How tillage practices can help you manage soil temperature

When does soil temperature matter? 

The short answer is all the time.

The weather is warming up and with that comes the excitement of planting season! But there’s one major factor to keep in mind before you start planting, and that is soil temperature. Soil temperature is important all year round, but it is especially important to consider when deciding on start dates for planting your crop. Let’s explore some of the ways management can impact temperature.

What affects soil temperature?

Soil moisture is an important factor in soil temperature as water takes much longer to change temperature than air. This can work either for us, or against us, depending on the time of year and current weather conditions. Another important factor in soil temperature is soil residue. Both factors can act as insulators. 

How you manage conservation practices will add or remove moisture from your soils which depends on what your goals are for your operation. In addition, clayey soils will react differently than sandy soils and will require experimentation to see what management strategies work for your soil types.

As always, we recommend that you plant when your soils are fit, not when you are ready to plant. Soil temperatures that are too low and too high can largely impact your crop growth. 

How can different tillage practices affect soil at planting?

Cold soil, typically below 50 degrees Fahrenheit, prevents biological activity. This affects the crops that you plant and the microbes that mineralize nutrients. Hot soils have a similar effect, with biological activity slowing dramatically when soil reaches temperatures around 80 degrees F. We’ve included some key findings below on how different tillage practices impact soil temperature at planting:

• Conventional tillage systems tend to be both the warmest and driest. Conventional tillage systems were very necessary in the past as we had no other way to manage our soils. This practice, however, destroys soil aggregation and prevents good water intake due to crusting issues. Because of this, conventional tillage systems pose a high risk to crop yield in drought or even just poorly timed rainfall.
• Reduced tillage practices, like strip tillage, typically perform similarly to conventionally tilled fields but manage to help the soil maintain moisture This may be ideal in wetter locations that want to minimize fuel costs, reduce drought risk, and protect soil health.
• No-till practices, as shown by research from several universities, typically have lower soil temperatures and higher water content. This is ideal in the hotter, drier parts of the Midwest as well as in sandy soils. These soils also tend to insulate from extreme temperature swings better than dry soils.
• No-till practices combined with cover crops also perform very closely to conventionally tilled systems. This is likely due to better porosity and the ability to handle water more efficiently. This practice differs from conventional systems in that it is less damaging to the soil. The cover crop utilizes the water at the soil surface, allowing it to warm faster. The cover crop can then protect the soil surface during the hotter parts of the year.

Your soil type, combined with your soil health management goals will guide you to what practice is best for you. Keep in mind that these management systems take a few years before you will see true and consistent results. 

The two images below were taken in April 2023 in northwest Ohio. The image on the left is one that is rotationally tilled. The image on the right is a continuous no-till and cover crop field. Healthy soil can maintain soil temperatures close to or above tilled fields.

Photos courtesy Matt Burkholder, Burkholder Healthy Farms

These next two images were taken in south central Minnesota on March 31, 2021 on the same field in management test strips. On the left is conventionally tilled soil and on the right is a no-till and cover crop system. As seen here early-season temperatures can be warmer and more insulated from cold weather snaps.

How do different tillage practices affect soil during the growing season?

Soil is at its hottest after planting and before canopy closure. Soil can reach over 100 degrees Fahrenheit during this time, putting crops under stress and preventing nutrient and water uptake. With a lack of soil moisture, this soil condition and time can have the largest impact on your crop.

Soils that are protected from the sun, however, can maintain soil moisture for when your crops need it. With cooler roots and adequate moisture, growth can continue, and nutrients are better able to mineralize for crops where, in hot soil, they might otherwise slow down or stop altogether.

A lack of water during the critical reproductive stages for crops will ultimately determine how good of a crop you will have. With several years of extreme drought and indications there may be more in the future, consider carefully how you are protecting your soil’s moisture, especially since water is our most limiting factor for crop production.

We’ve compiled a few other reminders to help you this growing season when it comes to managing soil temperatures:

• If too much soil moisture is a consistent problem in your fields, it will be very difficult to “out-manage”. You may consider tilling that field to help remove excess moisture before implementing soil health practices.
• Increasing soil porosity, soil aggregation, and soil organic carbon through reducing tillage and adding cover crops can all lead to better water infiltration. This will allow you to capture and utilize the water you get at times when you need it.
• Exposed bare soils may heat up more quickly in the spring but they are also at the highest risk for soil erosion from wind or water. That can cost you over time through loss of topsoil and nutrients.

There will always be some action that you can take on managing soil moisture. Understanding what impact that your soil management strategies are having and utilizing new strategies to address issues will be your best course of action. Soil temperature is critical for good crop establishment and in season growth and, while you can’t control mother nature, you can do your best to reduce risks for your crop. 

 

Resources:

Water Holding Capacity

Managing Wet and Cold Soils

Upper Midwest Tillage Guide

Impacts of Extreme Heat Stress and Increased Soil Temperature on Plant Growth and Development

Extreme soil surface temperatures reflect need to rethink agronomic management

The Cost of Soil Erosion