Digging Deeper into Plant Population Pays Dividends
Variables…variable…variables. There are so many variables that go into corn yield.
But, corn yield is highly influenced by cropping practices – in fact, more so than any other crops we raise in the northern plains. So let’s not worry so much about the variables of which we do not have control. Let’s focus on a few of the ones we can control!
One of the things I look for early in the season is plant spacing and emergence. Most of us know that having that ideal “picket fence” stand is desirable and will add yield at harvest. That ideal stand optimizes consistent spacing between stalks, minimizing plant-to-plant competition. After planting, I utilize a simple stand evaluation form we created to grade the grower’s corn emergence and spacing.
This past year as part of our Plus20 Club, we worked with a group of growers to measure emergence rates and stand quality. Our guidelines called for Population Emerged to fall within 1,500 plants of Population Planted. The average across all participants was 2,000. This number was higher than we wanted to see, but we attributed some of it to the tough conditions we had last spring after planting with the cool/wet weather (those variables we can’t control).
We also generate a Stand Quality Report for each field. We count and measure the plant-to-plant spacing for 60 corn plants in a row. These numbers are then plotted to form a bell curve graph. 80% of the plants should be within 2 inches of the ideal spacing. For example, in a 22” row with a population of 32,000 the ideal spacing should be 8.91”.
Our results from 2010 were a bit disappointing. Less than 30% of the fields we checked had ideal spacing, or they were out of the 2” window. This was, however, a great reality check for the growers involved as it can be used as a good gauge of their planting performance. The next question is to figure out why – was it due to planter settings (variables that can be controlled) or environmental factors (variables that cannot be controlled)? If we found a spot where the spacing was over 12”, we dug in the soil to see if a seed was there that did not germinate or if it was a mechanical skip. Normally with skips you end up with a double right after. I saw one field where I could even tell which direction the rows had been planted due to all the skips and doubles and their location all going one way.
Another thing to note about plant spacing – tissue testing is often done early to assess the plant’s early fertilizer usage. Great idea! But, make sure to only use plants that are spaced correctly as to not skew the results.
