Should I Consider Applying Lime This Fall?​

Fall is a busy time on the farm. Harvesting, trucking, applying fall burndown herbicides, planting cover-crops, tillage, nitrogen applications and many more tasks are essential to making the subsequent growing season a successful one. One of these practices that can contribute to season long success is applying lime in the fall (Figure 1).

The fall and winter seasons are great times to apply lime as it is not a very leachable input in most soil types except for very sandy soils, thus allowing for the lime to begin contributing its neutralizing properties in the field prior to planting. Additional bonuses associated with fall lime application: time savings and weather assurance! Each spring is a precious commodity in most farming operations, and having lime and fertilizer applications done represents another chore complete. Not to mention the fact that Mother Nature (too much water) can often limit timeliness of lime and fertilizer applications in the spring. Having liming application done in the fall can ultimately limit spring soil/field compaction.

To understand the importance of prioritizing a fall application of lime, it is important to understand what lime is, why it is important in the growth and development of row crops, and what forms are available.

1. According to the University of Kentucky, “Lime is composed of either limestone rock, ground-up marl, or made up of products containing limestone rock that have been altered by burning to make them more water soluble than ground rock alone.”
2. Lime is applied to soils to reduce soil acidity and stabilize soil pH (raise the pH) to allow for maximum nutrient uptake by a given row crop. Soils that are acidic can limit plant growth, inhibit root development, limit plant physiological processes and restrict yield potential. It is important to note that lime forms are not created equal. Each form of lime is distinguished by its grade and effective neutralizing value (ENV). Grade is established based on particle size; finer-grade size will lend itself to greater ease and speed of soil incorporation, while ENV represents a measure of the efficacy of the lime to neutralize.
3. Lime used in agriculture is available in several forms including:
   • Agricultural limestone (AgLime): these limes are comprised of calcium carbonate (CaCO₃) with content ranging from 48% to 97%. This is likely the most cost-effective lime form for many agricultural applications.
   • Dolomitic lime: these products contain magnesium carbonate (MgCO₃) in addition to the CaCO₃.
   • Slaked lime (hydrated lime): is made up of calcium hydroxide (Ca(OH)₂) and has a higher ENV, and is usually more expensive.
   • Burnt lime (quick lime): made up of calcium oxide (CaO). As its name suggests, it is a fast-acting lime with the highest ENV. Thus, it is more commonly used in horticultural systems.
     • It is important to note that a soil test and local fertility recommendations can help decide which type, ENV and grade of lime is best for a given field and its individual yield goals. Also, geographic location may also expand or limit the forms (and quality) of accessible lime in each area.

Lime represents a key input to most cropping systems in the U.S. that allow for more considerate management in acidic soil types. Moreover, being more proactive with lime applications in the fall and winter represents a greater opportunity to capture more potential yield the following fall.

Wells, K. 1996. When to apply lime and fertilizer. AGR-5. University of Kentucky. http://www2.ca.uky.edu/agcomm/pubs/agr/agr5/agr5.pdf.

Ritchey, E.L., Murdock, L.W., Ditsch, E., McGrath, J.M., and Sikora, F.J. Agricultural lime recommendations based on lime quality. ID-163. University of Kentucky. http://www2.ca.uky.edu.

Carey, P., Ketterings, Q., and Hunter, M. 2006. Liming materials. Agronomy Fact Sheet Series. Fact Sheet 7. Cornell University Cooperative Extension. http://cceonondaga.org/

Additional information:

Applying lime and fertilizer in the fall. Agronomy ADVICE. Channel.com. http://www.channel.com/agronomics/Documents/AgronomicContentPDF/ApplyingLimeandFetilizerintheFall.pdf.