scholarly journals Monitoring water content changes in a soil profile with TDR-probes at just three depths - How well does it work?

RBRH ◽  
2020 ◽  
Vol 25 ◽  
Author(s):  
Jens Hagenau ◽  
Vander Kaufmann ◽  
Heinz Borg
Keyword(s):  
Time Delay ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
High Precision ◽  
Soil Profile ◽  
Reliable Data ◽  
Short Term ◽  
True Values ◽  
Daily Changes

ABSTRACT TDR-probes are widely used to monitor water content changes in a soil profile (ΔW). Frequently, probes are placed at just three depths. This raises the question how well such a setup can trace the true ΔW. To answer it we used a 2 m deep high precision weighing lysimeter in which TDR-probes are installed horizontally at 20, 60 and 120 cm depth (one per depth). ΔW-data collected by weighing the lysimeter vessel were taken as the true values to which ΔW-data determined with the TDR-probes were compared. We obtained the following results: There is a time delay in the response of the TDR-probes to precipitation, evaporation, transpiration or drainage, because a wetting or drying front must first reach them. Also, the TDR-data are more or less point measurements which are then extrapolated to a larger soil volume. This frequently leads to errors. For these reasons TDR-probes at just three depths cannot provide reliable data on short term (e.g. daily) changes in soil water content due to the above processes. For longer periods (e.g. a week) the data are better, but still not accurate enough for serious scientific studies.

Response of wheat to single short-term waterlogging during and after stem elongation

1988 ◽  
Vol 39 (1) ◽  
pp. 11 ◽  
Author(s):  
WS Meyer ◽  
HD Barrs
Keyword(s):  
Grain Yield ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Root Length ◽  
Stem Elongation ◽  
Stem Growth ◽  
Yield Reduction ◽  
Growth Stages ◽  
Short Term

Transient waterlogging associated with spring irrigations on slowly draining soils causes yield reduction in irrigated wheat. Physiological responses to short-term flooding are not well understood. The aim of this experiment was to monitor above- and below-ground responses of wheat to single waterlogging events during and after stem elongation and to assess the sensitivity of the crop at these growth stages to flooding. Wheat (cv. Bindawarra) was grown in drainage lysimeters of undisturbed cores of Marah clay loam soil. A control treatment (F0) was well-watered throughout the season without surface flooding, while three others were flooded for 96 h at stem elongation (Fl), flag leaf emergence (F2) and anthesis (F3), respectively. Soil water content, soil O2, root length density, leaf and stem growth, apparent photosynthesis (APS), plant nutrient status and grain yield were measured. Soil water content increased and soil O2 levels decreased following flooding; the rate of soil O2 depletion increasing with crop age and root length. Leaf and stem growth and APS increased immediately following flooding, the magnitude of the increases was in the order F1 >F2>F3. A similar order existed in the effect of flooding which decreased the number of roots. Subsequently, leaf and stem growth decreased below that of F0 plants in F1, and briefly in F2. Decreases in APS of treated plants compared to F0 plants appeared to be due to their greater sensitivity to soil water deficit. There was no effect of flooding on grain yield. It is suggested that, while plant sensitivity to flooding decreased with age, flooding at stem elongation had no lasting detrimental effect on yield when post-flood watering was well controlled.

Modelling leaching and recharge in a bare transitional red-brown earth ponded with low salinity water in summer

1994 ◽  
Vol 34 (7) ◽  
pp. 1085 ◽  
Author(s):  
L Cai ◽  
SA Prathapar ◽  
HG Beecher
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Profile ◽  
Soil Surface ◽  
Saturated Hydraulic Conductivity ◽  
Rate Dependent ◽  
Water And Salt Movement ◽  
Winter Fallow

