As I make presentations across the country so many, many times I have been asked about planting population. Should I increase?? My yields are not where we want them. My question to them is what population are you at now? So many times, I am told 32-36,000 at planting with the average farm yield between 180-205 bushel per acre. Using those numbers with a harvest stand at 30-34,000 that’s an average of 6-6.83 bushels per thousand.
Folks, in my experience you are spending way too much on seed and certainly not getting the nutrient values in the plant to support ear weight needed to be efficient. Until you are above 10 bushels per one thousand harvested plants per acre, a higher population is not the answer! Lower the population until you are harvesting in the 8-12 bushel per thousand. Then manage your nutrient levels as you increase population. You must manage the plant. Remember it takes a lot more water for higher populations and in the south those higher populations hold the heat beneath the canopy longer, which can really hurt yield.
There are fixed ear and flex ear varieties. No question a fixed ear won’t flex at lower pops, I hear that all the time, but regardless of the variety fixed or flex, ear weight is what pays the bills. You need to have test plots to find out where that sweet spot is on your ground. Please do it on your own ground, don’t rely on your neighbors plot!
On our farm there are areas in the fields that have really good dirt; a 24,000 harvest population has yielded over 300 bushels per acre figuring out to 12.5 bushels per thousand. Now that is certainly not the whole field average but that shows when the plant is happy, the potential is there!
Our average upland population on our farm is 22-24,000 plants per acre. We know in a good year our upland can yield 200 bushel per acre but those good years are few and far between. A 165-185 bushel per acre yield is more reasonable and every year we keep testing lower populations to become more efficient on these marginal acres. On our river bottoms and good ground we plant at 26-28,000 plants per acre and expect a 200-230 bushel per acre crop. Seed is a very expensive input cost. The ability to cut back population, saving on seed cost without a yield loss is very rewarding.
Earlier I wrote about managing the nutrients in your plants. One way to learn to do this is by tissue sampling on a weekly basis. This is a good way to learn the most efficient nutrient levels and to see what limiting nutrient factor you may be dealing with on your farms. Learn where your nutrient levels should be to maximize the ear weights at different populations. You could even create a spreadsheet from your tissue test result history and utilize this to adjust your populations. Your goal should always be 10 bushels per thousand harvested plants.