Irrigated Agriculture in the San Luis Valley 17 
The best varieties to grow are the Baltic, Grimm, and Hardy Turk¬ 
estan, in the order given considering local preference or comparative 
value for the Valley conditions. Baltic alfalfa is, in a way, a se¬ 
lection from Grimm, but is somewhat better than the parent va¬ 
riety. Common alfalfa, the seed of which has been obtained from 
long established fields from which practically all of the non-hardy 
plants have been killed, can be grown to a considerable extent, but 
it is not advisable to use common alfalfa for seed if the hardy va¬ 
rieties can be obtained and their propogation effected. Such ‘‘nat¬ 
urally selected” common alfalfa will stand the winters very well, 
but it does not stand the soil water conditions nor the effects of late 
spring frosts, which are often accompanied with Black Stem Rot or 
Alfalfa Blight, as well as do the hardy types. 
Preparation of Seed Bed .—One of the first considerations in 
the preparation of a seed bed is to have the land properly leveled. 
After this feature has been taken care of, the immediate preparation 
will depend a great deal on previous cultivation. Relatively new 
lands should be deeply plowed, preferably in the fall, where alfalfa 
is to be planted the following spring. Sometimes in preparing a 
seed bed it is advisable to plow deeply and thoroly for a grain 
crop and then disk the stubble of the grain in the fall after the grain 
is removed and the following spring drill the alfalfa in on the land 
so prepared. This is especially advisable for sandy lands, and will 
do away almost entirely with any need for a nurse crop. Where 
land has been plowed it should be worked down thoroly by disk¬ 
ing and repeated harrowings until the sub-surface is well packed, 
with a granulated surface to conserve moisture and to prevent, as 
far as possible, the winds froiu blowing the soil. 
Sometimes there is sufficient spring moisture in the soil to ger¬ 
minate the seed and start the crop off. In such cases planting may 
be done at once. Where the soil holds insufficient moisture, as is 
often the case after dry winters, it may be necessary to irrigate for 
seeding. On heavy adobe or clay lands, or even heavy loam lands, 
it is advisable to thoroly level and prepare the land, irrigate, 
and then, just as soon as the surface can be worked, plant with a 
disk drill. If such a tool is not available, it is advisable to disk the 
surface and follow the disk with a harrow and alfalfa drill or 
seeder. 
In the case of sandy lands it is usually best to thoroly pre¬ 
pare the seed bed, seed the alfalfa and irrigate afterwards, because 
on sandy land there is no danger of the formation of a crust and 
sand is not retentive enough of moisture to hold moisture in contact 
with the seed any great length of time consequently the seed should 
