Re: O Horizon.

It is not a Horizon it is a an Organic Soil Layer overlay the A layer formed by the accumulation of organic matter mainly of resent slightly decomposed plant's parts an this layer subdivided in to :O1,O2 and O3 according to the degree of decomposition of the organic matter .
with my appreciations and regards.
Yours faithful
Prof. Dr. Abdulellah A. Abughanem
Head of Soil & Water Department
Faculty of Agriculture ,Sana'a University
Republic of Yemen, P.O. Box 13511Sana’a
Tel.00967-1441912 Mobile :00967-777188264