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Horizonte B planico (SiBCS Cap 2, p 65-66)

Source: R/diagnostics-horizons-sibcs.R
B_planico.Rd

"E um tipo especial de horizonte B textural, com ou sem carater sodico, subjacente a horizontes A ou E, apresentando mudanca textural abrupta ou transicao abrupta associada a relacao textural com valor dentro do especificado para o horizonte B textural (subitem h), porem calculado entre o primeiro sub-horizonte B e o horizonte imediatamente acima (A ou E)".

Usage

B_planico(pedon)

Arguments

pedon

A PedonRecord.

Value

A DiagnosticResult recording whether the diagnostic is present, the qualifying layers, and the supporting evidence.

Details

Since v0.9.244 the horizon is looked for where the book puts it, in the first B sub-horizon, below an A or an E, by one of the two:

  • a mudanca_textural_abrupta from the A or E to it; or

  • a transition recorded as abrupt (boundary_distinctness) with a ratio of its clay to that of the horizon above over the limit of item (h) of the B textural (1.50, 1.70 or 1.80).

As a type of B textural, that sub-horizon has a texture francoarenosa or finer (p. 54): one known to be coarser is no B planico, whatever its clay over that of the E. The structure and the colours below are asked of that first sub-horizon. Until v0.9.243 any layer with a jump of clay over the layer above it could be the B planico, the second way was not tested, and the structure and the colours were asked of the layer with the jump. A profile with no horizon designation at all is still tested that way.

The structure (p. 65): "Apresenta estrutura prismatica, colunar ou em blocos angulares e subangulares grandes ou medios e, as vezes, estrutura macica". It is tested where the sheet records it (structure_type, structure_size): a prismatic, columnar or massive structure passes; blocks pass when medium or larger, or when their size is not recorded; any other recorded structure does not pass.

The colours "devem atender a pelo menos um dos seguintes requisitos" (p. 65-66):

  • (a) the matrix colour, with or without mottles: "Matiz 10YR ou mais amarelo, cromas <= 3" or "Matizes 7,5YR ou 5YR, cromas <= 2";

  • (b) "Coloracao variegada com pelo menos uma cor apresentando matiz e croma conforme especificado no item (a)" (variegated_colors);

  • (c) "matiz 10YR ou mais amarelo, cromas >= 4, combinado com mosqueado de croma conforme especificado no item (a)": a mottle colour (mottle_colors) that satisfies item (a).