16 Colorado Expkriment Station 
the surface will soon exhaust the water supply in the limited area 
of the surface soil. Under such conditions the crop ceases grow¬ 
ing and will perhaps wither and die. While proper varieties can 
be grown where the subsoil water is very close to the surface, they 
will not make as good development nor produce as heavy tonnages 
thru so long a period of time as will be the case when the soils 
are watered by correct methods. Where the farming methods are 
such as to provide a considerable depth of soil properly moistened, 
alfalfa sends out an extensive root system which enables it to draw 
its moisture and food supplies from large areas of the soil and sub¬ 
soil. These are the conditions best suited for the proper and 
heaviest development of the crop. 
Under best management it is not advisable to seed alfalfa on 
new land or on old land that has not been properly leveled. Al¬ 
falfa is a cro'p which will remain on the land several years. Im¬ 
properly leveled land increases the work of irrigation and will often 
leave pockets which will receive so much water that the alfalfa will 
be killed. On the other hand, ridges and knolls may be left to 
which water cannot be supplied in sufficient quantity to keep the 
crop going. These conditions increase labor and reduce the yield 
of hay. 
An additional reason exists for delaying planting on new lands. 
When first broken up and put under irrigation, these settle unevenly. 
They should therefore be irrigated at least one or two years sO' that 
these inequalities can be leveled off and settling effected by the use 
of irrigation water may be finished before the ground is planted to 
alfalfa. Such practice will do away with the evils which often 
appear from gopher and other rodent holes before the alfalfa is put 
on the land. 
In San Luis Valley it is seldom advisable to use a nurse crop 
with alfalfa. Generally only two conditions occur where the use of 
a nurse crop is advisable, these being found upon the heavy abode 
and clay lands which tend to bake and crack at the surface. Here 
a nurse crop may break up the surface and enable the young plants 
to appear, which they might be unable to do otherwise. • In sandy 
lands which are subject to plowing, it is sometimes advisable to put 
in a nurse crop to hold the surface soil. Under practically all other 
conditions alfalfa will do better and can be more successfully started 
when planted by itself. 
Variety .—Both the costly experience of farmers who have 
made failures and the direct experiments bv the Experiment Sta¬ 
tion have shown that it is not advisable to plant the southern types 
of alfalfa in the Valley, and, in general, even common alfalfa is not 
adapted to the soil and climatic conditions which are found there. 
