Influence of soil, land use and climatic factors on the hydraulic conductivity of soil

Abstract

Due to inadequate data support, existing algorithms used to estimate soil hydraulic conductivity, <i>K</i>, in (eco)hydrological models ignore the effects of key site factors such as land use and climate and neglect the significant effects of soil structure on water flow at and near saturation. These limitations may introduce serious bias and error into predictions of terrestrial water balances and soil moisture status, and thus plant growth and rates of biogeochemical processes. To resolve these issues, we collated a new global database of hydraulic conductivity measured by tension infiltrometer under field conditions. The results of our analyses on this dataset contrast markedly with those of existing algorithms used to estimate <i>K</i>. We show that the saturated hydraulic conductivity, <i>K</i>_s, in topsoil (< 0.3 m depth) is only very weakly related to texture. Instead, <i>K</i>_s depends more strongly on bulk density, organic carbon content and land use and management factors. In this respect, the results show that arable sites have, on average, ca. 2 to 3 times smaller <i>K</i>_s values than natural vegetation, forests and perennial agriculture. The data also clearly demonstrates that clay soils have smaller <i>K</i> in the soil matrix and thus a larger contribution of soil macropores to <i>K</i> at and near saturation

Effects of Soil Compaction and Organic Carbon Content on Preferential Flow in Loamy Field Soils

“…Norgaard et al (2012) found that these BTC peaked after a very short time, generally less than 1 h, representing a soil structure with a few well-aligned and wellconnected macropores. Thus, the more clayey texture (average CL content of 16.4 kg kg −1 ) in Silstrup exhibited a lower degree of matrix conductivity and a higher degree of preferential flow resulting in rapid transport of tritium (Norgaard et al, 2012), according to previous studies (Lin et al, 1999;Jarvis et al, 2013).…”

Macropore Flow as a Groundwater Component in Hydrologic Simulation:Modelling, Applications and Results

“…Few studies reported contradictory correlation results in macropore flow. Correlation between macropore flow and bulk density of soil was reported to be: negative 47 , positive 48 , and oscillatory with a maximum at an intermediate level of bulk density or compaction 49 . As macropore flow is influenced more by soil structure and aggregates, which are not satisfactorily represented quantitatively, a generally acceptable model is not yet available 50 .…”

“…Land uses have a definite bearing on the formation and modification of macropores 1,47 . PTFs were formulated to estimate macroporosity factor A (ref.…”

Thematic Issue on Soil Water Infiltration

“…Soil hydraulic properties controlling infiltration generally exhibit a dynamic nature, being influenced by different interrelated factors including soil nature and stability, climate, land use, dynamics of plant canopy and roots, or tillage operations (Jarvis et al, 2013) as well as measurement techniques (Bagarello et al, 2014). The spatial and temporal variability of ponded infiltration was measured in a long-term experiment on a grid of 18 permanent measurements points established in a coarse sandy loam soil prone to preferential flow paths (Votrubova et al, this issue).…”