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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 2005 Subsoil Moisture Survey Results

  • Counties:  Carroll, Calhoun, Sac, Crawford, Monona and Ida
  • Date Sampled:  October 24 and 27

The ISU Extension Fall 2005 subsoil moisture survey has been completed for Carroll, Calhoun, Crawford, Monona, Ida, Sac and Pocahontas counties.  Results form this fallís sampling indicate a great need for fall and spring rains to replenish dry soils.  The current 60-inch soil moisture status contains 50% less moisture than is typically observed at this time of year (compared to the previous five years).   

Results from the soil moisture survey taken in late October indicate that west-central IA had on average 2.8 inches plant available water (PAW) in the 60-inch soil profile or 25% of capacity.  This compares to last year's 5.0 inches and 43% of capacity.  Sac county appears to be in the best shape with an average of 5.6 inches PAW followed by Pocahontas and Ida counties with 4.6 and 3.5 inches PAW respectively.  Carroll and Calhoun counties were definitely on the dry side with only 3.2 and 2.0 inches PAW respectively.  The driest soils I've ever encountered while performing this survey were found this fall in Crawford and Monona counties with only 0.7 and 0.0 inches PAW in the top sixty inch profile.  Far west-central Iowa will definitely need fall and spring rains to help replenish soil moisture and allow the potential to raise a crop next year.  Other falls with similar PAW readings include 2003 with 2.5 inches PAW and 2000 with 2.8 inches PAW.

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. 

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

 

2005 Fall Subsoil Moisture Survey Results

      Previous Sample Plant Available Water    60-inch soil profile
County Township Town Crop Date Inches % of Capacity
Carroll Washington Carroll Soybean 10/24/05 3.2 26.0%
             
Crawford Paradise Dow City Corn 10/27/05 0.3 2.7%
      Soybean 10/27/05 1.0 8.6%
        County Average 0.7 5.7%
             
Ida Grant Kiron Corn 10/27/05 2.2 18.9%
  Maple Battle Creek Corn   1.9 15.3%
  Griggs Holstein Corn   6.3 50.7%
        County Average 3.5 28.3%
             
Monona Center Castana Soybean 10/27/05 0.0 0.0%
      Corn   0.0 0.0%
      Soybean   0.0 0.2%
        County Average 0.0 0.1%
             
Sac Richland Odebolt north Corn 10/27/05 5.8 46.8%
  Eurek Schaller Soybean 10/27/05 6.5 52.6%
  Jackson Sac City Corn 10/24/05 6.8 62.3%
  Sac Auburn Soybean      
  Wheeler Odebolt South Corn 10/27/05 3.1 25.1%
        County Average 5.6 25.1%
             
Pocahontas Roosevelt Gillmore City C 10/24/05 4.6 41.3%
             
Calhoun Elm Grove Yetter Corn 10/24/05 2.0 17.8%
             
Area Average         2.8 24.6%


Historical Fall Sample Results

          PAW - Inches (Fall) % of Fall Average
County Township Town 2005 2004 2003 2002 2001 2000 1999 2005
Carroll Washington Carroll 3.2 7.1 3.9 11.5 8.0 5.8   49%
                     
Crawford Paradise Dow City 0.3 3.4 1.8 3.0 2.1 3.9 3.3 12%
Crawford Paradise Dow City 1.0 3.2 2.2 7.3 4.3 3.6 1.8 30%
    County Average 0.7 3.3 2.0 5.2 3.2 3.8 2.5 21%
                     
Ida Grant S-C Ida County 2.2 2.9 1.3 7.6 3.4 1.8 4.0 67%
Ida Maple Battle Creek 1.9 3.6 2.2 8.5 5.5 1.2 2.5 52%
Ida Griggs Holstein 6.3 10.3 3.4 11.3 7.3 1.6 2.0 104%
    County Average 3.5 5.6 2.3 9.1 5.4 1.5 2.9 75%
                     
Monona Center Castana 0.0 2.1 0.5 4.4 1.8 1.2   0%
Monona Center Castana 0.0 2.2 1.3 5.2 4.0 2.2   0%
Monona Center Castana 0.0 2.2 1.0 3.5 0.7 0.0   0%
    County Average 0.0 2.2 1.0 4.4 2.2 1.1   0%
                     
Sac Richland Odebolt north 5.8 6.5 2.6 11.8 7.8 4.4 5.4 91%
Sac Eurek Schaller 6.5 6.0 2.8 11.3 9.8 3.8 2.3 108%
Sac Jackson Sac City 6.8 7.8 4.0 12.8 8.5 4.7 4.8 97%
Sac Sac Auburn   7.6 6.4 8.8 7.7 2.8 4.4 0%
Sac Wheeler Odebolt South 3.1 6.3 2.8 9.6 6.2 3.4 4.1 61%
    County Average 5.6 6.9 3.7 10.9 8.0 3.8 4.2 71%
                     
Pocahontas Roosevelt Gillmore City 4.6 7.4 3.2 8.5 6.2     77%
                     
Calhoun Elm Grove Yetter 2.0 2.7 1.9 8.0 0.0     68%
                     
Area Average     2.8 5.0 2.5 8.1 5.1 2.8 3.4 49%

 

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 11/21/05

IOWA STATE UNIVERSITY
OF SCIENCE AND TECHNOLOGY

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