Humification amended soils

A number of indexes based on the distribution of organic C in humic and nonhumic fractions are used for the evaluation of the humification level in organic amendments and amended soils (Senesi, 1989). Among others these include the degree of humification (DH), which is calculated as DH% = 100 x (HAC + FAC)/ TEC the humification rate (HR), which is calculated as HR% = 100 x (HAC + FAC)/ TOC and the humification index (HI), which is calculated as HI = NHC/ (HAC + FAC) (Sequi et al., 1986 Ciavatta et al., 1988). TOC represents the total organic carbon in the sample TEC represents the total extractable C by an alkaline solution (NaOH and/or Na4P207) HAC and FAC represent the C content in HA and FA fractions, respectively and NHC represents the nonhumified C content calculated by difference, that is, NHC = TEC - (HAC + FAC). 

Senesi, N., and Plaza, C. (2007). Role of humification processes in recycling organic wastes of various nature and sources as soil amendments. Clean Soil Air Water 35, 26 11. 

Figure L Schematic of soil labeling and humification setups. Experimental design is explained in the text The l setup for labeling soil is a polysulfone airtight filtration system, while the right setup for humification of organic amendments consists ofparts for a polypropylene solid-phase extraction device.

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