Compost maturity: Extractable lipids as indicators of organic matter stability

An organic matter stability test was developed for assessing compost maturity. Lipids extracted sequentially with diethyl ether (DEE) and chloroform (CHCl3) from four composted manure mixes and four commercially produced composts were used to set and test the limits of gravimetrically based indices of maturity. Limits of <2.50 for DEE-/CHCl3-extractable lipid ratios and >0.25 for CHCl3-extractable/total lipid ratios constitute acceptable limits for mature composts. The proposed test for compost maturity is scientifically-sound, relatively inexpensive and universally applicable, and can be performed by workers with low technical skills.