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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 525666
Title Kwantitatieve aspecten van humusopbouw en humusafbraak
Author(s) Kortleven, J.
Source University. Promotor(en): A.C. Schuffelen. - Wageningen : Pudoc - ISBN 9789022000854 - 109
Publication type Dissertation, internally prepared
Publication year 1963
Keyword(s) humus - humushorizonten - strooisel - bodemchemie - humus horizons - litter (plant) - soil chemistry
Categories Soil Fertility / Soil Chemistry
Abstract Some common expressions on humus were current that were not based on exact or quantitatively analysed data.
To achieve a desirable humus content, it was necessary to know the relation between supply of humus and humus content, here studied, and the relation between humus content and productivity.

A field trial begun in 1911 to compare complete fallow with normal exploitation indicated two axioms: from a supply of crude organic matter a certain constant part became humus each year; from humus in soils a certain constant part was mineralized each year.

If supply was equal each year it was possible to derive the following formula for the rise or fall in humus content: y = y m - (y m - y 0 ) (1 - K 2 ) t, where y = humus content, y m = humus content at ultimate equilibrium,y 0 = initial humus content, K 2 = rate of mineralization (see axiom 2), and t = time in years. Further y m = K 1 /K 2 x, where K 1 = rate of humification (see axiom 1), and x = supply with raw organic material.

These formulae were tested in the few available experiments, suitable for the purpose (which did not include the classical Rothamsted fields). K 1 was 0.4; thus 40 % of the supply becomes humus each year. K 2 had values between 0.015 and 0.02; from this it followed that 2 % of the humus was yearly mineralized. No difference was yet found in the value of either coefficients for different organic materials and in different soils.
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