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Don’t sweat a drought . . . yet

Worried what this “brown winter” and low soil moisture levels in many areas will have on next year’s growing season moisture levels and yields?

Don’t sweat it . . . yet. A low soil moisture profile after harvest doesn’t mean the profile will be low in the next spring. Nor is there any firm correlation on yield the following year.

That’s the case at the University of Minnesota (U of M) Southern Research and Outreach Center at Waseca, Minnesota. Center scientists recorded 18 years of rainfall and yield data starting in 1988 through the present year. (Data was not included for several years in the early 1990s, but has been kept every year since 1996.) Center officials reported on findings during this week’s U of M Winter Crops Day.

Fall to spring moisture gains occurred in 12 out of the 18 years. In 6 of those years, spring levels were lower than fall levels. Remember the drought year of 1988? Fall soil moisture that year was a low 5.06 inches. By the time spring rolled around in 1989, soil moisture had risen to 8.98 inches, a 3.92-inch gain.

Ditto for 2000, when a fall soil profile moisture of 7.85 increased in spring 2001 to 11.48, a 3.63-inch gain. Or 2003, when the fall’s 7.21-inch fall soil moisture level increased to 10.58 inches in spring 2004, a 2.87-inch gain.

The highest decrease occurred from 2009 into 2010, when the fall soil profile moisture level of 10.93 inches decreased to 9.73 inches, a 1.18-inch decrease.

The data also points out there is no correlation between fall moisture levels and corn yields the following year. In 2002, a plentiful soil moisture profile level of 10.92 inches was followed by a 55 bushel per acre plunge in 2003 compared to 2002 yields. Meanwhile, 1989 corn yields were 46 bushels per acre above those of 1988, even with a scant 1988 fall soil moisture level of 5.06 inches.

“By the time spring comes and planting starts, we normally get a significant recharge of rainfall in March, April, and May,” says Jeff Vetsch, a U of M soil scientist at the Center. “If it gets late May and we have these moisture deficits, that’s the time to get concerned.”

For now, though, it’s too early to tell if the area will be short on 2012 moisture.




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