Wise liming choices bring big results
Lime neutralized Jim Book’s crop problems.
Back in the early 1990s, Book had trouble with the growth of vegetable crops on his Starlight farm. He raises grain, vegetables, corn, soybeans and dairy cattle.
“I started looking to see what [I was doing] wrong, and I came across this group of people telling me about lime,” says Book, a lifelong farmer. “For three years, I was talking to them and couldn’t believe what I was hearing.”
Book encountered a fellow farmer who recommended using a liming program, starting with a test plot. Book divided a field and applied 5, 10, 15 and 20 tons per acre of high-calcium lime. After seeing growth improvements, Book was convinced of the power of lime.
• Correcting pH to a desirable range can produce remarkable results.
• Lime needs time after application to reduce soil acidity.
• The benefits of lime are easy to see in alfalfa and vegetable crops.
Why liming helps
“I found out I wasn’t putting enough lime on the ground to make things work right,” says Book.
Applying lime corrects more than calcium deficiency. Lime reduces soil acidity and gives the field a more neutral pH. Most crops flourish with a pH of 6.0 to 7.0.
Jim Camberato, associate professor of agronomy at Purdue University, says that low soil pH impedes root development, meaning plants have less access to water and nutrients. Plants are smaller, less efficient and lower yielding.
“The farther south you go in Indiana, the more likely it is you need to lime,” he says.
Camberato says sampling is essential for correct liming. “The worst problem is not liming because soil samples aren’t taken,” he says. Samples should be collected soon after harvest and tested. If results show low pH, you have several decisions to make.
• Choose dolomitic or calcitic lime. Apply either dolomitic lime, which contains calcium and magnesium carbonates, or calcitic lime, which contains only calcium carbonate. Consider soil-test levels of calcium and magnesium, plus lime cost.
• Consider calcium carbonate equivalence. The neutralizing value of lime is based on a standard 100% pure calcium carbonate. Typical ag lime is 90% to 95% calcium carbonate equivalence. The application rate should be adjusted upward for lower calcium carbonate equivalence.
• Adjust for particle size. The more finely ground the lime, the faster and more complete its reaction in the soil.
Lime requires time to neutralize soils, Camberato says. Ideally, lime should be applied after harvest and plowed under where plowing is permitted for maximum effect.
“We spread [lime] on top, then plow it under, then spread it on top again,” says Book.
According to Camberato, it’s difficult to economically quantify the results of lime application, but all crops grow better at the proper pH.
“We’ve seen some big results, especially in shelf life [of vegetables],” he says. “It increased marketable-type yields, and we didn’t have so much stuff go bad.” He’s had fewer diseases and seen better growth, too.
For more information on lime, consult Purdue Extension Publication AY-267-W, “Soil acidity and the liming of Indiana soils.”
Hubbard is a senior in Purdue Ag Communications.
This article published in the February, 2010 edition of INDIANA PRAIRIE FARMER.