Development of a soil water dispersion index (SOWADIN) for testing the effectiveness of soil-wetting agents

Soil Research ◽  
1989 ◽  
Vol 27 (1) ◽  
pp. 17 ◽  
Author(s):  
Y Sawada ◽  
LAG Aylmore ◽  
JM Hainsworth
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Water Distribution ◽  
Soil Column ◽  
Water Repellent ◽  
Computer Assisted ◽  
Dispersion Index ◽  
Soil Columns ◽  
Water Dispersion ◽  
Soil Wetting

Computer-assisted tomography (CAT) applied to gamma-ray attenuation measurements has been used to develop an index termed the soil water dispersion index (SOWADIN), which describes quantitatively the amount and distribution of water in soil columns. The index, which is determined by classifying pixels in a scanned slice into three categories according to their attenuation coefficients, contains two numerical values. The first value corresponds to the water content of the scanned slice and the second value is a measure of the dispersion of the water throughout the slice. Artificially wetted zones were created in soil columns to give one-third of the scanned layer wetted with various patterns of wetted-area distribution. The SOWADIN values obtained accurately reflected the differences in water distribution associated with the different patterns. Application of SOWADIN to columns of a water-repellent sand before and after treatment with a soil-wetting agent clearly illustrates both the increase in water content and improvement in water distribution in the soil column following treatment.

A note on the methods for determining soil water diffusivity

Soil Research ◽  
1982 ◽  
Vol 20 (1) ◽  
pp. 61
Author(s):  
HS Acharya
Keyword(s):  
Quadratic Programming ◽  
Soil Water ◽  
Water Distribution ◽  
Soil Column ◽  
Experimental Methods ◽  
Soil Columns ◽  
Method Of Calculation ◽  
Water Diffusivity ◽  
Horizontal Infiltration

In experimental methods for determination of soil water diffusivity using the water distribution from horizontal infiltration into a soil column, hand smoothing of the experimentally obtained distribution introduces uncertainties in the calculations. A method of calculation involving techniques of quadratic programming has been used to minimize the possible errors caused by inhomogeneous packing of the horizontal soil columns. Examples are given to illustrate the method of calculations.

scholarly journals Spatially variable soil water repellency enhances soil respiration rates (CO<sub>2</sub> efflux)

2017 ◽  
Author(s):  
Emilia Urbanek ◽  
Stefan H. Doerr
Keyword(s):  
Soil Moisture ◽  
Soil Respiration ◽  
Soil Water ◽  
Water Distribution ◽  
Preferential Flow ◽  
Water Repellency ◽  
Water Repellent ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Soil Water Repellency

Abstract. Soil CO2 emissions are strongly dependent on water distribution in soil pores, which in turn can be affected by soil water repellency (SWR; hydrophobicity). SWR restricts infiltration and movement of water, affecting soil hydrology as well as biological and chemical processes. Effects of SWR on soil carbon dynamics and specifically on soil respiration (CO2 efflux) have been studied in a few laboratory experiments but they remain poorly understood. Existing studies suggest that soil respiration is reduced in water repellent soils, but the responses of soil CO2 efflux to varying water distribution created by SWR are not yet known. Here we report on the first field-based study that tests whether soil water repellency indeed reduces soil respiration, based on in situ field measurements carried out over three consecutive years at a grassland and pine forest site under the humid temperate climate of the UK. CO2 efflux was reduced on occasions when soil exhibited consistently high SWR and low soil moisture following long dry spells. However, the highest respiration rates occurred not when SWR was absent, but when SWR, and thus soil moisture, was spatially patchy, a pattern observed for the majority of the measurement period. This somewhat surprising phenomenon can be explained by SWR-induced preferential flow, directing water and nutrients to microorganisms decomposing organic matter concentrated in hot spots near preferential flow paths. Water repellent zones provide air-filled pathways through the soil, which facilitate soil-atmosphere O2 and CO2 exchanges. This study demonstrates that SWR have contrasting effects on CO2 fluxes and, when spatially-variable, can enhance CO2 efflux. Spatial variability in SWR and associated soil moisture distribution needs to be considered when evaluating the effects of SWR on soil carbon dynamics under current and predicted future climatic conditions.

