Buyer beware when it comes to “alternatives” to ag lime

Josh McGrath and Edwin Ritchey, Extension Soil Specialists, University of Kentucky

Over the past few months we’ve had farmers at each county agronomy meeting ask about liquid lime. After a little investigation we found out that what was being marketed as a liquid lime with neutralizing value was in fact calcium chloride (CaCl₂). This was bad news because CaCl₂ provides NO liming value and is in fact not “liquid lime.” Calcium chloride is used for many purposes including road salt or tractor tire ballast, it however cannot be used to neutralize soil acidity. This post is intended to provide some information on liming materials, the lime reaction, and explain why CaCl₂ is not a lime source.

Focus on These Two Things, Cut Costs Elsewhere

Chad Lee, Extension Agronomist, University of Kentucky

Farmers are looking where to cut production budgets for 2015. Three of my colleagues and I were honored to speak at the National Commodity Classic this year. During our presentation, one of my colleagues closed out our session by saying that the two things farmers need to do is: 1) use appropriate soil-applied fertilizers based on soil tests; and 2) use highly effective weed control, which probably includes a soil residual herbicide. All of us in the room agreed that these are probably the two things many farmers will cut in 2015.

Should Lime and Phosphorus be applied at the Same Time?

Lloyd Murdock, Extension Soils Management, University of Kentucky

No matter how phosphorus (P) is applied or when it is applied it will be tied up with something. A soil pH of 6.5 is the very best one can do to reduce this fixation of P. If fertilizer P is applied below a pH of 6.5, especially below 6.0, more of it will be tied up with aluminium and iron in the soil. So not applying lime would be bad also. If the pH is above 7 then more of the P will be tied up by calcium in the form of insoluble calcium phosphates (rock phosphate). So you cannot win either way. If you have a low pH, say in the high 5’s, and you apply lime and you add P also. You would have to get the soil pH where the lime is placed above 7 for much of this additional fixation to occur and it is going to be difficult for this to happen since you are starting at a low pH and lime is a rock and is only slowly soluble.

Bottom line is do not worry about P fixation and keep the soil pH about 6.5. Under the best of circumstances, you are only going to get about 30% of the P you apply in the crop. Very small differences in P fixation would happen with or without the lime.