The science behind seed singulation
Nov. 23, 2018
Many factors that go into achieving the maximum genetic potential of today’s hybrids and varieties. From a farmer’s perspective, attaining top yield starts when they empty their bag or box of seed into the planter. The precision with which that planter places seed into the soil will help determine the crop’s eventual yield. The role of seed singulation involves more than lateral seed placement. Vertical seed position and seed-to-soil contact both affect seedling emergence. Planter maintenance and seed coatings also affect seed placement and have a direct yield impact.
During the 2016, 2017 and 2018 growing seasons, AGCO Corporation research agronomists actively monitored plot locations in the Midwest, plus several locations in Kansas, to examine just how planting affects yield. The study started by looking at downforce control on individual planting units, the depth of planting, seed spacing and residue management. In 2017, they added in-furrow firming and furrow closing to the mix. The 2018 data analysis is ongoing.
“We believe that planting is one of the most critical steps that farmers can do to ensure optimum yields,” says Darren Goebel, AGCO Corporation agronomist and director of Global Agronomy and Farm Solution. “It’s interesting, as a seed agronomist before coming to work at AGCO, I was often called out to look at problems in the field. And now that we’ve done this research, I can certainly say a lot of that could have been attributed to planters, planting practices and even some tillage in the field.”
In 2016, the researchers flagged each hybrid as it was emerging in the field. On the first day when seedlings emerged, the emerged plants were flagged. For the next seven days, newly emerged seedlings were marked with color-coded flags. then one day later, two days later and seven days later. Ears associated with the individual days were harvested and respective yield results were calculated.
“From personal experience, in general we find if we have a plant that’s one leaf collar behind its neighbors, it will typically only produce about one-half of an ear. And that’s under fairly good conditions,” Goebel says. “If it is two leaf collars behind, it will typically produce no ears.
“Anything that emerges more two days later is just a weed. Emergence is incredibly important. This is why we did the research to look at those factors that affect even emergence.”
“Looking at two years of data, we found that as long as we plant at least 1.5 inches deep all the way through to 3 inches, we get maximum yield,” Goebel says. “When we get outside this range, yield decreases.”
Several things happen whenever seed is planted less than 1.5 inches deep. First, he says moisture in the furrow might not be uniform because of the soil close to the surface is drying out. The other thing that typically happens, Goebel explains, is problems with no root formation causing “floppy corn syndrome.”
To get good, strong root development, Goebel says it is important to plant at least 1.5 inches deep. Beyond the magic 1.5-inch depth, it is important to plant into uniform moisture. Ideally, seed is planted into a minimum of 30 percent, preferably 40 percent moisture, in the furrow.
“Now for the first time, we have the ability to actually measure that with a smart firmer tool,” Goebel shares.
Downforce Unit Calibration
It’s also important that individual row planting units be calibrated to manage the downforce needed to maintain a uniform planting depth. A planter row unit will achieve depth if there is appropriate force down on the gauge wheels to hold it in the soil as it encounters different barriers, such as compaction, residue and differences in tillage systems.
Downforce is associated with depth control. The researchers analyzed three different levels of downforce to determine its effects of yield. Light downforce pressure simulates a very small spring on a planter comparable to the springs used in the 1970s and early 1980s before no-till planters became popular. Contrast these planters to heavy duty, no-till downforce systems set at the heaviest setting possible.
“We found yield loss due to both too light downforce and excessive downforce,” Goebel says. “Downforce control, in my opinion, is one of the biggest problems for the planter pass.”
With too little downforce, he says, planter row units bounce, sometimes going too deep into the ground and sometimes not going into the ground deep enough. The result is variable plant emergence.
On the flipside, too much downforce, results in “hatchet roots” that follow the seed furrow because the gauge wheels are putting so much pressure on the soil surface which stunts the roots that are trying to grow along the furrow.
Ideally, each individual planter row unit should react allowing each row unit to maintain proper depth control without excessive pressure.
