No. 17 Article 4/July 29, 2011

Appearance of Nutrient Deficiencies Is Causing Concern

Weather conditions have been very hot and dry for most of Illinois all last week, with maximum air temperatures in the upper 80s to upper 90s. The only area that received rain before Sunday was the upper northern portion of the state. On Sunday (July 24), most of Illinois received some precipitation, ranging from only a tenth of an inch to slightly more than 1.5 inches (Table 1). Because of the dry conditions, some fields have started to show some nutrient deficiencies, specifically of potassium (K). While I suspect that in most cases the deficiencies will disappear with more rain, they are a matter of concern to some farmers. In certain situations deficiencies have shown up even in fields with high or very high fertility, but typically they have occurred in fields with marginal fertility or that are just above critical soil test levels.

Table 1. Precipitation for various Illinois locations, July 18 to 24.

Station

County

Rain (in.)

July 18

July 19

July 20

July 21

July 22

July 23

July 24

Total

Freeport

Stephenson

0.05

0

0

0.01

2.41

0.48

1.54

4.49

DeKalb

DeKalb

0.09

0

0

0.09

0.41

0.40

1.42

2.41

St. Charles

Kane

0.03

0

0

0.03

1.16

0.86

0.17

2.25

Big Bend Con-servation Area

Whiteside

0

0.14

0

0.20

0.20

1.81

1.41

3.76

Peoria

Tazewell

0

0

0

0

0

0

1.26

1.26

Stelle

Ford

0.02

0

0

0

0

0

1.09

1.11

Kilbourne

Mason

0

0

0

0

0

0

1.21

1.21

Bondville

Champaign

0

0

0

0

0

0

1.26

1.26

Champaign

Champaign

0

0

0

0

0

0

1.13

1.13

Perry

Pike

0

0

0

0

0

0

0

0

Brownstown

Fayette

0

0

0.01

0

0

0

1.28

1.29

Olney

Richland

0

0

0

0

0

0

0.69

0.69

Rend Lake

Jefferson

0

0

0

0

0

0

0.81

0.81

Fairfield

Wayne

0

0

0

0

0

0

0.34

0.34

Carbondale

Jackson

0

0

0

0

0

0

0.53

0.53

Dixon Springs

Pope

0

0

0

0

0

0

0.11

0.11

Springfield

Sangamon

0

0

0

0

0

0

0.56

0.56

Belleville

St. Claire

0

0

0

0

0

0

0.16

0.16

Monmouth

Warren

0

0

0

0.85

0

0

1.06

1.91

Source: http://www.isws.illinois.edu/warm/soiltemp/displaymap.asp.

While very little can be done at this point to correct the problem (besides getting rain in the field), the locations of deficiencies should be noted to determine if something should be done for next year. The cause may simply be that the crop cannot access the nutrients present in the soil, even at adequate levels, because of the lack of moisture, but in some situations action may be warranted to correct the problem for the next crop.

If you are seeing nutrient deficiencies, consider the following points in deciding whether they are worth worrying about and whether any response is appropriate.

--Fabián G. Fernández

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