Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 9, 2004
Publication Date: June 4, 2005
Citation: Nemes, A., Rawls, W.J., Pachepsky, Y.A. 2005. The Influence of Organic Matter on the Estimation of Saturated Hydraulic conductivity. Soil Science of America Journal. 69:1330-1337.
Interpretive Summary: Soil saturated hydraulic conductivity is needed for many environmental applications. Some of existing methods to estimate saturated hydraulic conductivity of the soil, using organic matter content as one of the input variables. Most estimation procedures indicate a increase in saturated hydraulic conductivity with increasing organic matter content. Using a international data base, it was determined that for certain soil textures organic matter content caused a decrease in saturated hydraulic conductivity.
Estimation of soil hydraulic properties by pedotransfer functions (PTFs) can be used in many applications. Some of existing PTFs estimate saturated hydraulic conductivity (Ks) of the soil, using organic matter (OM) content as one of the input variables. Common knowledge assumes an increase in Ks with increasing OM content, which presumably improves soil structure. We used three widely renowned PTFs to examine the correlations between OM content and Ks. We also used data originating from the US, Hungary and the European HYPRES database, to develop additional PTFs using Group Method of Data Handling. It appears that existing PTFs negatively correlate Ks with OM content for some soils. We found the negative correlation between OM content and Ks with the newly developed PTFs both for directly estimated Ks, and for Ks estimated via the effective porosity of the soil, using a generalized Kozeny-Carman approach. It is not straightforward to define the exact range of soils with the negative correlation estimated between OM and Ks. The range appeared to be data set dependent, but it was extensive within the valid input range of each PTF.