also grows tillers (or stools out), in fact it needs to tiller to get higher yields.

      If an early frost burns the plant but doesn't kill it completely, tillers will start growing from the base (for some unknown reason, those are usually called suckers) and those suckers are the ones that can kill your cattle with prussic acid poisoning after a frost.

      The problem is that the tillers don't all emerge at the same time so the bigger head on the main stalk will be ready to harvest while a bunch of smaller heads will still be green. Nobody will buy grain sorghum unless the moisture levels are below 14% because it's impossible to dry in the bin, so you have to wait for the little green heads to dry, while the birds and deer eat the ready to harvest grain (ask me how I know all that).

      To avoid most of that, I've tried to plant hybrids that are less prone to tillering, but I still think it's important to manage planting rates to deal with excessive tillering. The irritating part is about picking a lower tillering grain sorghum is that most hybrids claim they are somewhat less prone to tillering, while at the same time the company's literature talks about grain sorghum's tillering advantage compensating for a thinner stand compared to other crops like corn.

      Writing all that makes me wonder why I'm even messing with trying to grow such a temperamental crop.

      I doubt if I'll get the call to do any advertisements anytime soon about why people should be growing more grain sorghum saying stuff like "It's great if you can somehow manage to harvest it before the birds and deer eat it, and it's great for cattle grazing if you follow the instructions to avoid killing them". "Grain sorghum, the less glamourous, more finicky alternative to corn, at least it costs less to grow".