432 ALFALFA FARMING IN AMERICA. 



The Weather. In the opinion of many alfalfa growers the 

 weather is a more important factor than the soil in determining 

 the production of a good crop of alfalfa seed. On a given soil 

 capable of growing alfalfa, the weather is the determining factor 

 in seed production, or it may be as truly said that the moisture 

 supply, in time and amount, largely determines the alfalfa seed 

 crop on any field. On this point a majority agree that the alfalfa 

 should have a moderate supply of water in the early part of the 

 season, and during the early growth of the seed crop just suffi- 

 cient moisture to produce a vigorous, healthy plant. To insure a 

 good crop of seed no heavy rains should fall after the alfalfa be- 

 gins to blossom until most of the bloom has fallen, and then the 

 weather should continue rather dry until the seed crop is har- 

 vested and threshed, or put into the stack. Wet weather in the 

 latter stage of its growth causes a continuation of blooming and 

 the starting of a second growth of alfalfa, which interferes with 

 an even and proper maturing of the seed. Also it has been ob- 

 served that the hot, dry weather, with a deficiency of moisture in 

 the soil during the seed-forming period, has resulted in light, 

 blasted seed and a low yield. It is said that under the conditions 

 observed alfalfa flowers fail to secrete nectar and are hence not 

 fertilized because not visited by bees and other insects. 



Other Factors. A rather thin stand of alfalfa with vigorous 

 plants of average growth favors the development of seed, while a 

 thick stand and a rank growth of plant are considered unfavor- 

 able conditions for seed production. The seed fields should be 

 comparatively free from weeds. By cultivating the alfalfa early 

 in the spring, or perhaps after the first or second hay crop is re- 

 moved, the weeds may be held in check and the soil kept in good 

 tilth, resulting in strong, well developed plants, capable of pro- 

 ducing large yields of sound, plump seed. 



Effect of Bees and Other Insect. Until recently it was gen- 

 erally understood that to fertilize alfalfa blossoms required that 

 pollen from a separate flower be brought in contact with the 

 pistil of another flower. This, it was explained, was doubtless 

 largely accomplished by insects, which transferred the pollen 

 from blossom to blossom while they sipped the nectar which each 

 flower secretes apparently for this very purpose of attracting in- 

 sects. It is probable that cross-fertilization is largely accom- 

 plished in this way, but, as shown by Roberts and Freeman of 

 this station, alfalfa blossoms may be self-fertilized. It is only 

 necessary that the "trigger mechanism" which controls the fer- 

 tilizing organs be sprung by the touch of an insect or other 

 means, possibly the shaking of the plant in a strong wind, when 



