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United States Department of Agriculture

Agricultural Research Service

Title: Comparison of Three Protocols to Determine Ph and Electrical Conductivity of Compost

item Watson, M. - OHIO STATE UNIV.
item Thompson, W. - EDAPHOS INTL
item Millner, Patricia
item Leege, P. - P.B.LEEGE CO., LTD.

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: August 15, 2001
Publication Date: October 29, 2001

Technical Abstract: We evaluated the effect of three analytical methos on two key measures of compost quality: electrometric pH and electrical conductivity (EC). Samples representing a variety of feedstock mixes were provided for analysis by 15 US compost facilities over two sample collection periods in 2000. For each sample period and facility, three samples of finished, market-ready commercially available compost were analyzed using 1) a saturated paste extract method, 2) a 1:5 weight basis (dw/w) dilution, and 3) a 1:5 volume basis dilution. Minor within-facility differences were observed among samples for pH or EC. Very large differences due to method were observed for EC, and numerically small differences between methods were observed for pH. Preliminary examination reveals that the median for the 1:5 dw/w EC method is 1.5 dS/m higher than that of the saturated paste extract method, and 6.5 dS/m higher than that of the 1:5 v/v EC method.

Last Modified: 4/22/2015
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