scholarly journals INFLUÊNCIA DA TEXTURA E PROFUNDIDADE DO SOLO NA CALIBRAÇÃO DA SONDA DE NÊUTRONS

Irriga ◽  
1998 ◽  
Vol 3 (1) ◽  
pp. 6-12
Author(s):  
Reginaldo Ferreira Santos ◽  
Reimar Carlesso
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Texture ◽  
Correlation Coefficients ◽  
Regression Equations ◽  
Transparent Plastic ◽  
Neutron Probe ◽  
Calibration Curves ◽  
Santa Maria

INFLUÊNCIA DA TEXTURA E PROFUNDIDADE DO SOLO NA CALIBRAÇÃO DA SONDA DE NÊUTRONS   Reginaldo Ferreira SantosDepartamento de Engenharia Rural - UNESP, CP: 237 - CEP:18603 970, Botucatu, SP Reimar CarlessoDepartamento de. Engenharia da Universidade Federal de Santa Maria, - UFSM, Campus Universitário, CEP: 97119 900, Santa Maria - RS  1 RESUMO A sonda de nêutrons é um equipamento usado na determinação do conteúdo de água do solo baseado no espalhamento e atenuação de nêutrons rápidos. Para tanto, há necessidade de calibração no campo e, conseqüentemente, verificar a influência da textura e da profundidade do solo e determinar as curvas de calibração em relação ao conteúdo de umidade. O trabalho foi desenvolvido na Universidade Federal de Santa Maria em um conjunto de lisímetros, protegidos das precipitações pluviométricas com plástico transparente. Foram usados três solos de diferentes texturas e quatro repetições e em três profundidades (10, 30 e 50 cm) a partir da superfície do solo. Foram determinadas as equações de regressão lineares entre as contagens propiciadas pela sonda e o conteúdo de umidade do solo respectivos pelo método gravimétrico. Os resultados demonstraram que houve interferência da textura e da profundidade do solo, analisados conjuntamente, nas curvas de calibração, sendo que os valores observados e os estimados variaram entre 0,02 e 0,06 cm3/ cm3 do conteúdo de água do solo e os coeficientes de correlação foram 0,86, 0,95 e 0,89 para os solos de textura argilosa, franco-argilo-siltoso e franco-arenoso, respectivamente. Já para os fatores textura e profundidade dos solos, analisados separadamente, as diferenças entre os valores observados no campo e os estimados, variaram entre 0,0 e 0,02 cm31cm3 do conteúdo de água do solo e apresentaram coeficientes de correlação entre 0,97 e 1,0. UNITERMOS: sonda de nêutrons. umidade do solo. textura e profundidade do solo  SANTOS, R.F., CARLESSO, R. Soil texture and depth influence on the neutron probe calibration   2 SUMMARY  The neutron probe is an equipment used on determination of the soil water content, based on the fast neutron attenuation. Therefore, there is a calibration need in the field and, consequently, to verify the soil texture and depth influence for to determining the calibration curves in relation to the water content. The study was developed at Santa Maria's Federal University in a lisímeter group, protected from the rains with transparent plastic. Three different soil textures, three depths (10, 30 and 50 cm from the soil surface) and four replicates were used. Linear regression equations between neutron counts and soil water contents were made. The results showed that there was interference of the texture and depth of the soil, analyzed jointly, on the calibration curves, and the observed and estimated values varied from 0,02 to 0,06 cm3 / cm3 of the soil water content and the correlation coefficients were 0,86, 0,95 and 0,89 for clayay, franc-silt-clayay and franc-sandy, respectively. For soil texture and depth, analyzed separately, the differences among the values observed in the field and the estimated ones, varied from 0,0 to 0,02 cm3/cm3 soil water content and presented correlation coefficients between 0,97 and 1,0. KEYWORDS: neutron probe, soil water content, soil texture and depth.

scholarly journals Overstory–Understory Vegetation Cover and Soil Water Content Observations in Western Juniper Woodlands: A Paired Watershed Study in Central Oregon, USA

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 151 ◽  
Author(s):  
Grace Ray ◽  
Carlos G. Ochoa ◽  
Tim Deboodt ◽  
Ricardo Mata-Gonzalez
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Texture ◽  
Canopy Cover ◽  
Understory Vegetation ◽  
Watershed Scale ◽  
Shrub Cover ◽  
Western Juniper ◽  
Tree Canopy Cover

The effects of western juniper (Juniperus occidentalis) control on understory vegetation and soil water content were studied at the watershed-scale. Seasonal differences in topsoil (12 cm) water content, as affected by vegetation structure and soil texture, were evaluated in a 96-ha untreated watershed and in a 116-ha watershed where 90% juniper was removed in 2005. A watershed-scale characterization of vegetation canopy cover and soil texture was completed to determine some of the potential driving factors influencing topsoil water content fluctuations throughout dry and wet seasons for approximately one year (2014–2015). We found greater perennial grass, annual grass, and shrub cover in the treated watershed. Forb cover was no different between watersheds, and as expected, tree canopy cover was greater in the untreated watershed. Results also show that on average, topsoil water content was 1% to 3% greater in the treated watershed. The exception was during one of the wettest months (March) evaluated, when soil water content in the untreated watershed exceeded that of the treated by <2%. It was noted that soil water content levels that accumulated in areas near valley bottoms and streams were greater in the treated watershed than in the untreated toward the end of the study in late spring. This is consistent with results obtained from a more recent study where we documented an increase in subsurface flow residence time in the treated watershed. Overall, even though average soil water content differences between watersheds were not starkly different, the fact that more herbaceous vegetation and shrub cover were found in the treated watershed led us to conclude that the long-term effects of juniper removal on soil water content redistribution throughout the landscape may be beneficial towards restoring important ecohydrologic connections in these semiarid ecosystems of central Oregon.

