Category: Agriculture

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Illinois Agricultural Disaster Declaration Due to Drought

Press release on disaster declaration

On January 26, 2011, the USDA granted the Illinois Department of Agriculture’s request for federal disaster assistance for southern Illinois farmers who suffered crop losses caused by drought in 2010. The 16 counties are for the most part south of Interstate 64. The full press release can be seen here.

What happened

Rainfall amounts in parts of southern Illinois were much below normal from May all the way through October. However, the pattern and sequence of rain events varied from month to month and place to place.  Therefore it’s hard to make a general statement about all the counties in the declared region. For example, Cairo IL received 28.6″ of rain from April to September (over 6 inches above normal) while Fairfield received only 17.1 inches (over 6 inches below normal).
Two contributing factors to crop losses are the regions shallow soils that hold less water and temperatures that were about 3 degrees above normal.
Here are two maps that show the percent of normal precipitation for the period of April-June 2010 and July-September 2010. As a rule of thumb, any 3-month rainfall totals less than 70% of normal is cause for concern. Click maps to enlarge.

April-June, 2010, precipitation departures from normal.

July-September, 2010, precipitation departure from normal.

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First Half of November – Warm and Dry

First Half of November

The first half of November in Illinois has been warm and dry, according to preliminary data from November 1-15, 2010. The statewide average temperature was 47.3 degrees, 2.9 degrees above normal. The statewide average precipitation was only 0.21 inches, only 13 percent of normal for the first half of November.

Past November’s in Illinois

  • The driest November on record was 1904 with 0.28 inches.
  • November 2007 was the 25th driest with 1.75 inches.
  • November 2008 was the 20th driest with 1.48 inches.
  • November 2009 was near-normal with 2.47 inches.
  • Normal state-wide precipitation for November is 3.34 inches.

The term “normal” refers to the 1971-2000 average.

Precipitation percent of normal for first half of November 2010
Precipitation (Percent of Normal) for the First Half of November 2010.

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More on Soil Temperatures in Illinois

Here are the average dates in fall when the 4-inch soil temperature falls below 50 degrees (left panel) and below 60 degrees (right panel). Consider these as a “rule of thumb” for planning purposes. Consult the current soil temperatures, as discussed in the earlier post, for decisions on applying nitrogen in the fall.
 

Average date when 4-inch soil temperature drops below 50 and 60 degrees.
Average date in fall when the 4-inch soil temperature drops a) below 50 degrees, and b) below 60 degrees.

 

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Daily Soil Temperatures Across Illinois

The Illinois State Water Survey operates a network of 19 sites that report daily soil temperatures at 4 and 8 inches.
Soil temperatures in the fall are critical for the application of nitrogen (N) fertilizer. According to the Agronomy Handbook (University of Illinois), “fall N applications should be done when daily maximum bare soil temperature at 4 inches is below 50 degrees.”
The daily maximum and minimum soil temperatures are measured over grass. In addition, the values are adjusted using regression to estimate the bare soil temperatures, to better represent the soil temperatures in a cultivated field. Grass tends to insulate the soil so the daily temperature swing is a little smaller than over bare ground. In addition,  soil temperatures within a particular field may vary due to soil color, soil moisture, and crop residue on the surface.
You can see the daily data and maps at http://www.isws.illinois.edu/warm/soiltemp.asp