Harvesting Alfalfa, Harvesting Data

By Olivia Steinmetz   |   August 17, 2022

As a Plant Breeder, one of the biggest “crops” that I harvest is data. From May until September, the primary data point that I am collecting is yield.

Our alfalfa breeding program has always focused on yield, quality, and persistence as the foundations of any new varieties. That’s what makes our alfalfa so superior! But how do we end up with high yielding varieties? That process takes a few years, from development to testing (read more about the developmental process at “Selecting The Next Generation”).


Harvesting yield data at the Research and Learning Center in Waupaca, WI.

Every spring we seed our newest experimental lines of alfalfa into yield trials at various locations across the state. Yield trials provide a unique opportunity to test many different alfalfa varieties against each other on the same piece of ground: within one trial we will often have a total of 20 different alfalfa varieties, all replicated four times. Out of those 20 varieties, 10-13 of them will be brand new experimental lines, 3-5 of them will be top performing competitor varieties, and the remaining 3-5 will be our own best Legacy alfalfas. This way we know that anything new that we want to move forward with is actually better than what we already have and is better than other alfalfas currently out on the market.

We go through the process of planting new yield trials every single spring, as we always have new experimental lines to test. Each yield trial stays in the ground for at least three years, but often longer, as the more Wisconsin winters they go through the better. This means that on one piece of ground – at our Research Farm for example – we can “walk through time” by collecting data from brand new yield trials, a trial that is one year old, two years old, three years old, and so on all on the same day.

alfalfa field

Yield trial a few days post-harvest. Each individual variety plot is 17.5’ long and consists of five rows. You can see where each of the replications ends/begins (where the orange flags are)

Our first yield data point can be collected towards the end of the seeding year once a yield trial is established. The following summers we will harvest the alfalfa just about every 28 days starting around Memorial Day and ending around Labor Day, giving us four harvests of yield data from each trial each summer, in each location. As we gather more and more data on each experimental line, we can see which ones consistently perform at the top and which ones do not perform well over time or at certain locations to know that we are only moving the best of the best forward in our program.

We manage all the yield trials the same: same seeding rate, fertilization schedule, weed management, etc. to ensure that when we collect data on yield, the difference in yield that we see is due only to genetics. This gives us confidence when we are seeing some of our experimental lines yielding an extra ton of air-dry hay per acre over a summer compared to certain competitor varieties, that the improvement is real and it is genetic: the difference is in the bag.

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