There is a lot of interest in narrow- and twin-row applications to increase yields. With today’s implement technology, we now have planters that will do an excellent job of planting corn in narrow and twin rows. Some things to consider are the hybrids you use and the fertility programs to go along with your yield goals.
In an irrigated, narrow- and twin-row application, you need to plant 4,000 to 8,000 more plants per acre to increase your yield potential. With these extra plants you need to increase your N, P, K and micronutrients to feed these plants. Using the same fertility program you used in the past for 30-inch-row plant populations will not be enough. Work with your local fertility professional for the correct recommendations for each individual field. You will also find planting populations in this seed guide for irrigated, narrow- and twin-row applications, in the Corn Products section.
Producers in the western Corn Belt, using lower plant populations as a hedge against drought, or producers farming sandier, drought-prone soil types, can benefit from flex-ear genetics because they develop larger ears with above-average rainfall. Southern, Western, Tropical and High Yield flex-ear hybrids respond to lower populations by forming longer or girthier ears. Using flex-ear hybrids at lower populations can keep the yield ceiling high, while minimizing risk if the weather turns dry. However, other genetic families with strong silking characteristics offer excellent drought tolerance without lowering population.
Stalk quality is a greater problem in continuous corn because insects and diseases overwinter on the residue. Lowering the plant population, which reduces interplant competition, produces corn plants with shorter, thicker stalks; lower ear placement; and thicker stalk rind. These plant responses to population reduction improve stalk quality. Lower population is a method for reducing risk with continuous corn.
The flex-ear type hybrid maintains high-end yield potential in spite of lower population. Therefore, reducing the plant population of Southern, Western, Tropical and High Yield genetic types increases their tolerance to continuous corn by improving stalk quality, yet retaining yield potential by flexing ear size.
Flex-ear hybrids planted at low populations conserve the limited supply of soil nutrients for grain fill. With fewer plants in an acre, fewer nutrients are utilized to produce the vegetative part of the corn plant and fewer total nutrients are required. Western, Northern and High Yield types planted at low populations outperform hybrids developed from other genetic families in fields with low fertility, especially low nitrogen.
Western Genetic Family hybrids produce shorter plants that require fewer nutrients for development. They are therefore a key component of a high-acreage, low-input crop production strategy, especially with new herbicide-tolerant systems. These products provide improved weed control in low-leaf-area-index cropping systems, particularly Western Genetic Family hybrids with Roundup Ready® and LibertyLink® herbicides.
The last aspect of plant population management that must be considered is seed cost. As more technologies are added to seed, such as Bt and corn rootworm resistance, the cost of seed goes up. Strong flex-ear hybrids allow the use of lower populations, which means a lower seed cost per acre. For example, current triple-stacked hybrids cost about $200 per unit or $2.50 per thousand kernels. Using a flex-ear hybrid that requires 4,000 fewer plants per acre can potentially save $10 in seed input costs.