Variation in matric potential at field capacity in stony soils of fluvial and alluvial fans

Three avenues of experimental observation detail aspects of plant available water holding capacity in compacted stone-soil media designed for urban tree establishment in paved situations. The various compacted media provided an estimated plant available moisture content of 7%–11% by volume, comparable to a loamy sand. Changes in aggregate and of soil influenced initial field capacity moisture content, but high matric potential moisture content was consistent, presumably as a reflection of the aggregate content of the designed system. A large portion of plant available moisture was weakly held in large voids, consistent with related infiltration and permeability data, and could be an influence in water storage and irrigation planning to use layers of designed soils in a layered pavement section for urban vegetation.

Download Full-text

euptfv2: updated hydraulic pedotransfer functions for Europe

10.5194/egusphere-egu21-904 ◽

2021 ◽

Author(s):

Brigitta Szabó ◽

Melanie Weynants ◽

Tobias Weber

Keyword(s):

Hydraulic Conductivity ◽

Soil Properties ◽

Water Content ◽

Hydraulic Properties ◽

Field Capacity ◽

Pedotransfer Functions ◽

Predictor Variables ◽

Soil Hydraulic Properties ◽

Matric Potential ◽

Soil Hydraulic

We present improved European hydraulic pedotransfer functions (PTFs) which now use the machine learning algorithm random forest and include prediction uncertainties. The new PTFs (euptfv2) are an update of the previously published euptfv1 (T&#243;th et al., 2015). With the derived hydraulic PTFs soil hydraulic properties and van Genuchten-Mualem model parameters can be predicted from easily available soil properties. The updated PTFs perform significantly better than euptfv1 and are applicable for 32 predictor variables combinations. The uncertainties reflect uncertainties from the considered input data, predictors and the applied algorithm. The euptfv2 includes transfer functions to compute soil water content at saturation (0 cm matric potential head), field capacity (both -100 and -330 cm matric potential head) and wilting point (-15,000 cm matric potential head), plant available water content computed with field capacity at -100 and -330 cm matric potential head, saturated hydraulic conductivity, and Mualem-van Genuchten parameters of the moisture retention and hydraulic conductivity curves. The influence of predictor variables on predicted soil hydraulic properties is explored and suggestions to best predictor variables given.The algorithms have been implemented in a web interface (https://ptfinterface.rissac.hu) and an R package (https://doi.org/10.5281/ZENODO.3759442) to facilitate the use of the PTFs, where the PTFs&#8217; selection is automated based on soil properties available for the predictions and required soil hydraulic property.The new PTFs will be applied to derive soil hydraulic properties for field- and catchment- scale hydrological modelling in European case studies of the OPTAIN project (https://www.optain.eu/). Functional evaluation of the PTFs is performed under the iAqueduct research project.&#160;This research has been supported by the Hungarian National Research, Development and Innovation Office (grant no. KH124765), the J&#225;nos Bolyai Research Scholarship of the Hungarian Academy of Sciences (grant no. BO/00088/18/4), and the German Research Foundation (grant no. SFB 1253/12017). OPTAIN is funded by the European Union&#8217;s Horizon 2020 Program for research and innovation under Grant Agreement No. 862756.

Download Full-text

Estimation of field capacity from ring infiltrometer-drainage data

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832014000600011 ◽

2014 ◽

Vol 38 (6) ◽

pp. 1765-1771 ◽

Cited By ~ 1

Author(s):

Theophilo Benedicto Ottoni Filho ◽

Marta Vasconcelos Ottoni ◽

Muriel Batista de Oliveira ◽

José Ronaldo de Macedo

Keyword(s):

Field Capacity ◽

Soil Science ◽

Matric Potential ◽

Volumetric Soil Water Content ◽

Double Ring ◽

Infiltration Test ◽

Drainage Data ◽

Volumetric Soil Water

Field capacity (FC) is a parameter widely used in applied soil science. However, its in situ method of determination may be difficult to apply, generally because of the need of large supplies of water at the test sites. Ottoni Filho et al. (2014) proposed a standardized procedure for field determination of FC and showed that such in situ FC can be estimated by a linear pedotransfer function (PTF) based on volumetric soil water content at the matric potential of -6 kPa [θ(6)] for the same soils used in the present study. The objective of this study was to use soil moisture data below a double ring infiltrometer measured 48 h after the end of the infiltration test in order to develop PTFs for standard in situ FC. We found that such ring FC data were an average of 0.03 m³ m- 3 greater than standard FC values. The linear PTF that was developed for the ring FC data based only on θ(6) was nearly as accurate as the equivalent PTF reported by Ottoni Filho et al. (2014), which was developed for the standard FC data. The root mean squared residues of FC determined from both PTFs were about 0.02 m³ m- 3. The proposed method has the advantage of estimating the soil in situ FC using the water applied in the infiltration test.

