A wide variety of plants are analyzed throughout the year. The appropriate part of the plant to sample varies with the crop, growth stage, and purpose of sampling. Several kinds of solutions are analyzed for chemical properties and minerals that affect water quality and its utilization in agriculture. Solid wastes, such as compost and litter, are subsampled to determine dry matter content. Plant and solid waste samples are dried to remove moisture and stabilize nutrient content.
Acid is added to the samples to begin the digestion process.
Samples are digested in a special microwave oven to break down organic compounds into the elements to be measured. Distilled water is added to bring digested samples to a standard volume. Block digestion with sulfuric acid breaks down liquid organic waste products for nitrogen analysis. Total Kjeldahl nitrogen is determined on liquid waste products by autoanalyzer. Total nitrogen and carbon of composted materials, other solids, and plant samples are measured by a combustion analyzer.