ESTIMATES OF SEEDING DATES OF SPRING WHEAT ON THE CANADIAN PRAIRIES FROM CLIMATE DATA

1988 ◽  
Vol 68 (2) ◽  
pp. 513-517 ◽  
Author(s):  
A. BOOTSMA ◽  
R. DE JONG
Keyword(s):  
Linear Regression ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Spring Wheat ◽  
Correlation Coefficients ◽  
Standard Errors ◽  
Climate Data ◽  
Canadian Prairies ◽  
Seeding Date

Estimates of seeding dates of spring wheat based on climatic criteria at selected prairie locations were compared with observed dates for corresponding crop districts using linear regression and correlation analyses. Correlation coefficients ranged from 0.11 to 0.76 and standard errors of estimates of regression from 3.9 to 8.5 d. Average estimated seeding dates were consistently earlier by about 3–8 d than average observed values reported for periods ranging from 24 to 33 yr.Key words: Correlation, regression, seeding date criteria, soil water content

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 Predicting Soil Water Content on Rainfed Maize through Aerial Thermal Imaging

2021 ◽  
Vol 3 (4) ◽  
pp. 942-953
Author(s):  
Matheus Gabriel Acorsi ◽  
Leandro Maria Gimenez
Keyword(s):  
Linear Regression ◽  
Spatial Variability ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Status ◽  
Canopy Temperature ◽  
Crop Water ◽  
Soil Water Status ◽  
Physical Attributes

Restrictions on soil water supply can dramatically reduce crop yields by affecting the growth and development of plants. For this reason, screening tools that can detect crop water stress early have been long investigated, with canopy temperature (CT) being widely used for this purpose. In this study, we investigated the relationship between canopy temperature retrieved from unmanned aerial vehicles (UAV) based thermal imagery with soil and plant attributes, using a rainfed maize field as the area of study. The flight mission was conducted during the late vegetative stage and at solar noon, when a considerable soil water deficit was detected according to the soil water balance model used. While the images were being taken, soil sampling was conducted to determine the soil water content across the field. The sampling results demonstrated the spatial variability of soil water status, with soil volumetric water content (SVWC) presenting 10.4% of variation and values close to the permanent wilting point (PWP), reflecting CT readings that ranged from 32.8 to 40.6 °C among the sampling locations. Although CT correlated well with many of the physical attributes of soil that are related to water dynamics, the simple linear regression between CT and soil water content variables yielded coefficients of determination (R2) = 0.42, indicating that CT alone might not be sufficient to predict soil water status. Nonetheless, when CT was combined with some soil physical attributes in a multiple linear regression, the prediction capacity was significantly increased, achieving an R2 value = 0.88. This result indicates the potential use of CT along with certain soil physical variables to predict crop water status, making it a useful tool for studies exploring the spatial variability of in-season drought stress.

scholarly journals COMPARAÇÃO ENTRE CURVAS DE RETENÇÃO DE ÁGUA OBTIDAS EM LABORATÓRIO E A CAMPO

Irriga ◽  
2019 ◽  
Vol 24 (1) ◽  
pp. 125-142
Author(s):  
Rafael Gotardo ◽  
Adilson Pinheiro ◽  
Vander Kaufmann ◽  
Gustavo Antonio Piazza ◽  
Edson Torres
Keyword(s):  
Linear Regression ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Field Measurements ◽  
Sao Paulo ◽  
Time Domain Reflectometry ◽  
Native Forest ◽  
São Paulo ◽  
Land Uses

