Even With Low Crop Prices, Lime is an Important Part of a Fertilizer Program.

Even With Low Crop Prices, Lime is an Important Part of a Fertilizer Program.

“I only have so many dollars to spend on inputs this year, why should I worry about liming?” This is a question that is very common this Fall and a very understandable one.

Aglime (Calcium Carbonate) is not as high profile a nutrient at Nitrogen, Phosphorus, or Potassium but its job is no less important as it helps stabilize and balance the pH of the soil. Soil pH is crucial because most field crops perform best when the soil is at a pH of 6.0-6.8. At this level we maximize nutrient availability and activity of soil microbes, reduce availability of toxic elements such as aluminum, and generally get optimal performance/carryover of certain herbicides that are sensitive to pH. Periodic soil sampling and testing for pH is crucial because fertilization practices such as application of ammonium-based fertilizers and some manures (especially swine) will continue to acidify the soil. It is important to only apply lime where soils have a low pH and using sampling practices such as soil type/zone or grid sampling can help manage pH variability within a given field. Applying lime to areas of high pH (6.5-7.0 and higher) can impact your bottom dollar because the application is not needed and will make those areas of high pH worse – leading to nutrient tie up, Iron Deficient Chlorosis in soybeans, and can impact certain herbicides. While it is relatively easy to fix low pH with lime application, correcting high pH takes multiple years, is expensive, and university trials show inconsistent results.

Some general thoughts on lime

  • One size does not fit all when it comes to lime! Look at each field individually when assessing lime needs as soil type and history play huge roles in pH. Focus on fields with the lowest pH.
  • The general rule of thumb in Iowa is “soil pH 6.5 is considered to be sufficient in areas with low-pH subsoil, but 6.0 is sufficient in areas with high-pH (calcareous) subsoil within a four-foot depth of the surface. Soil associations with high pH subsoils include Clarion-Nicollet-Webster, Galva-Primghar-Sac, Moody, Monona-Ida-Hamburg, Marshall, and Luton-Onawa-Salix.” (ISU PM1688)
  • Pelleted lime use has increased because it is made very fine lime material that is quick to react in the soil but it is generally much more expensive. On owned ground or long term lease regular aglime is sufficient.
  • Lime recommendations are generally made for the top 7-8 inches of soil. In no-till operations, reduce lime rates to 30 percent of the conventional tillage rec. (UNL G1504)

. If you would like to learn more, contact your Jacobsen Seed Representative for more information and resources.