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Methods of Analysis

Drying

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.

Exceptions:

    • Range samples take 24 hours or more to dry. Power plant ash samples take 3 days to dry. Solid pieces of wood take 24 hours to dry. Rice soils takes 2 days to dry. Any material larger than gallon size will take 1 or more days to dry. Fruits and vegetables go through the freeze drying process, pureed if needed, and weighed before and after the freeze drying process. All samples are turned every 24 hours except freeze drying material.

Grinding

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.

Exceptions:

    • 20 mesh screen used on grape blades due to tricomb separation from leaf. 20 mesh screen used on sugar beet petioles due to high sugar content. 20 mesh screen used on walnut leaf due to fibers in veins. 10 mesh screen used on corn stalks due to high sugar content. Freeze dried samples are easily crushed manually. Soil for carbon analysis is ground to a powder fine enough to pass a 50 mesh sieve. Timing: Most samples that are smaller than the size of a fist are processed through the Wiley Mini-Mill. On the average, 1 minute per sample if less than 15 grams or 3-4 minutes for samples of 100-150 grams. Samples larger than two fists are sent through the model 4 Wiley Mill. Average time is 4-5 minutes per sample. Samples between the size of one and two fists are ground through either grinder depending upon the type of material. All residual material held in either grinder is put with the ground material and thoroughly incorporated. Soil grinding time is from 1-4 minutes per sample. Fine soils vs. large hard soils that need to be pounded smaller first. Clean soils without debris vs. with debris that needs to be sieved out. Material size runs from 100 grams to 2 kg. Any material smaller than 100 grams is ground by mortar and pestle. All other samples that are not dried and ground are refrigerated until analysis.

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. Grind to pass through a 40 mesh screen. The maximum unground sample size is one (1) large #56 grocery bag.

Method Summaries

  • 615 — Crude Fat 
  • 625 — Total Crude Protein - Combustion Method 
  • 640 — Acid Detergent Fiber (ADF), Lignin, Acid Detergent Insoluble Nitrogen (ADIN), Total Digestible Nutrients (TDN) and Cellulose - Reflux Method 
  • 650 — Neutral Detergent Fiber (NDF) and Hemicellulose - Reflux Method 
  • 670 — Ash Content in Botanical Materials - Gravimetric Method 
  • 680 — Soluble Carbohydrates - HPLC Method 
  • 690 — Total Glucose for Total Nonstructural Carbohydrates (TNC) and Starch 
  • 695 — Resveratrol - HPLC Method
  • Power plant ash samples take three days to dry Solid pieces of wood take 24 hours to dry

Sample Amount: Submit one cup manure or compost.

Manure and Compost Preparation: Samples should be frozen if not delivered to the lab immediately upon collection.

Containers: Submit samples in plastic containers.

  • 705 — pH 1:5
  • 715 — Estimated Soluble Salts

Sample Amount

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.

Note: Samples for N and C analysis need to be ground to pass through a 60 mesh sieve.

Storage and Containers

  • 505 — Dry Matter Determination for Botanical Materials 
  • 507 — Partial Dry Matter 
  • 510 — Extractable Nitrate and Ammonium in Botanical Materials - Diffusion-Conductivity Analyzer Method 
  • 512 — Extractable Nitrate in Botanical Materials - Flow Injection Analyzer Method 
  • 515 — Total Kjeldahl Nitrogen (TKN) [Note: This is the same method as SOP# 315.] 
  • 522 — Total Nitrogen and Carbon-Combustion Method 
  • 530 — Extractable Sulfate-Sulfur in Botanical Materials 
  • 540 — Extractable Phosphorus in Botanical Materials 
  • 550 — Extractable Potassium in Botanical Materials 
  • 561 — Extractable Chloride in Botanical Materials -ION Chromatrography Method 
  • 585 — Total Silicon-HF 
  • 590 — Total Elements-Nitric Acid Digestion 
  • 594 — Selenium 
  • 596 — Arsenic

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 require one (1) gram 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 40°C). Grind to pass through a 2 mm sieve. Analysis for N, C, TKN and "total" metal analysis require grinding to pass through a 60 mesh screen.

Containers: Submit samples in pint-size plastic containers or in bags (plastic or paper).

Notes:

Sodium Adsorption Ratio and Exchangeable Sodium Percent are calculations derived from analysis of Ca, Mg and Na.

For N and C by combustion (Carlo-Erba), 1 gram of sample material needs to be finely ground to pass through a 60 mesh sieve.

