22 . FARMERS BULLETIN 836. 



excess required by them for seed production. In this event many 

 of the seed pods will abort and fall when partly mature. Pods 

 abort and fall in a very short tune, so that partly shriveled ones 

 seldom are found on the plants, although the extent of the aborting 

 is shown by the number of barren racemes. When such weather 

 conditions prevail, the second crop usually will produce a heavier 

 yield than the first crop. This is due for the most part to the inability 

 of the large plants to obtain sufficient water for seed production. 

 The much smaller plants of the second crop do not require as much 

 moisture as the larger plants of the first crop, as the vegetative growth 

 is seldom more than half as much. 



The type of root growth has much to do with the quantity of water 

 the plants are able to obtain during droughty weather. When 

 sweet clover is planted on soil that has a tendency to be wet, the 

 plants will produce a much-branched shallow root system instead of 

 the normal deep roots which are found on well-drained soils. During 

 dry weather the upper layers of soil become so depleted that plants 

 having a very large percentage of their roots in these layers can not 

 obtain a sufficient quantity jof moisture to supply their requirements 

 for seed production. 



It is often stated that the first crop of sweet clover will produce 

 more seed to the acre than the second crop. This depends very 

 largely upon the thickness of the stand and on weather conditions. 

 In regions where two crops may be grown in a season, the first usually 

 will produce more seed to the acre than the second if the field has a 

 thin stand. When the stand is thick the second crop ordinarily 

 yields more seed. In regions where a crop of hay or pasturage may 

 be obtained in addition to the seed crop, it is seldom an economical 

 procedure to permit the first crop to mature. Not only will sweet 

 clover produce an abundance of nutritious pasturage or a cutting of 

 1 to 3 tons of hay in addition to the seed, but the difficulty of handling 

 the large, stemmy growth of the first crop for seed is avoided. 



Yields of sweet-clover seed have been reduced during the last two 

 seasons by several fungous diseases. Experimental work has not 

 been completed to show the percentage of damage done by these 

 organisms, but in some sections of the country seed yields were 

 reduced considerably. The clover stem borer/ which is prevalent in 

 red clover in certain sections of the country, also infests sweet clover. 

 It is probable that this insect did some damage to the seed crop in 

 certain sections of the country in 1916. 



The yield of sweet-clover seed varies from 2 to 10 bushels of re- 

 cleaned seed per acre. 



1 Languria mozardi. 