Analysis of Water Budgets in Semi-Arid Lands from Soil Water Records

1995 ◽  
Vol 31 (2) ◽  
pp. 131-150 ◽  
Author(s):  
C. J. Pilbeam ◽  
C. C. Daamen ◽  
L. P. Simmonds
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Surface ◽  
Total Evaporation ◽  
Growing Seasons ◽  
Neutron Probe ◽  
Unsaturated Hydraulic Conductivity ◽  
Probe Measurements

SUMMARYFour components of the water budget for a growing season, namely storage, drainage, transpiration and direct evaporation from the soil surface, were estimated using a suite of techniques. The only data requirements were rainfall, neutron probe measurements of soil water content and microlysimeter measurements of evaporation from the soil. Data from four growing seasons at Kiboko, Kenya between 1990 and 1992 were used to provide examples of the estimations. Drainage was significant (about 10% of rainfall) in one season only; in the other seasons, total evaporation comprised at least 95% of the seasonal rainfall.Drainage was determined using a relationship between unsaturated hydraulic conductivity and soil water content that was determined during the early part of the rainy season when water was penetrating to depth. This analysis made it possible to identify a critical water content at the base of the soil profile, above which there would be significant drainage. However, there are large errors associated with estimation of drainage if significant drainage occurs.Estimates of direct evaporation from the soil surface were used as the basis of distinguishing transpiration from total evaporation. Microlysimetry was used to develop a model of evaporation from these sandy soils, which was based on the assumption that the evaporation from the soil surface following heavy rainfall is a unique function of time from rainfall, and little influenced by the presence of a sparse crop. This method showed that direct evaporation from the soil accounted for between 70 and 85% of total evaporation in seasons when total evaporation estimates ranged from 150 to 325 mm.

Influence of temperature on soil water content measured by ECH2O-TE sensors

2012 ◽  
Vol 26 (3) ◽  
pp. 259-269 ◽  
Author(s):  
M. Kočárek ◽  
R. Kodešová
Keyword(s):  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Depth ◽  
Regression Equations ◽  
Influence Of Temperature ◽  
Reference Soil ◽  
Guideline Values ◽  
Influence Of Temperature On

Influence of temperature on soil water content measured by ECH2O-TE sensorsThe aim of this study was to investigate the influence of temperature on water content value measured by ECH2O-TE sensors. The influence of temperature on measured soil water content values was clearly demonstrated. Soil water content values measured during the day apparently oscillated with oscillating soil temperatures. Average daily temperature and soil water content were calculated for selected periods. Regression relationships between deviations of soil temperature and soil water content from their daily average values were evaluated. Correlation between the soil water content and temperature deviations increase with the soil depth due to the lower influence of rainfall and evaporation at the soil surface on measured soil water content values in deeper soil layersegsoil water content oscillation was controlled mostly by oscillating temperature. The guideline values of linear regression equations (R2>0.8) were very similar, close to value 0.002 and the intercept values were equal to zero. The equation for recalculation of measured soil water content values at given temperature to reference soil water content for reference soil temperature, was propozed on the basis of this analysis.

scholarly journals Evaluation of Improved Model to Accurately Monitor Soil Water Content

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3441
Author(s):  
Jingyu Ji ◽  
Junzeng Xu ◽  
Yixin Xiao ◽  
Yajun Luan
Keyword(s):  
Organic Matter ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Texture ◽  
Irrigation Management ◽  
Clay Fraction ◽  
Organic Matter Content ◽  
Matter Content ◽  
Improved Model

The accurate monitoring of soil water content during the growth of crops is of great importance to improve agricultural water use efficiency. The Campbell model is one of the most widely used models for monitoring soil moisture content from soil thermal conductivities in farmland, which always needs to be calibrated due to the lack of adequate original data and the limitation of measurement methods. To precisely predict the water content of complex soils using the Campbell model, this model was evaluated by investigating several factors, including soil texture, bulk density and organic matter. The comparison of the R2 and the reduced Chi-Sqr values, which were calculated by Origin, was conducted to calibrate the Campbell model calculated. In addition, combining factors of parameters, a new parameter named m related to soil texture and the organic matter was firstly introduced and the original fitting parameter, E, was improved to an expression related to clay fraction and the organic matter content in the improved model. The soil data collected from both the laboratory and the previous literature were used to assess the revised model. The results show that most of the R2 values of the improved model are >0.95, and the reduced Chi-Sqr values are <0.01, which presents a better matching performance compared to the original. It is concluded that the improved model provides more accurate monitoring of soil water content for water irrigation management.

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.

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