ReachOut: The Perils of the 75° Day

Mike Zwingman

Mike Zwingman

Here’re the good things that heat brings: shorts, grilling, eating outside, fire pits, baseball, lightning bugs, camping.  Here’re the bad things: weeds, soil that dries quickly, and N loss.

Normally I would wax poetically about N loss and the global imperative to improve our nutrient management.  I’m not feeling quite as poetic this week.  The stark fact is that as I write, our soil temperature is ten to fifteen degrees warmer than usual for this time of year.  Like I mentioned above, the heat brings with it a host of awesomeness, but it also pushes the schedule of all the bad things that can to our N into hyperdrive.

I don’t usually start having nightmares about nitrification until about April or May, but here we are in mid-March and don’t you know, I’ve woken up in a cold sweat twice already this week.  The long term forecast doesn’t look to offer me any reprieve either—it appears that the warm weather is here to stay.  That means a barbeque this weekend and that any N applied to our fields so far is subject to dreaded nitrification.

ReachOut: The Perils of the 75 Degree Day from Central Valley Ag on Vimeo.

I would love to offer you an easy answer here.  I’d get more sleep.  But the reality of the climate and the complexities of the N cycle don’t make for easy answers.  The clock has begun for us on N loss.  We need to be aware of this, and take care to protect the N we’ve yet to put down.  And we can’t be surprised if we wake up one day in June and find some unexpected ugly in our fields.  We’ll all live through this of course, but the quirks of the 2015 season have begun in earnest.

The really crazy-making thing about N loss is that while the process is linear, the timing of events in the N cycle isn’t standardized or dependable from a practical point of view.  When we get into the science of it and take a molecules-and-reactions angle, you can see that the cycle actually is predictable, but you’re a grower, not a chemist.  From your viewpoint, the cycle isn’t predictable.  This means that we can’t simply push our management plan ahead by a few weeks all season and expect that all will be well.  When the heat turns up, weird things happen in the N cycle.  Events A, B, and C can happen days apart, hours apart, or nearly all at once.

And as time goes by, this messy process also speeds up exponentially.  At 50 degrees, for example, it would take about six weeks to nitrify half of your N.  At 60 degrees, it would take two or three weeks to do the same.  At 75 degrees, you’ve got about ten days.Blue Box

So what’s a grower to do, right?  Well, for the N you’ve applied already, there isn’t much to be done.  If you’ve used a loss inhibitor, it will help your cause, but be aware that the clock is ticking on it as well.  For the N you’re yet to apply, a loss inhibitor is a good option for protecting your investment from nitrification, but in this climate, it’s not foolproof.  Splitting your future applications is another tried and true strategy for reducing loss simply because it reduces the time N is sitting in the field and subject to loss.  Combining split application with an inhibitor is the most effective loss prevention strategy, but of course, the most involved.

And hey, while you’re chewing on this, go check your fields for weeds because they’re bad, too.