From the Field:

Knee High By 4th of July…or not

You may have heard the old phrase, “Knee High by the 4th of July,” used in reference to the corn crop and it’s growth stage. But the truth is, thanks to new technologies, diverse planting dates and weather patterns this phrase doesn’t really fit Kansas and our farming practices any more.

The phrase “Knee High By 4th of July” originates from Iowa, the state that most people consider to be the heart of the corn belt. Years ago, corn didn’t have the cold vigor that it has today. Meaning the soil temperature had to remain at a warmer temperature more consistently in order for the seed to emerge or sprout. So farmers had to wait longer, possibly even late May, to plant their corn in order for it to tassel in August and mature in time to harvest in the fall.

Iowa also has more consistent geographical characteristics as a state. While Kansas is known to be a flatter state, we have a large difference in elevation with the western part of the state being higher and then gradually going lower as you move east and south. Therefore farmers in Kansas plant corn at different times during the season depending on where they are located.

Because the nights stay warmer and the elevation is lower, farmers in southeast Kansas are usually the first to plant their corn. Some years they can start as early as the middle of March.

Bob Timmons is a farmer near Fredonia, Kansas. The earliest he remembers planting was March 26 and May 4 being the latest. He’s located in the southeast corner.

Another southeast Kansas farmer, Nicole Small, is a no-till farmer around Neodesha, Kansas and the earliest she’s ever planted was March 15 but now they like to start around April 1. But the latest planting date on farm record was July 7, when they had to replant after the flood of 2007 when they had 24 inches of rain in 24 hours and lost everything in the river bottoms.

And then you move north and west across the state with the planting schedules. The northwest area is usually the last to start planting. With colder temperatures and a high elevation, it’s not unusual for the farmers to still be planting during the first part of June.

Orrin Holle is a farmer in Rawlins County, Kansas. He recalls the earliest he’s planted corn being April 20 and the latest being June 11. His latest planting date was also caused by large rains and even a late snow storm or two.

The biggest determining factor is the weather, which can vary from year to year. Farmers wait for the right soil temperature, so if it’s a cold spring, like we saw this year, planting is pushed backed. It also depends on how wet the ground is. If it’s too dry, they might push back planting to get a little more soil moisture available for that seed to grow. On the flip side, if it’s a really wet spring, even if they wanted to plant might be able to get the tractor in the field to plant without getting stuck. It’s also not uncommon for some farmers to have to replant if a field gets flooded.

Weather plays a crucial role in the timing and planning for the corn growing season. Farmers rush to get the corn in the ground as soon as they can to help combat heat stress in the July and August months. Historically, Kansas sees it’s hottest temperatures in late July and early August. The best way to give that corn the chance to reach its potential is to use annual averages to predict when your corn can tassel and pollinate under the lowest amount of heat stress.

Thanks to genetic advancements made by corn breeders, the corn plant is able to withstand much more heat stress than it is used to but the Kansas climate still tries to give our crops a fight. The corn plant is most susceptible to heat stress during tasseling and pollination. The tassels are the white points on top of the corn plant. They produce the pollen so it’s important for them to mature correctly so there is enough pollen available for the plant. Then the ear grows silks, which are the fine strands of fiber that look like hair on the top of the ear. Each silk represents a potential kernel. During pollination, the breeze moves the corn plants dropping the pollen from the tassels and it is caught by the silks. Then the pollen travels down the pollen tubes inside the silks to the egg and then a kernel can start forming on the ear. However, if anything disrupts this cycle it leads to fewer kernels meaning a loss in how much corn that farmer can harvest.

Summer heat combined with dry soil conditions speeds up the tasseling and pollination process. While at the same time, the heat slows down the production of silks. So, the end result is less pollination tubes available to accept the pollen and create the kernels.

Traditionally the farmers in eastern half of Kansas have a much more humid climate then the western half, so unless they get rain during the time of tasseling and pollination they don’t have much reprieve from the heat. Farmers in the western side of the state have a much drier climate so the corn does get a little break from the heat in the evenings and early mornings. Rain and irrigation sprinklers greatly help in keeping the plant cool during these high-stress times but there are times and places where neither are available.

So, just as farmers continue to evolve with the technology they use, they also evolve their agronomic practices to maximize heat and moisture at the key times. They chnge these dates based on historical weather data along with their personal experiences with each of the different corn hybrids they plant to get the right combination.

So basically, the goal of a farmer is to maneuver the planting dates to “outguess” Mother Nature, which as you may guess isn’t always easy.