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Raising yields: Offsetting soybeans’ 75% natural attrition

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Raising yields: Offsetting soybeans’ 75% natural attrition

Variety selection, seed treatment and scouting are all important factors in boosting yields, and as the growing season progresses there are actions growers can take to maximize yields.

Matt Montgomery, Pioneer field agronomist in west-central Illinois, said in an Illinois Soybean Association webinar the 75% loss is a double-edged sword.

“It’s both a good thing, and it’s tough thing to deal with. It’s a good thing in the fact that the soybean plant producers many more flowers than it ever needs or that it ever will be able to support. And it also spreads that flower production period over a long period of time, which means that the plant spreads its risk a little bit,” Montgomery said.

“It’s not quite like corn. Corn has this really sensitive period that’s packed into a period of time of about a week and a half when it is incredibly vulnerable to environmental stress. Soybeans are vulnerable to environmental stress, but they spread out that period of time and because of that they aren’t quite showing that same degree of vulnerability.”

Montgomery provided recommendations to help produce as many pods and flowers as possible to offset that 75% attrition and win the pod count battle. Here’s what he said.

On The Preseason

“If we don’t get weed management to begin with, then every other conversation you and I have from here on out is for naught. Weeds have the ability to take all of the input decisions that we do for the rest of the season and basically zero out the impact of that.

“Stewardship of the products available is a part of weed control. There are over 200 cases of documented herbicide resistant weeds worldwide, one-third of which are within the United States.

“No new herbicide modes of action have been introduced since the 1980s and no new modes of action are anticipated until the 2030s. In addition, weeds are developing metabolic resistance where they produce their own safeners that enables them to metabolize or chew up the product before it can knock down that plant.

“There are two ways to lose herbicide or pesticide tools — regulations and resistance. An herbicide cocktail approach is absolutely essential using more than one mode of action.

“Weed management should also be viewed as an investment. Sometimes we’ve neglected to spend extra dollars because we thought about that as return we need to have this year. Herbicide purchases are much more akin to a fertilizer purchase; they’re much more akin to an equipment purchase.

“There’s a significant amount of good that you get out of that purchase this year, but it’s a long term investment in decreasing the weed seed bank and because of that perspective we should be a little bit more willing to do maybe that extra mile, maybe stretch just a little bit because we’re investing in something that’s going to benefit us over the long term by maintaining the long term viability of that farm.”

On Planting

“Multiple variety and maturity trials confirm that planting early matters. A one-third bushel per day per acre loss for later planting was noted in the 2014, 2015 and 2017 trials, one-fourth bushel loss per acre per day in 2016, and two-thirds of a bushel loss in 2018 based on the trials’ trend lines.

“I recognize that weather is not in our control and 2018 was a good example of a year that did not provide us with an opportunity to go early. But in many years we do have the opportunity to push things earlier.

“There was a thin relationship this year between planting date and yield — maybe only one-tenth of a bushel per day loss. That means a lot of other things after planting went right and that offset the delayed planting. We had a lot of other things occur that kind of masked the delayed planting.

“Early planting increases the likelihood of higher leaf area duration — the length of time leaf material is covering the ground. The more leaf material you have per period of time covering the ground is strongly correlated to yields because we’re increasing the photosynthetic hardware needed to support seeds that will be produced.

“Early planting will increase the likelihood of a higher pod count and in each node. If we can increase the number of nodes we inflate that pile and that natural 75% attrition doesn’t feel quite so severe and we actually have a net yield gain oftentimes from that.

“This is a very low to no cost way to bump up yield in the field with very little input cost. The thing I’ve stressed an awful lot with our growers is you don’t have to be the earliest. What I’m saying is nudge it earlier because there’s going to be some kind of benefit nine out of 10 times.”

On Protecting Stand

“If we want to inflate the pod pile we have to make sure we maintain as many plants as possible. Insects aren’t really the major pests we deal with or are usually thinking about in soybeans. We’re usually thinking about pythium, phytophthora, fusarium, rhizoctonia, all those kind of things.

“Neonicotinoids repressed grape colaspis over the last 20 years, but we are seeing resurgence recently despite the use of those materials. Grape colaspis is really tough on corn but I don’t think we fully appreciate how severe this pest is in soybeans.

“Early season has all of this temperature variability combined with moisture variability and because of that we stoke this incredible environment for soil-borne plant pathogens to take over the crop and cause a lot of problems. So, it’s really important that we invest in seed treatments.

“It’s a good thing that we now see the industry moving toward cocktails even on seed treatments because it’s absolutely imperative that we do that.”

On Mid To Late Season

“Seventy-five percent of fields in Illinois are probably infected with soybean cyst nematodes and resistance is developing. Soybeans are very hardy but the pest spectrum that we deal with does change and is changing a lot here recently.

“Other pests in Illinois are sudden death syndrome look-a-likes red crown rot, Dectes stem borer, frogeye leaf spot, and pod and stem blight.

“We continue to see responsiveness to fungicide. I don’t think you have to do much of a grower survey to find out that people do feel like they’re seeing value in fungicide. Some of that reason is physiological. We know that maybe something is happening within the plant.

“We are reminded that the pest environment will always change and adapt.

“Successful future soybean production requires that we not be lulled into complacency. Monitor SCN, rotate to corn, rotate resistant varieties, and utilize seed treatments. It’s imperative to use cocktail pest management strategies.”

On Nutrient Demand

“Phosphorous and potash are incredibly important. Something to keep an eye on is how sulfur is going to become one of those nutrients we’ll have to apply one of these days. A cleaner environment means less deposition of sulfur.

“We get roughly 25 pounds of sulfur out of air and out of decomposing organic material, and you look at an 80 bushel per acre soybean crop with 16 to 20 pounds of sulfur removed, you begin seeing very quickly how we might flirt very soon with sulfur supply issues on that crop.

“A foundational idea that you may to want to start in the near term is to do some sulfur strips from time to time in soybean fields. See if you get some response.”

On Pod Fill

“Spread your risk. Late July through August is a very critical time for soybean stress because that is when pod fill usually happens. There’s a lot of precipitation variability the beginning of the season and during that reproductive period, and risk must be managed. Moisture isn’t the only thing that matters to yield but it plays a big role.

“The ability to outguess Mother Nature and say we need to run to one side of the maturity spectrum that tends to be used in my area or the other is kind of a lost cause because we don’t know what’s going to happen with rainfall throughout the late July through August period. It’s one of the most variable periods of time and we can’t predict what’s going to happen with moisture.

“Little differences in temperature can move around the reproductive period a lot, meaning that we aren’t going to be able to predict which portion of the maturity spectrum is going to rise to the top.

“I would encourage you to strongly consider the strategy of spreading out your maturities because that spreads out your sensitivity to that variability that we see.

“You need to ask yourself, am I managing risk or flirting with it because a lot of the headaches that we deal with can be avoided by asking ourselves that question before we step into things.”

Tom C. Doran can be reached at 815-780-7894 or tdoran@agrinews-pubs.com. Follow him on Twitter at: @AgNews_Doran.

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