When selecting a soil sampler, the material composition is paramount; 304 or 316 stainless steel is highly recommended to prevent rust and avoid cross-contamination of samples. You must also evaluate the probe diameter and length based on your specific testing needs—standard agricultural testing usually requires a 12-inch to 24-inch depth. Additionally, look for reinforced handles and tapered tips which facilitate easier penetration into compacted or clay-heavy soils, ensuring a clean core sample every time.