# ca20

##### Calcium content in soil samples

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.

- Keywords
- datasets

##### Usage

`data(ca20)`

##### Format

The object `ca20`

belongs to the class `geodata`

and is a list
with the following elements:

`coords`

a matrix with the coordinates of the soil samples.

`data`

calcium content measured in \(mmol_c/dm^3\).

`covariate`

a data-frame with the covariates

`altitude`

a vector with the elevation of each sampling location, in meters (\(m\)).

`area`

a factor indicating the sub area to which the locations belongs.

`borders`

a matrix with the coordinates defining the borders of the area.

`reg1`

a matrix with the coordinates of the limits of the sub-area 1.

`reg1`

a matrix with the coordinates of the limits of the sub-area 2.

`reg1`

a matrix with the coordinates of the limits of the sub-area 3.

##### References

Oliveira, M.C.N. (2003) *M<e9>todos de estima<e7><e3>o de par<e2>metros
em modelos geoestat<ed>sticos com diferentes estruturas de
covari<e2>ncias: uma aplica<e7><e3>o ao teor de c<e1>lcio no solo.*
Tese de Doutorado, ESALQ/USP/Brasil.

Further information on the package geoR can be found at: http://www.leg.ufpr.br/geoR.

*Documentation reproduced from package geoR, version 1.8-1, License: GPL (>= 2)*