1930] PracH CULTURE IN CALIFORNIA 
20 
An orchard should be plowed or disked to a depth of 6 to 9 inches. 
Plowing too deep near the trees may injure the roots. When feasible 
the direction of the plowing should be changed. Cultivation of some 
sort should follow plowing or disking. Irrigated ground should be 
stirred when it has sufficiently dried to work without packing. Culti- 
vation generally begins in March or April and is continued intermit- 
tently to keep down weeds until about September. Growers are find- 
ing, however, that the frequency of cultivation can be reduced with 
satisfactory results and lessened costs; by not cultivating, the expense 
of re-making the furrows is saved. Any growth during the fall and 
winter is plowed under the following March or April. The trees are 
irrigated with sufficient frequency to keep the soil moist. Tillage in 
the larger orchards is more cheaply done by use of a tractor. Many 
farms, however, require one or two horses in addition to the tractor to 
do odd jobs. 
Intercrops—Many peach growers plant intercrops in the young 
orchard as a source of income. The possible danger of this practice 
in the young orchard is that the trees may be neglected or injured by 
too intensive interplanting, resulting from severe competition between 
the trees and the intercrop for moisture and soil nutrients. Among 
erops commonly grown are: berries, grapes, beans, lettuce, cabbage, 
onions, peppers, squashes, tomatoes, rhubarb or potatoes. It appears 
that cotton may be a good intercrop in the upper San Joaquin Valley. 
It is not difficult to grow these crops, but there may be difficulty. in 
profitably marketing them. Furthermore, their care may conflict with 
the care of the peaches. Naturally, the crop should not injure the 
growth of the trees; should not interfere with the work of irrigating 
and cultivating the trees and of harvesting the peaches, and should 
not demand special ability in harvesting and marketing. Leguminous 
crops are to be preferred where they are profitable. Sufficient culti- 
vated ground should be left between the intercrop and the tree rows. 
The amount of space devoted to intercrops should be gradually 
reduced so that the trees will have the entire area when in bearing. 
Cover Crops.—The planting of some crop in the fall, to be turned 
ander early in the spring, while green, is being increasingly practiced. 
This is to be recommended, where there is sufficient rainfall or irriga- 
tion water available in the fall, since the annual plowing under of a 
cover crop improves the tilth and helps to maintain the soil nitrogen 
supply. 
Among the cover crops most often used there are three that lead: 
sour clover (Melilotus indica), common vetech (Vicia sativa), and 
Canada field peas (Pisum arvense). A good growth of weeds will