Download Full-text

Automation of irrigation by electronic tensiometry based on the arduino hardware platform

Ambiente e Agua - An Interdisciplinary Journal of Applied Science ◽

10.4136/ambi-agua.2567 ◽

2020 ◽

Vol 15 (4) ◽

pp. 1

Author(s):

Rodrigo Moura Pereira ◽

Delvio Sandri ◽

Gervásio Fernando Alves Rios ◽

Daniel Ataydes de Oliveira Sousa

Keyword(s):

Soil Water ◽

Irrigation System ◽

Soil Water Potential ◽

Field Capacity ◽

Matric Potential ◽

Pressure Transducers ◽

Automation Control ◽

Variation Tolerance ◽

And Control ◽

Plastic Containers

This study developed and evaluated an electronic irrigation system controlled by soil water matric potential. The controller uses tensiometers and pressure transducers as a reading mechanism, integrated with an Arduino microcontroller board that drives the solenoid valves and a 1/3 hp single-phase motor. Four electronic tensiometers were installed in plastic containers filled with 6 kg of Red-Yellow Latosol (RYL) with a clayey texture, and another four in plastic containers filled with 7 kg of Regolitic Neosol (RN) with a sandy texture. Irrigation automation components were activated autonomously at the critical potentials of -20, -25, -30, and -35 kPa for RYL, and -10, -15, -20, and -25 kPa for RN, with a 20% variation tolerance. The entire system is able to monitor and control irrigation based on soil water matric potential. Components were deactivated when the soil water potential reached the field capacity of each soil type. Irrigation automation performance was considered satisfactory, as it kept critical potentials within the pre-established thresholds in both soil types. Automation control was set for matric potentials between -10 kPa and -35 kPa in RYL, and between -5 kPa and -25 kPa in RN.

Download Full-text

Broom snakeweed (Gutierrezia sarothrae) dispersal, viability, and germination

Weed Science ◽

10.1017/s004317450009250x ◽

1997 ◽

Vol 45 (1) ◽

pp. 77-84 ◽

Cited By ~ 8

Author(s):

Ballard L. Wood ◽

Kirk C. McDaniel ◽

Dennis Clason

Keyword(s):

Seedling Survival ◽

Soil Surface ◽

Field Capacity ◽

Water Application ◽

Seedling Mortality ◽

Matric Potential ◽

Influence Of Water ◽

Gutierrezia Sarothrae ◽

Achene Production ◽

Water Amount

Broom snakeweed achene dispersal was monitored by placing surface-level traps outwards in the cardinal directions from 12 plants and collecting the achenes weekly or biweekly from September 1993 until seeds were no longer retained by the plants after 42 wk. About 50% of the achenes dispersed between October and December. Especially high numbers of achenes were dislodged during periods of intense winter winds and rains, with 78% of the seed placed into the east tray and 86% falling within 50 cm of the parent plant. Achene production averaged 3,928 (± 1,146) per plant in 1993 and 2,036 (± 987) per plant in 1994. Achenes collected over time directly from the inflorescence and achenes stored in nylon packets on the soil surface averaged 82% viability during fall and winter. Achene viability declined rapidly in late spring, and few remained viable before the next seed crop. Greenhouse experiments compared the influence of water application interval and water amount on broom snakeweed germination and seedling survival. Treatments consisted of 4 water intervals: daily, 5-d, 10-d, and 15-d intervals; and 4 water amounts: field capacity (1/1 fc), 3/4 fc, 1/2 fc, and 1/4 fc. Germination was 52% at daily 1/1 fc, and no seed germinated at daily 1/4 fc. Data suggest that optimum germination occurs when soils are maintained at a minimum soil matric potential (Ψm) > −180 kPa for at least 4 d. Optimum Ψm for seedling survival appears to range between −300 and −900 kPa, while seedling mortality would generally be expected with a Ψm of > −1800 kPa.

Download Full-text

DESEMPENHO DE SISTEMAS DE LEITURA DE TENSIÔMETRO EM CONDIÇÕES DE TEMPERATURA CONTROLADA

Irriga ◽

10.15809/irriga.2017v22n4p735-756 ◽

2017 ◽

Vol 22 (4) ◽

pp. 735-756

Author(s):

Josimar De Azevedo ◽

Alcione Guimarães Freire ◽

Thiago Leite de Alencar ◽

Carlos Levi Anastácio dos Santos ◽

Raimundo Nonato de Assis Júnior ◽

...

