Irrigated Agriculture in the San Luis VaueEy 13 
lambs are fed yearly and if the feeding industry were properly de¬ 
veloped the number of sheep, cattle and hogs now sent out of the 
Valley could be very largely increased. This could probably be ac¬ 
complished by increasing the amount of stock on the smaller land 
holdings, rather than by increasing the large herds already in the 
valley. No one kind of stock holds aii}^ particular advantage over 
the others, altho cattle, sheep and hogs will constitute the chief 
market for feed crops produced. 
Even in sections where livestock feeding is undertaken on a 
large scale it will be necessary to practice some sort of rotation by 
which green manure crops may assist in building up soil fertility. 
The best of management cannot keep the soil in high productivity 
by reliance solely upon the animal manures available for fertilizing 
purposes, since the supply of these is, in any circumstances, limited. 
Crops capable of cultivation are necessary because of the prev¬ 
alence of weeds and occasional plant pests and cultivation must be 
clean to keep down undesired vegetation, simply as a protection of 
the moisture supply. Incidentally, such cultivation prevents the for¬ 
mation of a surface crust and the moisture losses and poor physical 
conditions which result from such formation. 
ROTATION. 
In starting a rotation it must be kept in mind that perennial 
crops, such as alfalfa, should be seeded only on well-leveled land, 
consecjuently, in starting a rotation on new land or on old land 
which is improperly leveled, annuals should be used at first, thus 
permitting time being spent for proper leveling of the land for irri¬ 
gation. Peas is one of the best crops available for the first planting 
on new land or to start a rotation on old land, is an excellent feed 
crop, and is also an annual. Alfalfa should never be seeded until 
the land is well leveled, because poor levelling results in irregular 
stands and bad conditions for watering—some parts will be killed out 
because of excess water, and others will do poorly because of a lack 
of water. Since alfalfa is a perennial and will probably occupy the 
land for several years it should be put in with that expectation. A 
ro-tation may then be practiced on the portion of the farm not in 
alfalfa, while the latter may stand until its yield commences to 
weaken. In other words, alfalfa should form part O'f a long rota¬ 
tion, while the rotation of peas, grain and cultivated crops should 
be shorter. In the shorter rotation, peas 01* pea-grain mixtures 
should be the first crop on the land. Potatoes, if grown at all,' 
should follow peas or alfalfa. Where peas is grown some trouble 
is experienced with weeds, especially if the crop is grazed. Har¬ 
vesting the peas takes the weeds ofY before seeding, permits early 
