Ruth Correll: Fall is great time to apply lime

Ruth Correll • Updated Nov 1, 2017 at 6:00 PM

Although lime can be applied anytime during the year whenever soil, weather, crop and labor conditions permit, fall is an excellent time for application. 

Farm fields are usually dry, and lime dealers are less rushed. Farmers may have more time for this project rather than waiting for the spring rush. If not limed as needed, soils tend to continue to become more acidic, reducing the potential for production of healthy plants and profitable yields. 

Several factors contribute to an increase in soil acidity such as soil erosion, leaching and plant or crop removal, In addition, the use of acid-forming fertilizers greatly enhances acid levels. “Clayey soils” tend to be more acidic than silty or sandy soils.  

The pH of the soil and the lime recommendation has a direct relationship. The pH is a measure of how acid or alkaline a solution may be. The natural pH range of soils in Middle Tennessee runs from 4.5 to 7.5. As the soil pH decreases below 7.0, the amount of acidity rapidly increases. Lime is the product that is applied to the soil to raise the pH toward the neutral pH of 7.0 

Plants are sensitive to the pH of a soil. The pH of the soil can determine if you have good growth or little to no growth. The pH of the soil determines whether certain nutrients from the soil are absorbed by the plant roots in quantities that are sufficient, or in some instances, too much.  

Plants are categorized according to their preference for a particular pH range.  For instance blueberries, rhododendrons and azaleas are classified as “acid loving plants.”  These plants grow and produce much better when the pH of the soil is well below a pH 5.8. The nutrients they need are more available when the soil pH is lower.  

On the other hand, pasture grasses, lawn grasses and most vegetables plants prefer a pH range of 6.0-6.8. They will not thrive when the soil is too acidic. The soil test results will recommend lime be applied when the pH is too low for these plants.  

So…your soil test results recommends lime be applied. Will the lime work immediately to adjust the pH? The answer is a resounding no. It takes time for lime to react with the soil.  Water is required for lime to react with the soil. During dry years, this process takes much longer. The reactivity time also depends on the type of lime used. Liming materials differ widely in their neutralizing powers due to variations in the percentage of calcium and/or magnesium. The coarseness of the liming material will also influence how fast the lime will react. In other words, the finer the liming material, the faster the reactivity up to a point. 

Another factor that affects the reactivity time is that lime applied to the surface only such as on pastures and in no-till situations is slower to react with the soil than when the lime is worked into the soil as with row crops.  Lime will react faster on tilled land than non-tilled land.

There are several other benefits of adding lime, which include supplying calcium and magnesium, which are essential plant nutrients. Liming improves the ability of plants to take up the three macronutrients, nitrogen, phosphorus and potassium and improves the microorganism activity in soils, which has an impact on the ability of legumes to fix nitrogen and the decomposition of organic matter. Research shows that the effectiveness of corn and soybean herbicides improves when the soil pH is within the desired range.

The bottom line is to get your soil tested, and then follow the recommendations. Lime is important for lots of reasons. 

For more information, contact the UT-TSU Extension Office in Wilson County at 615-444-9584. You can also find us on Facebook or visit extension.tennessee.edu/wilson.

Through its mission of research, teaching and extension, the University of Tennessee Institute of Agriculture touches lives and provides Real. Life. Solutions. ag.tennessee.edu. Ruth Correll, UT Extension-TSU Cooperative Extension agent in Wilson County, may be reached at 615-444-9584 or [email protected]


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