A modelling study was conducted to evaluate water and salt movement within a transitional red-brown earth with saline B horizon soil when such waters are used for ponding in summer. The model was calibrated using previously published experimental data. The calibrated model was used to evaluate the effect of depth to watertable, saturated hydraulic conductivity, and ponding water salinity on infiltration, water and salt movement within the soil profile, and recharge. The study showed that when initial soil water content and the saturated hydraulic conductivity (Ks) are low, infiltrating water will be stored within the soil profile even in the absence of a shallow watertable. Once the soil water content is high, however, recharge will be significant in winter, even if there is no net infiltration at the soil surface. Infiltration rates depend more on Ks than the depth to watertable if it is at, or below, 1.5 m from the soil surface. When Ks is high, recharge under ponding will be higher than that under winter fallow. Subsequent ponding in summer and fallow in winter tend to leach salts from the soil profile, the leaching rate dependent on Ks. During winter fallow, due to net evaporation, salts tend to move upwards and concentrate near the soil surface. In the presence of shallow watertables, leached salts tend to concentrate at, or near, the watertable.

The impact of ski slopes management on Krvavec ski resort (Slovenia) on hydrological functions of soils

Biologia ◽  
2009 ◽  
Vol 64 (3) ◽  
Author(s):  
Marina Pintar ◽  
Bostjan Mali ◽  
Hojka Kraigher
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Profile ◽  
Ski Resort ◽  
Ski Resorts ◽  
Upper Timberline ◽  
Profile Characteristics ◽  
Summer Time ◽  
The Impact

AbstractThe study was performed on the ski resort Krvavec, which is one of the most frequented ski resorts in Slovenia. The ski slopes serve as pastures for cattle during summer time and range from 1500 to 2000 m a.s.l., which is at or above the upper timberline. To offer a longer ski season and to profit snow better (either natural or artificial one) the slopes have been levelled and consequently the soil profile has been changed. Such altered soil profile characteristics strongly impact hydrological functions of soils.To study these impacts, five plots (20 × 20 m) have been chosen on the slopes with a different history: pasture without any amelioration work, a patch of forest in the ski resort without any ameliorations, and three plots with different intensity of amelioration.Dynamics of soil water content on each plot has been determined by measuring soil water content in-situ with portable TDR system during several days after long lasting heavy rains. Statistically significant differences were shown in soil water content between the plots after the rain, although some differences between plots have disappeared in the following days.

scholarly journals Impacts of grass removal on wetting and actual water repellency in a sandy soil

2017 ◽  
Vol 65 (1) ◽  
pp. 88-98 ◽  
Author(s):  
Klaas Oostindie ◽  
Louis W. Dekker ◽  
Jan G. Wesseling ◽  
Violette Geissen ◽  
Coen J. Ritsema
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Profile ◽  
Water Repellency ◽  
Bare Soil ◽  
Soil Profiles ◽  
The Impact ◽  
Water Contents ◽  
Soil Water Contents

Abstract Soil water content and actual water repellency were assessed for soil profiles at two sites in a bare and grasscovered plot of a sand pasture, to investigate the impact of the grass removal on both properties. The soil of the plots was sampled six times in vertical transects to a depth of 33 cm between 23 May and 7 October 2002. On each sampling date the soil water contents were measured and the persistence of actual water repellency was determined of field-moist samples. Considerably higher soil water contents were found in the bare versus the grass-covered plots. These alterations are caused by differences between evaporation and transpiration rates across the plots. Noteworthy are the often excessive differences in soil water content at depths of 10 to 30 cm between the bare and grass-covered plots. These differences are a consequence of water uptake by the roots in the grass-covered plots. The water storage in the upper 19 cm of the bare soil was at least two times greater than in the grass-covered soil during dry periods. A major part of the soil profile in the grass-covered plots exhibited extreme water repellency to a depth of 19 cm on all sampling dates, while the soil profile of the bare plots was completely wettable on eight of the twelve sampling dates. Significant differences in persistence of actual water repellency were found between the grass-covered and bare plots.

scholarly journals Changes to soil water content and biomass yield under combined maize and maize-weed vegetation with different fertilization treatments in loam soil

