A data frame with 256 observations on the following 10 variables.
Xa numeric vector with X-coordinates of the plot centres.
Ya numeric vector with X-coordinates of the plot centres.
Pa numeric vector, phosphorous content.
PHa numeric vector, soil pH.
Ka numeric vector, potassium content. (Cmol/dm^3)
MOa numeric vector, organic matter. (percentage)
SBa numeric vector, basis saturation.
iConea numeric vector, cone index, measuring mechanic
resistence of the soil. (kg/cm^2)
Renda numeric vector, total soya production within
the plot (kg).
PRODa numeric vector, production converted to
productivity by a unit of area - hectare (ton/ha).