SOIL CONDITIONS. 23 
region, but that will support some form of tree growth. The 
soil best adapted to all kinds of trees is one that is moderately 
but evenly moist, porous, deep and well drained; yet with a 
subsoil compact enough to transmit the subsoil water from 
below upwards without its being so solid that it cannot be easily 
penetrated by the roots. It does not matter about its being 
stony if it has these qualities. On land that is very wet in 
this section, as the muskegs of northern Minnesota, which are 
covered with Tamarack and Spruce, the trees never get to be 
of large size. In the case of one Spruce grown on such land, 73 
years was occupied in growing a tree 1% inches in diameter, 
and a Tamarack under similar conditions formed a diameter of 
only 1 1-10 inches in 48 years. We also find that growth is 
extremely slow on very dry land. On very open porous land 
the water sinks quickly out of reach of the roots, and where the 
soil is too compact it cannot be penetrated by the water or by 
the roots, so that on such soils trees generally suffer for moisture 
a part of the year. 
Relation Between Trees and Soils. The growth of trees 
and the kinds growing on land are good though not infallible 
indexes to the value of the soil for agricultural purposes. For 
instance, land on which Black Walnut, Hard Maple, Hackberry 
or Hickory grow to large size is of good quality for grasses, 
grains and other agricultural crops, while Black Oak is gener- 
ally abundant on dry, gravelly ridges and sandy soil. Where 
White Pine in this section is the prevailing tree the land is gen- 
erally of good quality. Norway Pine will endure more drouth 
than the White Pine, outgrows it, and becomes the prevailing 
tree on drier land, while the Jack Pine is the most abundant on 
the very dry sandy lands of Northern Minnesota. In the more 
humid climate of the eastern states the White Pine grows on 
very sandy soils. 
Mechanical Condition of Land in Forests. The agri- 
culturist aims to keep the soil porous, yet moderately compact, 
that the roots may penetrate it easily and the subsoil waters 
may be readily transmitted upwards to the roots of plants. He 
aims to prevent the soil from becoming too compact and from 
the loss of water from evaporation by cultivating the surface 
soil, and to keep out standing water by drainage. The forest 