2016 ◽  
Vol 64 (2) ◽  
pp. 150-159 ◽  
Author(s):  
Éva Lehoczky ◽  
Mariann Kamuti ◽  
Nikolett Mazsu ◽  
Renáta Sándor
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Profile ◽  
Field Experiments ◽  
Developmental Stages ◽  
Early Stage ◽  
Crop Growth ◽  
Long Term Study ◽  
Loam Soil

AbstractEspecially during early developmental stages, competition with weeds can reduce crop growth and have a serious effect on productivity. Here, the effects of interactions between soil water content (SWC), nutrient availability, and competition from weeds on early stage crop growth were investigated, to better understand this problem. Field experiments were conducted in 2013 and 2014 using long-term study plots on loam soil in Hungary. Plots of maize (Zea maysL.) and a weed-maize combination were exposed to five fertilization treatments. SWC was observed along the 0–80 cm depth soil profile and harvested aboveground biomass (HAB) was measured.Significant differences were found between SWC in maize and maize-weed plots. In all treatments, measured SWC was most variable in soil depths of up to 50 cm, and at the 8–10 leaves (BBCH19) growth stage of the crop. The greatest depletion of SWC was detected within PK treatments across the entire soil profile and under both vegetation types, with depletion also considerable under NPK and NP treatments. Biomass growth was significantly influenced by weeds in treated plots between the BBCH 13 and 19 phenological stages, but water availability did not hamper growth rates in non-fertilized conditions. These findings suggest that, at early stages of crop growth, SWC model simulations need to include better characterisation of depth- and structure-dependent soil water uptake by vegetation.

scholarly journals Optimizing the Positioning of Soil Moisture Monitoring Sensors in Winter Wheat Fields

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1707
Author(s):  
Xiaojun Shen ◽  
Jing Liang ◽  
Ketema Zeleke ◽  
Yueping Liang ◽  
Guangshuai Wang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Winter Wheat ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Profile ◽  
Root Distribution ◽  
Soil Surface ◽  
Soil Moisture Sensors ◽  
Total Average

Collecting accurate real-time soil moisture data in crop root zones is the foundation of automated precision irrigation systems. Soil moisture sensors (SMSs) have been used to monitor soil water content (SWC) in crop fields for a long time; however, there is no generally accepted guideline for determining optimal number and placement of soil moisture sensors in the soil profile. In order to study adequate positioning for the installation of soil moisture sensors in the soil profile, six years of field experiments were carried out in North China Plain (NCP). Soil water content was measured using the gravimetric method every 7 to 10 days during six growing seasons of winter wheat (Triticum aestivum L), and root distribution was measured using a soil core method during the key periods of winter wheat growth. The results from the experimental data analysis show that SWC at different depths had a high linear correlation. In addition, the values of correlation coefficients decreased with increasing soil depth; the coefficient of variation (CV) of SWC was higher in the surface layers than in the deeper layers (depths were 0–40 cm, 0–60 cm, and 0–100 cm during the early, middle, and last stages of winter wheat, respectively); wheat roots were mainly distributed in the surface layer. According to an analysis of CV for SWC and root distribution, the depths of planned wetted layers were determined to be 0–40 cm, 0–60 cm, and 0–100 cm during the sowing to reviving stages (the early stage of winter wheat), returning green and jointing stages (the middle stage of winter wheat), and heading to maturity stage (the last stage of winter wheat), respectively. The correlation and R-cluster analyses of SWC at different layers in the soil profile showed that SMSs should be installed 10 and 30 cm below the soil surface during the winter wheat growing season. The linear regression model can be built using SWC at depths of 10 and 30 cm to predict total average SWC in the soil profile. The results of validation showed that the developed model provided reliable estimates of total average SWC in the planned wetted layer. In brief, this study suggests that suitable positioning of soil moisture sensors is at depths of 10 and 30 cm below the soil surface.

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