Most samples that are received fresh or are suspected moist will be put into paper bags with adequate room for air movement within the bag and dried at 55-60°C for approximately 12 hours or until the material snaps or breaks easily.
Most plant samples are ground to pass through a 40 mesh screen on the Wiley Mini-Mill or a 1 mm screen on a model 4 Wiley Mill. Soil is crushed in a Bico-Braun soil pulverizer to pass through a 2 mm sieve.
Sample Amount: Send 50 g of dried and ground sample. The maximum unground sample size is one (1) large grocery bag.
Feed Preparation: Oven-dry samples at 55-60°C for 24 hours. For Phenols: Dry samples at 50 - 52°C for 24 hours using a forced air oven. Avoid drying higher than 55°C as it could affect phenolic quantification.
Grind to pass through a 40 mesh screen. HOWEVER, for methods 635, 640, and 650, the grind must be larger and pass through an 18 mesh screen The maximum unground sample size is one (1) large #56 grocery bag.
Sample Amount: Submit 20 g of dried and ground sample. For extracts/solutions, five (5) mL per element is required.
Plant Preparation: Oven-dry samples at 55-60°C. Grind to pass through a 40 mesh screen.
Containers: Submit samples in coin envelopes.
Sample Amount: Submit 300-500 g of dried and ground sample. Five (5) mL per element is required for samples submitted in extract form. N & C requires five (5) grams of finely powdered soil (to pass through a 60 mesh sieve).
Soil Preparation: Air or oven-dry soil at 35-55°C (the Lab oven dries at 55°C). Grind to pass through a 2 mm sieve. Analysis for N, C, TKN, CaCO3, and "total" metal analysis require that the sample be ground to a powder fine enough to pass through a 60 mesh sieve (<0.25 mm).
Containers: Submit samples in pint-size plastic containers or in bags (plastic or paper).
Sodium Adsorption Ratio and Exchangeable Sodium Percent are calculations derived from analysis of Ca, Mg and Na.
To determine available N-P-K on California soils, we normally analyze for NO3-N, Olsen-P and Exchangeable K.
Sample Amount: 250 mL per sample (5 mL per element for extracts) is required.
Water Preparation: Samples submitted for alkalinity, ammonium, nitrate, soluble phosphorus, solids, sulfate and turbidity analysis should be kept under refrigeration. More detailed sample preservation guidelines are available on the Lab's web site Sampling and preparation.