32 OECHARD GKEEN-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 is 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, II, 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 difiicult 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 

 plover in particular can be effectively used. 



190 



