Planting corn or soybeans in sod

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Column by Matt Adams, Hardin County Extension Service agent

As grain markets have soared to more profitable levels over the last few years, I have seen and heard of countless hay and pasture fields that will be planted with corn or soybeans this spring.

In spite of record high cattle prices, the balance sheet simply continues to favor grain crops over cattle, assuming cattle are being pastured on land suitable for row cropping.

If you plan to be one of these modern day “sodbusters,” here are a few things to consider as you drop the planter into that long established hay field or pasture this spring

First of all, let’s take a look at pest management. Weed control is essential and can be difficult to achieve in a corn following sod application. Two herbicide applications may be required to achieve proper burn down before planting. Sod also is known to have high insect populations, especially wireworms and white grubs. If these insects are present and are left uncontrolled, they can cause severe stand loss and decreased seedling vigor.

Control options include liquid or granular soil-applied insecticides at planting or an insecticide seed treatment. With large insect populations usually present in sod ground, the higher end rate of application on the insecticide label typically is required for control.

 Voles, birds and other small rodents and animals can cause problems in corn following sod by digging up planted seed or creating tunnels, holes and mounds which can make operating equipment difficult. Early burn down or mowing will help by reducing the amount of plant material present for these animals to hide in.

Next, let’s look at nutrient requirements for corn following sod. Corn planted into grass sod usually requires 25-50 fewer pounds of nitrogen per acre than corn following soybeans or corn. This reduction is mainly because of the breakdown of the organic matter from the previous sod crop and the resulting release of Nitrogen. But what if the previous forage crop was a legume? Sod containing at least a 25 percent legume content credits 40 pounds of nitrogen per acre. A stand of red clover credits 90 pounds of nitrogen per acre. A 50 percent or greater stand of alfalfa will credit 120 pounds of Nitrogen per acre to the following corn crop.

Amounts of phosphorus and potassium available in the soil will vary depending on how the existing forage crop had been managed, however, hay and pasture fields are known for having low potassium levels, because of the amount of material removed by hay production and pasturing, and the nutrient cycle. The pH levels are often less than desirable in hay and pasture fields, so an application of lime may be needed. No matter what level of management the previous sod crop was under, a soil test always should be done to ensure the proper supply of phosphorus, potassium and lime.

One also should consider tillage options when planting into sod. As mentioned before, chemical control of weeds and grasses in sod ground can be difficult. Conventional tillage is a simple solution, as this buries much of the plant residue present in a sod field, exposes some insects to birds, and loosens the soil, making planting easier. However, we all know tillage destroys soil structure, and promotes soil erosion. Also keep in mind the reason most of our sod fields were planted to hay and pasture to begin with is the fact the ground is rolling or on fragile soils. Some of our county’s pasture land also is very rocky. Conventional tillage should be avoided on soils such as these.

If no-till is chosen, then planters may need to be modified to allow the planter to penetrate the dense sod, and plant at the proper depth. Producers also should consider going over these no-till sod fields with a minimum till sub-soiler or ripper, if that is an option. Hay and pasture ground encounters a lot of wheel and hoof traffic, which can create compaction problems. No matter what tillage system is chosen, proper grass waterways always should be left to manage water runoff.

Also remember to consult your crop insurance agent before planting a crop into sod. Sod ground can have severe limitations on the crops insurability.

For more information on planting corn or soybeans into sod, contact the Hardin County Extension Service at (270) 765-4121

C.A.I.P grant program. The County Agriculture Investment Program soon will be offered in Hardin County. Applications for this 50/50 cost-share program can be picked up at the Hardin County Extension Service from May 1-15.

All applications must be turned in to the Hardin County Extension Service no later than close of business on May 15. Cost share programs available include agriculture diversification, large animal (beef, dairy, equine), small animal (goat, sheep, bee, rabbit), farm infrastructure, fencing and on-farm water, forage and grain improvement, on-farm energy, poultry and other fowl, technology and leadership development, and value-added and marketing. For more information, contact the Hardin County Extension Service at (270) 765-4121.

Matt Adams is a Hardin County Extension Service agent for agriculture and natural resources.