“…The studies on the role of specific humus in the growth and development of plants have received considerable studied. It has been reported that these substances extracted from soil, organic mature, peat, and even coal, exert favorable influence on the growth, nutrient uptake and health of plants (Burroni et al, 1994;Adani et al, 1995;Lulakis and Petsas, 1995;Valdighi et al, 1995). Although there is no agreement as yet with regard to the mechanisms of action of humus substances on plants.…”