The question has been asked 'how does the subsoil moisture levels from the fall of 2020 compare to other dry falls'.
A look back shows the following levels of fall subsoil moisture from 2011 and 2012 - for the six sites where I survey soil moisture in northwest Iowa.
Rainfall - for the sites at or near the sites below - from November 1, 2011 to April 21, 2012 was 6.5 to 7.0 inches.
The amount of subsoil moisture recharge was around 3 to 4 inches (table 1) - so less than the rainfall that occurred during that time period. I forget the specific weather conditions - but the soils may have been frozen when some of that rainfall occurred. And therefore the rainfall did not contribute to subsoil moisture.
Table 1. County subsoil moisture – fall 2011 and spring 2012.
County plant available moisture,
Fall inches
County average, in. location Nov. 1, 2011 April 23, 2012
Dickinson 5.7 Spirit Lake 1.4 5.2
Emmet 5.9 Estherville -
Clay 5.7 Rossie 5.0 7.8
Buena Vista 6.0 Newell -
Pocahontas 6.0 Rolfe 3.3 7.0
Sac 5.9 Schaller - 7.8
Rainfall - for the sites or near the sites below - from November 1, 2012 to April 23, 2013 was 5.0 to 6.0 inches. The exception was Storm Lake - which only had 3.8 inches for this time period.
Another way to view it - there was 7.0 to 9.0 inches of rain from September 1 of 2012 - or about the time of crop maturity - until April 23 of 2013. Again - the exception was Storm Lake - which only had 5 inches during this time period.
Keep in mind this soil moisture recharge occurred before the spring of 2013 gained the reputation it was about to gain.
Table 2. County subsoil moisture – fall 2012 and spring 2013.
County plant available moisture,
Fall inches
County average, in. location Nov. 9, 2012 April 26, 2013
Dickinson 5.7 Spirit Lake 3.9 9.5
Emmet 5.9 Estherville 1.4 6.4
Clay 5.7 Rossie 5.8 10.3
Buena Vista 6.0 Newell 4.3 10.3
Pocahontas 6.0 Rolfe 3.2 7.2
Sac 5.9 Schaller 2.9 8.9
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on November 18, 2020. The information contained within may not be the most current and accurate depending on when it is accessed.