Compost Procedures

1. 1 pint of sample is required for analysis
2. Laboratory numbers are assigned to the sample submission form and the data sheet. The lab numbers are written on the sample bags with a sharpie. The first digit of the lab number is 4. The next two digits are the month. The last four digits are the sample number for the year.
3. Record tare weight of paper bag. Add 100 – 200 g sample, weigh and record wet weight. Place in the oven to dry at 60°C overnight. Record dry weight. Grind for nitrogen, carbon, mineral, organic matter, and nitrate nitrogen analyses. Record weight of 100 mL beaker. Add about 5 g dried and ground sample and record weight. Dry at 105°C for 3 hours. Record weight to get total dry matter.

1. Weigh about 2 grams of a representative sample into a tared Erlenmeyer flask. Record weight on flask to 2 decimal places. Add 20 mL 2 M KCl. Shake for 30 min.
2. Filter sample into digestion tube. Transfer weight to tube. Enter weight into distillation unit. Distill Sample. Titrate with H2SO4 solution using the boric acid indicator. Record value to 2 decimal places.
3. To make 2 M KCl, weigh 298.24 g KCl into a 2 L volumetric flask. Dilute to volume with deionized H2O.
4. Report 2 decimal places for solids.

Total Nitrogen and Total Carbon

1. Analyze dried and ground sample according to Elementar procedure.
2. Record value to 2 decimal places.

Mineral Analysis

1. Wet ash dried and ground sample according to plant tissue procedure.
2. Record results according to plant tissue procedure.

1. Number porcelain crucibles with wax pencil. Weigh crucibles to 4 decimal places. Scoop dried and ground samples into crucibles using 5 g soil scoop. Put crucibles plus samples on tray in furnace. Set temperature to 105 degrees C. Ash at this temperature for 2 h. (It takes 15 minutes for the furnace to reach this temp, so set the dial at 105 for a total of 2 h and 15 min.)
2. Remove samples from furnace with tongs, place in desiccator, and weigh to 4 decimal places immediately while still warm so moisture won’t be absorbed. Replace crucibles plus samples in furnace. Turn dial up to 360 degrees C.
3. Ash at this temp for 2 hours. (It takes ½ hour for the furnace to reach this temperature, so set the dial at 360 for a total of 2½ hour.) Turn furnace off and open door. Place samples in desiccator with tongs and allow samples to cool. Weigh samples to 4 decimal places.
4. Calculate OM% and record on data sheet with one decimal.

• Crucible wt = a
• Crucible wt + sample wt after 105 heating = b
• Crucible wt + sample wt after 360 heating = c

%OM = ((b-a)-(c-a))(100)/(b-a)

Reference

1. E. E. Schulte, Recommended Soil Organic Matter Tests.
   

EC: This test is performed on the as-received sample on a 1:5 (dw/v) basis. 

1. First determine the moisture content.
2. Then weigh into a 250 mL flask the equivalent wet weight to give 40 g of dry weight material (e.g. if the moisture is 50%, weigh out 80 g fresh to get 40 g dry material).
3. Add water to bring final volume to 200 mL. This will give a dilution ratio of 1:5. Shake on shaker for 20 minutes.
4. Determine the electrical conductance of the 1:5 slurry with a conductivity meter.
5. Read and record the conductivity of the slurry in mmhos/cm to 2 decimal places.

pH:

1. Scoop 15 mL fresh compost. 
2. Bring volume to 30 mL with deionized water. 
3. Stir and let sit for 30 minutes. 
4. Analyze pH on Analyzer.

Nitrate Nitrogen

1. Analyze according to animal waste procedure.
2. Record to 0 decimal places.

Bulk Density (Volume Basis)

1. Spread about 3 liters of media in soil tray and dry overnight at 80oC.
2. Measure out and weigh five – 500 mL amounts in a 600 mL beaker.
3. Average the 5 values. Multiply averaged value by 3.38 to get lbs/cubic yd.