Sensitivity of soil structure to changes in organic carbon content: Predictions using pedotransfer functions

1997 ◽  
Vol 77 (4) ◽  
pp. 655-667 ◽  
Author(s):  
B. D. Kay ◽  
A. P. da Silva ◽  
J. A. Baldock

Pedotransfer functions (PTFs) were used to assess the sensitivity of the structural characteristics of coarse- and medium-textured calcareous illitic soils at different levels of relative compaction (RC) to changes in the organic carbon (OC) content. The analyses predicted that an increase in the OC content of 0.01 kg kg−1 would:• increase the available water content from 0.02 to 0.04 m3 m−3 with the largest increases occurring in coarser-textured soils and not being strongly influenced by RC;• decrease the air-filled porosity at field capacity from 0.01 to 0.04 m3 m−3 with the largest decreases occurring in the finer-textured soils and not being strongly influenced by RC;• decrease the soil resistance to penetration with the decreases most pronounced at lower water potentials and higher RC; at the permanent wilting point and a RC of 0.95 the decrease would range from 1.2 to 3.8 MPa;• increase the least limiting water range from 0.01 to 0.05 m3 m−3 with the increase varying with clay content.A comparison with predictions based on PTFs derived from data sets from other parts of the world indicated caution should be exercised in applying PTFs to soil and climatic conditions that are different from those from which the PTFs were derived until the impacts of these conditions are better understood. Key words: Bulk density, field capacity, permanent wilting point, available water; aeration, soil resistance, least limiting water range

2018 ◽  
Vol 10 (9) ◽  
pp. 105
Author(s):  
Antonio Carlos da Silva ◽  
Jeane Cruz Portela ◽  
Rafael Oliveira Batista ◽  
Rutilene Rodrigues da Cunha ◽  
Joaquim Emanuel Fernandes Gondim ◽  
...  

From the physics point of view, soil structure is a dynamic attribute that is affected by genetic conditions and anthropogenic changes and requires an integrated approach. Soil water retention curve is one of the main tools used in soil structure evaluations. The objective of this work was to evaluate the structural and chemical attributes of soils of different classes and agroecosystems in the Terra de Esperança Settlement (Governador Dix Sept Rosado, Rio Grande do Norte, Brazil) to distinguish these environments. Disturbed and undisturbed soil samples were collected in horizons of 10 soil profiles of the soil classes: Cambissolo Háplico (Haplustepts), Latossolo Vermelho-Amarelo (Eutrustox), Chernossolo Rêndzico (Calciustolls), and Neossolo Flúvico (Usticfluvents). The soil physical attributes evaluated were granulometry, soil density, total porosity, aeration porosity, macroporosity, microporosity, field capacity, permanent wilting point, available water, and water retention curve. The results were expressed in averages of four replicates per horizon (in laboratory) by multivariate analysis, which detected the most sensitive attributes for the distinction of the environments. The soil physical attributes of the different classes and its inorganic fractions, especially silt and clay, were determinant to distinguish the environments; they affected the microporosity; aeration porosity; and available water. The source material of the Chernossolo Rêndzico, which is rich in calcium and magnesium, affected its physical attributes, characterized by the predominance of the silt fraction. Clay was the determinant fraction of the Cambissolo Háplico, and Neossolo Flúvico; and the sand fraction on the surface layer, and clay fraction in the Bw horizon were determinant of the Latossolo Vermelho-Amarelo. The more expressive physical attributes were soil density, sand content, macroporosity (Latossolo Vermelho-Amarelo), microporosity, field capacity, available water, permanent wilting point, total organic carbon, mass-based moisture, volume-based moisture, clay, aeration porosity (Cambissolo Háplico, and Neossolo Flúvico), and silt (Chernossolo Rêndzico).


Irriga ◽  
2020 ◽  
Vol 25 (1) ◽  
pp. 69-86
Author(s):  
Fernanda Helena Nascimento Andrade ◽  
Ceres Duarte Guedes Cabral de Almeida ◽  
Brivaldo Gomes de Almeida ◽  
João Audifax Cézar Albuquerque Filho ◽  
Bruno Campos Mantovanelli ◽  
...  