COMPARAÇÃO ENTRE CURVAS DE RETENÇÃO DE ÁGUA OBTIDAS EM LABORATÓRIO E A CAMPO     RAFAEL GOTARDO1; ADILSON PINHEIRO2; VANDER KAUFMANN3; GUSTAVO ANTONIO PIAZZA4 E EDSON TORRES5   1Eng. Agrônomo, Doutor, Programa de Pós-Graduação em Engenharia Ambiental (PPGEA), Fundação Universidade Regional de Blumenau (FURB), Rua São Paulo, n° 3250, Itoupava Norte, Blumenau-SC, Brasil,  [email protected]. 2Eng. Civil, Doutor, Programa de Pós-Graduação em Engenharia Ambiental (PPGEA), Fundação Universidade Regional de Blumenau (FURB), Rua São Paulo, n° 3250, Itoupava Norte, Blumenau-SC, Brasil. [email protected]. 3Químico, Biólogo, Doutor, Programa de Pós-Graduação em Engenharia Ambiental (PPGEA), Fundação Universidade Regional de Blumenau (FURB), Rua São Paulo, n° 3250, Itoupava Norte, Blumenau-SC, Brasil. [email protected]. 4Eng. Ambiental, Doutor, Programa de Pós-Graduação em Engenharia Ambiental (PPGEA), Fundação Universidade Regional de Blumenau (FURB), Rua São Paulo, n° 3250, Itoupava Norte, Blumenau-SC, Brasil. [email protected]. 5Químico, Mestre, Departamento de Engenharia Ambiental, Fundação Universidade Regional de Blumenau (FURB), Rua São Paulo, n° 3250, Itoupava Norte, Blumenau-SC, Brasil. [email protected].     1 RESUMO   O objetivo do estudo foi comparar dados do conteúdo de água do solo obtidos por técnicas laboratoriais (Extrator de Pressão de Richards) e por técnicas de determinação em campo (tensiômetros e TDR) em diferentes usos do solo. Os usos do solo estudados foram: agricultura, floresta nativa (Bioma Mata Atlântica), reflorestamento e pastagem. O conteúdo de água no solo determinado pelas curvas de retenção foi menor na camada superficial do solo, com aumento gradativo em relação a profundidade. Com o TDR, os valores do conteúdo de água alternaram nas profundidades e para os diferentes usos. Este resultado foi associado ao fato de que curvas de retenção ficam restritas a pressões máximas de 916 kPa em períodos de restrição hídrica. O método de Richards subestimou os valores de umidade nas áreas de agricultura, pastagem, reflorestamento, e superestimou os valores na área de floresta. O método de Richards também apresentou ineficiência na saturação (θs) das amostras e no equilíbrio hidráulico da umidade residual (θr). Apesar de alguns valores terem sido subestimados, a regressão linear do conteúdo médio de água no perfil do solo obtido pelos diferentes métodos apresentou correlação positiva para as áreas de agricultura e floresta e baixa correlação para as áreas de pastagem e reflorestamento. Estes resultados foram confirmados na regressão linear da variação diária de armazenamento de água ao longo do perfil.   Palavras-chave: Reflectometria no Domínio do Tempo (TDR), Richards, tensiometria.     GOTARDO, R.; PINHEIRO, P.; KAUFMANN, V.; PIAZZA, G. A.; TORRES, E. COMPARISON OF WATER RETENTION CURVES OBTAINED IN LABORATORY AND FIELD MEASUREMENTS       2 ABSTRACT   The aim of this study was to compare soil water content data obtained by laboratory techniques (Richards Pressure Extractor) and field measurements (tensiometers and TDR) in different land uses. The land uses analyzed in this study were agriculture, native forest (Atlantic Forest), reforestation and pasture. The soil water content determined by the retention curve was lower in the soil surface with  gradual increase in dept. With TDR, the values of water content​ ​alternated in depths and for different uses. This result was associated to the fact that retention curves are restricted to maximum pressures of 916 kPa in periods of water restriction. Richards’ method underestimated moisture values ​​in agriculture, pasture and reforestation areas, and overestimated these values ​​in  forest area.  Richards’ method also showed inefficiency to calculate  saturation of  samples (θs) and hydraulic balance of residual moisture (θr). Despite the underestimation, the linear regression of  average water content in the soil profile obtained by these methods showed a positive correlation for agriculture and forestry, and negative to pasture and reforestation. These results were confirmed by the linear regression of daily variation water storage along the profile.   Keywords: Time Domain Reflectometry (TDR), Richards, tensiometers.  

Improvements to the accuracy of modelled soil water content from the Second Generation Prairie Agrometeorological Model

2010 ◽  
Vol 90 (3) ◽  
pp. 523-526 ◽  
Author(s):  
M. Gervais ◽  
P. Bullock ◽  
M. Mkhabela ◽  
G. Finlay ◽  
R. Raddatz
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Second Generation ◽  
Regional Scale ◽  
Canadian Prairies ◽  
Growing Seasons ◽  
Crop Development ◽  
Plant Available Water ◽  
Water Values

