Field Observations of Regional Controls of Soil Hydraulic Properties on Soil Moisture Spatial Variability in Different Climate Zones

AbstractPlants can affect soil moisture and the soil hydraulic properties both directly by root water uptake and indirectly by modifying the soil structure. Furthermore, water in plant roots is mostly neglected when studying soil hydraulic properties. In this contribution, we analyze effects of the moisture content inside roots as compared to bulk soil moisture contents and speculate on implications of non-capillary-bound root water for determination of soil moisture and calibration of soil hydraulic properties.In a field crop of maize (Zea mays) of 75 cm row spacing, we sampled the total soil volumes of 0.7 m × 0.4 m and 0.3 m deep plots at the time of tasseling. For each of the 84 soil cubes of 10 cm edge length, root mass and length as well as moisture content and soil bulk density were determined. Roots were separated in 3 size classes for which a mean root porosity of 0.82 was obtained from the relation between root dry mass density and root bulk density using pycnometers. The spatially distributed fractions of root water contents were compared with those of the water in capillary pores of the soil matrix.Water inside roots was mostly below 2–5% of total soil water content; however, locally near the plant rows it was up to 20%. The results suggest that soil moisture in roots should be separately considered. Upon drying, the relation between the soil and root water may change towards water remaining in roots. Relations depend especially on soil water retention properties, growth stages, and root distributions. Gravimetric soil water content measurement could be misleading and TDR probes providing an integrated signal are difficult to interpret. Root effects should be more intensively studied for improved field soil water balance calculations.

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Effects of Soil Hydraulic Properties on the Spatial Variability of Soil Water Content

CSA News ◽

10.2134/csa2015-60-3-3 ◽

2015 ◽

Vol 60 (3) ◽

pp. 11-11

Keyword(s):

Spatial Variability ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Hydraulic Properties ◽

Soil Hydraulic Properties ◽

Soil Hydraulic

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Near-Surface Soil Moisture Assimilation for Quantifying Effective Soil Hydraulic Properties under Different Hydroclimatic Conditions

Vadose Zone Journal ◽

10.2136/vzj2007.0048 ◽

2008 ◽

Vol 7 (1) ◽

pp. 39-52 ◽

Cited By ~ 39

Author(s):

Amor V.M. Ines ◽

Binayak P. Mohanty

Keyword(s):

Soil Moisture ◽

Hydraulic Properties ◽

Surface Soil ◽

Surface Soil Moisture ◽

Soil Hydraulic Properties ◽

Near Surface ◽

Soil Hydraulic

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Earthworm Burrowing Activity and Its Effects on Soil Hydraulic Properties under Different Soil Moisture Conditions from the Loess Plateau, China

Sustainability ◽

10.3390/su12219303 ◽

2020 ◽

Vol 12 (21) ◽

pp. 9303

Author(s):

Shuhai Wen ◽

Ming’an Shao ◽

Jiao Wang

Keyword(s):

Soil Moisture ◽

Loess Plateau ◽

Hydraulic Properties ◽

Soil Depth ◽

Soil Aggregates ◽

Field Capacity ◽

Soil Hydraulic Properties ◽

The Loess Plateau ◽

Burrowing Activity ◽

Soil Hydraulic

Earthworm activity has become more important in the Loess Plateau, where hydrological processes are crucial for ecosystem sustainability. In this study, we conducted a laboratory microcosm experiment to determine the various burrowing activities of Eisenia fetida and their impact on the soil hydraulic properties in response to different levels of soil moisture (50%, 70%, 90% of field capacity) in two common soil types (loessial and Lou soil) obtained from the Loess Plateau. Burrowing activity of E. fetida increased with higher soil moisture and was greater in loessial than in Lou soil. Most burrowing activities occurred within the top 5 cm and decreased with increasing soil depth. Macropores and burrow branching, which are highly related to the earthworm burrowing, were more prevalent in wetter soil. Earthworms significantly altered the formation of large soil aggregates (AGL, diameter >2 mm) under different soil moistures and depths. Distinct earthworm burrowing activities, controlled by soil moisture, altered soil hydraulic properties. However, soil saturated hydraulic conductivity (Ks) showed little differences between different treatments due to the horizontal and high–branched burrows of E. fetida, although higher burrowing activities were found in wetter soil. Soil field capacity was highest in drier soil due to the less macropores and burrowing activities.

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Spatial Variability of Soil Physical and Hydraulic Properties in a Durum Wheat Field: An Assessment by the BEST-Procedure

Water ◽

10.3390/w11071434 ◽

2019 ◽

Vol 11 (7) ◽

pp. 1434 ◽

Cited By ~ 8

Author(s):

Mirko Castellini ◽

Anna Maria Stellacci ◽

Matteo Tomaiuolo ◽

Emanuele Barca

Keyword(s):

Spatial Variability ◽

Crop Yield ◽

Soil Texture ◽

Hydraulic Properties ◽

Wheat Yield ◽

Structure Stability ◽

Soil Hydraulic Properties ◽

Field Scale ◽

Cross Correlation Analysis ◽

Soil Hydraulic

Spatial variability of soil properties at the field scale can determine the extent of agricultural yields and specific research in this area is needed. The general objective of this study was to investigate the relationships between soil physical and hydraulic properties and wheat yield at the field scale and test the BEST-procedure for the spatialization of soil hydraulic properties. A simplified version of the BEST-procedure, to estimate some capacitive indicators from the soil water retention curve (air capacity, ACe, relative field capacity, RFCe, plant available water capacity, PAWCe), was applied and coupled to estimates of structure stability index (SSI), determinations of soil texture and measurements of bulk density (BD), soil organic carbon (TOC) and saturated hydraulic conductivity (Ks). Variables under study were spatialized to investigate correlations with observed medium-high levels of wheat yields. Soil physical quality assessment and correlations analysis highlighted some inconsistencies (i.e., a negative correlation between PAWCe and crop yield), and only five variables (i.e., clay + silt fraction, BD, TOC, SSI and PAWCe) were spatially structured. Therefore, for the soil–crop system studied, application of the simplified BEST-procedure did not return completely reliable results. Results highlighted that (i) BD was the only variable selected by stepwise analysis as a function of crop yield, (ii) BD showed a spatial distribution in agreement with that detected for crop yield, and (iii) the cross-correlation analysis showed a significant positive relationship between BD and wheat yield up to a distance of approximately 25 m. Such results have implications for Mediterranean agro-environments management. In any case, the reliability of simplified measurement methods for estimating soil hydraulic properties needs to be further verified by adopting denser measurements grids in order to better capture the soil spatial variability. In addition, the temporal stability of observed spatial relationships, i.e., between BD or soil texture and crop yields, needs to be investigated along a larger time interval in order to properly use this information for improving agronomic management.

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