Soil samples from the various horizons have been collected from points in a square lattice in two areas representing typical Swedish forest types, at Garpenberg (60°27' lat.N, Dalarna) and Vindeln (64°17' lat. N, Västerbotten). The samples were analysed for N, P, K and loss on ignition, and the values obtained were expressed both as percentages and per unit area. The conclusion to be drawn from the results is that to obtain good precision in analytical values, it is necessary to take a greater number of samples when the results are expressed in weight per unit area than when they are expressed in percentages by weight. As a rule, it is necessary to use samples from at least 10-15 points (often more)-aggregated to a composite sample-to depress the coefficient of variation below 10 per cent for the values per unit area of the studied elements. The paper also contains tables showing the distribution of these elements in the profiles examined.
展开▼
