April 15, 2011

Many decisions need to be made when planning to convert CRP ground to row crop production, including what crop to plant.  Practically, in eastern Nebraska, it will be soybeans or corn. Before selecting the crop, consider factors particular to post-CRP production. Like working through a maze, sometimes it is easier to start at the end and find the beginning.

Growing corn can be more difficult than growing soybean after CRP for several reasons.

• Corn following CRP requires more nitrogen than a normal corn crop. We recommend adding 50 lb more N than you would apply to similar corn grown conventionally. (See UNL Nebguide G1970.)
   
• The seedbed for corn needs to be in better condition than that for soybean since plant population and spacing are more critical in corn than in soybeans.
   
• Corn will need to be planted earlier than soybeans, so there will be less time between now and when you want to plant to kill the existing grass. Ideally, CRP grass was killed last fall, and any land preparation issues have been addressed.
   
• This spring you could plow the ground, disk it several times to prepare a seedbed, and then use a glyphosate-resistant corn variety. However, even if you can find a plow, the tillage would be expensive and you would lose many of the gains you made from having the field in CRP.

Given all these factors, corn does not seem like a good choice to plant after CRP. However, depending on the costs, it still may be profitable. There are just more risks and unknowns.

No-till soybeans have worked well for many planting into CRP. Soybeans can be planted later than corn, giving you time to kill the grass with herbicide. They also can be no-tilled with a slightly higher than normal population and inoculation. After emergence, post-emergence herbicides can be used to control weeds.

Before making a decision about which crop to plant, work through your plan to make sure it is cost effective and agronomically sound. Several UNL NebGuides and other resources (see box) offer more information on converting CRP to crop ground.

Much of the previous research on transitioning CRP to crop production was before the development of glyphosate-resistant crops. This technology makes weed and grass control much easier, but doesn’t change the need for additional nitrogen.

Charles Shapiro, Soil Scientist - Crop Nutrition
Haskell Ag Lab, Concord