Consider Agronomics and Economics for 2014 Crop Rotations

With the 2013 growing season behind us, we can begin planning for 2014! Both agronomics and economics (A&E) will play a part in your decision-making. Obviously, crop prices will determine which crops you even consider. But agronomic factors, such as fertility needs, weed control, crop residue, and harvest timing must also be considered when planning an optimal rotation. What makes the most sense for your farm?

A corn-on-corn (CC) rotation requires significantly different management techniques than a corn-on-soybean (CS) rotation. Fertility and crop residue-handling are unique to each. Many university research studies reveal reduced corn yields when a continuous rotation is used, yet most record-breaking corn yields in the US have occurred in fields with a CC rotation. What does that mean? Were these plots fertilized enough to account for the tie up these fields need?

I believe increased fertility makes the difference, and low fertility may be the cause of lower yields in most plots. Nitrogen must be 30 to 50lbs higher in a CC rotation. Without Nitrogen from a previous legume crop, the increased corn residue uses most of the available Nitrogen in the soil.

Proper handling of the increased crop residue is critical to achieving top yields in a CC rotation. Increase yields by working the soil into a dark seed bed in the spring. Research from the University of Wisconsin illustrates that yield drag in CC rotations can be reduced by an aggressive tillage program.

Evaluate the two-year profitability of each of your fields. If the field is not productive for soybeans, a reduced corn yield in the second year may still be more profitable than planting soybeans that are not suited for that particular ground. Select high-yielding hybrids with traits, but also consider soil fungicide as a good alternative.

In our region, wet soil conditions in the spring lead to later planting and reduced short season options. For this reason, a continuous soybean rotation is more prevalent than a CC rotation. The biggest challenges we face with a soybean-on-soybean (SS) rotation are disease-related, as our soils are prone to root rot and other pathogens that affect soybean yields. Most of these pests can be effectively managed with the use of seed treatments and variety selection.

Fungicide seed treatment should be a regular practice, regardless of your rotation, but make sure fungicide rates will cover your targeted pathogens. Phytophthora has been the most common root rot disease in our area. It can be reduced with seed treatment, but the selection of Phytophthora genes in the variety planted is also helpful. The Rps1k gene has been the preference when selecting a variety to combat this pest; however, heavy use has caused predominant races of Phytophthora to adapt to it, reducing its effectiveness. The Rps3a gene is now the best defense against this pathogen, and displays excellent results in controlling Phytophthora.

Choosing your rotation should involve analysis of many factors besides the commodity price of the grain. Be sure to consider both A&E – agronomics and economics – so you’re able to avoid yield robbers that may reduce expected profit.