SOIL 3600 Lecture Notes - Lecture 22: Total Organic Carbon, Humus, Exponential Function
13 Dec 2017
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Friday class: get lab 4 marks and midterms back. Lab 5 and 6: put a table in report, due on nov. 17th. How is humus (som) content measured: by the walkley-black digestion of organic carbon, by measuring total organic carbon content (% o. c. , the % humus is calculated from % oc using a conversion factor, universally accepted. If measured, this leads to an erroneously high result of % Most inorganic carbon is in the form of carbonates, therefore pre-treat the soil sample with dilute acid. The % som is calculated from the % oc. % oc in som: = (%som/1. 724) x 100, = 58% Factors governing the steady state accumulation of som. It is one of net loss: why, accumulation and losses, with a net loss, challenge, maintain som levels, slow down the loss, conservation practices. See graph: sharp and steady loss, after a certain point flatten out, become nearly a constant low % som.
