Past IEM Features tagged: soil
Using hourly soil temperature observations, the featured chart looks at periods of having the temperature above 50 degrees for 48+ straight hours for the first time each spring season and any subsequent periods below 50 for that same year. The featured chart is for Nashua (near Waterloo, Iowa). Having the soil cool back below 50 degrees after its first long stretch above is typical. The prolonged cool stretches are not desirable for crops that are already in the ground. The forecast has a return of warmer weather next week, so hopefully our current stretch of cool soils will reverse soon.
The day with the least amount of daylight is also the start of the winter season. This at first may seem counter-intuitive as the sun is the energy source for heating the ground which then heats the air. We have about another month yet to go before we see the coldest average air temperatures as shown by the featured chart presenting the daily climatologies of air and soil temperatures along with daylight length. You can see that none of these curves exactly line up with their maximums and minimums shifted in time slightly.
Tags: daily climate soil daylight
Our mostly sunny and mild October has helped keep 4 inch depth soil temperatures well above 50 degrees which is a key threshold used for fall nitrogen application in fields (temperatures need to be colder than 50 to make the application successful). Our recent stretch of cool weather has allowed temperatures to dip below 50 for the first time this fall and as is shown in the featured chart, this makes for the latest date in the fall season for the first sub 50 degree to have occured based on our data back to the mid 80s.
Tags: soil 2010