AbstractsBiology & Animal Science

In 1809, A. von Thaer wrote in his book "Grundsatz der Rationell Landwirtschaft" that, except for water, the humus in the soil is the sole substance which supplies nutrients for the growth of plants. Since then, the role of humus in soil has been intensively studied and the meaning of humus has varied from the "organic fraction of soil" to "a dark incoherent and heterogeneous colloidal mass in soil" (Buckman and Brady 1960). Based on the latter meaning the term humus does not include any undecayed organic materials or micro-organisms in the soil. However, in the practical consideration of humus, the presence of microorganisms is usually neglected. For exemple, the well known humus fractionation method of Tyurin mentioned by Kononova (1958), does not consider that the treatment with solvent, alkali, and acid will fractionate not only the colloidal organic matter (humus) but also the undecayed organic materials and microorganisms. [...]