Digital soil mapping can be defined as
the creation, and population of spatial soil information systems by the
use of field and laboratory observational methods coupled with spatial
and non-spatial soil inference systems. More details
here and
here
Book on Digital Soil Mapping
There has been considerable expansion in the use of digital soil mapping
technologies and development of methodologies that improve digital soil
mapping at all scales and levels of resolution. These developments have
occurred in all parts of the world in the past few years and also in
countries where it was previously absent. There is almost always a
shortage of data in soil research and its applications and this may lead
to unsupported statements, poor statistics, misrepresentations and
ultimately bad resource management. In digital soil mapping, maximum use
is made of sparse data and this book contains useful examples of how
this can be done. This book focuses on digital soil mapping
methodologies and applications for areas where data are limited, and has
the following sections (i) introductory papers, (ii) dealing with
limited spatial data infrastructures, (iii) methodology development, and
(iv) examples of digital soil mapping in various parts of the globe
(including USA, Brazil, UK, France, Czech Republic, Honduras, Kenya,
Australia).
Written for: Scientists, researchers, engineers and scholars
interested in new soil survey approaches with the use of numerical
techniques
Keywords: covariates, digital soil mapping, pedology, soil map
density, sparse data
Below a brief summary of the Southern Africa Project, more are in
the pipeline.
Land Cover, Extent and Properties of
Arenosols in Southern Africa
Arenosols cover about
13% in Sub-Saharan Africa and are widely spread in the Southern part of
the continent where crop yields are low and poverty and malnutrition are
endemic. Knowledge about the spatial distribution, properties and land
cover of Arenosols can be used to design programs to alleviate the major
constraints upon agricultural production. This paper reviews the
importance of Arenosols in eight countries of Southern Africa (Angola,
Botswana, Lesotho, Mozambique, Namibia, South Africa, Swaziland and
Zimbabwe). Estimates of their extent are based on
SOTER databases. The total extent of Arenosols in the eight
countries is 169 million ha: extensively in Angola and Botswana (>50% of
total land area) but also in Zimbabwe, South Africa and Mozambique (>15%
of total land area). About 26.3 million ha of Arenosols are under
forest; 104.7 million ha under savannah and 3.5 million ha is desert and
dunes. In total, 6.5 million ha of Arenosols are under agriculture
cropland, most of which is located in Angola, Botswana and South Africa.
Arenosol topsoils in Namibia and South Africa are mostly alkaline but in
Angola and Zimbabwe, the average topsoil pH of Arenosols is below 6.
Organic carbon is uniformly low in Arenosols of Southern Africa and
rarely exceeds 10 g kg–1. Higher C contents are found in
soils with slightly higher clay content, whereas higher C contents are
also associated with higher cation exchange capacities (CECs). The low
CEC and low water holding capacity necessitates addition of organic
manures, but quantities available are very limited. Although water is
limiting in many areas, inorganic fertilizers are indispensable to
increase agricultural production on Arenosols in Southern Africa.

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