Keyword(s):

Soil Moisture ◽

Field Capacity ◽

Equilibration Time ◽

Matric Potential ◽

Vacuum Gauge ◽

Alternative Systems ◽

The Times ◽

Definition Of ◽

Water Tension ◽

E Mail

DESEMPENHO DE SISTEMAS DE LEITURA DE TENSIÔMETRO EM CONDIÇÕES DE TEMPERATURA CONTROLADA JOSIMAR DE AZEVEDO1; ALCIONE GUIMARÃES FREIRE1; THIAGO LEITE DE ALENCAR1; CARLOS LEVI ANASTÁCIO DOS SANTOS1; RAIMUNDO NONATO DE ASSIS JÚNIOR1; FRANCISCO MARCUS LIMA BEZERRA2 E JAEDSON CLÁUDIO ANUNCIATO MOTA1 *Artigo extraído da dissertação do primeiro autor.1Departamento de Ciências do Solo, Universidade Federal do Ceará, UFC, Av. Mister Hull, 2977, 60.021-970, Fortaleza, CE, Brasil. E-mail: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected] de Engenharia Agrícola, Universidade Federal do Ceará, UFC, Av. Mister Hull, 2977, 60.021-970, Fortaleza, CE, Brasil. E-mail: [email protected]. 1 RESUMO Objetivou-se aferir sistemas alternativos ao vacuômetro de mercúrio para a quantificação do potencial mátrico da água no solo, definir o tempo para reestabelecer o equilíbrio entre as tensões da água no interior do tensiômetro e no solo após a inserção da agulha do tensímetro no tensiômetro, e quantificar erros na determinação do potencial mátrico e da umidade a partir dos sistemas alternativos. O ensaio foi realizado em vasos, em laboratório, com três tensiômetros por vaso, seis repetições, nas profundidades de 0,20, 0,35 e 0,50 m. Definido o tempo de equilíbrio comparou-se o potencial mátrico e a umidade volumétrica nos três sistemas de leitura. Concluiu-se que a leitura do tensímetro pode ser realizada em quaisquer dos tempos desde 30 a 180 segundos; o tensímetro substitui o vacuômetro de mercúrio desde a saturação até a capacidade de campo, e o vacuômetro de Bourdon da condição na ou próxima à capacidade de campo até a situação mais seca; e os erros decorrentes dos sistemas alternativos se refletiram na estimativa da umidade do solo, com subestimativa dos valores a partir da capacidade de campo. Palavras-chave: Potencial mátrico, água no solo, irrigação. AZEVEDO, J.; FREIRE, A. G.; ALENCAR, T. L.; SANTOS, C. L. A.; ASSIS JÚNIOR, R. N.; BEZERRA, F. M. L.; MOTA, J. C. A.PERFORMANCE OF TENSIOMETER READING SYSTEMS UNDER CONTROLLED TEMPERATURE CONDITIONS 2 ABSTRACT The study aimed at assessing alternative systems to the mercury vacuum for quantification of water matric potential, to define the time for restoring the equilibrium between the water tension in the interior of the tensiometer, and in the soil after the insertion of the needle in the tensiometer, and to quantify errors in the determination of the water matric potential and the soil moisture from the alternative systems. The essay was carried out in pots in the laboratory. Three tensiometers were installed per pot, six replications, at depths of 0.20, 0.35 and 0.50 m. After the definition of the equilibration time, the matric potential and volumetric moisture were compared in the three systems. It was concluded that after the insertion of the needle of the tensiometer the reading can be performed in any of the times from 30 to 180 seconds; The tensiometer replaces the mercury vacuum gauge from saturation to field capacity and the Bourdon vacuum gauge from the condition at or near the field capacity to the driest condition; and the errors resulting from alternative systems were reflected in the estimation of the soil moisture whereas the alternative systems underestimated the values from the field capacity. Keywords: Matric potential, soil water, irrigation.

Download Full-text

Effects of the texture and organic matter values in the estimation of the soil water content at a regional scale

Cuadernos de Investigación Geográfica ◽

10.18172/cig.3484 ◽

2018 ◽

Vol 44 (2) ◽

pp. 697 ◽

Cited By ~ 1

Author(s):

P. Pérez-Cutillas ◽

G.G. Barberá ◽

C. Conesa-García

Keyword(s):

Organic Matter ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Hydraulic Properties ◽

Regional Scale ◽

Field Capacity ◽

Pedotransfer Functions ◽

Matric Potential ◽

Wilting Point

This study compares two methods for the estimation of hydraulic properties of the soil at the regional scale. Soil water content (θ) values was estimated at two fixed soil matric potential values), associated with the field capacity (θfc) and wilting point (θwp). The first method is carried out directly using (θ) values of analytical determinations, by modeling them as a function of environmental variables. The second method employed texture and organic matter (OM) information to obtain (θ) values by pedotransfer functions (PTFs). The comparison of both methods allows evaluating the effect of the textures and OM, of which a significant effect of these variables is produced, suggested that there is a considerable level of consistency between the two methods, despite some differences induced by coarse textures (sand) and OM.

Download Full-text