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

Spring 2003 Subsoil Moisture Survey Results

• Counties:  Carroll, Calhoun, Sac, Crawford, Monona and Ida
• Date Sampled:  April 3 (Sac County), April 10 (Carroll, Calhoun and Pocahontas Counties) and April 15 (Ida, Crawford and Monona Counties)

Last fall’s sampling indicated very good soil moisture profiles across the region and despite last winter’s lack of moisture, most areas picked up some additional moisture for this seasons crop.  When compared to the average spring moisture levels (1999 – 2003), the spring 2003 sub-soil moisture condition is about 115% of the 5-year average, with a range of 94% (soybean field near Dow City) to 138% (corn field near Castana).  Interestingly, the Castana location with 138% of the spring average is still one of the driest sample sites in west-central IA.  On average across sampling locations, 8.6 inches of plant available water (PAW) is stored in the 60-inch rooting zone.  This is the best spring sub-soil moisture condition the area has been in since 1999 when an average 10.1 inches of PAW was stored in the 60-inch rooting zone. 

Carroll, Calhoun, Sac, Ida and Pocahontas counties have very good soil moisture profiles, averaging 10.25 inches of plant available water in the top 60-inches, 1.75 inches more than last spring and 0.65 inches more than last fall.  Carroll and Pocahontas counties have the best sub-soil moisture profile with their PAW capacities filled to 97% and 100% respectively.  On the other hand, Monona and Crawford counties (although improved from last fall) need substantial spring rains to replenish the soil moisture profile.  These 2 counties have an average of 6.4 inches (PAW), which is 55% of the soils holding capacity.  The soil profile in the driest counties needs to be recharged in the 36 – 60 inch depth level.

Graphs
Detailed Excel worksheet

State-wide map and Commentary by Elwynn Taylor