That’s a good question as high-population corn (36,000 to 48,000 plants per acre), planted in narrow rows, is generating lots of interest. The foundation of success with high populations is hybrid selection.
When choosing a hybrid and population for narrow rows, consider leaf architecture and ear type. There are essentially three types of leaves--upright, pendulum and semi-upright.
· Upright-leaf hybrids grow straight up like a pineapple; in high populations an upright leaf structure lets sunlight reach deeper into the canopy, to increase photosynthesis. Upright leaves maximize photosynthesis when high populations are planted in narrow rows.
· Pendulum hybrid leaves are suited for lower populations, to decrease water loss by evaporation while maintaining photosynthetic activity. Pendulum-leaf hybrids flop out and intercept sunlight like solar panels, capturing light before it gets down low in the canopy.
· Semi-upright hybrids have upper leaves that are more upright in structure and the lower leaves more pendulum.
Along with deciding which leaf architecture you need, look at ear type. Determinate-ear hybrids change their ear size very little, so you have to plant them at the higher end of the population range to optimize yield.
Flex-ear hybrids will get bigger, given the right agronomic conditions. Semi-flex hybrids flex their size somewhat less than true flex-ear hybrids.
Failing to understand leaf structure and ear types can be costly. In my experience, if you use a flex-ear hybrid in a pendulum-leaf format, high populations will cause the hybrid to flex the opposite direction, and yield will suffer.
Consider your own unique objectives and growing conditions. If you have highly productive soil with good drainage, plenty of nutrients and good rainfall or irrigation, that’s a racehorse environment for corn production. You want to maximize interception of sunlight, so you don’t waste any. A short-statured hybrid with an upright leaf will let light down through the canopy, to maximize photosynthesis for food production. A determinate-ear hybrid will let you push the population as hard as possible.
A grower on doughtier soils needs to manage water use while maintaining yield. He would want a pendulum-leaf hybrid, along with narrow rows, in order to canopy as quickly as possible and minimize evaporation of water from the soil surface. A flex-ear hybrid would maximize yield on lower populations while conserving water.
Many growers farm both types of soil in the same field. In that environment, they should use a hybrid with a semi-flex ear type, pushing populations in their heavy soil and pulling back in their lighter ground.
A semi-upright-leaf hybrid will provide some row shading in the light soil while also intercepting sunlight in the heavy soils. A semi-flex hybrid will maintain ear size at higher populations and flex out to maintain yield at lower populations.
Also, if the highest yielding hybrid for your situation doesn’t contain enough disease resistance, you may need to apply a fungicide. High populations and narrow rows are very attractive to insects such as corn aphids and corn borers. Scout carefully, and be ready to treat if you find a problem.
When pushing population, standability may become an issue. Apply a fungicide if it’s needed for disease control. Have sufficient harvest capacity, and plan to harvest early.
When to Switch to Narrow Row Corn
Ken Ferrie answers a viewer’s question in this episode of Corn College TV. In episode 4 of season 2 Corn College TV, Ken Ferrie is asked what farmers should consider if they are thinking of a switch to narrow row corn.
Can Narrow Rows Yield More Corn?
Narrow rows can be a good agronomic decision under the right situation
Plant Narrow and Numerous, Boost Yields
Improved corn genetics might favor high seeding rates and ultra-narrow rows, helping boost yields.