AGCO agronomists also performed a singulation study and, according to Goebel, this is one of the first multiyear, multilocation studies to specifically look at singulation without the inclusion of population.
They blocked off some holes in the planter’s seed disc and then drilled a corresponding number of new into the seed disc to maintain the proper population. The effect was to create an uneven seed drop with a poor (93.1 percent) singulation compared to the control (99.6 percent singulation). The result was about a 7 bushel per acre difference.
Then in 2017, the research team did a closing study. The most aggressive mode resulted in some soil pinching between the closing wheels that in some cases pushed the seed up in the furrow. The result was variable seeding depth. Compaction over the row also prevented some seeds from emerging uniformly.
“The main takeaway is to make sure that you’re closing the furrow well with good seed-to-soil contact, and use only enough pressure to do that consistently,” Goebel says.
He tells growers to consider adding soil firmers to get a little bit better firming down around that seed, especially in silt loam soils. These firmers can have a payback of just 40 acres, Goebel notes.
While equipment plays a large role in helping farmers achieve proper singulation, lubricants are another critical component to success during the planting season.
First Is Adherence
Seedcare Application lead for North America. He adds that this can alter the singulation process.
Seed treatments shouldn’t negatively impact seed handling and performance. But, he cautions, not all formulations are built the same.
“Seed lubricants are an important piece of technology that can be used to make sure there is proper seed singulation,” says Baker. “One of the most important things to do is to always use these lubricants on treated seeds.”
Baker explains that every new formulation that Syngenta Seedcare puts on the market undergoes numerous quality tests. Singulation is just one of the qualities tested and evaluated.
“Some of Syngenta Seedcare’s formulations might have more than 15 components in its composition, including surfactants, stabilizers, anti-foam agents, flow aids, and many other components,” Baker says. “Our scientists and formulation chemists add these components to ensure these formulations are stable and that they form a more uniform seed coating.”
The goal: to improve adherence of the seed treatment to the seed.
The seed treatment is supposed to stick on the seed. But what happens when it doesn’t? During the planting season, it can be transferred from the seed to the planting disc as a form of rub-off or product build-up.
When there is a buildup of treatment on the planting disc, seeds get stuck in some of the disc cavities. Then, with every revolution of the planting disc, some seeds aren’t being put in the ground. This is not uncommon, Baker says, especially if you aren’t using a good quality seed treatment formulation on the seed.
“And this is assuming that you are using all the correct configurations for your planter and that you have added your seed lubricants. This is mainly because of adherence of the seed treatment on the seed, if you don’t have a good adherence, you may end up with a lot of abrasion and some of those products will be transferred to the planting disc.”
The Role of Lubricants
Other than the seed treatment quality and getting the planter’s settings right, the other consideration to highlight is using seed lubricant. Seed lubricants are there to make sure you have a smooth planting process. They diminish abrasion between treated seeds and the planter seed disc. Using those according to the recommendation of the planter manufacturer is very important.
Shiny powders are being widely used on soybeans and some other crops as well. They are based on titanium dioxide or mica. They are not a seed lubricant and will not lubricate seeds or planter parts. Because of their shiny appearance it may seem that the seeds are actually lubricated, but they’re not.
“There is a certain misunderstanding in the marketplace that when farmers and growers see shiny seeds, they think that they don’t need to add any seed lubricant,” Baker says. “We have run several tests in the Seedcare lab, and we see big drops in terms of seed singulation when seed lubricants are not used on top of the shiny powders.”
Flowability agents like polymers do not lubricate the seed enough during the planting process. It is very important to acknowledge that seed lubricants are still needed even though some type of flowability agent is included in the seed treatment either in the formulation or in a form of a polymer.
There are other non-lubricating products that are used to help dry the seed. These products have a purpose, but they are not lubricants. Always refer to the planter manufacturer’s information for seed lubricant recommendation. Most of the time when growers are having seed plantability or singulation issues, it is because they are not following best practices in terms of using seed lubrication.
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