Conduct a ferrous iron test. A colorimetric field test kit has 

 been developed for this purpose. A reducing soil environment 

 is present when the soil extract turns pink upon addition of 

 d-cc-dipyridil. 



Determine the color(s) of the matrix and any mottles that may 

 be present. Soil color is characterized by three features: 

 hue, value, and chroma. Hue refers to the soil color in rela- 

 tion to red, yellow, blue, etc. Value refers to the lightness 

 of the hue. Chroma refers to the strength of the color (or 

 departure from a neutral of the same lightness) . Soil colors 

 are determined by use of a Munsell Color Book (Munsell Color 

 1975).* Each Munsell Color Book has color charts of different 

 hues, ranging from lOR to 5Y. Each page of hue has color chips 

 that show values and chromas. Values are shown in columns down 

 the page from as low as to as much as 8, and chromas are 

 shown in rows across the page from as low as to as much as 8. 

 In writing Munsell color notations, the sequence is always hue, 

 value, and chroma (e.g. 10YR5/2). To determine soil color, 

 place a small portion of soil** in the openings behind the 

 color page and match the soil color to the appropriate color 

 chip. Note: Match the soil to the nearest color chip. Record 

 on DATA FORM 1 the hue, value, and chroma of the best matching 

 color chip. CAUTION: Never place soil on the face or front of 

 the color page because this might smear the color chips. Min- 

 eral hydric soils usually have one of the following color fea- 

 tures immediately below the A-horizon or 10 inches (whichever 

 is shallower) : 



(1) Gleyed soil. 



Determine whether the soil is gleyed. If the matrix color 

 best fits a color chip found on the gley page of the 

 Munsell soil color charts, the soil is gleyed. This indi- 

 cates prolonged soil saturation, and the soil is highly 

 reduced. 



(2) Nongleyed soil. 



(a) Matrix chroma of 2 or less in mottled soils.** 



(b) Matrix chroma of 1 or less in unmottled soils.** 



(c) Gray mottles within 10 inches of the soil surface in 

 dark (black) mineral soils (e.g., Mollisols) that do 

 not have characteristics of (a) or (b) above. 



Soils having the above color characteristics are normally satu- 

 rated for significant duration during the growing season. How- 

 ever, hydric soils with significant coloration due to the 

 nature of the parent material (e.g. red soils of the Red River 

 Valley) may not exhibit chromas within the range indicated 

 above. In such cases, this indicator cannot be used. 



* See references at the end of the main text. 

 ** The soil must be moistened if dry at the time of examination. 



D3 



