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Farmers Race Against The Clock For Needed Growing-Degree Days
When it comes to fall harvest, many area farmers are hoping things heat up.
This year’s crop has become a race against the clock to overcome a slow start to the planting season. As a result, many crops are lagging in the number of growing-degree days (GDDs) needed for maturity.
Now, farmers are hoping their fields receive an above-normal amount of heat units for this time of year, according to Dennis Todey with the U.S. Department of Agriculture.
That’s particularly true for corn, said Todey, a former South Dakota state climatologist.
“The importance this year is that corn needs a certain amount of GDDs to reach maturity. Because of the late planting, we needed additional heat along the way to ‘catch up,’” he told the Press & Dakotan.
“September is a mixed message depending on the time period of the outlook. Right now, the next couple weeks look warmer than average.”
Hope remains for both corn and beans, Todey said. “Both crops are in decent condition, given the year. They’re just late,” he added.
While calculating GDDs follows a complex formula, the basic idea remains the same, he added.
“GDDs are a way of taking maximum and minimum temperature measurements on a daily basis and creating a value that, accumulated over time, relates to the growth of crops,” he said.
“Corn is the most directly related because you can pretty well assess how far along corn is during the year compared to the number of total GDDs needed. You can also use GDDs to track certain insects.”
The problems began last year with heavy rains in the fall and heavy snow in the winter. Those issues were compounded by a March bomb cyclone that dumped several inches of rainfall over a wide region within a few hours.
The continued heavy rains through spring and summer delayed or prevented planting for many producers, particularly in southeast South Dakota.
Fields remained flooded and roads were impassable because of the continued standing water and mud. Many farmers were blocked from entering or even reaching their fields, let alone working them.
“South Dakota was one of the largest locations with prevented planting this year,” Todey said.
The Yankton region set an all-time precipitation mark dating back 124 years of recorded data, according to South Dakota state climatologist Laura Edwards.
Southeastern South Dakota set a new precipitation record for the 12-month period of September to August, according to data released Monday by the National Oceanic and Atmospheric Administration (NOAA). The region received 37.42 inches compared to the long-term average of 23.46 inches, Edwards said.
“This has been a very wet year, no doubt about that,” she said.
In terms of precipitation, Nebraska recently saw a record-setting month, according to state climatologist Martha Shulski.
“August 2019 ranks as the wettest on record (since 1895) for Nebraska. This was driven by heavy rains in the central portion of the state,” she said. “(Year to date), we are third wettest.”
Northeast Nebraska fared better in terms of getting a crop into the ground. However, portions of northern Knox County were hit by a late summer hailstorm that wiped out a number of fields.
Because of this year’s adverse conditions, farmers need a number of factors to fall their way — including a rapid number of GDDs, Todey said.
This year’s problems became compounded in August when areas didn’t receive the full “dog days” of summer, or last blast of heat, Todey said.
“We’ve actually lost more ground over the last 30 days with some below-average temperatures,” he said. “Corn can shorten the amount of GDDs it needs a little, but we need warm temperatures now and as late a freeze as possible.”
Earlier in the season, crops needed timely rains for developing the root systems, but that’s no longer the case, Todey said.
“At this point, root systems are developed,” he said. “Warm weather to push the crop is what is needed. Crops should have the moisture they need to finish. Dry down is most important now.”
However, the Yankton region has seen continued rainfall. The wet weather isn’t helping the situation, Todey said.
“If conditions were dry, crops would probably start running out of moisture and start drying down. That’s not the case anywhere in South Dakota this year,” he said.
“Crops will also take some time to dry down after freezing. Producers should be ready for a long fall waiting. The wet soils could make the situation even worse in keeping people out of fields. There may be crops that need to wait for harvest until the ground freezes.”
Both southeast South Dakota and northeast Nebraska trended cooler during the past week, according to the High Plains Regional Climate Center (HPRCC).
High temperature readings at some points only reached 70 degrees or cooler, but temperatures bounced back into the mid-80s and even higher, the center added in its weekly report.
The HPRCC report shows southeast South Dakota has varied from the average for both temperature and precipitation, Edwards said.
She noted the last 120 days — which captures most of the growing season — showed rainfall of 150 percent of normal for parts of the Yankton region.
“For temperature, it has overall been cooler than average, but there have been some warmer periods mixed in as well,” she added.
The one-two punch has affected the GDDs, Edwards said.
“As far as corn GDD goes, what I see from some spot checking in the area is that anything planted mid-April to mid-May is behind average on accumulated GDD,” she said.
“Depending on where you are, this could be 50 to 150 or more GDD behind. For anything planted around June 1, accumulated GDD are about on the long-term average, but then your likelihood of reaching maturity before frost/freeze also depends if you changed maturity to account for a shorter growing season.”
The mercury readings have remained a mixed bag, Edwards said.
“For temperature, it has overall been cooler than average, but there have been some warmer periods mixed in as well,” she said. “This region has been below average for much of the year, but not record cold.”
An active weather pattern appears on the horizon, Edwards said.
“The forecast for the coming weeks show a wet pattern to start, that will likely transition to a drier pattern about 1.5 to two weeks from now,” she said. “The next seven days could bring 1.5 inches or more of rain to most of the state. The outlook for 3-4 weeks from now, which is September 21 to October 4, is indicating a drier pattern over the Northern Plains and Midwest states.”
The region needs as late a freeze as possible, Todey said.
“Right now, we don’t see any indications of an early freeze,” he said. “Typically, we would be concerned around the end of September as the first times to start really being concerned for that hard freeze. But the average date is into October, depending on the location. And the trend in first fall freeze is toward later. That would be good news.”
The dates and types of frost or freeze play a major role in the outcome of a particular crop, Todey said.
“Some horticultural crops can be damaged (with temperatures) in the mid- to low 30s. Row crops can usually handle below 32 (degrees) for a period of time,” he said.
“Once we fall to 28 (degrees) or below, the crop is probably done for the year. Crops that are stressed can sometimes be damaged at higher temperatures.”
Edwards also doesn’t see an early frost this year for southeast South Dakota.
“Given the outlook and likely transition to a warmer-than-usual pattern at the end of September, I think we will see an average or later killing frost this year. Every day counts (during) this fall, and warmer-than-average days are even better,” she said.
“Also in our favor for an average or later frost are two other factors: our long-term trend is towards later frost/freeze in the fall; and we have high humidity in the environment.
“Typically we see early frost/freeze during drought years when the air is drier and cools down faster at night. We’ve had some cool nights, but the humidity has been high, which makes it hard to get a rapid drop in temperatures.”
The average killing frost of 28 degrees can vary, and the Yankton region benefits in that regard.
“Early October is typical for much of our region, but maybe middle of October in parts of the southeast and south central South Dakota,” she added.
The National Weather Service (NWS) forecast for Yankton region calls for possible heavy rain through tonight (Wednesday). The area could see more than 2 inches in many locations.
The Thursday forecast calls for a slight chance of thunderstorms, with the chance returning Saturday.
The temperature forecast calls for the mid-80s today, dropping to the low to mid-70s Thursday and Friday before rising to the lower 80s Saturday.
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