Book Description

"This publication describes how to estimate lime application rate and lists criteria for choosing liming materials (source), lime application method (placement), and how often to apply lime (frequency). Lime application rate is determined using the lime requirement test (SMP buffer method). For established perennial or no-till crops, a top-dress lime application (1 to 2 t/a) may be beneficial. When very different soils are present within a field, variable-rate lime application is usually advantageous. Liming materials vary in effectiveness. The carbonate in traditional aglime (calcium or magnesium carbonate) reacts with soil acidity to neutralize it. Liming materials have very limited movement into the soil without incorporation. Tillage increases effectiveness of all lime materials by mixing them into the rooting zone. Evaluate liming materials based on effectiveness (lime score) and cost. Calculate product cost per ton of 100-score lime. By-product lime products can be a cost-effective substitute for traditional aglime. Their characteristics should be evaluated carefully. For certified organic crops, use only lime approved by your certification agency. Lime application method (placement) takes two forms. Lime is either applied and left on the soil surface or incorporated. In the absence of tillage, soil pH increases only in the top inch or 2 of soil since lime's limited solubility means that the liming material must contact acidic soil before it will react and change soil pH. Frequency of lime application is determined primarily by cation exchange capacity (CEC) and crop management practices, especially N fertilizer rate. Soil pH declines faster in sandy (low CEC) soils than in soil with moderate to high clay content. The typical rate of pH decline is approximately 0.1 pH unit per year when 100 lb ammonium N/a is applied. For annual crop rotations, apply lime about a year before planting the crop that is most sensitive to soil acidity. For perennial crops, soil test and apply lime prior to tillage for crop establishment."--Page 2.