Part 1 – Introduction to Agricultural Lime and Liming. This section contributes to the discussion on the increasing incidence and severity of acid soils in the Inland Pacific Northwest (IPNW) and emphasizes: i) soil sampling and monitoring concepts to consider when managing acid soil conditions; ii) the role of soil testing; and iii) characterization of liming materials used to elevate pH of acidified soil.
Part 2 – Laboratory Testing to Determine Lime Requirements. This section delves more deeply into variations among soil types and why laboratory testing is used to characterize soil pH. We define the term “lime requirement” and how it relates to soil buffering capacity. We also provide information on lime requirement test methods commonly performed by soil testing laboratories. A companion Lime Requirement Worksheet based on common buffer tests and base saturation is provided for reference.
Part 3 – Aglime Product Selection and Comparison Calculator User Guide. This is a user’s guide for the interactive online Agricultural Liming Material Selection and Comparison Calculator. The publication describes the attributes used to perform calculations to characterize liming material, while the interactive utility provides a platform to compare up to three liming materials for their relative effectiveness, costs, and economic efficiency.
Agricultural liming materials are applied as soil amendments to raise the pH of acidified soil (Collins 2012). Liming material characteristics, cropping system, and tillage practice are considered when calculating the appropriate application rate (Anderson et al. 2013). Liming materials vary in chemical purity, particle size distribution or fineness, and moisture content, while depth of soil incorporation varies with crop residue management systems and tillage practices (NRCS 1999).
The online Agricultural Liming Material Selection and Comparison Calculator is used to characterize liming materials, calculate agricultural lime application rates, and assess product pricing relative to application costs. Individual attributes listed in Table 1 are presented in the order provided in the Agricultural Liming Material Selection and Comparison Calculator and further described in the following sections of this document.
A lime requirement is determined by soil testing. Soil pH alone can be used as an indicator that a lime application is needed, but it does not provide enough information to determine an appropriate liming rate. More information on lime requirement tests and laboratory determinations is provided in Agricultural Lime and Liming – Part 2. Laboratory Testing to Determine Lime Requirements.
Liming Product Label
All agricultural liming materials sold in the state of Washington are regulated as fertilizers by the Washington State Department of Agriculture (WSDA) and possess a product label that contains a guaranteed analysis and other product information, i.e., trade name, company name, and company contact information (Figure 1).