﻿8 BULLETIN 4, U. S. DEPARTMENT OP AGRICULTURE. 



respectively, gave partly or wholly satisfactory returns. In the case 

 of alfilaria. 28.57 per cent of the experiments gave good results. The 

 alfilaria, however, requires a high temperature during the growing 

 season and therefore it can not be successfully introduced except in 

 the lower elevations. In southern California, where this plant flour- 

 ishes, it fails to produce much herbage above an altitude of 6,000 feet. 

 In the Northwest it should not be sown above 3,000 feet elevation. 



While the locations at which the best results from reseeding have 

 been obtained are not shown in Table 4, it may be stated, allowing 

 for local variations, that the best returns were secured in the North- 

 west and the poorest in the more arid Southwest. No species yet 

 tried can be economically introduced in the hot, dry foothills of Cali- 

 fornia, Arizona, and New Mexico, where the lands are distinctly arid. 



SPRING VERSUS AUTUMN SEEDING. 



The most convenient way in which to note the time at which seed- 

 ing has yielded the best results is by means of curves showing the 

 percentages of successful and partially successful experiments and 

 of failures during the spring, summer, autumn, and winter periods, 

 classifying the months as follows : Spring — March, April, and May ; 

 summer — June, July, and August ; autumn — September, October, and 

 November; and winter — December, January, and February. 



Plate II shows emphatically that autumn is the most satisfactory 

 time to sow, the spring period coming second; the summer and 

 winter periods are the most unsatisfactory. By months, October 

 and May, in the order named, proved the most satisfactory. The 

 reason why fall seeding, and especially the month of October, yields 

 the best results, aside from the more elaborate root development pro- 

 duced, is doubtless primarily the fact that all plant activities have 

 ceased at that time, and thus a weak autumnal growth and subsequent 

 winter killing is avoided. Then, too, during the dormant period the 

 seeds are worked into the ground by physical agencies, and when 

 conditions for germination become favorable the seeds are not only 

 well planted but the seed coats are softened and germination takes 

 place promptly and simultaneously. 



CAUSES OF FAILURE. 



The causes of failure in the unsuccessful experiments are numer- 

 ous. Often several factors are operative in bringing about unsatis- 

 factory results, and it is sometimes difficult to determine which is 

 the most potent. 



The six chief causes of failure, in the order of importance, are as 

 follows: 



1. Lack of soil treatment. 



2. Drought. 