scholarly journals The effect of a prototype hydromulch on soil water evaporation under controlled laboratory conditions

2020 ◽  
Vol 68 (4) ◽  
pp. 404-410
Author(s):  
Antoni M.C. Verdú ◽  
M. Teresa Mas ◽  
Ramon Josa ◽  
Marta Ginovart
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Course ◽  
Linear Models ◽  
Water Evaporation ◽  
Mechanical Resistance ◽  
Evaporation Process ◽  
Soil Columns ◽  
Dry Conditions

AbstractOrganic hydromulches can be an interesting alternative for weed control in perennial crops, but can also reduce soil water evaporation. To examine the effect of a hydromulch layer on soil water content in dry conditions laboratory experiments were conducted at constant 25°C, 40% air RH. Both for small soil containers with a short time course and for larger soil columns (with two sensors at depths of 6 cm and 11 cm) with a longer time course, the presence and also the thickness of hydromulch were significant factors for the temporal evolution of soil water content. Two distinct stages of the evaporation process, the first or initial stage and the last or final stage, were identified, analysed and compared for these experiments. General linear models performed on the soil water content temporal evolutions showed significant differences for the first and last stages at the top and bottom of the soil columns with and without hydromulch. Hydromulch application delayed the evaporation process in comparison with the control. Moreover, the hydromulch layer, which was tested for mechanical resistance to punching, offered enough resistance to prevent its perforation by the sprouts of weed rhizomes.

Mobility of a Polyether Trisiloxane Surfactant in Soil: Soil/Water Distribution Coefficients and Leaching in a Soil Column

2016 ◽  
Vol 227 (2) ◽  
Author(s):  
Amandine Michel ◽  
Conrad Dietschweiler ◽  
Martina Böni ◽  
Michael Burkhardt ◽  
Heinz-Jürgen Brauch ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Distribution ◽  
Soil Column ◽  
Distribution Coefficients ◽  
Soil Water Distribution

scholarly journals Monitoring of Soil Water Content in Maize Rotated with Pigeonpea Fallows in South Africa

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2761
Author(s):  
Misheck Musokwa ◽  
Paramu L. Mafongoya ◽  
Paxie W. Chirwa
Keyword(s):  
South Africa ◽  
Water Content ◽  
Soil Water ◽  
Water Distribution ◽  
Smallholder Farmers ◽  
Block Design ◽  
Maize Production ◽  
Soil Water Tension ◽  
Continuous Maize ◽  
Water Tension

Maize production under smallholder systems in South Africa (RSA) depends on rainfall. Incidences of dry spells throughout the growing season have affected maize yields negatively. The study examined water distribution and water use efficiency (WUE) of maize rotated with two-year pigeonpea fallows as compared to continuous maize without fertilizer. A randomized complete block design, replicated three times, was used with four treatments, which included continuous unfertilized maize, natural fallow-maize, pigeonpea + grass-pigeonpea-maize, and two-year pigeonpea fallow-maize. Soil water mark sensors were installed 0.2; 0.5; and 1.2 m on each plot to monitor soil water tension (kPa). Soil samples were analyzed using pressure plates to determine water retention curves which were used to convert soil water tension to volumetric water content. Maize rotated with two-year pigeonpea fallows had higher dry matter yield (11,661 kg ha−1) and WUE (20.78 kg mm−1) than continuous maize (5314 kg ha−1 and 9.48 kg mm−1). In this era of water scarcity and drought incidences caused by climate change, maize rotated with pigeonpea fallows is recommended among smallholder farmers in RSA because of its higher WUE, hence food security will be guaranteed.

