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\name{ca20}
\alias{ca20}
\alias{ca20.df}
\docType{data}
\encoding{latin1}
\title{Calcium content in soil samples}
\usage{data(ca20)}
\description{
This data set contains the calcium content measured in soil samples
taken from the 0-20cm layer at 178 locations within a certain study area divided in three
sub-areas. The elevation at each location was also recorded.
The first region is typically flooded during the rain season and not
used as an experimental area. The calcium levels would represent
the natural content in the region. The second region has received
fertilisers a while ago and is typically occupied by rice fields.
The third region has received fertilisers recently and is frequently
used as an experimental area.
}
\format{
The object \code{ca20} belongs to the class \code{geodata}
and is a list
with the following elements:
\describe{
\item{\code{coords}}{a matrix with the coordinates of the soil samples. }
\item{\code{data}}{calcium content measured in \eqn{mmol_c/dm^3}. }
\item{\code{covariate}}{a data-frame with the covariates
\describe{
\item{\code{altitude}}{a vector with the elevation of each
sampling location, in meters (\eqn{m}).}
\item{\code{area}}{a factor indicating the sub area to which the
locations belongs.}
}
}
\item{\code{borders}}{a matrix with the coordinates defining the
borders of the area. }
\item{\code{reg1}}{a matrix with the coordinates of the limits of
the sub-area 1. }
\item{\code{reg1}}{a matrix with the coordinates of the limits of
the sub-area 2. }
\item{\code{reg1}}{a matrix with the coordinates of the limits of
the sub-area 3. }
}
}
\source{
The data was collected by researchers from PESAGRO and EMBRAPA-Solos, Rio
de Janeiro, Brasil
and provided by Dra. Maria Cristina Neves de Oliveira.
Capeche, C.L.; Macedo, J.R.; Manzatto, H.R.H.; Silva, E.F. (1997)
Caracterizao pedolgica da fazenda Angra - PESAGRO/RIO -
Estao experimental de Campos (RJ). (compact disc).
In: Congresso BRASILEIRO de Cincia do Solo. 26.,
Informao, globalizao, uso do solo; Rio de Janeiro, 1997.
trabalhos. Rio de Janeiro: Embrapa/SBCS.
}
\references{
Oliveira, M.C.N. (2003) \emph{Mtodos de estimao de parmetros
em modelos geoestatsticos com diferentes estruturas de
covarincias: uma aplicao ao teor de clcio no solo.}
Tese de Doutorado, ESALQ/USP/Brasil.
Further information on the package \pkg{geoR} can be found at:\cr
\url{http://www.leg.ufpr.br/geoR/}.
}
\keyword{datasets}
|
