How to Estimate Yield - August 2013
[Ryan Van Roekel, PhD Candidate, University of Arkansas. U of A University of Arkansas Division of Agriculture Research and Extension University of Arkansas System, Arkansas Soybean Promotion Board.]
Hi, I’m Ryan Van Roekel, PhD candidate with the University of Arkansas. My adviser, Dr. Larry Purcell, and I are working on the maximum yield of soybeans and we are out here today near one of our strip trials by England, Arkansas. [Video shows Ryan standing in a soybean field.]
What we are trying to do here is apply some of our maximum yield practices to large production fields and see if we can increase yield and maybe break a hundred bushels out here. So looking out over this field, from the road and from the edge of the field, you can’t see a lot. What we need to be doing is getting down into these beans. [Video shows soybean field with plants and close-up of soybean pods.]
Looking closely, you can see that there are a lot of pods underneath this canopy. Quick growth stage when the seeds fill the whole cavity. There it looks like it’s about R6 growth stage. And then we’re looking at the foliar canopy seeing if we have any diseases showing up, any problems. We’ve got a little bit of lodging here you see they are starting to fall over for a little bit, leaning where they should be straight up and down. That’s generally OK, in a high fertility field like this it’s kind of expected. They end up growing a little bit tall and leaning over, and there’s not a lot we can do about that.
At this R6 growth stage, now is a great time to estimate yields and the best way to do it is estimate the number of seeds per acre. So you should already know your plants per acre and then you want to count pods per plant. Multiply that together, assume maybe two-and-a-half seeds per pod is a common assumption and then divide that by seed weight. Now an average seed weight is about 29-hundred seeds per pound, and then remember 60 pounds per bushel. You can get a yield estimation that way.
The problem is with soybeans it’s going to be very variable. You have one big plant, one small plant, your pod count are going to vary quite a bit. And if your plant density is really wide, you are not going to get a very good estimation. If you want a really rough quick estimate, figure about two bushels per pod (per plant).
For more information on these maximum yield results and other podcasts, check us out online. [For more information visit www.uaex.edu. University of Arkansas Division of Agriculture Research and Extension University of Arkansas System, Arkansas Soybean Promotion Board.]