An assessment of soil moisture in the MARINE flash flood model using in situ measurements, reanalysis and satellite derived estimates

2020 ◽  
Author(s):  
Judith Eeckman ◽  
Hélène Roux ◽  
Bertrand Bonan ◽  
Clément Albergel ◽  
Audrey Douniot
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Model Calibration ◽  
Flash Flood ◽  
Soil Column ◽  
Subsurface Flow ◽  
Soil Layer ◽  
Observation Network

&lt;p&gt;The representation of soil moisture is a key factor for the simulation of flash flood in the Mediterranean region. The MARINE hydrological model is a distributed model dedicaded to flash flood simulation. Recent developments of the MARINE model lead to an improvement of the subsurface flow representation : on the one hand, the transfers through the subsurface take place in a homogeneous soil column based on the volumic soil water content instead of the water height. On the other hand, the soil column is divided into two layers, which represent respectively the upper soil layer and the deep weathered rocks. The aim of this work is to assess the performances of these new representations of the subsurface flow with respect to the soil saturation dynamics during flash flood events. The performances of the model are estimated with respect to three soil moisture products: i) the gridded soil moisture product provided by the LDAS-Monde assimilation chain. LDAS-Monde is based on the ISBA-a-gs land surface model and integrates high resolution spatial remote sensing data from the Copernicus Global Land Service for vegetation through data assimilation; ii) the upper soil moisture measurements taken from the SMOSMANIA observation network&amp;#160;; iii) The satellite derived surface soil moisture data from Sentinel1. The case study is led over two french mediterranean catchments impacted by flash flood events over the 2017-2019 period and where one SMOSMANIA station is available. Additionnal tests for the initialisation of MARINE water content for the two soil layers are assessed. Results show first that the dynamic of the soil moisture both provided by LDAS-Monde and simulated for the upper soil layer in MARINE are locally consistent with the SMOSMANIA observations. Secondly, the use of soil water content instead of water height to describe lateral flows in MARINE is cleary more relevant with respect to both LDAS-Monde simulations and SMOSMANIA stations. The dynamic of the deep layer moisture content also appears to be consistent with the LDAS-Monde product for deeper layers. However, the bias on these values strongly rely on the calibration of the new two-layers model. The opportunity of improving the two-layers model calibration is then discussed. Finally, the impact of the soil water content initialisation is shown to be significant mainly during the flood rising, and also to be dependent on the model calibration. In conclusion, the new developments presented for the representation of subsurface flow in the MARINE model appear to enhance the soil moisture simulation during flash floods, with respect to both the LDAS-Monde product and the SMOSMANIA observation network.&lt;/p&gt;

scholarly journals Water Distribution in Reconstructed Soil of Nonmetal Mines and the Ecological Effect in Xinjiang, China

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Zizhao Zhang ◽  
Xiaoli Guo ◽  
Qianli Lv ◽  
Ruihua Hao ◽  
Zezhou Guo ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Distribution ◽  
Land Reclamation ◽  
Observation System ◽  
Neutron Probe ◽  
Matrix Potential ◽  
The Law ◽  
Reconstructed Soil

Because of the arid climate and fragile ecological environment in Xinjiang, China, land reclamation should be carried out after mining. The core of land reclamation is the water content of the surface covering soil. In this paper, the law of water distribution in reclamation reconstructed soil of nonmetal mines in Xinjiang was studied. In order to obtain the law of water distribution in reconstructed soil, we set up an observation system of the neutron probe and tensiometer. The neutron probe was used to monitor the soil water content. The tensiometers were used to obtain the matrix potential of soil for verifying the water distribution in reconstructed soil. Volumetric water content and matrix potential of reconstructed soil during 1-year period of management and irrigation were obtained by long-term monitoring. After one year’s field in situ test, 2424 sets of neutron probe data and 1368 sets of tensiometer data were obtained. By studying the above parameters, we summarized the law of water distribution in reconstructed soil of variable thickness and degree of compaction with nonmetallic waste rock filling. The results showed that covering soil was helpful to retain water content. Whether the soil was compacted or uncompacted, the soil water content at the depth of 10 cm was less than that at other depth of reconstructed soil because it was greatly affected by meteorological factors. The water content of reconstructed soil at 30 cm depth was greater than that at other depths. Under the influence of factors such as the thickness and compaction of the soil, the response time of soil water content and matrix potential to each irrigation infiltration was different. According to the characteristics of reclamation-vegetation such as alfalfa growth in Xinjiang, the thickness of surface reconstructed soil should be not less than 50 cm. Over time, soil that was compacted once was better for the vegetation. The research results could provide a reference for the land reclamation of nonmetallic mines in Xinjiang, China.

