Soils: January 2004

The Noble Foundation, land grant universities and private seed companies publish variety test information evaluating new crop varieties and strains annually. These tests provide producers valuable information about new genetics as they become available and how they compare to old standards that have been around for years. The question is how to use all this information to make a decision about what to plant to benefit your operation.

There are several factors to consider when looking at variety test information:

The location and conditions under which the test was conducted.
Results for testing done in Minnesota are probably not applicable in North Texas. Be sure to look at where the testing was done, the soil type, rainfall and other management information provided. Look for sites with conditions similar to the area you will plant.

Who is conducting the test?
Testing done by unbiased parties is usually best.

How many years of data exist?
Looking at the average of several years of testing increases the confidence we have in the results. Multiple years give us an idea of the yield "stability"of a variety under different environmental conditions, i.e., wet versus dry years.

What is the LSD?
Yields, and other factors, must differ by a value noted as the least significant difference (LSD) to be considered truly different. LSD is a statistical tool that allows us to determine differences between entries considering the error associated with the experiment. If the LSD for a wheat yield test is 6 bu./ac., then two varieties must differ by more than 6 bu./ac. for us to be able to say one yielded better than the other. If they don't differ by 6 bu./ac., then (within the accuracy of the experiment) we can't say that one would be better than the other if we ran the test again.

Other than yield, what should I consider?
Producers should think about time to maturity, quality, disease and insect resistance and seed price.

OK. You have picked several test reports with conditions similar to your farm, and you have identified a high-yielding variety that also produces adequate quality at a reasonable price. How much additional production can you expect from improved genetics on your farm? It is difficult to predict this with any accuracy, but if you already have some of the standby varieties on your place, you could compare your production to that listed in the test to get an idea of potential improvement. Take the average yield reported across several years of testing and compare them to your actual yields over that same time. Table 1 gives an example of how this might work. A producer has been growing Jagger and Custer and is considering planting 2174. In this case, farmer yields were subtracted from the test yields to get an average of how much yield to expect from planting 2174 "on the farm." This average was then subtracted from the test information present for the higher yielding variety to get an estimate of the advantage due to better genetics.