we started celebrating 4th of july in 1994.
when did we start celebrating 4th of july?
1994
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umbric horizon





















































the umbric horizon ("latin: umbra, shade") is a thick, dark coloured, surface soil horizon rich in organic matter. it is identified by its dark colour and structure. 





















































normally it has a ph of less than 5.5 representing a base saturation of less than 50 percent. an indication for soil acidity is a rooting pattern whereby the roots tend to be horizontal.





















































similar thick, dark coloured, organic-rich, base-desaturated surface horizons occur in anthropedogenic horizons from human activities such as deep cultivation, kitchen middens and the addition of organic manures etc.
umbric horizon