To determine available N-P-K on California soils, we normally analyze for NO3-N, Olsen-P and Exchangeable K.

Soil Salinity

  • 200 — Saturated Paste and Saturation Percentage
  • 205 — Soil pH
  • 210 — pH of a 1 + 10 Soil Suspension
  • 215 — Estimated Soluble Salts (ECe)
  • 220 — Bicarbonate and Carbonate in Saturated Paste Extract
  • 227 — Chloride in Saturated Paste Extract - Flow Injection Analyzer Method
  • 235 — Potassium, Sodium, Calcium, Magnesium, Boron and Sulfate-Sulfur in Saturated Paste Extract
  • 240 — SAR (Sodium Adsorption Ratio) and ESP (Exchangeable Sodium Percentage)

Soil Fertility

  • 312 — Soil Nitrate and Extractable Ammonium-Flow Injection Analyzer Method
  • 315 — Total Kjeldahl Nitrogen (TKN)
  • 320 — Total Nitrogen and Carbon - Combustion Method
  • 322 — Total Organic Carbon - Combustion Method
  • 330 — Sulfate - Sulfur
  • 340 — Extractable Phosphorus - Olsen Method
  • 355 — Extractable Phosphorus - Bray Method
  • 360 — Exchangeable Potassium, Calcium, Magnesium, Sodium and Estimated Cation       Exchange Capacity
  • 370 — Potassium -Sulfuric Acid Extraction
  • 380 — Extractable Micronutrients using DTPA Extraction - Zinc, Manganese, Copper, and Iron
  • 390 — Total Elements (includes Phosphorus, Zinc, Manganese, Iron, Copper, Molybdenum, Cadmium, Chromium, Lead and Nickel)
  • 392 — KCL Extractable Aluminum
  • 394 — Selenium
  • 396 — Arsenic

Physio-Chemical

  • 410 — Organic Matter - Walkley-Black Method
  • 415 — Organic Matter - Loss On Ignition Method
  • 420 — Gypsum Content
  • 430 — Cation Exchange Capacity
  • 440 — Calcium Carbonate and Calcium Carbonate Equivalent
  • 450 — Lime Requirement
  • 460 — Moisture Retention
  • 470 — Particle Size Analysis
  • 480 — Bulk Density

Sample Amount: Submit 50mL for chemical testing.

Storage: Store sample at room temperature.  Avoid direct sunlight.

Containers: Amber or foil wrapped glass bottles.

Method Summaries:

  • 972 — Sterols and Triterpene Dialcohols in Oil by Gas Chromatography
  • 974 — Wax Content in Oil by Gas Chromatography
  • 976 — Triacylglycerols (ECN 42) in Oil by HPLC
  • 978 — Stigmastadiene in Oil by gas Chromatography

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 (http://anlab.ucdavis.edu) in the section titled Sampling and Preparation).

Method Summaries

  • 805 — pH
  • 810 — Turbidity
  • 815 — Estimated Soluble Salts by Electrical Conductivity
  • 820 — Alkalinity, Bicarbonate and Carbonate
  • 822 — Total Carbon and Inorganic Carbon 
  • 830 — Chloride - Flow Injection Analyzer Method
  • 835 — Soluble Elements
  • 837 — Copper in Water by Graphite Furnace
  • 840 — Sodium Adsorption Ratio (SAR) and Exchangeable Sodium Percentage (ESP)
  • 845 — Nitrate and Ammonium - Diffusion-Conductivity Analyzer Method
  • 847 — Nitrate, Nitrite and Ammonium - Flow Injection Analyzer Method
  • 848 — Ammonium - Distillation Method
  • 850 — Total Kjeldahl Nitrogen (TKN)
  • 855 — Total Nitrogen - Combustion Method
  • 865 — Soluble Phosphorous in Water
  • 870 — Total Solids, Total Suspended Solids, Total Dissolved Solids, Volatile Suspended Solids
  • 875 — Hardness
  • 880 — Anions in Water by Ion Chromotography
  • 890 — Total Elements (includes Phosphorus, Sulfur, Potassium, Calcium, Magnesium, Sodium, Boron, Zinc, Manganese, Iron, Copper and Molybdenum) [Note: This is the same method as SOP# 590.]
  • 891 — Total Copper in Water by Graphite Furnace
  • 894 — Selenium
  • 896 — Arsenic
  • 898 — Mercury

Miscellaneous Methods