Premium
Cation and Nitrogen Contents of Organic Matter Determine Its Soil Liming Potential
Author(s) -
Pocknee Stuart,
Sumner Malcolm E.
Publication year - 1997
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1997.03615995006100010014x
Subject(s) - chemistry , organic matter , soil ph , lime , mineralization (soil science) , soil organic matter , topsoil , decomposition , nitrification , environmental chemistry , calcareous , nitrogen , soil water , soil science , botany , environmental science , organic chemistry , geology , biology , paleontology
The effect of organic matter addition to soil in relation to soil pH changes is not well understood. Organic matter additions to soil have been reported to both increase and decrease soil pH. An investigation of the effects and mechanisms involved was undertaken. Plant materials of different types were incubated with an acid Cecil topsoil (clayey, kaolinitic, thermic Typic Kanhapludult) (pH KCl 4.01) in a glasshouse experiment at rates equivalent to 50 and 200 Mg ha −1 (dry mass). Soil pH was measured with time and increases of up to 4 pH units were observed followed by attainment of a steady state at or above the original soil pH, depending on the type of organic matter added. The final pH was well correlated with the amount of basic cations present in the organic matter ( r 2 = 0.92). The initial short‐term fluctuations in pH were due to mineralization and nitrification of the N added in the material. A separate factorial study using simple organic sources of Ca (calcium gluconate) and N (β‐alanine) supported this contention. The short‐term organic liming effect stemming from N transformations is strongly dependent on the kinetics of the organic matter decomposition, which are, in turn, biologically mediated. Decomposition of Ca‐containing organic molecules was shown to have an effect on pH analogous to that of mineral lime (CaCO 3 ).