GROUP OF HARVEY HOI EH. 
21 
of this element per acre to a depth of 8 inches. This is a suf¬ 
ficient supply to meet the demands of heavy crops for several 
hundred years. The entire problem with reference to potas¬ 
sium therefore, is connected with its availability. When a good 
supply of active organic matter is present it can be assumed 
that there is sufficient potassium made available for practically 
all crops grown on this land. In the case of a few special crops 
requiring unusually large amounts of this element, such as cab¬ 
bage and tobacco, the use of potash fertilizers may in some cases 
be profitable. The system of farming followed will also influ¬ 
ence the potassium supply. A large paid of this element goes 
to the stalks and straw of the plant so that if the hay and rough 
forage is fed the greater portion of this element is returned to 
the land in the manure—differing radically from phosphorous 
which goes to the grain and is, therefore, more likely to be sold. 
Organic matter and nitrogen .—Compared with prairie soils 
which have shown a lasting fertility, these soils are distinctly 
low in organic matter and nitrogen. In fact, most upland soils 
of wooded regions are low in organic matter. However, the vege¬ 
table matter which they do contain when first cleared and broken 
is of an active character, but provision should be made for 
maintaining and increasing this material. When stock raising 
is practiced manure is available and is of course good as far as 
it goes, but on comparatively few farms is there sufficient ma¬ 
nure produced to maintain the organic matter in soils of this 
character and other means should be used to supplement the 
barnyard manure. Green manuring crops should be used as far 
as possible, turning under the second crop of clover whenever 
this can be done rather than using it for pasture. Seeding 
clover in corn at the last cultivation will secure good growth 
when the season is favorable. Cultivated ground when used for 
pasture should not be grazed closely. 
Nitrogen is perhaps the most essential element of plant food 
and large amounts are used by all crops. It exists only in the 
organic or vegetable matter of the soil, there being none what¬ 
ever in the earthy material derived from the rocks. Soils 
which are low in organic matter are therefore, also low in ni¬ 
trogen. By all means the cheapest source of this element is 
through the growth of legumes such as clover, alfalfa, soy beans, 
etc., which collect it from the atmosphere. When these crops 
are turned under thev contain an abundance of this element. 
