scholarly journals Estimating Seasonal Changes in Volumetric Soil Water Content at Landscape Scales in a Savanna Ecosystem Using Two-Dimensional Resistivity Profiling

2008 ◽  
Vol 12 (2) ◽  
pp. 1-25 ◽  
Author(s):  
Diana C. Garcia-Montiel ◽  
Michael T. Coe ◽  
Meyr P. Cruz ◽  
Joice N. Ferreira ◽  
Euzebio M. da Silva ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Depth ◽  
Dry Season ◽  
Ecosystem Structure ◽  
Two Dimensional ◽  
Wet Season ◽  
Short Period ◽  
2D Resistivity

Abstract Water distributed in deep soil reservoirs is an important factor determining the ecosystem structure of water-limited environments, such as the seasonal tropical savannas of South America. In this study a two-dimensional (2D) geoelectrical profiling technique was employed to estimate seasonal dynamics of soil water content to 10-m depth along transects of 275 m in savanna vegetation during the period between 2002 and 2006. Methods were developed to convert resistivity values along these 2D resistivity profiles into volumetric water content (VWC) by soil depth. The 2D resistivity profiles revealed the following soil and aquifer structure characterizing the underground environment: 0–4 m of permanently unsaturated and seasonally droughty soil, less severely dry unsaturated soil at about 4–7 m, nearly permanently saturated soil between 7 and 10 m, mostly impermeable saprolite interspaced with fresh bedrock of parent material at about 10–30 m, and a region of highly conductive water-saturated material at 30 m and below. Considerable spatial variation of these relative depths is clearly demonstrated along the transects. Temporal dynamics in VWC indicate that the active zone of water uptake is predominantly at 0–7 m, and follows the seasonal cycles of precipitation and evapotranspiration. Uptake from below 7 m may have been critical for a short period near the beginning of the rainy season, although the seasonal variations in VWC in the 7–10-m layer are relatively small and lag the surface water recharge for about 6 months. Calculations using a simple 1-box water balance model indicate that average total runoff was 15–25 mm month−1 in the wet season and about 6–9 mm month−1 in the dry season. Modeled ET was about 75–85 mm month−1 in the wet season and 20–25 mm month−1 in the dry season. Variation in basal area and tree density along one transect was positively correlated with VWC of the 0–3-m and 0–7-m soil depths, respectively, during the wettest months. These multitemporal measurements demonstrate that the along-transect spatial differences in soil moisture are quasi-permanent and influence vegetation structure at the scale of tens to hundreds of meters.

scholarly journals SURFACE RESIDUES: EFFECTS ON SOIL MOISTURE AND TEMPERATURE1

2021 ◽  
Vol 34 (4) ◽  
pp. 887-894
Author(s):  
GUSTAVO HADDAD SOUZA VIEIRA ◽  
ARILDO SEBASTIÃO SILVA ◽  
ARUN DILIPKUMAR JANI ◽  
LUSINERIO PREZOTTI ◽  
PAOLA ALFONSA VIEIRA LO MONACO
Keyword(s):  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Depth ◽  
Block Design ◽  
Soil Disturbance ◽  
Dry Season ◽  
Depth Range ◽  
Sunn Hemp

ABSTRACT This study aimed to determine how crop residue placement and composition would affect soil water content and temperature during the dry season in the central region of Espírito Santo state, Brazil. A 19-week field study was conducted from April to August 2017. A 2 x 4 factorial study with four replications was implemented using a randomized complete block design. Factors were soil management [conventional tillage (CT) and no soil disturbance (ND)] and residue amendment [maize (Zea mays L.), sunn hemp (Crotalaria juncea L.), a maize-sunn hemp mixture, and a no amendment control]. Soil water content and temperature were measured weekly at predetermined soil depth intervals. Soil water content was higher in ND plots amended with surface residues than under all other treatments in the 0 to 0.05 m depth range. All residue amendments in this range were equally effective in conserving soil water. Surface residues reduced soil temperature by up to 8.4 °C relative to the control in ND plots. Incorporating residue amendments by CT cancelled all temperature-moderating benefits provided by surface residues. These results indicate that surface residues from cereals, legumes, or cereal/legume mixtures are equally effective in conserving soil water and moderating soil temperature during the dry season. Additional research is needed to determine how improved soil environmental conditions, generated by surface residues, would affect nutrient acquisition and crop performance.

