Soil is oven-dried at 38°C and ground to pass a 2 mm screen. A soil-water paste is created by adding 10 ml of water to 10 cm³ of soil and stirring with a glass rod and letting stand for at least 15 minutes but not more than 2 hours. A glass electrode is placed in the mixture to measure pH. After pH measurement, 10 ml of Sikora Buffer (a mixture of triethanoloamine, imidazole, MES, acetic acid, and KCl) is added to the soil-water paste and shaken for 10 minutes. A glass electrode is then placed in the mixture to measure Buffer pH within 2 hours after shaking. Soil pH and buffer pH are reported as unitless values.
Phosphorus, K, Ca, Mg, and Zn are determined in a Mehlich III extract which contains 0.2 N acetic acid, 0.25 N NH₄NO₃, 0.015 N NH₄F, 0.013 N HNO₃, and 0.001 N EDTA. Twenty ml of Mehlich III extract is added to 2 cm³ soil, shaken for 5 minutes, and immediately filtered through Whatman #2 filter paper. Filtration is terminated at the end of 10 minutes. In Lexington, the filtrate is analyzed via ICP (inductively coupled plasma spectroscopy). In Princeton, K, Ca, Mg, and Zn are analyzed in the filtrate via atomic absorption spectrophotometry and P is determined colorimetrically. The analytes are reported as lbs of nutrient / acre of land. The assumptions made with this reporting is that an acre of land contains 2 million pounds of soil and the density of air-dried ground soil is 1 g/cm³.

Soil and Plant Analysis Council. 2000. Chapter 3. Soil pH, and exchangeable acidity and aluminum. In: Soil analysis handbook of reference methods. Soil and Plant Analysis Council, Inc., CRC Press, Boca Raton, FL.

Soil and Plant Analysis Council. 2000. Chapter 6. Phosphorus. In: Soil analysis handbook of reference methods. Soil and Plant Analysis Council, Inc., CRC Press, Boca Raton, FL.

Soil and Plant Analysis Council. 2000. Chapter 7. Major cations (potassium, calcium, magnesium, and sodium). In: Soil analysis handbook of reference methods. Soil and Plant Analysis Council, Inc., CRC Press, Boca Raton, FL.

Soil and Plant Analysis Council. 2000. Chapter 8. Micronutrients (boron, copper, iron, manganese, and zinc). In: Soil analysis handbook of reference methods. Soil and Plant Analysis Council, Inc., CRC Press, Boca Raton, FL.

Sikora, F.J. 2005. Replacing SMP buffer with Sikora Buffer for Determining Lime Requirement of Soil (A Technical Review).

Sikora, F.J. 2006. A buffer that mimics the SMP buffer for determining lime requirement on soil. Soil Sci. Soc. Am. J. 70:474-486.

Soil is oven-dried at 38°C and ground to pass a 2 mm screen. One-half gram of soil is weighed in porcelain boats and injected into a dry combustion instrument (LECO or Elementar). The instrument determines%C in the material. Organic matter is calculated as %C x 1.72 = % organic matter. Organic matter is reported as % by weight of air-dried soil.

Nelson, D.W. and L.E. Sommers. 1982. Total carbon, organic carbon, and organic matter. In: A.L. Page, R.H. Miller, D.R. Keeney (eds.) Methods of Soil Analysis, Part 2. Chemical and microbiological properties, 2nd ed. ASA-SSSA, Madison, WI.

Soil is oven-dried at 38°C and ground to pass a 2 mm screen. Ten g of soil is added to a 500 ml digestion flask. Twenty ml of dilute CaCl₂ (0.01 M) is added to the soil. With the flask attached to a condensor, the solution is heated at boiling for 5 minutes. After cooling, the soil-solution mixture is filtered through Whatman #2 filter paper. The filtrate is analyzed for B via ICP (inductively coupled plasma spectroscopy). Boron is reported in units of lbs/acre with the assumption that an acre of land contains 2 million pounds of soil.

