South Central College
A few years ago, I attended the Crop Pest Management (CPM) Short course at the Minneapolis Convention Center. This event is sponsored by the University of Minnesota and others as an opportunity to share the latest research on a variety of agronomic topics including fertilizer recommendations, weed and insect control, tillage, disease control and other pertinent topics. This is where many agronomists, coop personnel, independent crop consultants and others who work in a consulting role with farmers get information that will be shared with farmers as they make their planting decisions for the coming planting season. One of the sessions that I attended was presented by Dr. Fred Below from the University of Illinois. He is a research agronomist at the University of Illinois and presented some research that he called the "Seven Wonders of the Corn Yield World" This research focused on the main factors that influenced corn yield and how many bushels of corn could be attributed to each factor. Some of his observations were obvious, but some were items that you wouldn't think would be quite so important.
First of all, the pre-requisites for the research were that we had good pest and weed control. This is an obvious one and we know that without good weed control, for instance, we will not realize the full yield potential of our corn crop. The second pre-requisite is that we had adequate levels of Phosphorus (P) and Potassium (K) as well as proper soil pH. The latter is especially important as important soil nutrients such as P and K are not available under low ph conditions. And finally, the study allowed for a one-time improvement such as drainage to be considered in the research. Following are some of the observations from Dr. Below's research.
1. Weather 70 bushels per acre
This seems rather obvious, but we forget that weather includes not only the amount of rain that we get but also the temperature, wind, hail, clouds and temperature. If any one of these is out of wack we have a major problem. Too much rain during the month of July, for example, negates a lot of good crop husbandry.
2. Nitrogen 70 Bushels per acre
Corn is a grass and thus needs supplemental nitrogen fertilizer in order to grow and yield the way that we want it to. Legumes such as soybeans fixate their own nitrogen from the atmosphere. Fertilizer is no place to try and save money by applying less then what is needed.
3. Hybrid Selection 50 bushels per acre
We have had a tremendous improvement in corn hybrid development in the past 20 years. Corn hybrids from the 1980's would have collapsed during the summer of 2009 due to lack of consistent moisture. A good corn hybrid can make a lot of difference on your farm. However, weather still plays the largest role.
4. Previous Crop 25 bushels per acre
We do know that we can give a nitrogen credit of 40 50 pounds to a previous crop of soybeans. We also know from research that we take a yield hit when we plant corn following corn. That yield hit varies and is not as big of a problem as it used to be.
5. Plant Population 20 bushels per acre
Corn seed is not the item to cut to keep costs down. The optimum population for soils without any compromises is around 34,000 harvest population.
6. Tillage 15 bushels per acre
There are issues between timing of tillage operations and type of tillage.
7. Chemicals 10 bushels per acre
Current research shows that there may be beneficial interactions between certain fungicide usage and the longevity of the plant. Fungicide use may slow the rate of loss of leaves, thus keeping the plant green a little longer. This needs more research before we can recommend it.