The Ecology of the Puparium of Glossina in Northern Nigeria

1939 ◽  
Vol 30 (2) ◽  
pp. 259-284 ◽  
Author(s):  
T. A. M. Nash
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Adult Population ◽  
Dry Season ◽  
Breeding Ground ◽  
Wet Season ◽  
Breeding Grounds ◽  
Open Woodland ◽  
Forest Islands

1. The female tsetse extrudes her larva on soils ranging from fairly heavy clay to coarse sand; the presence or absence of organic matter seems to be immaterial.2. The soil temperature varies greatly in different breeding-grounds in the dry season, but little in the rains.3. The soil water content varies greatly in different breeding-grounds in the rains, but little in the dry season.4. The soil water content in some of the breeding-grounds falls so low in the dry season that there can be no doubt that the atmosphere in these soils is below saturation.5. Evaporation measured at 5 inches above ground-level varies little from site to site; bigger and important differences occur at greater heights above the ground where the screening effects of thicket become operative.6. The seasonal changes are so great at Gadau that no one breeding-ground can satisfy the female's requirements throughout the year; instead, different breeding-places are selected for different seasons.7. The cycle for G. morsitans is as follows: In the rains breeding occurs under palm fronds and logs in the open woodland. In the early dry season breeding continues in the open woodland, but shifts from the palm and log sites to the small thickets; breeding also starts in the more open parts of the forest islands. At the beginning of the very hot weather all the thickets of the open woodland are evacuated, and breeding is confined to the densest parts of the forest islands. In the early rains the movement is reversed: breeding shifts out into the open woodland, and in the heavy rains is confined to the log and palm sites.This cycle fits in closely with the cycle for the seasonal concentration and dispersal of the adult population (Nash 1937, pp. 85–90).8. The major wet season breeding-ground of G. tachinoides is unknown, but the cycle is believed to be as follows: In the early dry season breeding shifts from the log, palm, and probably from the unknown site, to the small thickets and forest islands, and becomes maximal in the cold season. Breeding now decreases in all sites, suggesting that none is really suitable—a surmise which is strengthened when tremendous breeding activity starts in the river-bed, as soon as it becomes available at the beginning of the hot season. In the early rains this site is destroyed and breeding is believed to commence in the unknown site, as it certainly does under the logs and palms.

scholarly journals Variations in Soil Water Content, Infiltration and Potential Recharge at Three Sites in a Mediterranean Mountainous Region of Baja California, Mexico

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1844 ◽  
Author(s):  
Francisco Del Toro-Guerrero ◽  
Enrique Vivoni ◽  
Thomas Kretzschmar ◽  
Stephen Bullock Runquist ◽  
Rogelio Vázquez-González
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Profile ◽  
Baja California ◽  
Soil Depth ◽  
Critical Role ◽  
Soil Conditions ◽  
Wet Season ◽  
Potential Recharge

In this research, we examined temporal variations in soil water content (θ), infiltration patterns, and potential recharge at three sites with different mountain block positions in a semiarid Mediterranean climate in Baja California, Mexico: two located on opposing aspects (south- (SFS) and north-facing slopes (NFS)) and one located in a flat valley. At each site, we measured daily θ between 0.1 and 1 m depths from May 2014 to September 2016 in four hydrological seasons: wet season (winter), dry season (summer) and two transition seasons. The temporal evolution of θ and soil water storage (SWS) shows a strong variability that is associated mainly with high precipitation (P) pulses and soil profile depth at hillslope sites. Results shows that during high-intensity P events sites with opposing aspects reveal an increase of θ at the soil–bedrock interface suggesting lateral subsurface fluxes, while vertical soil infiltration decreases noticeably, signifying the production of surface runoff. We found that the dry soil conditions are reset annually at hillslope sites, and water is not available until the next wet season. Potential recharge occurred only in the winter season with P events greater than 50 mm/month at the SFS site and greater than 120 mm/month at the NFS site, indicating that soil depth and lack of vegetation cover play a critical role in the transport water towards the soil–bedrock interface. We also calculate that, on average, around 9.5% (~34.5 mm) of the accumulated precipitation may contribute to the recharge of the aquifer at the hillslope sites. Information about θ in a mountain block is essential for describing the dynamics and movement of water into the thin soil profile and its relation to potential groundwater recharge.

