An automated computer-controlled sampling system and related methods for collecting, processing, and analyzing agricultural samples for various chemical properties such as plant available nutrients. The sampling system allows multiple samples to be processed and analyzed for different analytes or chemical properties in a simultaneous concurrent or semi-concurrent manner. Advantageously, the system can process soil samples in the as collected condition without drying or grinding. The system generally includes a sample preparation sub-system which receives soil samples collected by a probe collection sub-system and produces a slurry (e.g., mixture of soil, vegetation, and/or manure and water), and a chemical analysis sub-system which processes the prepared slurry samples for quantifying multiple analytes and/or chemical properties of the sample. The preparation sub-system may comprise a slurry recirculation flow loop configured with devices to stir, measure, and adjust a water to solids ratio of the slurry.

A method for producing a suspension, the method including feeding water by a pump from a storage container through a mixing chamber; mechanically comminuting plant parts from real nuts, kernels, grains, and/or seeds by a comminuting element to form comminuted plat parts; mixing the comminuted plant parts with the water in the mixing chamber to form a mix; pressing the mix through a filter that passes the suspension through and retains a pomace that remains from the plant parts, wherein a pump wheel of the pump forms the comminuting element.