Foreword.qmd

# Foreword {#sec-foreword}

Many technical terms are used throughout this report in the keys and definitions. These technical terms, printed here in italics, are defined in this book in the section [Diagnostic horizons and other differentiae](Diagnostics.qmd#sec-diagnostics) and the [Glossary](glossary.qmd).

Further details and technical terms are defined in other resources:

-   *Horizon notations* are defined by @clayden1989.
-   *Soil morphology* terms are defined by @milne1995.
-   *Classes of the US Soil Taxonomy* are defined by @soilsurveystaff1999 and @soilsurveystaff2022.
-   *Soil colours* are defined by @pantone2017 (see also @soilcol1993).
-   *Soil mineralogy classes* are defined by @whitton1989 or @childs1990a. Note that the soil mineralogy class names given here are based on the following control section: 25 cm to 100 cm or to a lithic or paralithic contact if shallower.
-   *Soil chemical terms* are explained and the analytical methods are described by @blakemore1987. Note that soil pH measurements are made in water with a ratio of 1 part of soil to 2.5 parts of water, by weight.
-   *Soil physical terms* are explained and the analytical methods are described by @gradwell1979 and @mcqueen1993
-   A comprehensive overview of the diversity of soils and landscapes in Aotearoa-New Zealand is given by @hewitt2021.
-   Many other soil science concepts and technical terms are explained, in a New Zealand context, by @mclaren1990.

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The following abbreviations are used for soil chemical terms.

CEC -- Cation exchange capacity.

ECEC -- Effective cation exchange capacity, which is the CEC at natural field pH, estimated by the sum of basic cations + KCl-extractable aluminium.

P retention -- Phosphate retention.

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