The term precision agriculture has a nice ring to it, but we’re not there yet. With so many agronomic questions still unanswered, what we have is best de-scribed as approximate agriculture, best guess agriculture or perhaps what-has-worked-in-the-past agriculture.
You can feel rather precise pulling the seeding outfit down the field with hands-free GPS guidance, but what about fertilizer placement, particularly nitrogen. According to one of our most prominent soil scientists, Rigas Karamanos, who works for Koch Agronomic Services, shallow fertilizer banding results in more nitrogen losses than broadcasting.
Karamanos says there are virtually no losses if the band is three or four inches deep, but the banding during the seeding operation is typically shallow, leading to volatilization. To cut the losses, one of the various nitrogen stabilizers should be used, but that comes with a significant additional cost.
So while we know precisely how much fertilizer per acre we’re applying, we really don’t know how much nitrogen we’re losing and it will vary widely with the weather. A rain soon after seeding minimizes losses.
Seeding rates also defy precision. Thousand kernel weight is a valuable tool for knowing just how many seeds are going in the ground per square foot or square metre. However, the seed survival rate varies widely, particularly for small seeded crops like canola. Plus the recommended range for plant populations is quite wide.
Despite the question being around for years, there are still differing opinions on optimum row spacing. Do you get the best yields with nine inch spacing or can you go all the way to 12 or 14 inches without sacrificing yield? Is the answer different for different crops, different soil zones and different years?
Even if you have a new drill, is the seed and fertilizer distribution equal across the entire length? I’ve never done any tests, but I’d bet there is a significant deviation based on hose length and airflow.
It’s also interesting how many producers end up with serious seed rate issues on new outfits. Sometimes it’s operator error as they try to learn a new system.
Other times the machine has come out of the factory with some glitch or flaw that leads to issues.
Reseeding a field or knowing a field has a much higher seeding rate than intended doesn’t fit the precision moniker very well.
Sprayers have become technological marvels, but how we use them varies greatly. Some agronomists advise that higher water volumes provide better coverage and therefore better weed control. Many producers in the interests of time and efficiency use lower water volumes in their glyphosate burn-off operation and report great results.
What rate of glyphosate do you use in the spring? What rule of thumb do you follow if there has been an overnight frost? How long should you wait to spray to make sure the weeds are actively growing again?
Basic agronomic research is often incomplete or we’re relying on decades old studies. Or the research information hasn’t been incorporated into useful recommendations.
Most producers rely on past experience, use common sense and seek opinions of others. Agriculture is a science, but there are a multitude of variables and unknowns. For the most part, the equipment has the capacity to be quite precise.
However, our knowledge is still evolving and Mother Nature is highly variable. We haven’t arrived at precision just yet.