Acreage battle updateDecisions, decisions
Many growers still may be deciding whether to plant corn after corn, soybeans or other crops following corn. Agronomy experts with Pioneer Hi-Bred International, Inc., 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, according to a Pioneer report.
"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, Minnesota. "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.