Tips for Corn and Soybean Planting

 

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It's that time of the year that the planter will again enter the field and begin the process of providing feed and forage for farms across the commonwealth. If you remove weekends and bad weather, University Specialists estimate only several days are open to planting the crop when conditions are ideal. The planting operation is one of the most critical steps in achieving yield and quality. It also is the biggest reason why the adoption of narrow rows and high populations has failed on some farms, due to improper planter tune-up. The goal of the planter or drill is to open a furrow place the seed at the same depth so that each seed will develop and create a tabletop look in the field. Here we see a double planted corn seed result in the left of the picture (Figure 1). This creates a major problem later in the season. When I took this image, we were conducting a survey of corn stands to see how accurate growers were planting at emergence stages.

 

 

This uniform stand and emergence time will allow the plants to compete evenly throughout the season and achieve maximum sunlight interception and conversion to economic yield. When plants fail to emerge uniformly the late-emerging plants will act as a weed and result of a net loss in yield. In this image (Figure 2) we can then see the consequence of this late emergence. The smaller plant will certainly affect the plants surrounding it and will not be adding much to the final yield.

 

 

Skips in the row will result in weed encroachment and the loss of yield from that part of the field. Those late emergers also end in barren or nubbin ears and further reduce quality. Lynn Hoffman, former Penn State Agronomist, related that in some cases missing plants (skips) and late emergers due to seed depth variation may result in a 30% reduction in overall yield. These ears (Figure 3) are from a field that had issues at planting and the nubbins can be seen easily at harvest.

 

 

This is the reason why planter maintenance is critical to maximize that field's yield. Growers only have one chance to set the crop stage for success and it begins by getting the planter into the shop and tuning it and not during the key times that the planter should be planting instead of sitting in the shop. Purdue Extension (as well as other Universities) had done some research into the losses that were due to plant error in the deviation from the mean spacing. What they found was that for each inch deviation from 2 inches, there was a 2.5 bushel loss per acre. I am sure this might have changed over the last couple of years, but the point is losses occur when the plants get too far or too close from each other within the row. Basically, if you were shooting for say 5 inches between plants on average (mean) how close to that were actually in the field at that spacing. I surveyed a planter for each row. Here (Figure 4) is a schematic of 19 plants that resulted in a terrible 5.3-inch deviation. That means that the plants could be 10 or more inches between each other in the field. I use a simple excel sheet on my smartphone to do this but there are planting monitors that do this all for you in the cab as you plant! Wow! Look at that; some were almost 25 inches from the mean!

 

 

In this example (Figure 5) 28 plants in another row unit are deviating only 2.2 inches STD and that is pretty much about as good as I have seen even in some tremendous 300 bushel fields. Still, there are some 12-inch plant spacings but overall pretty acceptable. In this case, we could check the planter and find out why the one row is not performing and sure enough there were issues with the tube feeding that row.

 

 

So what? A few years ago our team did a random survey of fields just to check out PA growers’ deviations.

We should really repeat this as I am sure and hopeful that our accuracy in PA has increased as with over 58% of our fields there is some room for an economic return just by taking time to adjust the planter. One corn contest grower member I sampled had a 1.8 STD and achieved over 300 bushels per acre!

 

 

Here are some points to consider. Starting at the front and working to the exit.

Now we can focus on soybeans! Data can really get confusing, due to the fact, that soybeans can and will respond to planting date and population by varying the pod counts. This negates a lot of the issues with corn. Here is a picture (Figure 6) of pod counts from our PSB On-Farm Soybean test of soybean populations. The far left has pods of over 150 per plant vs only about 40 on the far right what’s the difference ... population. 25000 ppa vs 140000 ppa respectively. Yes, each and every plot were counted and tabulated with some areas over 250 pods per plant in the lower population area.

 

 

The key to all of this was that soybeans can adapt to a lot of variability at planting and still yield well. This table then is an example of that ability. Our data really supports the Agronomy guide replanting soybean guidelines and below 90,000 ppa replanting becomes more important. For more on this please visit the planting guide for soybeans in the Agronomy Guide.

 

 

So here are some tips for planting soybeans:

On a final note, I encourage readers to check out the Agronomy guide planting recommendations for corn and soybeans. We have added some very useful tables and planting date maps for the state as well as detailed replant instructions should one be in need of direction to that end. Below (Figure 7) I snapped a quick picture of our planter set up at SEAREC. Once set, everything worked well and we continue to produce exceptional yields at the station.