The Science of Growing Corn - 2020 Edition

One could just plant the corn. (Of course, there is a lot more than "just" planting corn: soil prep, weed prevention and then control, fertilizer, the right seed, more weed prevention and control, possibly more fertilizer... it takes some corny wisdom to get it all right within budget!  But anyway....) 

OR one could plant the corn and keep a scientific eye on it, just for fun.  The corn is going to grow whether or not record keeping is kept, but Josh keeps track of the weather each day just for fun and interest. Here's why:

A piece of seed corn takes so many "heat units" to mature into the corn that is harvested.  From the time the kernel is planted, Josh keeps a running record of the high and low for each day.  He plugs the highs and lows into a formula: high - low / 2 - 50 = the daily heat unit.  He keeps a running total of the heat units acquired throughout the growing season.  It takes approximately 2500-2600 heat units for corn to go from being dropped in the ground to being mature and ready for harvest.  From this amount, he can determine at what stage the corn is entering or finishing.

Josh has always loved farming and weather. This is an interesting way to combine the two.
Here's an example of his records, a picture of this year's chart so far into the year.

Obviously each year varies depending on what day the seed is planted and how warm and cool it is.  Out of curiosity, I went back through all of Josh's records and compared each year's amassed heat units up to this date, June 11:

2020:  550.5

2019:  185   

2018:  790.5

2017:  574  

2016:  593 

2015:  550 

2014:  590.5

2013:  401 

2012:  611

2011:  577.5

2010:  323.5

One interesting item to note is that corn will reach different milestones as it matures.  One of these milestones is called "black layer".  When the kernel of corn is done growing, it will develop a literal layer of black at the base of the kernel at the cob.  This indicates the kernel is done growing and now will start drying down, readying for harvest.  As mentioned previously, the black layer indicating maturity happens between 2500-2600 heat units.  

This picture shows the stages of black layer: from still milky on the right to black layered on the left.
Photo credit: arkansas-crop . com

                                   

As Josh is keeping track of his records, he always notes the date he discovers the black layer in the corn.  Here are the past dates:

2020:

2019: not noted (hmmm... I wonder what happened there?)

2018: August 28

2017: September 9

2016: September 5

2015: not noted (tsk tsk, another record slacking year)

2014: September 12

2013: September 13

2012: August 31

2011: August 30

2010: September 9

If you compare the June 11 heat unit dates to the black layer dates by year, you can tell how much difference each year can be.  The warmer the weather, generally the quicker the corn matures.  Even if the corn is planted "late", it could still catch up to a "normal" year if the weather is right.  Likewise, if the corn is planted "on time", it could lag if the weather is too cool.  You just can never tell what the year will bring!

It's always fun to keep track of the heat units, check on the corn and discover that once again the heat units and the milestones match up.  It's like the Jack that's in the box that pops up every time and yet, still a surprise!