ATRIBUTOS FÍSICO-HÍDRICOS DO SOLO VIA FUNÇÕES DE PEDOTRANSFERÊNCIA EM SOLOS DOS TABULEIROS COSTEIROS DE PERNAMBUCO   FERNANDA HELENA NASCIMENTO DE ANDRADE1; CERES DUARTE GUEDES CABRAL DE ALMEIDA2; BRIVALDO GOMES DE ALMEIDA3; JOSÉ AUDIFAX CÉZAR DE ALBUQUERQUE FILHO1; BRUNO CAMPOS MANTOVANELLI4 E JOSÉ COELHO DE ARAÚJO FILHO5   1 Departamento de Engenharia Agrícola, Programa de Pós-Graduação em Engenharia Agrícola da Universidade Federal Rural de Pernambuco - UFRPE, Rua Dom Manuel de Medeiros, S/N, Dois Irmãos, CEP: 52171-900, Recife, PE, Brasil, [email protected], [email protected] 2 Colégio Agrícola Dom Agostinho Ikas, Programa de Pós-Graduação em Engenharia Agrícola da Universidade Federal Rural de Pernambuco - UFRPE, Rua Dom Manuel de Medeiros, S/N, Dois Irmãos, CEP: 52171-900, Recife, PE, Brasil, [email protected]. 3 Departamento de Agronomia, Programa de Pós-Graduação em Ciência do Solo da Universidade Federal Rural de Pernambuco - UFRPE, Rua Dom Manuel de Medeiros, S/N, Dois Irmãos, CEP: 52171-900, Recife, PE, Brasil, [email protected]. 4 Departamento de Ciências Rurais, Programa de Pós-Graduação em Ciência do Solo da Universidade Federal de Santa Maria - UFSM, Avenida Roraima, n° 1000, Camobi, CEP: 97105-900, Santa Maria, RS, Brasil, [email protected]. 5 Empresa Brasileira de Pesquisa Agropecuária, EMBRAPA Solos - UEP Recife, Rua Antônio Falcão, n° 402, Boa Viagem, CEP: 51020-240, Recife, PE, Brasil, [email protected].     1 RESUMO   Objetivou-se gerar funções de pedotransferência (FPT) com base em dados das frações granulométricas, distribuição do tamanho de poros, densidade do solo e de partículas para estimar a umidade do solo equivalente à capacidade de campo (CC), ponto de murcha permanente (PMP) e a capacidade de armazenamento de água disponível (CAD) em Argissolos Amarelos representativos dos tabuleiros costeiros na zona da mata norte de Pernambuco. Para isso, foram coletadas amostras deformadas e indeformadas na camada 0,00 - 0,20 m de profundidade. As FPTs foram geradas a partir do método de regressão linear múltipla aplicando a técnica de stepwise backward. Este método eliminou alguns atributos físico-hídricos do solo baseado nos valores de R2 e no Teste t. Os coeficientes de regressão do modelo proposto para predição de CAD, CC e o PMP apresentaram significância de 1% de probabilidade para as variáveis independentes selecionadas para cada modelo, indicando que esses parâmetros podem ser preditos, com ótima precisão, a partir do conteúdo de areia, argila, mesoporosidade, microporosidade e densidade do solo, as quais são fáceis de serem determinadas e obtidas, pré-requisito básico para construção das FPTs.   Palavras-chave: manejo de irrigação, stepwise backward, índices estatísticos.     ANDRADE, F. H. N.; ALMEIDA, C. D. G. C.; ALMEIDA, B. G.; ALBUQUERQUE FILHO, J. A. C.; MANTOVANELLI, B. C.; ARAÚJO FILHO, J. C. SOIL PHYSICAL-HYDRIC PROPERTIES BY PEDOTRANSFER FUNCTION IN SOILS OF COASTAL PLAINS OF PERNAMBUCO   2 ABSTRACT   Aimed to generate pedotransfer functions (PTF) based on particle size, pore size distribution, soil and particle density to estimate the field capacity (CC), permanent wilting point (PMP) and available water capacity (CAD) in Ultisol Typic Fragiaquults in coastal plains of Pernambuco. Thus, deformed and undeformed samples were collected at 0.00 - 0.20m depth. PTFs were generated from multiple linear regression method by stepwise backward technique. This method eliminated some hydro-physical soil attributes, based on the values of R2 and t test. CAD, CC and PMP estimated values showed a significant correlation of 1% probability for independent variables selected for each model. Thus, available water capacity, field capacity and permanent wilting point can be predicted with great precision by sand, clay content, mesoporosity, microporosity and soil density, which are easy to determine and obtain, basic prerequisite for construction of PTFs.   Keywords: irrigation management, stepwise backward, statistical indexes.


Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2639
Author(s):  
Lindumusa Myeni ◽  
Thandile Mdlambuzi ◽  
David Garry Paterson ◽  
Gert De Nysschen ◽  
Mokhele Edmond Moeletsi

This study was undertaken to develop new pedotransfer functions (PTFs) for the estimation of soil moisture content at field capacity (FC, at −33 kPa) and permanent wilting point (PWP, at −1500 kPa) for South African soils based on easily measurable soil physico-chemical properties. The new PTFs were developed using stepwise multiple linear regressions with the dependent variable (either FC or PWP) against clay, silt, sand and soil organic carbon (SOC) content from a total of 3171 soil horizons as the explanatory variables. These new PTFs were evaluated and compared with five well-established PTFs using a total of 3136 soil horizons as an independent dataset. The coefficient of determination (r2) values for the existing PTFs ranged from 0.65–0.72 for FC and 0.72–0.81 for PWP, whilst those developed in this study were 0.77 and 0.82 for FC and PWP, respectively. The root mean square error (RMSE) values for the well-established PTFs ranged from 0.052–0.058 kg kg−1 for FC and 0.030–0.036 kg kg−1 for PWP, whilst those developed in this study were 0.047 and 0.029 kg kg−1 for FC and PWP, respectively. These findings suggest that PTFs derived locally using a large number of soil horizons acquired from different agro-climatic locations improved the estimation of soil moisture at FC and PWP. Due to the range of conditions and large soil datasets used in this study, it is concluded that these new PTFs can be applied with caution in other regions facing data scarcity but with similar soil types and climatic conditions.


2004 ◽  
Vol 7 (4) ◽  
pp. 535-541 ◽  
Author(s):  
Bilal Cemek . ◽  
Ramazan Meral . ◽  
Mehmet Apan . ◽  
Hasan Merdun .

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