Soil Solutions LLC - -

Should You Consider Higher Corn Plant Populations?

There is much that can go into answering this question. Some considerations are what type of hybrid are you planting? What is your current plant population? What is your soil type and texture? Do you have a full soil moisture profile? What is the expected long-term weather outlook? Is your field dryland or irrigated? What are the fertility levels in the fields?
In analyzing farmer’s corn yield data, I have been surprised at how many producers still plant populations of 28,000 or less. Although good yields can be achieved at these populations, data for many years have shown that populations higher than this give optimum yields in most years
I hear some of the “high yield corn” gurus speak of goals of reaching 10 bushels per 1,000 plants. At 28,000 plants per acre that is 280 bushels which is a lofty goal for most. This is possible, but it may be better and more energy efficient for the plant to attain 280 bushels with 31,000 plants per acre and only have 9 bushels per 1,000 plants or 33,000 plants per acre and attain 8.5 bushels per 1,000 plants.
I have recently reviewed some research comparing populations of 22,000 to populations of 36,000 across 88 hybrids. At high population (36,000 ppa) the average yield was 300 bushel per acre. This was 8.33 bushels per 1000 plants. At low population (22,000) the average yield was 241 bushels per acre. This was about 11 bushels per 1000 plants. Seed costs, if you average at $2.25 per 1000 plants, differed by $31.50 per acre. However, at $3.50 corn price, the high population gave $206.50 more in revenue. I think I would rather produce 8 bushels per 1000 plants and have more revenue and greater income.
As I mentioned earlier, hybrid differences can be huge. In this study, there was as much as a 158 bushel difference in narrow rows between the top yielder in high populations to the bottom yielder in low populations and 198 bushel difference in wide rows from top yielder in high populations to the bottom yielder in low populations. That is HUGE and can greatly alter your profitability!! Know your hybrids and how they fit in your environment.
Fertility can also be critical as you increase your populations. You may want to increase the nitrogen slightly or use nitrogen timing keyed to your particular variety to be more efficient. You may want to consider row placed nutrients to increase efficiency, improve stalk quality and standability as well as test weight. Be aware of where your pH is. This is the starting point of all fertility programs. Your best pH for optimum yields is in the 6.0 to 6.6 range. If on high pH soil you may want to consider ammonium sulfate to create more acidity and gypsum to increase your available calcium and root growth. Fulvic acid and humic acid should also be considered to enhance root growth and nutrient availability. If you haven’t tested for micronutrients in your soils, you may want to start. They could be more limiting as you push populations and yields.