ae ae 
WINTER GREEN-MANURE CROPS. ns 
sections. At least 80 pounds of seed per acre should be used, and 
unless seeding conditions are very favorable more rather than less 
’ is recommended. 
During the past few winters the general crops of field peas and 
vetch throughout the orchard sections of California have shown 
that peas make a stronger individual plant growth than vetch, but 
do not make as heavy a yield of green manure. When sown during 
the latter part of September the peas have made a growth of from 
24 to 36 inches, while common vetch made from 15 to 18 inches. 
This is representative of the usual comparative stem growth of the 
two crops. In the citrus orchards of southern California peas should 
be turned under early in February. and in the northern part of the 
State during the latter part of February or the first of March. 
BUR CLOVER. 
There are a number of kinds of bur clover, of which only two 
are yet much grown in California, namely, the common or toothed 
bur clover (JJedicago hispida denticulata) and the spotted bur clover 
(Medicago arabica). The toothed bur clover is the one most com- 
monly seen, being thoroughly naturalized. but the spotted bur 
clover, though less abundant, grows equally well. It differs from 
common bur clover in having a brown spot on each leaflet and 
longer and softer spines on the burs. 
Bur clover makes a decumbent growth, the stems being rather 
small and quite succulent when young, but it withstands considerable 
trampling. The roots are shallow but numerous and usually have 
many nodules. The crop has been grown to quite an extent for green 
manure, but on account of its not making a good early-winter growth 
its use will always be limited. In orchards where bur clover has 
been once planted it will spring up for several years. This is due 
to the hard seeds that do not germinate the first year. In the citrus 
orchards of southern California bur clover is sown at the same time 
as vetch, which is during September and early October. To obtain 
the best results, seeding as early as possible in September is advised. 
Twenty pounds of seed (hulled) per acre should be used, care being 
taken to plant shallow, as deeply covered seed will not germinate 
but will hold over in the soil. The sowing of seed in the bur is not 
recommended, because the bur delays germination and occasions 
very uneven stands, to say nothing of the greater difficulty in sowing. 
However, there is no longer need of using seed in the bur, as clean 
seed can be secured in quantity from western seedsmen. 
For use in deciduous orchards bur clover is of considerable import- 
ance and if properly handled will serve a very useful purpose. At the 
present time it.is utilized only where it volunteers as a weed and 
can be turned under at the regular spring plowing of the orchard. 
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