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Northwest Iowa Crops Page
Subsoil Moisture
by Todd Vagts
ISU Extension Crops Specialist
Counties Served:  Carroll, Calhoun, Crawford, Ida, Monona, Pocahontas and Sac.

[Home][ISU Extension][IA State University]

Fall 2004 Subsoil Moisture Survey Results

  • Counties:  Carroll, Calhoun, Sac, Crawford, Monona and Ida
  • Date Sampled:  October 27 and 28

The ISU Extension Fall 2004 subsoil moisture survey has been completed for Carroll, Calhoun, Crawford, Monona, Ida, Sac and Pocahontas counties.  Results form this fallís sampling indicate a sharp contrast in stored soil moisture between counties, yet west-central IA is going into the winter season in relatively good shape with a greater than average amount of moisture stored in the areaís sub-soil.  

Results from the soil moisture survey taken in late October indicate that west-central IA had on average 5.0 inches of plant available water (PAW) in the 60-inch soil profile or 43% of capacity.  This was 108 % of the last 6-year fall average and much above the last fallís total of 2.6 inches PAW.  Soils with the most stored moisture were found in Carroll, Sac, Pocahontas and northern Ida counties with an average of 7.9 inches PAW.  In contrast, Calhoun, Crawford and Monona county soils were holding only 2.6 inches PAW.

West-central IA has received between 2.0 to 4.0 inches of precipitation since the sampling period; therefore an additional 1.5 to 3.0 inches could be added to the location totals.

West-central IA began the cropping season in very good soil moisture condition with the areaís soils holding on average 8.5 inches of plant available water (PAW) which was 73% of capacity.  Precipitation was mostly adequate through early July, but then became short during late July through September in many areas.  Yet because of the below normal temperatures, soil moisture demand was less and moisture stress was not a problem in most areas.   Late summer and early fall precipitation recharged soil moisture in Ida, Sac and Pocahontas counties.

The maximum amount of plant available water (PAW) in the top five feet of soil is around eleven inches for most northwest Iowa soils.  The subsoil moisture samples are taken to a depth of five feet in one-foot increments.  Five feet is the normal depth that corn, soybeans and alfalfa can extract moisture.   On average, a corn and soybean crop requires 26 inches of water to produce a normal yield.  Timeliness and intensity of the rain events greatly effects water infiltration into the soil and the plant's ability to utilize the moisture.  Keep in mind that rainfall has been variable across the region and the samples capture only a snapshot of time and location of actual subsoil moisture status.  Rainfall has occurred since the samples have been taken so moisture levels in many areas may have improved since the sampling period.

Soil Profile Graphs
State-wide map and Commentary by Elwynn Taylor (coming soon)

 

2004 Spring Subsoil Moisture Survey Results

      Previous Sample Plant Available Water    60-inch soil profile
County Township Town Crop Date Inches % of Capacity
Carroll Washington Carroll     7.1 57.1%
             
Crawford Paradise Dow City     3.4 29.1%
          3.2 27.5%
        County Average 3.3 28.3%
             
Ida Grant Kiron     2.9 24.4%
  Maple Battle Creek     3.6 28.9%
  Griggs Holstein     10.3 83.4%
        County Average 5.6 45.6%
             
Monona Center Castana     2.1 18.0%
          2.2 18.8%
          1.5 12.9%
        County Average 1.9 16.6%
             
Sac Richland Odebolt north     6.5 52.7%
  Eurek Schaller     6.0 48.5%
  Jackson Sac City     7.8 70.8%
  Sac Auburn     7.6 78.4%
  Wheeler Odebolt South     6.3 51.0%
        County Average 6.9 60.3%
             
Pocahontas Roosevelt Gillmore City     7.4 66.6%
             
Calhoun Elm Grove Yetter     2.7 24.8%
             
Area Average         5.0 43.3%


Historical Fall Sample Results

        PAW - Inches (Fall) % of Fall Average
County Township Town 2004 2003 2002 2001 2000 1999 2004
Carroll Washington Carroll 7.1 3.9 11.5 8.0 5.8   98%
                   
Crawford Paradise Dow City 3.4 1.8 3.0 2.1 3.9 3.3 117%
Crawford Paradise Dow City 3.2 2.2 7.3 4.3 3.6 1.8 86%
    County Average 3.3 2.0 5.2 3.2 3.8 2.5 101%
                   
Ida Grant S-C Ida County 2.9 1.3 7.6 3.4 1.8 4.0 82%
Ida Maple Battle Creek 3.6 2.2 8.5 5.5 1.2 2.5 91%
Ida Griggs Holstein 10.3 3.4 11.3 7.3 1.6 2.0 173%
    County Average 5.6 2.3 9.1 5.4 1.5 2.9 115%
                   
Monona Center Castana 2.1 0.5 4.4 1.8 1.2   105%
Monona Center Castana 2.2 1.3 5.2 4.0 2.2   74%
Monona Center Castana 2.2 1.0 3.5 0.7 0.0   148%
    County Average 2.2 1.0 4.4 2.2 1.1   109%
                   
Sac Richland Odebolt north 6.5 2.6 11.8 7.8 4.4 5.4 101%
Sac Eurek Schaller 6.0 2.8 11.3 9.8 3.8 2.3 101%
Sac Jackson Sac City 7.8 4.0 12.8 8.5 4.7 4.8 110%
Sac Sac Auburn 7.6 6.4 8.8 7.7 2.8 4.4 121%
Sac Wheeler Odebolt South 6.3 2.8 9.6 6.2 3.4 4.1 117%
    County Average 6.9 3.7 10.9 8.0 3.8 4.2 110%
                   
Pocahontas Roosevelt Gillmore City 7.4 3.2 8.5 6.2     117%
                   
Calhoun Elm Grove Yetter 2.7 1.9 8.0 0.0     87%
                   
Area Average     5.0 2.5 8.1 5.1 2.8 3.4 108%

Soil Profile Graphs
 

Todd Vagts
Iowa State University Extension
Field Crops Specialist
1240 D. Heires Avenue 
Carroll, IA 51401 
Office: 712-792-2364; Cell: 712-249-6025;  Fax: 712-792-2366
Email: vagts@iastate.edu  

 

This page last updated on 11/23/04

IOWA STATE UNIVERSITY
OF SCIENCE AND TECHNOLOGY

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