52, ORCHARD GREEN-MANURE CROPS IN CALIFORNIA. 
TANGIER PEA. 
The Tangier pea (Lathyrus tingitanus) was originally introduced into 
this country from northern Africa. It is an annual legume resembling 
in general the garden sweet pea, to which it is related. 
During the past few years considerable attention has been given to 
the Tangier pea to determine its value as a green-manure crop, and 
results thus far indicate that it 1s of considerable value for this pur- 
pose. It makes a strong growth, yielding a heavier tonnage per acre 
than the common vetch (see Tables I, IJ, and III). Its dense growth 
enables it to overrun and smother out weeds, which is one of the very 
noticeable qualities of this crop. Though the stems are quite large 
they are not very succulent and stand considerable rough usage, 
being well adapted for orchard use in this respect. The large growth 
made by Tangier peas makes them somewhat difficult to turn under 
with an ordinary moldboard plow; with a disk plow but little trouble 
in this respect will be experienced. 
The root system is well developed. It has a more nearly definite 
central root than vetch, and the roots penetrate the soil more deeply. 
The nodules are large and numerous, indicating that the plant is a 
good nitrogen gatherer. 
For a green-manure crop Tangier peas should be handled like com- 
mon vetch, except that the seeding should be heavier, from 70 to 75 
pounds of seed per acre being required for obtaining the best results. 
COST OF SEED OF GREEN-MANURE CROPS. 
The cost of seed of green-manure crops is a factor of considerable 
importance in determining their relative value. The high price of 
seed may be the cause of the elimination from use of an otherwise 
good crop. In most orchard sections it is hardly practicable for the 
orchardist to attempt to raise his own seed, though with crops having 
good seeding habits this could be readily done. The commercial seed 
grower will very likely be depended upon for the supply of seed needed. 
The price that growers will pay for any new crop will probably be 
largely determined by the price of seed of common vetch and of field 
peas. A slightly higher price for a superior crop would undoubtedly 
be paid. However, a superior crop and cheap seed are what is 
desired. 
The practice of allowing enough seed to ripen in the orchard to 
volunteer a crop from year to year is the cheapest method of seeding 
a green-manure crop, but this is practicable only in deciduous orchards 
without irrigation, where the returns will justify but very little 
expense in connection with such a crop. Under such conditions bur 
clover in particular can be effectively used. 
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