Cation exchange capacity (CEC) is determined via ammonium saturation of exchange site and analysis of saturated ammonium using an ammonium ion-selective electrode. Soil is oven-dried at 38°C and ground to pass a 2 mm screen. Ten g of soil is mixed with 25 ml of 1 N ammonium acetate solution in a 250 ml beaker and let stand overnight to ensure complete saturation of exchange sites with ammonium. The sample is then vacuum-filtered through Whatman 42 filter paper placed in a Buchner funnel. Approximately 75 ml of ammonium acetate solution is added to the soil on the Buchner funnel in 10 to 15 ml increments. The filtrate is transferred to a 100 ml volumetric flask and brought to volume. This solution is analyzed for Ca, Mg, K, and Na via ICP (Inductively Coupled Plasma Spectrophotometry) which provides quantification of bases on soil exchange sites. The bases are reported in units of meq/100 g (equivalent to cmol/kg).

To determine total cation exchange capacity, the ammonium saturated soil in the Buchner funnel is leached with 200 ml of 10% NaCl at pH 3 in 35 to 45 ml increments. The leachate is transfered to a 250 ml volumetric flask and brought to volume with 10% NaCl. The resultant solution is diluted ten fold with water and ammonium is measured with an ammonium ion-selective electrode. One ml of concentrated NaOH is added to the solution to convert ammonium to ammonia which is directly measured by the electrode. The equivalents of ammonium in solution is converted to cation exchange capacity of soil in units of meq/100 g (equivalent to cmol/kg). Base saturation is determined as total bases/CEC x 100 and reported in %.

Soil and Plant Analysis Council. 2000. Chapter 7. Major cations (potassium, calcium, magnesium, and sodium). In: Soil analysis handbook of reference methods. Soil and Plant Analysis Council, Inc., CRC Press, Boca Raton, FL.

Micropipette method:
Soil is prepared by oven drying at 38°C and passing through a 2 mm screen. Four g of soil is treated with 10 ml H₂O and 10 ml of dispersing agent (sodium hexametaphosphate, 5 g/L) in a 50 ml centrifuge tube. The mixture is shaken for 2 hours. After shaking, add 20 ml of H₂O to each sample. Shake by hand to ensure all soil particles are in solution and place tubes in rack to allow settling. 5 ml of sample is taken in the middle of the tube at approximately 1 hour and 50 minutes (exact time depends on temperature) with a syringe. The sample is oven-dried and weighed to determine clay content. The whole tube contents in then poured through a #270 sieve. The particles remaining on the sieve are oven-dried and weighed to determine sand content. The silt content is determined as the difference between total weight and the weight of clay and sand. Sand, silt, and clay are reported as % of oven-dried soil. Textural class is also reported.

Miller, W.P. and D.M. Miller. 1987. A micropipette method for soil mechanical analysis. Commun. Soil Sci. Plant Anal. 18:1-15.

Burt, R., T.G. Reinsch, and W.P. Miller. 1993. A micro-pipette method for water dispersible clay. Commun. Soil Sci. Plant Anal. 24:2531-2544.

Soil is oven-dried at 38°C and ground to pass a 2 mm screen. Fifty ml of deionized water is added to 25 g of soil and shaken on a wrist action shaker for 30 minutes. The soil-solution mixture is completely filtered through Whatman no. 5 filter paper. Electrical conductivity in the filtrate is measured with a conductivity bridge and 1 cm conductivity cell. Soluble salts is reported as the conductivity in the solution in mmhos/cm (=dS/m).

Soil and Plant Analysis Council. 2000. Chapter 5. Conductance, soluble salts, and sodicity. In: Soil analysis handbook of reference methods. Soil and Plant Analysis Council, Inc., CRC Press, Boca Raton, FL.

Soil is oven-dried at 38°C and ground to pass a 2 mm screen. One-half gram of soil is weighed in porcelain boats and injected into a LECO combustion instrument. The instrument determines %N in the material by measuring the N₂ gas emitted upon combustion. Nitrogen is reported in units of lbs/acre assuming 2 million pounds of soil are in an acre (% x 20,000 = lbs/acre).