Spatial and temporal variation in soil respiration in a seasonally dry tropical forest, Thailand

2009 ◽  
Vol 25 (5) ◽  
pp. 531-539 ◽  
Author(s):  
Minaco Adachi ◽  
Atsushi Ishida ◽  
Sarayudh Bunyavejchewin ◽  
Toshinori Okuda ◽  
Hiroshi Koizumi
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Diurnal Variation ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Respiration Rate ◽  
Dry Season ◽  
Wet Season ◽  
Soil Respiration Rate

Abstract:Spatial and seasonal variation in soil respiration rates were investigated in a tropical dry forest in Thailand. The spatial variation was examined at 50 points within a 2-ha plot in the forest floor during the dry and wet seasons. The seasonal and diurnal variations in soil respiration were measured at 16 and 5 points, respectively. The mean soil respiration rate during the wet season was 1041 ± 542 mg CO2 m−2 h−1 (mean ± SD), which is about twice that during the dry season. Soil respiration rate was negatively correlated with soil water content during the wet season. A polynomial equation using seasonal data describes soil respiration and water content: soil respiration rate increased with soil water content, but started to drop when soil water content exceeded 21%. The diurnal variation in soil respiration rate during the wet season was positively correlated with soil temperature, whereas during the wet season it was not correlated with soil temperature. The diurnal variation in soil respiration rate during the dry season showed a midday depression. The estimation of soil carbon flux with polynomial equations should incorporate different functions for the wet and dry seasons in tropical dry forests.

scholarly journals Effects of different biomass materials as a salt-isolation layer on water and salt migration in coastal saline soil

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11766
Author(s):  
Mao Yang ◽  
Runya Yang ◽  
Yanni Li ◽  
Yinghua Pan ◽  
Junna Sun ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Salt Concentration ◽  
Saline Soil ◽  
Soil Depth ◽  
Soil Layer ◽  
Thick Layer ◽  
Peat Layer ◽  
Salt Accumulation

The aim of this study was to find a material suited for the prevention of evaporative water loss and salt accumulation in coastal saline soils. One-dimensional vertical water infiltration and phreatic evaporation experiments were conducted using a silty loam saline soil. A 3-cm-thick layer of corn straw, biochar, and peat was buried at the soil depth of 20 cm, and a 6-cm-thick layer of peat was also buried at the same soil depth for comparison. The presence of the biochar layer increased the upper soil water content, but its ability to inhibit salt accumulation was poor, leading to a high salt concentration in the surface soil. The 3-cm-thick straw and 6-cm-thick peat layers were most effective to inhibit salt accumulation, which reduced the upper soil salt concentration by 96% and 93%, respectively. However, the straw layer strongly inhibited phreatic evaporation and resulted in low water content in the upper soil layer. Compared with the straw layer, the peat layer increased the upper soil water content. Thus, burying a 6-cm-thick peat layer in the coastal saline soil is the optimal strategy to retain water in the upper soil layer and intercept salt in the deeper soil layer.

scholarly journals Relationship between Very Fine Root Distribution and Soil Water Content in Pre- and Post-Harvest Areas of Two Coniferous Tree Species

Forests ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1227
Author(s):  
Moein Farahnak ◽  
Keiji Mitsuyasu ◽  
Takuo Hishi ◽  
Ayumi Katayama ◽  
Masaaki Chiwa ◽  
...  
Keyword(s):  
Water Content ◽  
Root System ◽  
Soil Water ◽  
Soil Water Content ◽  
Tree Species ◽  
Fine Roots ◽  
Fine Root ◽  
Soil Depth ◽  
Tree Cutting ◽  
Coniferous Tree Species

Tree root system development alters forest soil properties, and differences in root diameter frequency and root length per soil volume reflect differences in root system function. In this study, the relationship between vertical distribution of very fine root and soil water content was investigated in intact tree and cut tree areas. The vertical distribution of root density with different diameter classes (very fine <0.5 mm and fine 0.5–2.0 mm) and soil water content were examined along a slope with two coniferous tree species, Cryptomeria japonica (L.f.) D. Don and Chamaecyparis obtusa (Siebold et Zucc.) Endl. The root biomass and length density of very fine roots at soil depth of 0–5 cm were higher in the Ch. obtusa intact tree plot than in the Cr. japonica intact plot. Tree cutting caused a reduction in the biomass and length of very fine roots at 0–5 cm soil depth, and an increment in soil water content at 5–30 cm soil depth of the Ch. obtusa cut tree plot one year after cutting. However, very fine root density of the Cr. japonica intact tree plot was quite low and the soil water content in post-harvest areas did not change. The increase in soil water content at 5–30 cm soil depth of the Ch. obtusa cut tree plot could be caused by the decrease in very fine roots at 0–5 cm soil depth. These results suggest that the distribution of soil water content was changed after tree cutting of Ch. obtusa by the channels generated by the decay of very fine roots. It was also shown that differences in root system characteristics among different tree species affect soil water properties after cutting.