scholarly journals Measuring Soil Water Content under Turfgrass Using the Dual-probe Heat-pulse Technique

1998 ◽  
Vol 123 (5) ◽  
pp. 937-941 ◽  
Author(s):  
Y. Song ◽  
J.M. Ham ◽  
M.B. Kirkham ◽  
G.J. Kluitenberg
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Tall Fescue ◽  
Soil Column ◽  
Gravimetric Method ◽  
Soil Surface ◽  
Heat Pulse ◽  
Pulse Technique ◽  
Dual Probe

Measurements of soil water content near the soil surface often are required for efficient turfgrass water management. Experiments were conducted in a greenhouse to determine if the dual-probe heat-pulse (DPHP) technique can be used to monitor changes in soil volumetric water content (θv) and turfgrass water use. `Kentucky 31' Tall fescue (Festuca arundinacea Schreb.) was planted in 20-cm-diameter containers packed with Haynie sandy loam (coarse-silty, mixed, calcareous, mesic Typic Udifluvents). Water content was measured with the DPHP sensors that were placed horizontally at different depths between 1.5 and 14.4 cm from the surface in the soil column. Water content also was monitored gravimetrically from changes in container mass. Measurements started when the soil surface was covered completely by tall fescue. Hence, changes in θv could be attributed entirely to water being taken up by roots of tall fescue. Daily measurements were taken over multiple 6- or 7-day drying cycles. Each drying cycle was preceded by an irrigation, and free drainage had ceased before measurements were initiated. Soil water content dropped from ≈0.35 to 0.10 m3·m-3 during each drying cycle. Correlation was excellent between θv and changes in water content determined by the DPHP and gravimetric methods. Comparisons with the gravimetric method showed that the DPHP sensors could measure average container θv within 0.03 m3·m-3 and changes in soil water content within 0.01 m3·m-3.

scholarly journals Modelling Projected Changes in Soil Water Budget in Coastal Kenya under Different Long-Term Climate Change Scenarios

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2455
Author(s):  
Cornelius Okello ◽  
Nicolas Greggio ◽  
Beatrice Maria Sole Giambastiani ◽  
Nina Wambiji ◽  
Julius Nzeve ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Budget ◽  
Clay Soil ◽  
Soil Column ◽  
Climate Change Scenarios ◽  
Deep Percolation ◽  
Rcp 8.5

The possible impacts that climate change will have on soil water budget and specifically on deep percolation, runoff and soil water content have been investigated using HYDRUS, a methodology based on numerical modelling simulations of vertical water movement in a homogenous soil column on a flat surface. This study was carried out on four typical soil types occurring on the Kenyan coast and the adjacent hinterlands of up to an elevation of 200 m above sea level (m a.s.l.) covered by five weather stations (two dry and three wet stations). Results show that deep percolation and runoff are expected to be higher in 2100 for both Relative Concentration Pathways (RCPs) 2.6 and 8.5 scenarios than they were for the reference period (1986–2005). The average deep percolation is expected to increase by 14% for RCP 2.6 and 10% for the RCP 8.5, while the average runoff is expected to increase by 188% and 284% for the same scenarios. Soil water content is expected to either increase marginally or reduce depend in the same scenarios. The average soil water content is also expected to increase by 1% in the RCP 2.6 scenario and to decrease by 2% in the RCP 8.5 scenario. Increase in deep percolation through clay soil is expected to be the largest (29% in both scenarios), while sandy and sandy clay soil are expected to be the least influenced with an average increase of only 2%. Climate change is expected to impact runoff mostly in sandy soils, whereas the least affected would be clay loam soils. These results further support the assertion that the change in climate is expected to impact the recharge of aquifers by triggering an increase in infiltration under both scenarios.

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