Factors Affecting Soil Temperatures

A large percentage of the 2026 corn and soybean crop is still in the bag waiting to be put into the ground. In some instances, the issue is having too much moisture and not being able to get in the field. In others, the issue is that the soils are too cold to plant, with no sign of warming up in the next few days.

With some areas of our geography being drier and warmer this fall, we may need to wait to apply some of our soil amendments until our soils cool down closer to 50°F so those products stay stable or attach to the soil. This is a concern with products that are or contain Nitrogen, such as Anhydrous Ammonia (NH3), that in drier conditions with no or little soil moisture to attach to, could volatilize, losing that fertilizer investment. 

Potential factors that can have an influence on soil temperature are:

• Air Temperature: Fluctuating air temperatures can and do influence soil temperatures. 
• Air Humidity: This may be slightly stretching it; however, humidity may have an influence on air temperature, in that air that is more humid tends to fluctuate less than air that is less humid.
• Sunlight/Cloud Cover: The radiant energy of the sun warms the soil as well as other objects even on cold days. If you have cloud cover, you do not have the radiant energy of the sun to warm the soil or other objects up. To reinforce this concept, I always think of snow melting off a roof on sunny days in the winter.
• Daylight/Nighttime Hours: This goes hand-in-hand with sunlight. However, as we increase or decrease the amount of potential sunlight during the day, this can and does impact soil temperatures. In much of the Corn Belt at this time of year, we are decreasing potential daylight hours by 2 to 3 minutes per day. In 10 days, the cumulative effect results in almost 30 less minutes of daylight. As we look at 20 days, that moves closer to 60 minutes, and when we stretch it out to 30 days, we are decreasing our available sunlight by 80 minutes or more.
• Soil Moisture: As we decrease soil moisture and more air enters the soil, air in the soil is influenced more by air temperatures as well as sunlight. Conversely, as we increase soil moisture, the amount of energy it takes to warm up increases. However, the moist soil tends to stay more constant in temperature.
• Soil Type or Texture: Lighter textured soils, such as sand, dries faster and are influenced by air temperature and sunlight more rapidly
• Crop Residue: Having a heavy residue or a cover crop on the soil surface due to production systems and/or trying to reduce erosion can shade the soil and reduce soil temperatures. In my experience. heavy residue has the potential to reduce soil temperature 5 to 10°F or more.
• Soil Temperatures: In lighter soil types like sand, soil temperatures fluctuate quicker than heavy type soils like clay which are slower to change or give up its temperature (and moisture).
• Soil Compaction: A compacted soil creates a layer that does not allow moisture or air to penetrate that layer of compaction as easily. Which, in a warm dry environment, could make the soil stay warmer longer.
• Soil Color: A darker soil absorbs the radiant energy of the sun and will warm up faster than a lighter colored soil.
• Direction of a Slope or Hill: Due to the amount of sunlight received, the south side of a slope or hill will warm up faster than the north side of the same hill or slope.

In my experience, I see differences in soil temperatures in fields/soils that are healthier or have more biological activity. I do not know if I can prove this, however, it seems that fields that have good fertility, neutral pH, as well as a history of some type of manure in my opinion tend to be more consistent in warming up in the spring and cooling down in the fall.