Pioneer Provides Growers Information for Crop Rotation Decisions, Planting Tips

Consider field selection, compaction, residue management and soil fertility

Many growers still may be deciding whether to plant corn after corn, soybeans or other crops following corn. Agronomy experts with Pioneer Hi-Bred, a DuPont business, say the most critical decisions begin with analyzing highly productive fields, managing residue and compaction in those fields, and maintaining soil fertility.

The trend toward corn after corn has been underway since grain prices moved higher in late 2006. Last year, U.S. growers planted a record 93.6 million corn acres, an increase from 78.3 million acres the previous year. Though the industry is predicting a decrease in corn acres for 2008, corn acreage is expected to remain at relatively high levels.

Choosing the Right Crops for the Right Fields
“For growers contemplating their crop rotation options, those choosing corn after corn should start by selecting fields that historically have higher corn yields, good drainage and medium-textured soils with ample water-holding ability,” says Paul Gaspar, Pioneer agronomy research scientist in Mankato, Minn. "Seedbeds need to be in top shape to handle the growing season challenges, no matter which rotation plan is in place.

“At planting time, however, corn-after-corn fields present a more adverse environment for the corn seed and seedling. It’s difficult to wait, not knowing what the weather forecast holds,” says Gaspar, “But don’t plant corn-after-corn fields too early - keep the planters in check if soils are below 50 degrees and warmer weather is not in the forecast.”

Wet fields also can cause problems. Surface compaction, sidewall compaction and/or deep compaction can restrict root growth and limit water uptake and yield, particularly if followed by drought conditions.

“Managing residue from the previous crop is also a key factor for a good start in 2008,” says Gaspar. “Corn produces more than twice the amount of residue as soybeans. Excessive corn residue can result in much cooler soil temperatures and higher soil moisture at planting and can be a concern no matter which crop is going into the ground this spring. The goal is to clear residue from the row area - potentially with row cleaners, coulters or other residue management attachments on the planter. These can help with more rapid germination and emergence, particularly if there were challenges in distributing residue evenly during harvest.”

In looking at crop rotation choices, soil fertility should be based on thorough soil testing and local Extension recommendations. Soil tests are needed to determine soil pH and existing levels of phosphorous and potassium. Soil pH should be at or above 6.2 for growing corn. If planter attachments are available for applying starter fertilizer, growers should consider applying appropriate rates of nitrogen, phosphorus and potassium at planting time. This will improve the uniformity and speed of emergence of corn in cooler soils.

Corn residue ties up more nitrogen than soybean residue as it decomposes, therefore growers should plan to apply about 50 pounds of additional nitrogen to corn-after-corn versus corn-after-soybean fields.

“In high residue fields, consider using 50 pounds of starter nitrogen to give plants a faster start,” says Gaspar. “In all fields, consider splitting nitrogen applications, if possible. This can reduce nitrogen losses and help ensure corn plants have adequate nitrogen throughout the season.”

“Traditionally, growers have rotated fields in a combination of corn and soybeans or other crops. That trend continued until recent years, with the most significant production change occurring in 2007,” says Dr. Emerson Nafziger, crop science and weed management specialist, University of Illinois-Urbana. "In the past, there was some concern of negatively impacting yield if rotation was not made each year, or in some cases, at least every few years. However, the latest hybrids are holding their own in agronomic terms through a combination of genetic improvement and crop management practices. Today’s hybrids have better disease resistance, root systems and seed treatments, particularly compared with hybrids from just a few years ago.

“Though corn-soybean rotations remain a stable production practice, there is no strong indication that it will continue to be the standard of stability,” says Nafziger. “In fact, 2007 brought very positive signs for corn-after-corn production. Yield tells the story and results were favorable this year for many growers.”

Larger farming equipment also has contributed to increasing corn-after-corn rotations, adds Nafziger. The time once required for corn planting has been reduced with the ever-increasing size of equipment.

Reviewing Harvest Data
“Harvest data from the ’year of the corn’ in 2007, will be of particular interest to growers,” says Murt McLeod, Pioneer agronomy research scientist at Windfall, Ind. “With increased corn-after-corn acreage, last year was an optimum time to analyze efficacy data for hybrid performance and insect control. For unknown 2008 growing conditions, selecting hybrids that have a broad spectrum of insect control and strong root systems is key.”

Post-harvest research summaries in 2007 from multiple Midwestern locations confirmed that Pioneer® brand hybrids with Herculex® XTRA were consistently superior to other corn rootworm management options, including other transgenic and soil insecticides. In seven university and 11 Pioneer agronomy science trials, Pioneer hybrids with the Herculex traits were more effective against root damage, compared to hybrids with the YieldGard® traits developed by Monsanto. For more information, go to Post-Harvest Research Confirms Pioneer® Brand Hybrids with Herculex® XTRA More Effective Against CRW.

Hybrids with Herculex XTRA insect protection contain both Herculex® I and Herculex® RW to guard against a broader range of above- and below-ground insects in corn than any other in-seed product on the market. While offering good control of western bean cutworms, research also showed that Herculex XTRA provided the highest protection against black cutworms, excellent control of European corn borer and southwestern corn borer, and good protection against fall armyworms.

“Corn rootworm (CRW) larvae are one of the most destructive insects of corn in North America,” says McLeod. "Feeding on the root system, damage from corn rootworms can affect standability and limit water and nutrient uptake in the plant, impacting overall plant health and grain development. The end result can be yield loss of 10 percent to more than 30 percent which is common with moderate to high corn rootworm populations in untreated fields.

“Though corn rootworm pressure was less this past growing season in several areas of the Corn Belt than the previous two years, research trials were good indicators of yield performance during lower pressure situations,” McLeod said. “Higher yielding corn is still the overall goal for growers, and hybrids need to perform in all levels of insect pressure.”

For further information on crop rotation and seedbed preparation, contact your local Pioneer sales professional. In addition to your local sales professional, Pioneer offers a national network of agronomists to provide assistance.