WINTER GREEN-MANURE CROPS. 17 



In February, 1908, at Redlaiids, Cal., which is representative of the 

 citrus sections, phmtings of vetch made in September, 1907, were from 

 12 to 15 inches high and in a fine condition to turn under. Plantings 

 made in October, 1907, from a month to six weeks Later, were but 

 6 inches higii. During the past season similar results were noted. 



The rate of seeding varies from 40 to 60 pounds per acre. Forty 

 pounds per acre has been more generally recommended, but the 

 heavier seeding is giving much better crops and more than makes up 

 for the difference in the cost of the seed. 



Early as well as heavy seeding is quite commonly recognized by 

 growers as necessary for obtaining the best results, and a deeper 

 seeding has also been found essential where the plantings are early. 

 In northern California under irrigation, vetches sliould be sown about 

 the first of October. They will then make sufficient growth to be 

 turned under in February or March. This later season of planting 

 in the northern part of the State is desirable in both citrus and 

 deciduous orchards on account of the heavy winter rainfall, which 

 does not permit turning under the crop as early as in the southern 

 section. Later planting in the deciduous-orchard sections is also 

 desirable on account of the possible injury from frosts when an early 

 succulent growth is made, as would be the case with earlier plantings. 



Experiments and observations have shown that vetch will make 

 but little growth by February or March when sown in the fall without 



irrigation. 



CANADA FIELD PEAS. 



The field pea was among the first crops tried in California for green 

 manuring and was the first one extensively used for this purpose. 

 Its early use was partly due to the fact that seed was readily obtain- 

 able. At the present time it still holds a prominent place as a green- 

 manure crop, and next to common vetch is most extensively used 

 (see fig. 4). 



Like the common vetch the field pea is adapted to varied conditions 

 and has succeeded wherever green-manure crops have been grown. 

 For making a growth during cool weather there is no other crop 

 known that equals it; but it has other characteristics that make 

 it less desirable for green manuring, especially in citrus orchards. 



The root s\^stem of the field pea, which is very extensive, consists 

 of a central or main taproot from which radiate the many finer 

 laterals. The roots extend (juite deep, and for this reason the crop is 

 favored by many orchardists for breaking up "plow sole." 



The vines, which are succulent and tender, are greatly damaged by 



the trampling necessitated during the harvesting of most citrus fruits; 



and on account of their making so much new growth during cold 



weather they are often severely injured by frost. Usually as the 



52810°— Bull. 190—10 3 



