Environmental and management influences on temporal variability of near saturated soil hydraulic properties

Abstract

Structural porosity is a decisive property for soil productivity and soil environmental functions. Hydraulic properties in the structural range vary over time in response to management and environmental influences. Although this is widely recognized, there are few field studies that determine dominant driving forces underlying hydraulic property dynamics. During a three year field experiment we measured temporal variability of soil hydraulic properties by tension infiltrometry. Soil properties were characterized by hydraulic conductivity, effective macroporosity and Kosugi's lognormal pore size distribution model. Management related influences comprised three soil cover treatment (mustard and rye vs. fallow) and an initial mechanical soil disturbance with a rotary harrow. Environmental driving forces were derived from meteorological and soil moisture data. Soil hydraulic parameters varied over time by around one order of magnitude. The coefficient of variation of soil hydraulic conductivity K(h) decreased from 69.5% at saturation to 42.1% in the more unsaturated range (− 10 cm pressure head). A slight increase in the Kosugi parameter showing pore heterogeneity was observed under the rye cover crop, reflecting an enhanced structural porosity. The other hydraulic parameters were not significantly influenced by the soil cover treatments. Seedbed preparation with a rotary harrow resulted in a fourfold increase in macroporosity and hydraulic conductivity next to saturation, and homogenized the pore radius distribution. Re-consolidation after mechanical loosening lasted over 18 months until the soil returned to its initial state. The post-tillage trend of soil settlement could be approximated by an exponential decay function. Among environmental factors, wetting-drying cycles were identified as dominant driving force explaining short term hydraulic property changes within the season (r2 = 0.43 to 0.59). Our results suggested that beside considering average management induced changes in soil properties (e.g. cover crop introduction), a dynamic approach to hydrological modeling is required to capture over-seasonal (tillage driven) and short term (environmental driven) variability in hydraulic parameters.

Management of crop water under drought: a review

“…Similar to other management measures, also crop rotation studies reveal the importance of the time scale of changes (Głąb et al 2013). A transient crop impact can be overlaid by several environmental factors such as wet-dry and freeze-thaw cycles or raindrop impact that commonly shape soil hydraulic properties (Logsdon et al 1993;Bodner et al 2013).…”

“…via high maximum rooting depth to exploitative patterns with an intense extraction, e.g. via high fine root density (Fitter 1987;Bodner et al 2013). Increasing importance of subsoil moisture for crop performance implies an advantage of strongly explorative root systems (Kirkegaard et al 2007;Wasson et al 2012).…”

“…Beside texture, structure is fundamental for the hydraulic behaviour of soils. Soil structure is a highly dynamic property varying over space and time (Schwen et al 2011;Bodner et al 2013). An important climate-soil interaction can be found between rainfall intensity and infiltrability.…”

Effect of Corn Residue Biochar on the Hydraulic Properties of Sandy Loam Soil

“…The values of K sat were well fit logarithmically to the increased BC500 application rate (y = 2.9943e −0.1989x , R 2 = 0.98; Table 1). Soil hydraulic conductivity primarily governs the soil water movement and retention [55]. Compared to other soil textures (i.e., clayey and silty), sandy soils (e.g., sandy loam) exhibit fairly high downward water movement.…”

New automatic minidisk infiltrometer: design and testing

“…Unsaturated hydraulic conductivity of soil in the meadow is approximately two times higher than the soil in the tilled field which is in contradiction with studies by Schwartz et al (2003) or Kelishadi et al (2014), who observed higher unsaturated conductivity in the tilled field than in the meadow for pressure head below -3 cm. However, as is generally known, there is a significant influence of the seasonal variability of soil hydraulic properties associated with agricultural practices (Alletto and Coquet, 2009;Bodner et al, 2013;Castellini and Ventrella, 2012;Logsdon et al, 1993). Thus, lower unsaturated hydraulic conductivity in the field site is probably a consequence of macropore formation after postharvest stubble-breaking.…”