scholarly journals Quantification of the least limiting water range in an oxisol using two methodological strategies

2014 ◽  
Vol 38 (6) ◽  
pp. 1772-1783
Author(s):  
Wagner Henrique Moreira ◽  
Cássio Antônio Tormena ◽  
Edner Betioli Junior ◽  
Getulio Coutinho Figueiredo ◽  
Álvaro Pires da Silva ◽  
...  
Keyword(s):  
Soil Water Potential ◽  
Soil Samples ◽  
In Situ Measurements ◽  
Soil Resistance ◽  
Suggested Approach ◽  
Least Limiting Water Range ◽  
Resistance To Penetration ◽  
Made In

The least limiting water range (LLWR) has been used as an indicator of soil physical quality as it represents, in a single parameter, the soil physical properties directly linked to plant growth, with the exception of temperature. The usual procedure for obtaining the LLWR involves determination of the water retention curve (WRC) and the soil resistance to penetration curve (SRC) in soil samples with undisturbed structure in the laboratory. Determination of the WRC and SRC using field measurements (in situ ) is preferable, but requires appropriate instrumentation. The objective of this study was to determine the LLWR from the data collected for determination of WRC and SRC in situ using portable electronic instruments, and to compare those determinations with the ones made in the laboratory. Samples were taken from the 0.0-0.1 m layer of a Latossolo Vermelho distrófico (Oxisol). Two methods were used for quantification of the LLWR: the traditional, with measurements made in soil samples with undisturbed structure; and in situ , with measurements of water content (θ), soil water potential (Ψ), and soil resistance to penetration (SR) through the use of sensors. The in situ measurements of θ, Ψ and SR were taken over a period of four days of soil drying. At the same time, samples with undisturbed structure were collected for determination of bulk density (BD). Due to the limitations of measurement of Ψ by tensiometer, additional determinations of θ were made with a psychrometer (in the laboratory) at the Ψ of -1500 kPa. The results show that it is possible to determine the LLWR by the θ, Ψ and SR measurements using the suggested approach and instrumentation. The quality of fit of the SRC was similar in both strategies. In contrast, the θ and Ψ in situ measurements, associated with those measured with a psychrometer, produced a better WRC description. The estimates of the LLWR were similar in both methodological strategies. The quantification of LLWR in situ can be achieved in 10 % of the time required for the traditional method.

scholarly journals Atmospheric Ice Particle Shape Estimates from Polarimetric Radar Measurements and In Situ Observations

2017 ◽  
Vol 34 (12) ◽  
pp. 2569-2587 ◽  
Author(s):  
Sergey Y. Matrosov ◽  
Carl G. Schmitt ◽  
Maximilian Maahn ◽  
Gijs de Boer
Keyword(s):  
Aspect Ratio ◽  
Particle Shape ◽  
Characteristic Size ◽  
In Situ Measurements ◽  
Department Of Energy ◽  
Depolarization Ratio ◽  
Suggested Approach ◽  
Aspect Ratios ◽  
Radar Measurements

AbstractA remote sensing approach to retrieve the degree of nonsphericity of ice hydrometeors using scanning polarimetric Ka-band radar measurements from a U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program cloud radar operated in an alternate transmission–simultaneous reception mode is introduced. Nonsphericity is characterized by aspect ratios representing the ratios of particle minor-to-major dimensions. The approach is based on the use of a circular depolarization ratio (CDR) proxy reconstructed from differential reflectivity ZDR and copolar correlation coefficient ρhυ linear polarization measurements. Essentially combining information contained in ZDR and ρhυ, CDR-based retrievals of aspect ratios are fairly insensitive to hydrometeor orientation if measurements are performed at elevation angles of around 40°–50°. The suggested approach is applied to data collected using the third ARM Mobile Facility (AMF3), deployed to Oliktok Point, Alaska. Aspect ratio retrievals were also performed using ZDR measurements that are more strongly (compared to CDR) influenced by hydrometeor orientation. The results of radar-based retrievals are compared with in situ measurements from the tethered balloon system (TBS)-based video ice particle sampler and the ground-based multiangle snowflake camera. The observed ice hydrometeors were predominantly irregular-shaped ice crystals and aggregates, with aspect ratios varying between approximately 0.3 and 0.8. The retrievals assume that particle bulk density influencing (besides the particle shape) observed polarimetric variables can be deduced from the estimates of particle characteristic size. Uncertainties of CDR-based aspect ratio retrievals are estimated at about 0.1–0.15. Given these uncertainties, radar-based retrievals generally agreed with in situ measurements. The advantages of using the CDR proxy compared to the linear depolarization ratio are discussed.

scholarly journals Soil resistance to penetration and least limiting water range for soybean yield in a haplustox from Brazil

2005 ◽  
Vol 48 (6) ◽  
pp. 863-871 ◽  
Author(s):  
Amauri Nelson Beutler ◽  
José Frederico Centurion ◽  
Alvaro Pires da Silva
Keyword(s):  
Water Content ◽  
Soil Compaction ◽  
Dry Matter ◽  
Field Capacity ◽  
Soil Resistance ◽  
Soybean Yield ◽  
Randomized Experimental Design ◽  
Least Limiting Water Range ◽  
Dry Matter Weight ◽  
Resistance To Penetration

The objective of this study was determine the resistance to penetration (PR), least limiting water range (LLWR) and critical bulk density (Db-crit) for soybean yield in a medium-textured oxisol (Haplustox). The treatments represented the soil compaction by passing a tractor over the site 0, 1, 2, 4, and 6 times, with 4 replications in a randomized experimental design. Samples were collected from 0.02-0.05, 0.07-0.10 and 0.15-0.18 m depths. Soybean (Glycine max cv. Embrapa 48) was sowed in December 2002. Plant height, number of pods, aerial dry matter, weight of 100 seeds, and the yield in 3.6 m² plots were recorded. Soybean yield started reduction at the PR of 0.85 MPa and Db of 1.48 Mg m-3. The LLWR was limited in highest part by water content at field capacity (0.01 MPa tension) and in lowest part by water content at PRcrit, achieved the Db-crit to yield at 1.48 Mg m-3.

