Cold Enough for Ya?

In a line in the movie 'Grumpy Old Men,' Walter Matthau's reaction to the weather man's question`on TV is priceless.  After the early start in the first few days after Easter, April has once again thrown us a curveball with daytime high temperatures some 10 to 15 degrees below the climate normal's average, while minimum daily air temperatures have dipped below 32F in 9 of the last 13 nights (Figure 1).

Figure 1. Daily minimum air temperatures and average bare soil temperatures at a depth of four inches as recorded by the NDAWN stations in Fargo, Grand Forks, and Humboldt, MN from April 5th, 2021 through the 18th, 2021.

You may wonder whether those earliest seeded fields are in trouble and whether the seed is still alive.  First, the daily average soil temperatures at a depth of four inches in bare soil at those same three NDAWN stations have not dropped below 32F as of yet. The NDAWN stations do not report hourly minimum soil temperatures, but if we look at the data from the weather station at the NWROC we can see that the minimum soil temperatures have not dropped below 33.5 degrees (Figure 2). Also, note that soil temperatures increase 5 to 6 degrees on sunny days and dissipate this accumulated heat much slow on overcast nights than on clear nights or when snow cover is present.

Figure 2. Daily minimum and maximum bare soil temperature at a depth of 4 inches as recorded by the weather station at the Northwest Research and Outreach Center near Crookston from March, 21st, 2021 through April 19th, 2021.

You may wonder whether this cold snap has put the earliest seeded wheat (or barley or oats) in peril.  This morning I checked a field west of Crookston that was seeded on April 6th.  The grower had attempted to put the seed onto moisture with a less than ideal seeding depth of 2.5".  After two weeks the seed had germinated and the radicle was just visible (Photo 1).  At his point in time and with the immediate forecast in mind there is no real concern that this field will not have an adequate stand once more spring-like weather returns to the region.

Photo 1. Germinating spring wheat seed with the radicle just visible.