Weekly Nebraska Soil Moisture Report - July 18, 2011

The High Plains Regional Climate Center is now featuring a weekly Nebraska Soil Moisture Index map.  For the next month or two, the HPRCC will feature a weekly Nebraska soil moisture report and map on the front page of the website, before moving it to a permanent location on the AWDN Soil Moisture page.  If you have any comments or questions about the SMI, please use the contact us page.

"The Soil Moisture Index (SMI) is an index applied to the volumetric water content at the depths of 10, 25, and 50 cm. It is averaged over those three depths and scaled such that 5.0 represents field capacity and -5.0 represents the wilting point.  Measurements are made under grass covered, rain fed conditions and may not be representative of soil moisture conditions in fields with standard row crops."  To learn more about the SMI, click here.

Nebraska Weekly Soil Moisture Report - July 18, 2011 

This week’s report contains good news and bad news. The good news is that a lot of the state received precipitation last week and therefore is relatively moist, with a statewide median SMI of 2.8. Most sites have more than 0.75 in. left in a 50 cm soil profile before reaching the 50% of available water point and several have over an inch. Only four sites have an SMI below 0.0 and one of those sites (Elgin) briefly went back to the halfway point last week. So as far as soil moisture is concerned...for the middle of July, this is good news. It is also good news considering now is a critical time for corn, as it heads into pollination and silking.

The bad news is that this week will be one of the warmest weeks in several years and some sites are already losing soil water at a rapid pace. Temperatures of 95-102ºF are expected over the state for most of the week and it would not be unfathomable for 0.30-0.45 in. to leave the soil via evapotranspiration several days in a row. With elevated ET rates this week, dewpoints will also be high (unusually high in northern and west central NE), and the heat will be even more miserable than the temperature indicates. The combination of heat and crop water demand will put a lot of the soil moisture surpluses in grave jeopardy as we head into next weekend. The HPC shows some precipitation over the eastern corner of the state later in the week as a cold front may push far enough south to give some minor relief. But that is far from a guarantee and producers in irrigated regions should keep a close eye on crop conditions this week. Many will be justified in turning on the pivots as soil water losses could easily exceed an inch this week.