Original: In soil science , humus refers to any organic matter that has reached a point of stability , where it will break down no further and might , if conditions do not change , remain essentially as it is for centuries , if not millenniaWhitehead , D.C. , Tinsley , J. , 2006 .
Simplified: In the earth sciences , '' humus '' means any organic matter which has reached a point of stability , where it will break down no further and might , if conditions do not change , remain essentially as it is for centuries , or millennia .