Oceanwide Precise Determination of Sea Surface Height from In-Situ Measurements on Cargo Ships

2014 ◽  
Vol 37 (1) ◽  
pp. 77-96 ◽  
Author(s):  
Ole Roggenbuck ◽  
Jörg Reinking ◽  
Alexander Härting
Keyword(s):  
Sea Surface Height ◽  
Precise Determination ◽  
In Situ Measurements ◽  
Sea Surface

scholarly journals INTERVALO HÍDRICO ÓTIMO EM ÁREA DE CANA-DE-AÇÚCAR COM DIFERENTES CICLOS DE COLHEITA MECANIZADA

Irriga ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 96
Author(s):  
Oswaldo Julio Vischi Filho ◽  
Zigomar Menezes de Souza ◽  
Gustavo Soares de Souza ◽  
Allan Charlles Mendes de Sousa ◽  
Reginaldo Barboza da Silva
Keyword(s):  
Saccharum Officinarum ◽  
Soil Resistance ◽  
Physical Quality ◽  
Physical Conditions ◽  
Cycle System ◽  
Commercial Farming ◽  
Soil Physical Quality ◽  
Least Limiting Water Range ◽  
Effective Use ◽  
Resistance To Penetration

INTERVALO HÍDRICO ÓTIMO EM ÁREA DE CANA-DE-AÇÚCAR COM DIFERENTES CICLOS DE COLHEITA MECANIZADA  OSWALDO JULIO VISCHI FILHO1; ZIGOMAR MENEZES DE SOUZA1; GUSTAVO SOARES DE SOUZA2; ALLAN CHARLLES MENDES DE SOUSA1 E ; REGINALDO BARBOZA DA SILVA3  1Laboratório de Solos,Faculdade de Engenharia Agrícola, Universidade Estadual de Campinas, Campinas, SP, [email protected], [email protected], [email protected] Experimental Bananal do Norte, Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural, [email protected] Executiva, Universidade Estadual Paulista “Julio de Mesquita Filho”, Campus de Registro, SP, [email protected]  1 RESUMO Este trabalho teve como objetivo avaliar a qualidade física do solo, por meio do intervalo hídrico ótimo (IHO), visando diagnosticar o comportamento estrutural de solo sob cultivo de cana-de-açúcar crua em diferentes ciclos produtivos. O experimento foi desenvolvido em lavoura comercial de cana-de-açúcar em um Latossolo Vermelho distrófico (LVd) com textura média. Os tratamentos foram: um (CM1) e três (CM3) ciclos produtivos da lavoura (em média seis anos por ciclo) com colheita mecanizada. O solo foi amostrado nas linhas de plantio e nas entrelinhas, distante 0,30 m da linha de plantio, nas camadas de 0,00-0,10, 0,10-0,20, 0,20-0,30 e 0,30-0,40 m. A qualidade física do solo foi avaliada por meio do IHO. O IHO foi maior no sistema de colheita mecanizada com três ciclos (CM3), quando relacionado com o sistema com um ciclo (CM1), sugerindo que esse sistema contribuiu para a melhoria das condições físicas do solo avaliado como densidade, porosidade, resistência do solo à penetração e capacidade de armazenamento de água. A maior faixa de água não limitante ao desenvolvimento radicular da cana no sistema CM3 foi decorrente da utilização efetiva do preparo mínimo da linha de plantio, permitindo uma recuperação dos atributos físicos do solo. O IHO foi maior na linha de plantio em relação à entrelinha. Palavra-Chave: Saccharum officinarum, água no solo, qualidade física do solo, resistência do solo à penetração.  VISCHI FILHO, O. J.; SOUZA, Z. M.; SOUZA, G. S.; SOUSA, A. C. M.; SILVA, R. B.LEAST LIMITING WATER RANGE ON SUGARCANE AREA WITH DIFFERENT CYCLES OF MECHANICAL HARVEST  2 ABSTRACT The present study aimed to assess the soil physical quality, through Least Limiting Water Range (LLWR), aiming to diagnose the soil structural behavior, under sugarcane cultivation at different times of handling. The experiment was conducted on a sugarcane commercial farming on Oxisol Typic Acrudox with medium texture. The treatments were: one (CM1) and three (CM3) handling cultivation cycles (six years average for cycle) through mechanical harvest system. Soil samples were collected on the planting rows and on between rows, distance of 0.30 m from planting rows, at layers of 0.00-0.10; 0.10-0.20; 0.20-0.30 e 0.30-0.40 m. Soil physical quality was assessed by LLWR. The LLWR was higher in mechanical harvesting system with three cycles (CM3), when related to one cycle system (CM1), suggesting that this system has contributed for the improvement of assessed soil physical conditions such as  bulk density, soil porosity, soil resistance to penetration and water storage. The largest LLWR at sugarcane root development on CM3 system was due to the effective use of row planting reduced tillage, allowing recovery of soil physical properties. The LLWR was higher on planting rows than between rows. Keywords: Saccharum officinarum, soil water, soil physical quality, soil resistance to penetration.

Sign in / Sign up

Export Citation Format

Share Document