The direct measurement of soil water on a regional scale is often not practical due to large instrumental and labour requirements. Alternatively, soil water estimates can be derived using models. The Second Generation Prairie Agrometeorological Model (PAMII) models soil water, crop development and evapotranspiration (ET) in order to derive an estimate of crop water use. The objective of this study was to validate, and if necessary modify, the soil water component of PAMII using weather and soil water data collected from several spring wheat trials in Saskatchewan and Manitoba during the 2003 though 2006 growing seasons. Comparison of modelled and measured soil water values yielded a RMSE of 62 mm. For most site-years, PAMII overestimated soil water during the second half of the growing season, which was caused by an increase in modelled canopy resistance (rc) before the crop experienced water stress. The rc function was thus modified so that rc would not increase until the soil water content was < 0.5 of plant available water. Overall this modification reduced the RMSE from 62 to 56 mm. In addition, modelled soil water was underestimated during periods that experienced consecutive days of precipitation. This was because the model stopped infiltration when the top-zone reached saturation. When modified to allow infiltration to continue independent of the top-zone’s water content, the RMSE was further reduced to 53 mm. Overall, both modifications reduced the RMSE of modelled soil water by 9 mm, and this reduction was highly significant (P < 0.01). Key words: Prairie Agrometeorological Model (PAMII), soil water modelling, evapotranspiration, Canadian prairies

scholarly journals Analysis of soil water content and crop yield after biochar application in field conditions

2017 ◽  
Vol 63 (No. 12) ◽  
pp. 569-573 ◽  
Author(s):  
Vitkova Justina ◽  
Kondrlova Elena ◽  
Rodny Marek ◽  
Surda Peter ◽  
Horak Jan
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Biomass Production ◽  
Spring Wheat ◽  
Field Experiments ◽  
Field Measurements ◽  
Dry Spells ◽  
Experimental Plots ◽  
Biochar Amendment

Biochar has been studied extensively in terms of its influence on soil hydrophysical properties, but only small part of results was obtained from the field experiments. In this study, the soil water content was measured in 5–10 cm depth at experimental plots which received 20 t/ha and 0 t/ha (control) of biochar amendment at the Malanta area (Slovakia). The experimental area was cultivated with maize in 2015 and spring wheat in 2016. Our field measurements show that the positive effect of biochar amendment (20 t/ha) on soil water content is strongly related to the type of the crop grown and not straightforward. Unexpectedly, during the monitoring campaign in 2015 the soil water content of the biochar-amended soil was lower than control. In 2016, negligible differences were observed in soil water contents at both experimental plots, especially during the dry spells. However, higher soil water content was measured at the plot with biochar amendment after the series of precipitation events during the physiological maturity of the spring wheat. Moreover, the biochar amendment did not increase the biomass production and yields of maize in 2015, but it significantly increased the biomass production and yields of spring wheat in 2016.

An empirical model for the evaluation of the degree of saturation of shallow soils in relation to rainfalls

2011 ◽  
Vol 48 (5) ◽  
pp. 795-809 ◽  
Author(s):  
Roberto Valentino ◽  
Lorella Montrasio ◽  
Gian Luca Losi ◽  
Marco Bittelli
Keyword(s):  
Time Series ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Empirical Model ◽  
Weather Conditions ◽  
Degree Of Saturation ◽  
Climate Data ◽  
Emilia Romagna Region ◽  
Shallow Soils

The evaluation of shallow soils water content is very important in many fields, and different hydrological models are widely applied to simulate field-scale water flow and soil water content. The degree of saturation of a shallow soil is a time-varying variable, depending on different weather conditions. In many applications, it is useful to directly correlate the soil degree of saturation to time series of rainfall amount. This paper presents a simplified empirical model, which allows for computation of the soil degree of saturation using readily available climate data on air temperature and rainfall depths. The model is tested with in situ measurements of soil water content collected at three sites in the Emilia Romagna region in northern Italy. The experimental data are compared with the results obtained from the simplified model over an observation period of almost 5 years. The model has been used to generate soil water content time series at different depths and requires a separate calibration for each depth where the degree of saturation is computed. A discussion on the model’s calibration is also carried out to clarify the model sensitivity to the different parameters and the choice of input data.

SOIL WATER CONTENT AFFECTS THE AVAILABILITY OF PHOSPHATE

1985 ◽  
pp. 185-189
Author(s):  
M.C.H.Mouat Pieter Nes
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Solution ◽  
Equivalent Reduction

Reduction in water content of a soil increased the concentration of ammonium and nitrate in solution, but had no effect on the concentration of phosphate. The corresponding reduction in the quantity of phosphate in solution caused an equivalent reduction in the response of ryegrass to applied phosphate. Keywords: soil solution, soil water content, phosphate, ryegrass, nutrition.

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