The effect of chisel ploughing and inter-row cultivation on soil water content and yield of bulrush millet (Pennisetum typhoides) at Katherine, N.T

1966 ◽  
Vol 6 (20) ◽  
pp. 48
Author(s):  
LJ Phillips ◽  
MJT Norman
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Dry Matter ◽  
Dry Matter Yield ◽  
Wet Season ◽  
Pennisetum Typhoides ◽  
Nitrogen Yield ◽  
Multifactorial Experiment

A multifactorial experiment comprising combinations of three pre-wet-season chisel ploughing treatments, three wet-season chisel ploughing treatments, and three inter-row cultivation treatments was carried out on bulrush millet (Pennisetum typhoides S. & H.) at Katherine, N.T., in 1963-64, and was repeated in 1964-65. Pre-wet-season ploughing throughout the growth of the nitrogen yield of millet when treatments had very little effect on the dry matter or nitrogen yield of millet crop. Increasing the depth of wet-season ploughing increased the dry matter and sampled at 7 and 12 weeks after sowing, but at the final sampling, 18 weeks after sowing, only the differences in dry matter yield were maintained. Responses in dry matter and nitrogen yield were obtained to one inter-row cultivation, but not to a second. Differences in dry matter yield due to wetseason ploughing and inter-row cultivation were associated with differences in soil water content measured in the 1-4 feet profile in 1964-65.

Temporal and spatial variation of surface soil water content on karst slopes in dry season

2015 ◽  
Vol 35 (19) ◽  
Author(s):  
张川 Zhang Chuan ◽  
张伟 Zhang Wei ◽  
陈洪松 Chen Hongsong ◽  
聂云鹏 Nie Yunpeng ◽  
叶莹莹 Ye yingying ◽  
...  
Keyword(s):  
Spatial Variation ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Surface Soil ◽  
Dry Season ◽  
Temporal And Spatial Variation ◽  
Temporal And Spatial

Root length density and soil water distribution in drip-irrigated olive orchards in Argentina under arid conditions

2009 ◽  
Vol 60 (3) ◽  
pp. 280 ◽  
Author(s):  
Peter S. Searles ◽  
Diego A. Saravia ◽  
M. Cecilia Rousseaux
Keyword(s):  
Water Content ◽  
Root System ◽  
Soil Water ◽  
Soil Water Content ◽  
Root Length ◽  
Root Length Density ◽  
Soil Depth ◽  
Drip Line ◽  
North West ◽  
Intensively Managed

Several studies have evaluated many above-ground aspects of olive production, but essential root system characteristics have been little examined. The objective of our study was to evaluate root length density (RLD) and root distribution relative to soil water content in three commercial orchards (north-west Argentina). Depending on the orchard, the different drip emitter arrangements included either: (1) emitters spaced continuously at 1-m intervals along the drip line (CE-4; 4 emitters per tree); (2) 4 emitters per tree spaced at 1-m intervals, but with a space of 2 m between emitters of neighbouring trees (E-4); or (3) 2 emitters per tree with 4 m between emitters of neighbouring trees (E-2). All of the orchards included either var. Manzanilla fina or Manzanilla reina trees (5–8 years old) growing in sandy soils, although the specific characteristics of each orchard differed. Root length density values (2.5–3.5 cm/cm3) in the upper soil depth (0–0.5 m) were fairly uniform along the drip line in the continuous emitter (CE-4) orchard. In contrast, roots were more concentrated in the E-4 and E-2 orchards, in some cases with maximum RLD values of up to 7 cm/cm3. Approximately 70% of the root system was located in the upper 0.5 m of soil depth, and most of the roots were within 0.5 m of the drip line. For each of the three orchards, significant linear relationships between soil water content and RLD were detected based on 42 sampling positions that included various distances from the trunk and soil depths. Values of RLD averaged over the entire rooting zone and total tree root length per leaf area for the three orchards were estimated to range from 0.19 to 0.48 cm/cm3 and from 1.8 to 3.5 km/m2, respectively. These results should reduce the uncertainty associated with the magnitude of RLD values under drip irrigation as intensively managed olive orchards continue to expand in established and new growing regions.

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